Cocos-Keeling Islands Geomagnetic Observatory Visit August...

Geomagnetism Note 2011-16

Cocos-Keeling Islands Geomagnetic Observatory Visit August 2011

CKI Geomagnetic Observatory Left to Right:Vector Variometer, Scalar Variometer, Solar Power System, Radio Mast, Absolute Pier AO

Peter Crosthwaite1 and Dave Pownall2

Geospatial & Earth Monitoring Division – Earth Monitoring Group 1 – Geomagnetism, 2 – Geophysical Networks

16/12/2011______________________________________________________________________________________________________ Geomagnetism Note 2011-16 Cocos-Keeling Island Geomagnetic Observatory Visit August 2011 1


Geoscience Australia Chief Executive Officer: Chris Pigram Department of Resources, Energy and Tourism Minister for Resources and Energy: The Hon. Martin Ferguson, MP © Commonwealth of Australia 2011 This work is copyright. Apart from any fair dealings for the purposes of study, research, criticism or review, as permitted under the Copyright Act, no part may be reproduced by any process without written permission. Inquiries should be directed to the Communications Unit, Geoscience Australia, GPO Box 378, Canberra City, ACT, 2601 Bibliographic reference: Crosthwaite, P. and D. Pownall, 2011, Cocos-Keeling Island Geomagnetic Observatory Visit August 2011 Geomagnetism Note 2011-16 Geoscience Australia has tried to make the information in this product as accurate as possible. However, it does not guarantee that the information is totally accurate or complete. Therefore, you should not rely solely on this information when making a commercial decision.


Table of Contents Table of Contents................................................................................................................................................................ 4 Figures ................................................................................................................................................................................ 5 Introduction ........................................................................................................................................................................ 6 Absolute Pier ...................................................................................................................................................................... 8 Position ............................................................................................................................................................................. 10 Azimuth Reference ........................................................................................................................................................... 11 Field variability................................................................................................................................................................. 11 Training ............................................................................................................................................................................ 12 Site Plan............................................................................................................................................................................ 12

As-constructed Site Layout........................................................................................................................................... 14 Solar Power System, Green Box, Communications and conduits .................................................................................... 15

State of health ............................................................................................................................................................... 17 Radio modem connection to BoM................................................................................................................................ 18 Magnetic effects of Solar Power System on the variometer ......................................................................................... 19

Solar Power Supply System...................................................................................................................................... 19 Background to CKI Solar Power Supply System ..................................................................................................... 20 Modelling of the magnetic effect of the charging currents ....................................................................................... 21

Vector variometer enclosure............................................................................................................................................. 22 DTU vector variometer installation .................................................................................................................................. 23 Scalar variometer enclosure.............................................................................................................................................. 25 GEM Systems scalar variometer installation.................................................................................................................... 25 Data Acquisition System .................................................................................................................................................. 28 Magnetic and State of Health data.................................................................................................................................... 28 Carrying absolute equipment to Pier AO.......................................................................................................................... 32 Threats to the Observatory................................................................................................................................................ 33

Relocation of Bureau of Meteorology .......................................................................................................................... 33 Cyclones ....................................................................................................................................................................... 33 Salt and humidity.......................................................................................................................................................... 33 Flora and Fauna ............................................................................................................................................................ 33 Vehicles ........................................................................................................................................................................ 33 Golf............................................................................................................................................................................... 33

Water intrusion into variometer........................................................................................................................................ 34 Technical Facilities on Cocos........................................................................................................................................... 34 Accommodation and Transport ........................................................................................................................................ 34 Inventory........................................................................................................................................................................... 35 Recommendations ............................................................................................................................................................ 35 Acknowledgements .......................................................................................................................................................... 35 References ........................................................................................................................................................................ 36 Appendices ....................................................................................................................................................................... 37

Freight........................................................................................................................................................................... 37 DTU Package............................................................................................................................................................ 37 DI Flux Package ....................................................................................................................................................... 37 Cardboard box 270x250x240mm 9kg ...................................................................................................................... 38 GSM90 Package ....................................................................................................................................................... 38 GSM90 silver Box unlabelled 10kg.......................................................................................................................... 38 CTBTO Infrasound shipping container / Geomagnetic Observatory equipment...................................................... 38 GSM90 Package (replacement electronics) .............................................................................................................. 39

Contacts ........................................................................................................................................................................ 39 Interested parties........................................................................................................................................................... 39 Funding and Support..................................................................................................................................................... 40 November 2011 Service ............................................................................................................................................... 40 Australian Geomagnetic Reference Field Computation ............................................................................................... 40 Cocos-Keeling Islands Climate .................................................................................................................................... 41

Packing List ...................................................................................................................................................................... 43 Log Pages ..................................................................................................................................................................... 44


Figures Figure 1 World map of proximity to existing magnetic observatories – Andy Jackson ..................................................... 6 Figure 2 Chosen location for the CKI observatory – Andy Jackson, Jakub Velímský ....................................................... 6 Figure 3 Absolute Pier AO. Left as used. Right with wind shield and weather protection cover installed ........................ 8 Figure 4 Absolute Pier and cover construction................................................................................................................. 10 Figure 5 Azimuth Mark “Windsock”................................................................................................................................ 11 Figure 6 “Agreed” variometer enclosure layout concept.................................................................................................. 13 Figure 7 “Constructed” F-sensor enclosure foreground, vector-sensor enclosure right. .................................................. 14 Figure 8 Layout of CKI – not to scale .............................................................................................................................. 15 Figure 9 Extra trenching, solar panels, Green Box, and radio mast.................................................................................. 17 Figure 10 Geomag Inverted antenna, GPS rack, BoM network equipment...................................................................... 19 Figure 11 Vector variometer enclosure............................................................................................................................. 22 Figure 12 Vector Variometer Installation ......................................................................................................................... 24 Figure 13 Installed GSM90 variometer sensor ................................................................................................................. 25 Figure 14 Scalar Variometer Installation.......................................................................................................................... 26 Figure 15 Data Acquisition System in Green Box ............................................................................................................ 28 Figure 16 Difference between Vector F and Scalar F – 10 minute averages 2011/241 to 2011/338................................ 30 Figure 17 Vector magnetic channels (~30counts/nT) – 10 minute averages 2011/241 to 2011/338 ................................ 30 Figure 18 Scalar F – 10 minute averages 2011/241 to 2011/338...................................................................................... 31 Figure 19 FGE Head and Electronics temperatures (0.01K/count) – 10 minute averages 2011/241 to 2011/338............ 31 Figure 20 SOH Vector enclosure and Green Box temperatures (unscaled) – 10m averages 2011/241 to 2011/338........ 32 Figure 21 SOH Current (unscaled) and Voltage (Volts) – 10m averages 2011/241 to 2011/338..................................... 32

Introduction In 2008, Professor Andrew Jackson (Swiss Federal Institute of Technology, ETH) contacted Geoscience Australia in regards to establishing a magnetic observatory at Cocos-Keeling Islands. ETH was interested in it for ground support for the upcoming European Space Agency’s Swarm magnetic satellite mission. In 2009 the Ionospheric Prediction Service (IPS) joined the planning process, having an interest in variometer data for space-weather monitoring. Geoscience Australia and its predecessors have made magnetic measurements at Cocos-Keeling Islands (West Island and Direction Island) since at least as far back as 1946; the most recent Repeat Station survey was in 1996. Dr C.E.Barton, former leader of the BMR/AGSO/GA Geomagnetism Project, requested Dr McElhinny to investigate a site for an observatory during the latter’s visit to Cocos in 1995, but no observatory was subsequently planned. An observatory on Cocos (south of the west of Sumatra) would fill in a data-hole in the east Indian Ocean – see Figure 1. The colour code in this figure is in kilometers. The closest observatory to CKI on this map is LRM, about 2140km away, placing CKI in orange area in the Indian Ocean.

Figure 1 World map of proximity to existing magnetic observatories – Andy Jackson

In 2009, Andy Jackson and Jakub Velímský visited Cocos and chose a site for the observatory following local magnetic surveys - see Figure 2.

Figure 2 Chosen location for the CKI observatory – Andy Jackson, Jakub Velímský



In October 2010, Mike Hyde of the Ionospheric Prediction Service constructed variometer enclosures in preparation for equipment installation. Also, after the October 2010 visit, an absolute pillar (built at Geoscience Australia, Symonston) was installed and surrounded by a slab and two walls on the side of the prevailing wind. This report describes a visit that was made to Cocos-Keeling Islands Geomagnetic Observatory between 19 and 29 August 2011 by Peter Crosthwaite and Dave Pownall of the Geoscience Australia (Geomagnetism and Geophysical Networks Projects). The purpose of the visit was to accomplish as many of the following as possible:

1. Repair absolute Pier A and install weather-cover to prevent further damage • accomplished

2. Determine the geographic location of absolute Pier A • accomplished; to be refined in a future visit using GPS

3. Determine an azimuth reference using sun shots and/or GPS • accomplished using sun shots; to be refined in a future visit using GPS

4. Determine field gradients in and about variometer and absolute sites • accomplished; to be expanded in a future visit

5. Train Bureau of Meteorology staff in Absolute Observations • only a basic introduction; requires much more training

6. Install a solar power system • accomplished

7. Install radio communications to Bureau of Meteorology • accomplished

8. Install a Danish Technical University (DTU FGE) vector variometer • accomplished; however the unit does not function properly

9. Install a Gem Systems (GSM90) scalar variometer • accomplished

10. Install a data acquisition system • accomplished

11. Ascertain what is needed to carry and weather-proof absolute instruments to Pier A • accomplished

12. Make calibration observations • accomplished; but very limited

13. Install secondary absolute station or determine status of any/all Repeat Stations A-E. • no repeat stations located on this occasion

Absolute Pier

. Figure 3 Absolute Pier AO. Left as used. Right with wind shield and weather protection cover installed

The naming of the pier AO was chosen as it is the primary observatory pier. This distinguishes it from Repeat Station A. Repeat Stations A, B, C, D, and E are nearby. The pier was constructed of fibre-glass with a marble top. Three V-grooved copper footpads locate magnetic instruments accurately on the pier. The pier is surrounded by a concrete apron. Pier AO top is 1.180m above the concrete. It is possible to use the DIM (Declination-Inclination Magnetometer) without the use of an angle telescope for the scale readings, although it is a little too low for comfortable observations, particularly for two of the DIM inclination readings (one of which is shown in Figure 3). It is my opinion that it is easier to endure the awkwardness of these two readings than the awkwardness of using the angle telescope. The concrete slab is 1.500m square. AO is in the centre. The two walls installed to protect the pier from prevailing winds are 2.220m tall. The SE wall is 2.580m long; the NE wall is 2.574m long; the diagonal is 3.520m. The walls reflect the afternoon sun and make the observing environment quite hot and uncomfortable, especially so as they do as intended and stop any breeze. They prevent any morning sun observations. There is no sun-protection after late morning for the observer or for the instruments. (Direct sunlight has an effect on a theodolite’s level and stability during observations.) The glue holding the copper footpads had failed during the several months of exposure to the elements since the pier’s installation until this visit. Indeed this was fortunately noticed several months before by Shane Nancarrow and Trevor Dalziell during an inspection. The footpads were removed, the marble scrubbed and the footpads were reattached using Loctite Grey Maxx -60-+200 RTV Silicone Gasket Maker. A heavy lid (made from marine-ply, wooden joiners, and glue only) 16/12/2011______________________________________________________________________________________________________

Geomagnetism Note 2011-16 Cocos-Keeling Island Geomagnetic Observatory Visit August 2011 8


was installed to provide some protection for the pier, and should be left on the pier between observations. See Figure 3. A security bar to protect accidentally dislodging the theodolite was installed – the threaded brass uprights were shortened slightly to prevent interference with the theodolite. A few more copper/brass nuts would make it easier and more effective to use. There were no cable restrainers installed to support the weight of DIM cables – two have since been sent for installation. The Geoscience Australia Geodesy GPS base station is visible to the right of the wind protection wall in Figure 3. It is just over 100m away, but the wall blocks its view from the pier. It would be a useful mark if a hole was made in the wall to make it visible. The Pier was examined before dispatch and the following notes were made then and comments added when it was discovered that the copper footpads had come loose at CKI after installation:

Examined pier in very nice bespoke transportation - nicely packed and all. Removed pier and determined that the 3 copper V-plates were not all the same. A sample Zeiss 020B theodolite tribrach fitted into only 1 of the V-plates properly. On the other 2 V-plates, the tribrach feet rested on the shoulder of the feet, and the points of the feet did not reach the bottom of the groove, and so had ~1mm of play in the positioning of the theodolite. (The play is equivalent to about 0.5 degrees, as distance between feet is ~100mm.) The copper V-plates were spares from previous installations. This raises the question "is this a problem elsewhere e.g. TND, GNG?" >>> The pier needs modification before being sent to Cocos Island <<< (and we should dispose any remaining improper V-plates!) Approx Dimensions

• Tube o 1800mm bottom to bottom of marble o diameter 248mm inside, 272mm outside, 11-12mm thick walls o two holes ~39mm diameter for stabilising rods

• Marble top o 320mm square with corners cut (i.e. quasi octagonal, sides 230mm and 60mm) o 46mm thick

Comments • 2010-06-21

Craig Wintle replaced the copper grooves and the Zeiss 020B tribrach fits well. The pier with cross bars for the concrete footings and instrument securing bar were boxed up for transport to CKI. A few new photos were taken today.

• 2011-04-18 Asked Craig to source alternate glue as copper grooves have come loose in weather. Need to build a cover for the pier to protect it from the weather.

• 2011-04-29 PGC built 18mm marine-ply cover for pier, ~square with 327mm x 329 mm (x205mm deep) inner dimensions. Hopefully it will fit over the pier. It has 50mm high x 36mm wide marine ply under the lid glued to the sides to keep the lid 50mm off the pier top to allow for the theodolite safety threaded keeper. There are two 8mm holes for dowels on each of two sides to be inserted as/if required to raise the lid from the pier top even more or to tilt the lid to shed water. The sides are about 205mm from the base of the lid. So they should extend down to 100mm below the bottom of the marble.

Figure 4 Absolute Pier and cover construction

Position The locations of the components of the observatory will be accurately measured by a relative GPS survey during a future visit to the observatory. The results of that survey will be far more accurate than any presented here. The location of the GA Geodesy GPS station is recorded as

S 12° 11’ 18.068” E 96° 50’ 02.274” Ellipsoid Ht -35.901m WGS84 S 12° 11’ 18.0591” E 96° 50’ 02.28175” Ellipsoid Ht -35.2782m ITRF2005

The GPS station had not been tied into the tide gauge at the time of this visit. However, Nick Dando estimated the height above mean sea level to be 2.7m. The height of Pier AO is probably about the same as the GPS antenna. The location of AO is 108m at about 340° (true), a location N 3.29” E -01.22” from the GPS. This indicates that the location of AO is

S 12° 11’ 14. 8” E 96° 50’ 01.1” AMSL Ht 2.7m WGS84 The location of the variometer Trimble clock was noted to be 12d11.2334S 96d50.0332E

S 12° 11’ 14.00” E 96° 50’ 01.99” WGS84 And the communications mast near the clock was 42m at about 65° from AO. The Green Box is close to the mast. This indicates that the location of AO is

S 12° 11’ 14.58” E 96° 50’ 00.73” WGS84


The two locations are in reasonable agreement, and for this report I will adopt the location of AO to be

S 12° 11’ 14. 8” E 96° 50’ 01.1” AMSL Ht 2.7m WGS84

Azimuth Reference

Figure 5 Azimuth Mark “Windsock”

The adopted location of AO was used to reduce 5 afternoon sun-shot observations made from AO on 2011-08-29 from 10:10 to 10:46 UTC to the chosen mark “Windsock”. The mark was the centre of the middle of the three bolts at the base of the windsock. No DUT1 corrections were made to these observations (the results would change little as the sun descended steeply). The calculated direction AO to Windsock was 256°15’17” ± 03” (256.2547°).

Field variability A preliminary F survey around the site was made on 2011-08-26 between 07:49 and 08:29. This was before the variometer was installed, and hence these data have had no variometer corrections applied.

AO 47715.49 Main observatory pier AOWL 47720.01 at corners of concrete around the pier AONL 47718.76 AOEL 47716.78 AOSL 47714.14 AO 47715.27 repeat for checking, Main observatory pier FOH 47715.44 On roof above observatory F pier VO 47713.45 Main variometer pier VOSEH 47712.76 roof external corners variometer, South East VONEH 47712.38 …, North East VONWH 47702.65 …, North West VOSWH 47709.22 …, South West



E3091316 VOH 47718.12 on roof, above VO VONWH 47701.32 repeat for checking VONEL 47712.42 floor internal corners variometer VOSEL 47714.54 VOSWL 47711.81 VONWL 47713.02

The DC power supply failed at this point in the measurements. The absolute GSM90 was damaged soon after. No further measurements were possible. There is no indication of high gradients anywhere. There is no indication of any difference of more than a few nT between the main pier AO, around AO at ground level, the vector and scalar variometer piers VO and FO (although only FOH slightly above FO was measured). The largest anomaly was on the NW corner of the roof of the vector variometer enclosure VONWH where there may be some magnetism in the brass rods or nuts.

Training Training was delayed until near the end of the visit when most of the observatory was installed and the repairs to the absolute pier had been made. Before the training, the switch on the battery box to power the absolute instruments had broken, and a quick attempt to repair it for normal use and for training resulted in damaging the absolutes GSM90 electronics E3091316 so that it had to be returned to GA for repair and was not available for training. The normal power supply had to be replaced by the battery and cables supplied with the DI fluxgate-theodolite. The situation was far from ideal and no doubt gave a non-professional impression. Trevor Menadue was shown the Geomagnetism Antarctic Observers Training Powerpoint presentation. He was given the Antarctic Observers training material, and additional notes that describe the differences between all other GA theodolites (Zeiss 020 in degrees and minutes, or Zeiss 010 in degrees, minutes and seconds) and the CKI theodolite supplied by ETH/Mingeo which is scaled in GRADs and hundredths of GRADs. The method of using the theodolite for measuring declination and inclination was demonstrated in the office. Trevor went through a single absolute observation on the pier AO – this was interrupted a few times by regular cloud observations and other routine meteorological duties. The GSM90 electronics has since been replaced at CKI, and the absolute battery box has been replaced. The absolute equipment should be satisfactory beginning October 2011. A few GSM90 observations and DI observations have been received since the visit described in this report; some were made by Trevor Menadue, and some by Will Tankard. The observations were promising, but showed some problems: probably some local magnetic contamination, and some confusion using the combination of supplied notes and the GRAD-graduated theodolite. Will Tankard arrived at Cocos Island (to replace Tom Chlebowski) after we departed and has received no training from GA staff – he did well to get results within a few minutes of the expected values. Trevor has mentioned there is a possibility he may not be on Cocos in 2012. Training is a high priority for the next visit, and the visit should be arranged for when Trevor and Will are available.

Site Plan The site plan of the observatory vector variometer enclosure, scalar variometer enclosure, solar power system/radio communications, absolute pier were discussed by email between ETH, IPS, and

GA. ETH was providing much of the funding, IPS had experience constructing variation stations, and GA had experience building observatories. The agreed plan Figure 6 was an interesting combination. One of the important considerations for GA was to house magnetic instruments in a very stable environment, particularly regarding temperature. GA had recently built the GNG observatory near Perth, Western Australia, and had much success creating a temperature stable environment, large enough to be self contained and house a dual vector variometer system, scalar variometer, and acquisition system (it has a mains supply power system with small DC backup). GNG was itself designed to match the excellent temperature stability of the GNA observatory (established 1957) which houses the variometers in a large buried concrete bunker, and the Canberra Magnetometer Calibration Facility which is a double concrete-block with foam insulation. Another important consideration for GA was to avoid contamination of the vector variometer data with scalar variometer polarisation currents, and contamination of the vector and scalar variometer data with magnetic effects of supply and charging currents through the batteries. Both of these problems have been issues at CTA and other observatories.

Figure 6 “Agreed” variometer enclosure layout concept

Figure 6 shows the agreed conceptual layout of the observatory. However the layout of enclosures, pad for the Green Box, and conduits actually built seems to have been based on a previous version of this conceptual diagram. The F-sensor enclosure was built on the same side of the vector-sensor enclosure as the slab for the Green Box, and 7m rather than 5m from the vector-enclosure. The door faced towards 120° rather than 180° (south) – this specification was elsewhere in emails and not on this diagram. The floors and roofs of the enclosures were built particularly level, rather than with a floor slope towards the door and a non-level roof, and the conduits were smaller than expected – again these specifications were elsewhere in emails and not on this diagram. The GA specifications for the Green Box pad and conduit entry location were not specific and the Green Box could not be mounted on the pad without extending the pad. The vector-sensor enclosure was constructed, as shown, with Hebel outer wall, foam cavity, but the inner wall was only partially built. 16/12/2011______________________________________________________________________________________________________


Figure 7 shows what was constructed in 2010 and 2011. The small F-sensor enclosure is in the foreground; the larger vector-sensor enclosure is at the right; the original Green Box pad is between the F-sensor enclosure and the installed Green Box (with solar panels) location. The radio mast is visible behind the Green Box (in the “lowered-for-maintenance” position). The Absolute Pier walls are in the centre distance behind the 3 coconut palms.

Figure 7 “Constructed” F-sensor enclosure foreground, vector-sensor enclosure right.

As-constructed Site Layout This layout (see Figure 8) is very rough and made using a hand compass and long tape measure. It is expected that a future visit will locate all of these components and Bureau of Meteorology buildings in absolute coordinates (using the Geoscience Australia Geodetic GPS reference) far more accurately.



Figure 8 Layout of CKI – not to scale

Solar Power System, Green Box, Communications and conduits The site prepared for the Green Box solar DC power supply system was judged to be too close to the site prepared for the scalar magnetometer. In any case it needed modification so that the Green Box could be mounted on it – as noted above the GA specifications were inadequate. We decided to shift the Green Box further from the variometer enclosures. In the end, this was a good decision and reduced several risk factors for the data. Fortuitously, the CTBTO team had several spare 4m lengths of UPVC Electrical AS2053 50mm and a 90° bend (600mm ¼ circumference) conduit, and this fitted the pre-installed conduit (even

Vector variometer sensor and vector/scalar electronics

Scalar variometer sensor

Original concrete pad for solar power system

Solar power system/Green Box

Radio communications mast to BoM

Absolute Pier AO

52m@25m

19m@345M

23m24.5m

20m

42m@65M

16.5m@5M

7.9m

6.7m

7.8m

4m

Small building 70m@310M

Geodetic GPS 108m@166M

Steel weather office sign 70m


though larger diameter conduits were requested). This defined the new location for the Green Box. In fact another length of conduit and bends were available for a connection from the Green Box to the mast for the radio-modem antenna. This involved quite a bit of shovel and crowbar work to prepare for the new Green Box concrete pad. The final conduit path was straight from the vector variometer enclosure to the original Green Box pad (8m), where the conduits were joined, and followed a curved path (12m further) to the new pad site. The Green Box sits on the pad, with 4 solar panels shading and sheltering the Green Box, supported by an aluminium poles east and west of the Green Box. There is then a conduit from the Green Box to the mast for the radio-modem antenna – about 4m or one conduit length. A length of copper earthing wire (and plastic “cable warning”) was buried above the conduits. Three 1.45m earth stakes (copper outer, steel core) were embedded beside the new conduit – one at the original pad, one at the new pad, and one in between. All earth stakes encountered wet hard ground. Each of the holes (~0.8m deep) for the solar panel poles and the hole (~0.9m deep) for the radio mast encountered this same layer of wet hard ground. Through miscalculation, the cable from the antenna to the radio modem had no slack whatsoever. The Green Box houses the 6 x 2V 600Ah batteries, solar battery charger system, fuse box, state-of-health monitors, data acquisition computer, GPS clock, and radio modem. It is sheltered and fed power from 4 x solar panels. See Trim D2010-217132 CKI Cocos Master Technical Manual. There is a mount point for the GPS clock on the west end of the solar panel support bar, but the GPS clock was left installed inside the Green Box where it appeared to have sufficient signal. The concrete was mixed with Novomesh Fibreglass Reinforcement (CE Industries, Fyshwick http://ceind.com.au/contact-us/act-canberra) a small electric concrete mixer taken especially for this job, powered by a portable 240V generator borrowed from the CTBTO group. The Green Box pad and poles for solar panels and mast consumed the entire 500kg of concrete taken for the job. The conduit from the Green Box to the vector-variometer enclosure contains

• two 12V power cables to the vector and scalar variometers • an RS484 data cable to the DTU vector variometer • an RS232 cable to the GSM90 scalar variometer • a State of Health temperature sensor cable

All power and data cable excess was withdrawn towards and stored in the Green Box to reduce data interference. The conduits at the Green Box are plugged with stainless steel wool to discourage animals entering.

http://ceind.com.au/contact-us/act-canberra

Figure 9 Extra trenching, solar panels, Green Box, and radio mast

State of health The Green Box is configured with State of Health monitors; these are connected to an ADAM A/D. The SOH information is recorded using the same programs that record magnetic data. (It should be possible to substitute the SOH A/D for the magnetometer A/D if the latter fails.) The SOH Adam D/A converter is wired as follows



Channel monitors MachR recording fieldChannel 0 Solar Current a Channel 1 System Current b Channel 2 Temperature h (variometer vault) Channel 3 Temperature/Ambient e (Green Box) Channel 4-6 spare Channel 7 Battery Voltage c

The data are recorded using the geomagnetism data recording program MachR as /soh/hyydddss.cks. The sampling is 1/minute for all channels.

Radio modem connection to BoM GA sent 3 Freewave radios to CKI to connect to the BoM network. One is set as gateway (the BoM end), and the other two (operational and spare, the Green Box end) as endpoints in point to point configuration. They use only the second group of 8 frequency zones (they do not use first 8 zones). AES encryption and IP addresses were set while at Cocos. The Windows programs Freewave Discovery and PingTest programs were useful during installation. IP addresses were allocated by the Bureau of Meteorology, and BoM and GA IT arranged for firewall rules to allow communication from Geomagnetism sun-geomag processing computer direct to ga-cki-mag1 data acquisition computer and to the two radio modems (through ssh, ftp, telnet, and for the radios http).

Advice from Alan Wong (BoM) • Magnetometer:

o cocos-mag.bom.gov.au 134.178.34.10 • Wireless Bridge:

o cocos-mag-br-a.bom.gov.au 134.178.34.203 BoM end o cocos-mag-br-b.bom.gov.au 134.178.34.204 Green Box end

• Subnet mask 255.255.255.0 • Gate is 134.178.34.250 with a mask of /24

The radio modems use AES encryption. The encryption key and admin-user/password for the radio modems may be required during visits to the observatory. Figure 10 shows the BoM end of the network connection. The Geomag antenna is mounted on the inverted support to keep it out of the way of many other antennae. The RF antenna cable passes through the asbestos wall using a pre-existing hole; the Freewave modem is located in the GA Geodesy rack; the UTP network cable follows other cables into the main BoM office and connects to the normal network (it is labelled as belonging to Geomagnetism or GA).

Figure 10 Geomag Inverted antenna, GPS rack, BoM network equipment

Magnetic effects of Solar Power System on the variometer The magnetic signature of the solar charging currents and system currents were not quantitatively taken into account in the design of the observatory. The location of the solar power system was altered at installation to be further from both the vector and scalar variometer locations. It was only during writing this report that it was investigated quantitatively whether this move was necessary, and indeed whether it was sufficient.

Solar Power Supply System The CKI solar power system and the communication equipment is constructed with mostly non-magnetic materials: glass-fibre reinforced concrete, fibreglass enclosure, aluminium poles and masts (galvanised steel has a short lifespan in the maritime environment), PVC conduits. Naturally some of the electronics is magnetic. There are four CNPV 185W Monocrystaline solar panels connected in series parallel configuration. Where possible the positive and negative power leads from the panels were twisted together, but the effects of the currents through the panels and some of 16/12/2011______________________________________________________________________________________________________



the wiring cannot be removed. The orientations of the four panels were chosen for convenience and there was no planning to minimise the magnetic effects with the most suitable combination of panel orientations. There are six batteries in the system (A600 Solar A602/600 2V 600Ah C100 Sonnenschein made by Exide Technologies GmbH Part Number NGS6020600HSOFA), each measured as 0.16mx0.16mx0.46m – although this is not consistent with the specifications: http://www.shop.solar-wind.co.uk/acatalog/SB_Dryfit_A600_Solar_Battery_Brochure.pdfType Part Number V Ah I100 l b/w h1 h2 l kg terminal poles 7 OPzV 600 NGS6020600HSOFA 2 600 6.0 168 208 475 513 175 42.0 F-M8 1pair The orientation of the batteries was constrained by the connectors for joining them and there was no planning to minimise the magnetic effects of the currents through the batteries. Although the current required to run the magnetic observatory equipment (variometers, state-of-health monitors, computers, and communications) is about 2A at 12V, the charging currents through the batteries at peak charge may be 20A or more. The current supplied by the solar cells is generally much less than this as it is at a higher voltage (up to 80V). The solar panels were oriented by compass to be about true north, and by guess to be 15° from horizontal (angled towards north). 15° is the minimum slope recommended so that the panels stay clean. Bird-deterrent spikes were placed on the high/southern edge. I calculate that the optimum angle for the panels is 20° tilted towards the north – optimising the most energy supplied on the least favourable day during the year. (This calculation assumes: the sun is visible from horizon to horizon; there is no regular daily or seasonal atmospheric conditions/cloud cover; there is no panel efficiency dependence on temperature or angle of incidence; there is no refraction of sunlight; ….See Geomagnetism Note 2011-21.) At 15°, there is about 17% variation in daily energy availability during the year. The minimum energy available daily occurs about the winter solstice, a secondary minimum about the summer solstice, and maxima around the equinoxes. I calculate changing the tilt to 20° would make a 4% improvement to the worst day performance, and reduce the variation in daily energy availability during the year to 12% by evening out the summer and winter minima.

Background to CKI Solar Power Supply System The Geophysical Network Group provides communication and electronic support for geomagnetism, seismology, geodesy, nuclear monitoring, and tsunami warning, and volcanology groups. It is in the interest of all of their clients to standardise systems where possible. The solar system for Cocos–Keeling Islands Geomagnetic Observatory CKI was based on similar systems already in use elsewhere. A related power system was installed at Charters Towers Geomagnetic Observatory (CTA) prior to the installation at CKI, although it was based on a mains supply it used similar batteries – it supplied power for seismic systems as well as the magnetic observatory. The CTA magnetic data was found to contain signatures of elevated charging currents following periodic battery monitoring of the power supply system. The CTA variometers had to be moved further from the power supply system. It was expected that this could be a problem at CKI – tests before equipment was sent from Geosciences Australia in the test enclosure at Symonston were inconclusive as the environment was too magnetically noisy. Installing the entire system at a quieter site was not feasible in the time available.

http://www.shop.solar-wind.co.uk/acatalog/SB_Dryfit_A600_Solar_Battery_Brochure.pdf


The CKI scalar and vector variometer enclosures, and the concrete pads for the solar system were not located as expected, and there was particular concern, unsupported by quantitative modelling or experiment, that the solar power system could corrupt the scalar variometer data. Consequently, the solar power system was moved from the original site to at least twice as far from both the scalar and vector variometers (from 7m/10m to 16m/20m).

Modelling of the magnetic effect of the charging currents The most significant currents are expected to be the charging currents through the batteries – these low voltage currents can be quite high – 20A or more – and clearly cannot be twisted. The details of the modelling of these currents are presented in Geomagnetism Note 2011-18. The effects of the Green Box battery currents at the vector variometer at a distance of 12m (the initial location was about 10m) are modelled to be about 200pT for a 20A charging current; the scalar variometer at 8m distant could be affected by up to 600pT, although at its particular azimuth, it may have been located near a nodal direction and had a fortuitously smaller magnitude. The effects of the Green Box battery currents at the installed location: at the vector variometer at 20m distance are modelled to be about 40pT for a 20A charging current; at the scalar variometer at 16m distant could be affected by up to 70pT, although again at its particular azimuth, it may be located near a nodal direction and have a fortuitously smaller magnitude. This modelling supports the decision to shift the solar system, but the added distance is apparently inadequate for a high quality INTERMAGNET 1-second observatory (which requires <10pT noise) using the installed battery configuration, although at its installed location the modelled noise is only a little larger than the resolution of the installed vector magnetometer (~30pT)..

An ad-hoc test of the effect of the solar system was made 2011-08-28 by switching the solar charging OFF at 09:53:12 and ON at 09:53:40 (timing not completely accurate). The magnitude

of the solar charging currents was not measured. There was no noticeable effect on either the vector or scalar variometer data.

If required, the interference could be reduced by reducing the maximum charge current to the batteries, or by reconfiguring the layout and wiring of the batteries as described in Geomagnetism Note 2011-18. Although the F variometer enclosure was located incorrectly and was too close to the prepared Green Box site, it appears that the prepared Green Box site was too close to the vector variometer in any case – an error of Geoscience Australia, partially due to the lack of familiarity with the magnitude of the charging currents in such systems. The F variometer location error prompted moving of the Green Box; this would not have been done otherwise and so it all worked out for the better.

Vector variometer enclosure

Figure 11 Vector variometer enclosure

The vector variometer sensor enclosure was constructed of an outer layer of 200mm Hebel blocks, a foam-filled cavity, an incomplete inner layer of 100mm Hebel blocks, with foam lid held down with Silastic, and eight brass nuts on threaded rods. Access is by unscrewing the door. When opened to install the variometer, the enclosure had a pool of clear water to the level of the door frame – a few centimetres. Figure 11 shows a notch cut in the door frame at the lower left to let water escape. This notch was left partially open (the cut-out wooden block was replaced but sitting on a layer of brass screws to let water from inside out, and to keep largish creatures out).



Both the floor and roof are quite level – water sits on the roof and has bubbled the paint. Water marks inside indicate water is leaking through the roof. The instrument pier is 0.400mx0.400m and 0.100m above floor level, topped with 4 red tiles. There is a clearance of 0.200m behind the pier, 0.330m either side, and 0.900m to roof. The long sides are aligned 295° magnetic, and the short sides (including the door) at 25° magnetic. The door clearance is 0.460m wide x 0.650m high (0.800m diagonal). The floor to roof height is 1.000m, but there are wooden beams supporting the roof in places. The external dimensions of the enclosure are:

• south 2.984m, west 1.839m, north 2.956m, east 1.836m • southwest-northeast diagonal 3.508m, southeast-northwest diagonal 3.475m • roof foam 0.120m thick, distance bottom of roof to top of door 0.280m

The Green Box is 20m from SW corner of this enclosure; the mast is 24.5m. The Green Box is 19m at 165° magnetic from SE corner; the mast is 23m in that direction. Should the brass rods be used to hold down any further roof structure, from the SW corner anticlockwise, the brass rods have 11, 14, 12, 14, 14, 10, 7 and 8 threads left above the brass nuts. The distances from the western wall to the rods along the

• southern wall are 0.100m, 0.615m, 1.815m, 2.885m (eastern wall is at 2.980m) • northern wall are 0.100m, 0.600m, 1.785m, 2.885m (eastern wall is at 2.960m)

The distances from the western rod were remeasured with slightly different results • southern wall are 0.000m, 0.520m, 1.720m, 2.785m • northern wall are 0.000m, 0.505m, 1.690m, 2.760m

The NS distances apart of pairs of rods from western pair were 1.640m, 1.635m, 1.630m, 1.650m. The SW-NE diagonal was 3.240m, and the NW-SE diagonal was 3.200m. The DTU FGE vector-variometer sensor is further insulated by a particle-board box with foam lining. The box is constructed so that the top, bottom, and front are screwed on and can be removed; the sides and back are glued. The box did not fit through the small door – the three glued sides were cut in two horizontally so that each part could be manoeuvred through the door, and the top and front could fit through the door diagonally. The bottom is not required for insulation. The box was reassembled inside the enclosure; the four foam side walls and top (none of which had to be cut) held each other up inside the box. The box was mounted on a layer of foam to stop it deteriorating in accumulating water. Note that the top half of the cut box could fall off when the un-cut front is removed and disturb the sensor. The front did not fit on easily probably because the top half was lowered by a saw-cut and the screw holes no longer aligned. A saw-cut spacer between the two halves would be useful. The box was built according to the equivalent item at GNG observatory and is likely to have dimensions 0.765m high, 0.680m/side.)

DTU vector variometer installation The Danish Technical University FGE suspended fluxgate magnetometer E0431/S0353 (purchased by ETH) was sent to Cocos by Toll air-freight on 2011-07-19 after many calibrations at the Canberra Magnetometer Calibrations Facility.

2010-06-22 Received from Danish Technical University/National Space Institute FGE suspended fluxgate magnetometer

• FGE E0431 o FGE-K2 118.0kOhm ~320nT/V 10.0mV/K

• FGM S0353 o X 37453 nT/mA o Y 37586 nT/mA o Z 37720 nT/mA

• with IPC CON 7017 A/D RS485 N81 1200 - 115200 bps and 7520AR 485/232 converter The CKI IGRF field was simulated in the calibration coils and the switches set for that field to X/Y/Z Coarse/Fine: A7 A7 DF, X and Z offsets switches OFF, before despatch. This aligns the sensor with the “X” channel magnetic north-west, “Y” channel magnetic north-east, “Z” channel vertical. The actual values used at installation were X:A6 Y:A6 Z:E0 (each 1 fine division of offset). A DI-fluxgate theodolite measurement 2011-08-30T02:40 shortly installation was used to estimate the actual alignment of the variometer. The D and I measurements, variometer data, and difference from the nominal variometer model were:

D=-2.5521°: 0 619.944 0 -83.1301 0 1116.59 47730.2 30019 30465 # Ed=-7.48'(0.02) I=-43.8362°: 0 684.131 0 -122.233 0 1128.22 47730.9 30019 30465 # Ei=-16.62'(0.02)

Figure 12 Vector Variometer Installation


Scalar variometer enclosure

Figure 13 Installed GSM90 variometer sensor

The scalar variometer sensor enclosure was constructed of a single layer of Hebel blocks with foam lid held down with Silastic, and brass nuts on threaded rods in each corner. Access is by removing the roof. When opened to install the sensor, the enclosure was dry. The distance from the vector-sensor enclosure to the F-sensor enclosure was further than expected (7m rather than 5m). The external dimensions of the enclosure are:

• south 0.746m, west 0.746m, north 0.746m, east 0.746m • southwest-northeast diagonal 1.050m, southeast-northwest diagonal 1.050m

The Green Box is 16.5m at 185° magnetic from this enclosure.

GEM Systems scalar variometer installation The GEM Systems GSM90 Overhausser magnetometer GSM90F1 0023526/03768 (purchased by ETH) was sent to Cocos by Toll air-freight on 2011-07-27 after calibrations at the Canberra. Of the following items received by GA:

2010-06-21 Received GSM90F1 0023526 + sensor 03768 • sensor cable • data/power cable • GPS cable – not installed at CKI


• GPS antenna – not installed at CKI • 4 pole segments + 1 pointy pole segment • USB-serial adaptor – not installed at CKI • GEMLinkW 4.0 CD • GSM-90 v7.0 Manual Release 7.4 July 2008

The GPS components were not installed. The electronics was installed in the vector variometer enclosure upside down on Hebel bricks right next to the conduit on the right of door so that the sensor cable reaches. The sensor was installed in the scalar variometer enclosure resting on Hebel blocks. The triaxial sensor cable with the long tail on the sensor together were only just long enough to connect the two through the conduit with no slack whatsoever – even so, the sensor tail had to be inserted as far as possible into the conduit.

Figure 14 Scalar Variometer Installation

Some preliminary tests reminded me of the numerous faults in the manuals (even latest version with this unit) and poor interface. It was initially 115200baud, set to 19200 baud. (N81) Here is an extract of a file capture of a conversation with the GSM90 unit (using a Zapper signal generator)

0-8-tune A-RF-on B-RF-off G-get-signal D-deflect M-memory R-rom i-info S-menu I-initialize-GPS |-test-GPS Gem Systems GSM-90F1 0023526 135 Spy Court Markham Ontario L3R 5H6 Canada tel 905-752-2202 fax 905-752-2205 www.gemsys.ca [email protected] v7.0 18 VIII 2009 M e90F1.v7s /Gem Systems GSM-90F1 0023526 v7.0 18 VIII 2009 M e90F1.v7s



?-menu &-defaults !-tests Cyymmddwhhmmss-set-time d-date(mm-dd-yyyy) t-time T-tuning F-field O-magnetic-observatory x-auto-tuning y-no-auto-tuning I-tuning-initialize 5-50Hz 6-60Hz 0-no-filter P-time-format Q-output-format [date hhmmss.s field] R-run cycle-time D-down U-up 0001.0s $-baud rate h-auto-cycle g-external-trigger q-mode[quiet] G-GPS 12.4V auto-tune no 050.0uT external-trigger 50Hz AC filter GPS no field 049999.66 99 1874 0880 4095 0-8-tune A-RF-on B-RF-off G-get-signal D-deflect M-memory R-rom i-info S-menu I-initialize-GPS |-test-GPS 4095 /Gem Systems GSM-90F1 0023526 v7.0 18 VIII 2009 M e90F1.v7 ?-menu &-defaults !-tests Cyymmddwhhmmss-set-time d-date(mm-dd-yyyy) t-time T-tuning F-field O-magnetic-observatory x-auto-tuning y-no-auto-tuning I-tuning-initialize 5-50Hz 6-60Hz 0-no-filter P-time-format Q-output-format [field] R-run cycle-time D-down U-up 0001.0s $-baud rate h-auto-cycle g-external-trigger q-mode[quiet] G-GPS 12.4V auto-tune no 050.0uT external-trigger 50Hz AC filter GPS no 1874zc 0880ms 4095 4095 04065 049999.66 99 1874 0880 4095 1874zc 0880ms 4095 4095 03000 GPS yes ! GPS WARNING ! GPS no GPS yes ! GPS WARNING ! GPS no 0-8-tune A-RF-on B-RF-off G-get-signal D-deflect M-memory R-rom i-info S-menu I-initialize-GPS |-test-GPS 4095 /Gem Systems GSM-90F1 0023526 v7.0 18 VIII 2009 M e90F1.v7s ?-menu &-defaults !-tests Cyymmddwhhmmss-set-time d-date(mm-dd-yyyy) t-time T-tuning F-field O-magnetic-observatory x-auto-tuning y-no-auto-tuning I-tuning-initialize 5-50Hz 6-60Hz 0-no-filter P-time-format Q-output-format [field] R-run cycle-time D-down U-up 0001.0s $-baud rate h-auto-cycle g-external-trigger q-mode[quiet] G-GPS 12.4V auto-tune no 050.0uT external-trigger 50Hz AC filter GPS no 1874zc 0880ms 4095 4095 04065 /Gem Systems GSM-90F1 0023526 v7.0 18 VIII 2009 M e90F1.v7s ?-menu &-defaults !-tests Cyymmddwhhmmss-set-time d-date(mm-dd-yyyy) t-time T-tuning F-field O-magnetic-observatory x-auto-tuning y-no-auto-tuning I-tuning-initialize 5-50Hz 6-60Hz 0-no-filter P-time-format Q-output-format [date hh:mm:ss field] R-run cycle-time D-down U-up 0005.0s $-baud rate h-auto-cycle g-external-trigger q-mode[quiet] G-GPS 12.4V auto-tune yes 050.0uT auto-cycle 50Hz AC filter GPS no field /Gem Systems GSM-90F1 0023526 v7.0 18 VIII 2009 M e90F1.v7s ?-menu &-defaults !-tests Cyymmddwhhmmss-set-time d-date(mm-dd-yyyy) t-time T-tuning F-field O-magnetic-observatory x-auto-tuning y-no-auto-tuning I-tuning-initialize 5-50Hz 6-60Hz 0-no-filter P-time-format Q-output-format [field] R-run cycle-time D-down U-up 0005.0s $-baud rate h-auto-cycle g-external-trigger q-mode[quiet] G-GPS 12.3V auto-tune no 050.0uT external-trigger 50Hz AC filter GPS no

049999.66 99 1874 0880 4095 049999.66 99 1874 0880 4095 1874zc 0880ms 4095 4095 03000 1874zc 0880ms 4095 4095 03000 024456.91 06 0002 0001 0651 0002zc 0001ms 0651 0494 11250 049999.66 99 1874 0880 4095 /Gem Systems GSM-90F1 0023526 v7.0 18 VIII 2009 M e90F1.v7s ?-menu &-defaults !-tests Cyymmddwhhmmss-set-time d-date(mm-dd-yyyy) t-time T-tuning F-field O-magnetic-observatory x-auto-tuning y-no-auto-tuning I-tuning-initialize 5-50Hz 6-60Hz 0-no-filter P-time-format Q-output-format [field] R-run cycle-time D-down U-up 0005.0s $-baud rate h-auto-cycle g-external-trigger q-mode[quiet] G-GPS 12.4V auto-tune no 050.0uT external-trigger 50Hz AC filter GPS no

Data Acquisition System A standard Geoscience Australia Geomagnetism QNX-based data acquisition system, using for the first time an Advantech ARK 3360F computer, was installed. Figure 15 shows the computer on a brick inside the Green Box (see below – water in Green Box). The Garmin 16HVS clock is at present installed at the top-left of the Green Box, the RS485/RS232 converter from the DTU magnetometer, Freewave radio, State Of Health are inside the box also, along with the Solar Power equipment and DC distribution box..

Figure 15 Data Acquisition System in Green Box

The computer was nearly drowned on its first night in the Green Box when rain-water entered: probably because the door was not tightly shut as cabling had not been completed. One corroded connector was cut off for safety, but otherwise the computer seemed to survive unharmed.

Magnetic and State of Health data


The vector and scalar variometers’ behaviour was not un-expected when they were installed. It is usual for vector baselines to change over a settling in period of a few days. In this case there was


not enough time for a long period of absolute calibrations to be performed to determine baseline stability. However the vector and scalar data from days following the installation showed poor consistency. The lack of consistency changed in nature, accelerated after about 40 days, and became highly erratic after about 70 days. Figure 16 shows a plot of the 10-minute average of FCheck – the difference between the vector-variometer derived F and the scalar variometer F. Figure 17 and Figure 18 show the magnetic channels from the vector and scalar variometers for this period. Note that there was a C range change on 2011-11-17 ~04:00 (just before the DTU electronics was swapped). This coincided with disturbance on A/X, B/Y, C/Z, and F channels, which appeared to be artificial magnetic disturbance such as site levelling or lawn mowing or something of that nature. The dominant problem occurs in the C (or Z) channel. Full resolution plots show that the C/Z channel is also noisier than the A/X and B/Y channels – this high C/Z noise started 2011-11-03. The horizontal channels are themselves not perfectly clean, but not nearly as bad as C/Z. There is no apparent problem in the scalar variometer, and a few absolute observations over this period indicate that the scalar variometer data has remained consistent. DTU supplied two new FGE electronics for testing failed magnetometers in mid November 2011. It happened that Trevor Dalziell was visiting Cocos a few days later for the CTBTO infrasound station installation a few days later. Hence there was a rushed opportunity to test the DTU electronics: FGE electronics E0462 was swapped in (E0431 was swapped out) on 2011-11-20 thanks to Trevor’s assistance. He also replaced the hard-wired power supply to both the vector and scalar variometers with plugs and sockets in the vector variometer enclosure. By coincidence, the C/Z channel had gone off scale the previous day 2011-11-19 and there were no C/Z data just prior to the electronics swap-over. The particular nature of the problem changed but was still far from satisfactory. It appears that the problem is connected with the FGE sensor S0353 – particularly the C channel.

Fcheck

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1 1441 2881 4321 5761 7201 8641 10081 11521 12961

Change of FGE electronics

Figure 16 Difference between Vector F and Scalar F – 10 minute averages 2011/241 to 2011/338

-30000

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1 1441 2881 4321 5761 7201 8641 10081 11521 12961 A countsB countsC counts

Figure 17 Vector magnetic channels (~30counts/nT) – 10 minute averages 2011/241 to 2011/338


F nT

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1 1441 2881 4321 5761 7201 8641 10081 11521 12961

Figure 18 Scalar F – 10 minute averages 2011/241 to 2011/338

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1 1441 2881 4321 5761 7201 8641 10081 11521 12961

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Figure 19 FGE Head and Electronics temperatures (0.01K/count) – 10 minute averages 2011/241 to 2011/338


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1 1441 2881 4321 5761 7201 8641 10081 11521 12961

T-EnclosureT-Green Box

Figure 20 SOH Vector enclosure and Green Box temperatures (unscaled) – 10m averages 2011/241 to 2011/338

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Figure 21 SOH Current (unscaled) and Voltage (Volts) – 10m averages 2011/241 to 2011/338

Figure 20 and Figure 21 show other from the State of health system – only the battery voltage has a known scale value at this stage, and Battery Volts are displayed on the right vertical axis of Figure 21. The System current is about 2A, so the current scale factor is probably about 5, and the peak solar currents about 20A.

Carrying absolute equipment to Pier AO The DI fluxgate theodolite was supplied by ETH/MinGeo in a tough plastic case with wheels and pull-handle. The GA supplied GSM90 magnetometer was supplied in a suitcase type box. The battery box, PDA etc required for absolutes had no container. The theodolite case has low magnetism and can be left 5m from the pier (this should be confirmed). The GSM90 box needs 16/12/2011______________________________________________________________________________________________________



checking. Although the theodolite box can be wheeled over the smooth golf-course grass, it is not really suitable for the rough grass. There is a need for a trolley to move the equipment from BoM to AO. An Ezy Beach Beach mate was confirmed to have low magnetism. See www.ezybeach.com.au. (Measurements at 1m: wheels 3nT, axle pins ½nT, axle 0nT, netting 0nT, all else 3nT. Assembled 0.1nT at 3m. Negligible at 5m.) The Beach Mate trolley is suitable and can be left at 5m from AO during observations. One was sent to on 2011-11-21. Another similar product was advertised on the glossy pamphlet that came with the Beach Mate – a Dock Cart, which may be more appropriate.

Threats to the Observatory

Relocation of Bureau of Meteorology The BoM buildings contain a lot of asbestos and apparently will be demolished and reconstructed, (or more likely reconstructed on a new site, and then the old buildings demolished). The new buildings may well be closer to the observatory and pose the threat of contamination.

Cyclones There are historic records of the coconut plantations on the islands being flattened by cyclones on several occasions. Although the observatory is on the lagoon side of the island, it is only a few meters above sea level and very close to the lagoon. There may be a possibility of inundation. There are nearby large trees (I am told the largest on the island) which have probably weathered significant weather in the past, and nearby coconut trees which could cause a problem. Apparently rain water soaks into the sandy soil quickly and does not pool very much.

Salt and humidity The salty environment is corrosive and the expected life of steel components, even galvanised, is limited. Most of the observatory installation is non-steel: aerated concrete bricks, glass-reinforced concrete, fibreglass, aluminium. The salt-effects should be minimised, but still the electronics could eventually fail due to corrosion. Rain-water entering and pooling in the almost air-tight variometer enclosures would no doubt raise the internal humidity to very high levels and could cause electronics problems.

Flora and Fauna The cabbage bush surrounding the observatory is very aggressive and nearly overwhelmed the site in between building construction and instrument installation. It needs to be kept in check. It is unlikely that large creatures could enter the variometer enclosures. However ants could enter through the small gaps left to let water exit. The conduits were plugged with stainless steel wool at the Green Box end, but not at the variometer end. It is unlikely that large creatures could enter by that route.

Vehicles Apparently some very-occasional heavy-vehicle traffic moves along the beach, but comes inland at the observatory location to avoid some “quick-sand” on the beach. Apart from data contamination, the cables from the Green Box to the variometers could be damaged.

Golf The observatory is accessed from BoM across a golf course fairway/green. Golf is played a few times a week. The Absolute Pier AO is close to the line of fire. The variometer parts (and in

http://www.ezybeach.com.au/


particular the solar panels) are more protected by vegetation but could be subject to damage from a particularly wayward shot.

Water intrusion into variometer At the time of this visit, water had pooled to several centimetres deep in the variometer enclosure. We noted that the floor and roof were very level. There was nothing to encourage water away from the construction. The brass threaded rods intended to secure the roof are at least in one case not secured to the brickwork. The Silastic between the roof and brickwork seems to secure the roof. It would be difficult to put a slope on the floor of the variometer enclosure at this stage. However the roof needs to be modified to make it water proof and sloped so that water does not sit on the roof. Denzo tape was applied to the threaded rods to try and reduce water intrusion.

Technical Facilities on Cocos Geoscience Australia operates the CTBTO Infrasound station, a Geodetic station, and the magnetic observatory. The magnetic observatory is a joint venture of ETH, IPS (part of BoM), BoM, and GA. BoM is next to the observatory and the BoM has agreed to do the absolutes. The BoM staff were very helpful during installation and have some limited workshop facilities. The Infrasound station is some distance from BoM, and has a workshop container, telephone line, portable generator and may be available for limited use – although there may be security issues as it is a CTBTO monitoring site.

Accommodation and Transport Transport route was to Perth (overnight) on Qantas, then via Perth Airport International Terminal to Cocos-Island via Christmas Island on Virgin airlines. Accommodation at Perth

Sullivans Hotel 08 9321 0822. A car was waiting for us (from Cocos Autos Car Rentals http://cocosautos.cc/ organised by Shane Nancarrow) at the terminal, and the accommodation at Cocos Beach Motel (http://www.cocoscoop.com/about.htm, also organised by Shane Nancarrow) was just across the road from the terminal. Accommodation was reasonably comfortable (although air conditioning was hit and miss), power supply was good, breakfast/lunch/dinner were available. Petrol is only available for 1 hour one day a week. There is no normal mobile phone coverage although it can apparently be arranged using a local phone card. A supermarket has limited produce available (sometimes). Return journey to Christmas Island (3 nights, ATWS maintenance), to Perth (overnight) on Virgin airlines, then to Canberra. Accommodation at Christmas Island

Contact TAMARA MANGO TREE LODGE Email: [email protected]: www.mangotreelodge.cxPh: + 61 8 9164 7189 Fax: +61 8 9164 7190 2 x superior sgl occupancy each Total: 3 nights each @$160.00/night room only

Accommodation at Perth Comfort Inn/Bel Eyre 285 Great Eastern Highway 08 9259 3888.

http://cocosautos.cc/

http://www.cocoscoop.com/about.htm

mailto:[email protected]

http://www.mangotreelodge.cx/


Inventory Absolute Instruments

o DIM • Theodolite Zeiss 020B(grad) 311864 with microscope angled eyepiece • Electronics DI0102 Sensor ??

o GEM Systems GSM90 E3091316 S761100 • E3091316 returned for repair, replaced by E3091315 (sent 2011-09-14)

o Battery Box/Charger o PDA iPAQ Box 0029739 o Stopwatch Multi Function Stop Watch

Variometer Instruments o DTU FGE-K2 E0431 S0353

• E0431 swapped out, E0462 swapped in 2011-11-20 o GEM Systems GSM90F1 E0023526 S03768

Power Supply o Green Box components

Communications o Freewave radio modems/power supply

• BoM end • Remote end • Spare

o Mast/antenna Data Acquisition

o Computer CKI PC 01 Advantech ARK 3360F KSA0197301 o Clock Garmin

Recommendations Replace the FGE variometer Improved absolute observation training for BoM staff at CKI Waterproof roofs of both variometer enclosures A complete GPS survey for positions and azimuths Install DC-DC converters inline to power both variometers New azimuth mark as Windsock suffers from heat haze – choose another higher mark Tie in repeat stations More nuts for tie-down bar on absolute pier Plastic boxes installed November 2011 were damaged in transit and should be replaced Take new cable clips for absolute pier in case others have been lost. The Absolute PPM stand was modified to fit between the theodolite securing bar supports –

it may need some adjustment

Acknowledgements Thanks to ETH: Andrew Jackson, Jakub Velímský who initiated the project, provided much of the funding and initial site survey IPS: Richard Marshall, Mike Hyde for project management and construction BoM/Cocos: Trevor Menadue, Tom Chlebowski, Will Tankard for their assistance during and after the visit BoM: Ian Wise, Alan Wong, Duy Hung Vu for their assistance establishing a network connection GA: Workshop: Ray de Graaf, Craig Wintle, Mark Sharah for building the absolute pier, solar panel mountings and antenna mast


GA: Networks: Dave Pownall, Trevor Dalziell, Lindsay Miller, Jim Whatman for preparing the electronics, power and communications equipment GA: Geomag: Adrian Hitchman, Peter Crosthwaite, Liejun Wang, Andrew Lewis, Bill Jones GA: CTBTO Infrasound team: Shane Nancarrow, Adrienne Moseley, Trevor Dalziell for help arranging the cars, accommodation, transport of equipment to Cocos, choosing materials, loan of tools, equipment, and facilities at Cocos, and many other things GA: Jamie Lankford for arranging transport of dangerous goods (GSM90 snesors) GA: Matt Collaery for arranging the GA end of firewall access to BoM/Cocos

References http://www.esa.int/esaLP/ESA3QZJE43D_LPswarm_0.html ESA Swarm satellite mission Peter Crosthwaite, “Cocos-Keeling Islands Geomagnetic Observatory Battery Configuration” Geomagnetism Note 2011-18 Peter Crosthwaite, “Solar Panel Alignment Calculations” Geomagnetism Note 2011-21 Trim Documents D2010-217132 CKI Cocos Master Technical Manual This should contain:

D2010-217453 Garmin RJ45 to PC CKI Cocos D2010-217450 Garmin DB9 to RJ45 to PC CKI Cocos D2010-217459 CKI Cocos DC Wiring Solar D2010-217461 Cocos Signal Diagram D2010-217448 Cocos Signal Diagram Trim Container 2010/5678: GEOSPATIAL & EARTH MONITORING - DATA ACQUISITION - PROCESSES - CKI Cocos Circuits & Drawings


http://www.esa.int/esaLP/ESA3QZJE43D_LPswarm_0.html


Appendices

Freight Heavy materials such as concrete (25 bags@20kg each), batteries (6@42kg each), Green Box, solar panels and poles, radio masts, cement mixer, etc. were packed in the shipping container used for the CTBTO Infrasound installation which had spare space. Some equipment such as shovels, crowbar, 240V generator, etc. were borrowed from the CTBTO group and Bureau of Meteorology. Toll Global was used for lighter freight. Freight can be very slow, even air-freight. Although the equipment was sent weeks ahead of this visit, the last of it arrived on the same day we left Canberra bound for Cocos – just in time! Experience has shown that freight can become stalled at Perth. The Toll Global, Perth Office contact is 08 9262 9200. Another alternative suggested but not used was

http://freightshop.com.au/ratespage.htmPlease deliver goods to Freightshop at Unit 7, 26 Fricker Road, Perth International Airport. Deliveries where there are no parcels over 30 kilos, go to the front door and deliveries over 35 kilos to the back door. (08) 9477 6088(International) U7/ 26 Fricker Rd Perth Airport WA6105 (08) 9477 6077Fax 0401 225 003

DTU Package 700 x 460 x 410 mm 28.6kg E0431 with 12V short power cable hardwired and battery box connection S0353 ICP CON i-7520AR RS232 to RS485 Converter I7520ARCR007HDD00210 (with 1.5-2.0m RS232 F-M cable, digital cable and connector to E0431, power with battery box connector) ALL CABLES are SHORT. Taken to GA Freight (Toll Global) 18 July 2011 http://www.toll.com.au/ 813001705375

DI Flux Package 2011-07-27 MinGeo yellow box 580x460x280mm 14kg, 2x60mm wheels and drag-handle Contains DI flux magnetometer

• DI0102 • MinGeo 020 B (grad) 311864, with

o Base plate for tripod o Angle eyepiece for scale

• sensor cable • power as supplied by MinGeo

o direct power supply/battery charger MW126CB08 230V 50Hz 19W, 6V/12V DC 800mA 9.6VA max requires Australian power adaptor

o joiner for battery charger/battery connector o battery cable

• screw driver, wrench, plumb bob • battery box power cable

http://freightshop.com.au/ratespage.htm

http://www.toll.com.au/


• (battery transferred to cardboard box)

Cardboard box 270x250x240mm 9kg Contains

• Geomag battery box 20110701 • Charger BVW24125 Rev C Type 00—3N

o 100-240V 50-60Hz 0.80-0.35A, 29.4VDC1.25A • battery FG20721 12V 7.2Ah with power connector (from above)

GSM90 Package 2011-07-27 (to Jamie Lankford) GSM90 Blue/silver Box labelled “GSM90 Serial 4081419” 11kg Contains GSM90F1

• E23526/S3768 • dual sensor cable • power/rs232 cable as supplied by GEM • DB9M + DB9F for making rs232 extension

GSM90 silver Box unlabelled 10kg Contains GSM90

• E3091316/S761100 • sensor cable • power/rs232 cable modified for battery box 20110701 • null modem DB9M-DB9M checked for function with HP200 • absolute GSM90 stand • 4 pole-segments for field measurements

CTBTO Infrasound shipping container / Geomagnetic Observatory equipment $Value 6 x Sonnenchein A600 600AH 2V Gel non spillable batteries 4500 4 x 190W solar panels and cables 2000 5 x aluminium poles and pins 500 2 x panel mounts 500 2 x rolls of flex conduit 60 3 x rolls of electrical cable 250 1 x antenna mount 40 2 x antennae 100 3 x Freewave radios with cables and surge suppressors 2000 25 x 20kg bags of concrete mix 150 1 x small bag of fibreglass concrete reo 20 3 x 3m earth stakes 50 1 x green equipment/power cabinet inc power system 1500 1 x GPS mounting bracket 20 1 x rubber mat 50 1 x bundle of bird spikes 50 2 x packets of scourers 10 1 x DIN rail 5 2 x 3m lengths of 75mm cable tray 40 1 x box of various nuts, bolts and screws 20 1 x battery fuse 30 1 x box of ss cable ties1 x small concrete mixer 80 2 x Flexmax solar regulator 1300 1 x mini Concrete mixer 200 1 x computer with associated cables 500 (? probably taken as hand-luggage)

16/12/2011_____ ________________________________________________________________________________________________ Geomagnetism Note 2011-16 Cocos-Keeling Island Geomagnetic Observatory Visit August 2011 39

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GSM90 Package (replacement electronics) Sent 2011-09-14 Cardboard box 2.2kg

• GSM90 E3091315 • Null modem DB9M/DB9M – should not be required, as one should be attached to the PDA cable • A clip to attach to the underneath of the marble pier top to hold the instrument cables in place during

observations. (1 x spare clip included.)

Contacts Cocos Island Meteorological Office 08 91626625 fax 08 91626626 Address: C/- Bureau of Meteorology Cocos Island Meteorological Office Cocos Island, WA 6799 Australia.

Trevor Menadue [ [email protected] ] Tom Chlebowski (since moved on from Cocos) Will Tankard (arrived at Cocos after this visit)

CTBTO Central Facility 08 9162 6502 (Fax/Phone) Andy Jackson [ [email protected] ] Jakub Velímský [ [email protected] ] Ian Wise Alan Wong [ [email protected] ] Duy Hung Vu [ [email protected] ] 07 3239 8771 Richard Marshall [ [email protected] ] Mike Hyde [ [email protected] ] [email protected] 6249 9500 Mobile at Cocos ? [email protected] 6249 9604 [email protected] 6249 9220 [email protected] 6249 9547 (0417274287) [email protected] 6249 9712 [email protected] 6249 9321 [email protected] 6249 9800 [email protected] 6249 5819 [email protected] 6249 9764 [email protected] 6249 9334 [email protected] 6249 9620

Interested parties • ETH Zurich Eidgenossische Technische Hochschule (Swiss Federal Institute of

Technology): o Professor Andrew Jackson o Jakub Velimsky

• Ionospheric Prediction Service o Richard Marshall o Mike Hyde

• Bureau of Meteorology o Ian Wise o Alan Wong




















o Trevor Menadue o Tom Chlebowski o Will Tankard

• Geoscience Australia o Adrian Hitchman o Geomagnetism Group

Funding and Support • Zurich Eidgenossische Technische Hochschule, provided

o Site survey to locate the observatory o Some construction costs o DTU FGE magnetometer/variometer o GEM Systems GSM90F1 magnetometer/variometer o DI Fluxgate theodolite magnetometer

• Bureau of Meteorology o Network/Communications support o Absolute Observations support o On-site assistance

• Ionospheric Prediction Service o Project management o Construction

• Geoscience Australia o GEM Systems GSM90 magnetometer/absolutes o Absolute Pier o Solar power supply o Network equipment o Installation of equipment o Real-time data collection and distribution to INTERMAGNET quasi-definitive

standards o Definitive data processing to INTERMAGNET standards

November 2011 Service Trevor Dalziell visited Cocos arriving 2011-11-19 for matters concerning the CTBTO Infrasound installation. He was able to swap over the DTU electronics at that time. On 2011-11-20T07:30 he powered off the DTU magnetometer, cut the power line and connected a standard Geomag Battery Box style socket. He removed the electronics E0431 and installed electronics E0462 which had a standard Geomag Battery Box style plug. The DTU variometer with E0462, with the same switch settings as E0431 was powered up again at 08:30. The X and Y channels were on scale and with the proper switch settings. Z was off scale – the appropriate setting was found to be Coarse C, Fine 4 – very different from the E0431 settings (E0). The variometer enclosure was noted to be damp and humid, but with no pools of water. Plastic boxes without lids were installed over the electronics – however at least one of the boxes sent was damaged in transit, and repaired with tape. E0431 was returned to Geoscience Australia/Canberra. E0462 was left at CKI in operation.

Australian Geomagnetic Reference Field Computation For Cocos Island area Requested: Latitude -12o 10' 00", Longitude 96o 49' 00", Elevation 0 km, Date 2010/01/1 Calculated: Latitude -12.1667o, Longitude +96.8167o, Elevation 0.00 km, Epoch 2010.0000

Location is outside the AGRF area. A global field model has been used

Magnetic Field Components D = -2.460 deg dD = 0.035 deg/yr I = -43.652 deg dI = 0.094 deg/yr F = 47801 nT dF = -21 nT/yr H = 34586 nT dH = 39 nT/yr X = 34554 nT dX = 40 nT/yr Y = -1485 nT dY = 20 nT/yr Z = -32996 nT dZ = 72 nT/yr

Cocos-Keeling Islands Climate Bureau of Meteorology website: http://www.bom.gov.au/climate/averages/tables/cw_200284.shtml

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Mean number of days >= 30 DegreesC for years 1952 to 2011 Mean number of days of rain >= 1 mmfor years 1907 to 2011 Mean number of days of rain >= 10mm for years 1907 to 2011 Mean number of days of rain >= 25mm for years 1907 to 2011



Packing List 1. Camera 2. Laptop + swap over ethernet 3. Differential GPS alternative: handheld GPS 4. Sunshots/sun filters 5. Pier B marker plate alternative details of Repeat Station at airport 6. Carry trolley for absolutes alternative investigate back pack or trolley 7. PDA for absolutes – cable, null modem, charger, SD card for CKI 8. Stop watch for absolutes. 9. Battery box for absolutes SENT 10. Absolute DIM with SENT

a. Angle eyepiece SENT b. Power from battery box cable SENT c. French/Australian power adaptor

11. Absolute PPM with a. Power from battery box cable and coms and DB9M/DB9M Null modem) b. Stand

12. Absolute observation sheets with pencilling board 13. Data acquisition computer with

a. DC VGA screen and USB keyboard for setup b. Ethernet cable to connect to Freewave radio c. RS232 cable for Adam

14. Manuals for Adam, DTU, computer 15. DTU variometer E0431 S0353 SENT

a. level bubble and compass for installation b. brass tools

16. GSM90 variometer 23526 Sensor 3768 (10m composite cable – 2 coax connectors at sensor, 500mm sensor tail) SENT

17. PowerPoint presentation on Geomagnetism 18. Geomagnetic training documents 19. Absolute observations sheets for the CKI DIM/PPM + template .txt.file, HP200 for gradient

survey 20. Keys for everything – no keys for mag enclosures 21. tape for fixing absolute pier

Computer CKI PC 01 Advantech ARK 3360F KSA0197301 + power lead + network cable Euro power adaptor for DIM battery charger Multi Function Stop watch Observation forms Repeat station equipment 12V VGA screen HP200 Other NiMH battery charger Ultra-Flat USB keyboard (tested with CKI PC 01) Compass for installation Zapper PMT2 2056 + 2036 25/33/40/50/66 Canon camera Passport Cabcharges


Theodolite filters and tommy bar and small angle mirror Repeat station documentation

Log Pages Cocos-Keeling Island 19 – 31 August 2011. Peter Crosthwaite/Dave Pownall Friday 2011-08-19 Flights as planned. Left Home 08:30, flight delayed but connection not affected. Bought sunglasses and water bottle at Perth. Saturday 2011-08-20 Flights as planned. Met Neil Williams during stop at Christmas and Keith Porritt who travelled on to Cocos. Changed Room 19 to 16 as 19 wasn’t ready. Visited Nuclear Monitoring sites. Sunday 2011-08-21 Went to Met at 09:00, met Trevor M. for briefing working around met. Last of equipment arrived on Friday! (The GSM90s.) Went back to NM site, borrowed shovels etc., then back to variometer site and spent some hours digging an extension trench as GSM90 enclosure was too close to the footing for the solar panels etc (6.7m) and we had to extend the base for the panels in any case. Finished > 05:00pm. Help and advice from Tom as well as Trevor. Borrowed tools from Tom. Monday 2011-08-22 (not recorded in log?) Tuesday 2011-08-23 08:00 – 17:15. Dug another trench from Green Box location to mast location (4m), set up boxing for Green Box foundation and dug holes for mast ~900mm, and two poles for solar panels ~800mm. Panels should shade the Green Box for most of the time. Installed and secured copper wire from Green Box to old location for Green Box and Green Box and mast. 3 earth stakes about 1.45m – one at each old and new Green Box locations, and one between. Filled in all trenches. This after loading and shifting more gear from container at Nuc’s. Tested generator and cement mixer ok. Slow going in weather conditions. Wednesday 2011-08-24 Started early 07:00 to get concreting done – did base for Green Box, then solar panel poles, then mast. Used all 25 bags (x20kg) – just enough. Dave tidied up and started on panels while Peter showed Trevor M the geomag ppt and then the basics of DIM indoors. Then we finished installing the solar panels. Meanwhile Dave discovered that the Vault had a lot of water inside – and held it very well. Still haven’t opened the PPM sensor vault. The Green Box vault can’t be tied down until concrete is harder on Friday. Trevor M will not be at work Thu/Fri – training deferred until Sun or Mon. Finished 17:30. Thursday 2011-08-25 08:00-17:45 + 20:00-21:00


Picked up gear and batteries from Nucs, Dave added bird repellent to solar panels, wired up panels and batteries A600 Solar A602/600 2V 500Ah C100

Sonnenschein (Exide Technologies GmbH) part number NGS6020600HS0FA, bolted Green Box to concrete, installed antenna. Configured remote end radio modem from 192.168.240.124 to 134.178.34.204 with AES cocos$geomag* Still need to configure spare remote end and BoM end. Var enclosure door clearance is 460Wx650H (800 diagonal). There are 8 brass rods holding on roof. From SW anticlockwise there are 11,14,12,14,14,10,7,8 threads left. The floor is quite level unfortunately there is no drainage towards the door. The roof is the same – water sits on the roof, and the paint is bubbling – I expect water might be leaking in through the roof, however we will try improving the Silastic seal of the roof to the walls.7. The pier is 100mm above floor and is topped with 4 red tiles. The pier is 400x400, and has a clearance of 900 to roof (floor to roof is 1000mm). There is 200mm clearance behind pier, and 330mm to either side. The 8 threaded rods holding on the roof are 100mm from ends and sides. Along southern long wall, they are from west end 100, 615, 1815, 2885 (east end is 2980mm). Along the northern wall, they are from west end 100, 600, 1785, 2855 (2960mm) Alternative measurements: Along southern wall starting at west rod, 0, 520, 1720, 2785 Along northern wall starting at west rod, 0, 505, 1690, 2760 Eastern end is 1830mm rods are 1650 apart. Next to eastern rods are 1630 apart. Western end rods are 1640mm apart. Next to western rods are 1635 apart. SW-NE diagonal 3240mm. NW- SE diagonal 3200mm. The var enclosure is aligned 295 (long side) and 25 magnetic (short side including door side). The Green Box is 19m at 165 magnetic from SE corner. The mast is further in same direction at 23m. The Green Box is 20m from SW corner of enclosure; the mast is 24.5m from SW corner. The PPM enclosure is 16.5m at 5 magnetic from the Green Box (The original site for Green Box was 7m along the same line from the PPM enclosure; the mast is in the same direction at 23m) There is a small building 70m at 310magnetic from Abs Pier. There is a CKI Weather Office (steel) sign 70m in opposite direction from radio mast which is 42m at 65 magnetic. The SW corner of var enclosure is 52m at 25 magnetic from Abs Pier. The mast is 42m from Abs Pier. Tried to run GPS on Abs Pier, but batteries were flat. However I measured the distance to GA GPS antenna – it was 108m but I have lost the piece of paper I wrote it on – the direction will have to be remeasured. Friday 2011-08-26 08:00-18:15 20:00-21:00 GPS-Pier direction is 340Magnetic Var GPS position 12d11.2334S 96d50.0332E (used qtalk/p232 dtr off 0x2f8) 6 batteries are 16x16x46cm arranged as follows – this leaves a large low-voltage (15A and more) current loop of some area to generate contaminating magnetic fields. Could it be arranged as two opposite loops with appropriate connectors?

Tom found the securing bar and threaded small rods for the absolute pier – discovered that the PPM stand (large base) cannot fit onto abs pier with the threaded rods in place. The rods are 145mm apart and the line between them goes right through the centre of pier. This is incorrect and not noticed before the pier was sent. Marked the location of the footpads for fixing later (soon I hope). Cut the DMI sensor insulation box in two to fit it in through the variometer door. Tested GPS clock – it appears just as good inside the Green Box (under solar panels) as it is mounted externally on the panel bar. Put the computer in the Green Box after configuring the correct clock and enabling SOH recording. Tidied up site. Finished installing radio link – seems OK locally, checked with AML earlier but should check again in final configuration. Measured F at some places – On and around Abs Pier, F var site and vector var site. The switch on the battery box fell apart during obs and had no power to complete a loop of observations. Temp_238.obs. All was quite reasonable except for NW corner on roof of variometer. SLOW SLOW going. Concentrate on Training and Magnetometer installations. Also what are SOH channels and need to configure spare radio. Note iPAQ box is 0029739.

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Saturday 2011-08-27 Rest day Sunday 2011-08-28 07:00-17:15 19:45-21:00 11mm rain over night left the var enclosure wet inside again. And when we opened the Green Box it too had a few cm water in upper compartment! The computer was sitting in water and had water inside. The spare power connector inside was corroded – Dave cut it off, and dried out inside, fortunately it still seemed to work OK. The wooden box I put inside the enclosure Friday was wet. We installed the GSM90 and DTU variometer with the electronics on concrete blocks and with an untidy plastic bag on top. The GSM90 cable was only just long enough using the reach the distance – in fact only using the tail of the sensor. We pulled through the extra temperature sensor for SOH as well. The GSM90 sensor enclosure was dry when opened. The GSM90 sensor 03678 was mounter on concrete blocks horizontal E-W in usual orientation. Dave denzo taped the nuts/threaded rods on roof of var enclosure – one threaded rod pulled out when the nut was loosened – it was about 25cm long and was very loose. SOH channels – Dave has them in doco.



Cleaned up some more of the site – tightened nuts on mast. Aligned DTU. Cleaned up Abs Pier top – but some glue etc was inside Met and it was closed when we needed it. DTU offsets changed from XYZ A7 A7 DF to A6 A6 E0. Left some small drainage exit in var enclosure. Tomorrow we need to fix Abs Pier, put hole in top compartment of Green Box for drainage, Sunshots, train Trevor, clean up Met, get rid of excess building material on site (concrete blocks). Turned solar charging OFF 09:53:12, ON at 09:53:40. Monday 2011-08-29 07:30-17:45 19:45-22:30 Re-adhered copper foot pads to pier Loctite Grey Maxx -60-+200C RTV Silicone Gasket Maker before 09:00 LT. Drilled two holes in shelf between chambers in Green Box to let water drain if it enters again. Withdrew spare power and data cable from var enclosure to Green Box to see if it will reduce the PPM sampling effect on vector data. Remeasured var enclosure roof – S wall 2984, W wall 1839, N wall 2956, E wall 1836; SW-NE diagonal 3508, SE-NW diagonal 3475; Roof is 120, distance from bottom of roof to top of door is 280. PPM enclosure S 746, W 746, N 746, E 745; SW-NE 1050, SE-NW 1050 Wall of abs site: SE 2580, NE 2574, NS diagonal 3520; slab is 1500x1500. Ht of wall 2220. Trevor M found the wall uncomfortable – it made the pier hotter with double the sun, and no wind to cool off. I found the pier (in the afternoon) hot and uncomfortable, while on the windy shady side it was quite pleasant. Cut some length off of the threaded brass rods of the abs instrument restrainer. They need and extra nut to work properly. The restrainer was not tested for magnetism. The (EW) restrainer is aligned with the centre of the pier – it should be offset the the N. The battery box not only has a damaged switch, but also the circuit board components have been crushed – possibly as the batteries were not restrained inside the box, and the damage happened during transportation to CKI. Dave hardwired the batteries to the plug so that it could be used today. Dave tidied the site, removing the heeble bricks (gave to CKI community) and pallets and plastic. Tested the GA signes and installed 4 signs: two on abs walls, one on Green Box, one on var enclosure. Adjusted the PPM stand – notched the sides to accommodate the restrainer – should have been bigger notches. Training: showed Trevor M a DIM observation with battery and cable supplied with the theodolite rather than the battery box. Only did one observation, very basic, with frequent interruptions to do short and long obs. A poor show not having the actual power source (battery box) working properly


– at the time I couldn’t show him an actual GSM90 observation as the battery box did not work at that stage. Did a few afternoon sunshots – AM sunshots not possible from pier, and of no use in middle of day as sun is so high. Interrupted by a golfer/yacht navigator questioning my methods. Results 256º15’17” ±3” (5 observations) using approximate position, no DUT1 correction. The pier is quite short – especially two of the I readings are difficult for Trevor. However it is possible to do the readings and I would say the effort for those two readings is worth not using the angle eyepiece. Solar charger turned from OFF->ON 03:41:00. Time it was turned OFF not recorded. At night – configured spare radio as ….204 AES encryprion. Data and report. Tuesday 2011-08-30 07:30-17:00 19:45-20:45 Only time left to finally check over the site, do some calibration observations, measurements… The GSM90 talked but did not give meaningful readings. I found that the voltage from the battery box was 24V rather than 12V – it may have damaged the GSM90. Modified the battery box connections to give 12V but still the GSM90 did not give meaningful results. Gave up on GSM90 with regret and did a DI observation. Only a single measurement made. Decided to take home battery box lid and GSM90 electronics. Slightly tidied up Met Office equipment. Left keys to Green Box with Met. Measured height of pier above concrete – 1180mm, quite low, and awkward for 2 of the I obs especially for Trev M. Photos of racks in Met. The theodolite restrainer was tested and is not magnetic at the distance of the DIM sensor. Verified that the variometer was still OK with AML before packing up, returning car, paying hotel bills (10nights @$120/night, + meals) Travelled to Christmas I, picked up car and to hotel ~17:00. CKI: Need a cable attachment for the pier. Rest of time – at Christmas I etc – worked on report some nights.

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