PLATO operation and Dome A

site properties Michael Ashley / University of New South Wales

Image: The Galactic Centre and aurora from the South Pole, Daniel Luong-Van, 2010

Anna Moore, Tony Travouillon California Institute of Technology, USA

Jingyao Hu, Zhaoji Jiang, Xu Zhou National Astronomical Observatory of China, China

Xiangqun Cui, Xuefei Gong, Xiangyan Yuan Nanjing Institute of Astronomical Optics Technology,

China

Longlong Feng, Zhenxi Zhu, Ji Yang, Xu-Guo Zhang, Jun Yan Purple Mountain Observatory, China

Yuansheng Li, Weijia Qin, Bo Sun, Huigen Yang, Zhanhai Zhang Polar Research Institute of China,

China

Michael Ashley, Colin Bonner, Jon Everett, Shane Hengst, Daniel Luong-Van, John Storey University of

New South Wales, Australia

John Lawrence Macquarie University and the Australian Astronomical Observatory Graham Allen Solar

Mobility, Australia

Nicholas Suntzeff, Lifan Wang Texas A&M University, USA

Reed Riddle Thirty Meter Telescope Project, USA

Zhaohui Shang Tianjin Normal University, China

Craig Kulesa, Chris Walker University of Arizona, USA

Stuart Bradley University of Auckland, NZ Donald York University of Chicago, USA Carlton

Pennypacker University of California at Berkeley, USA Nick Tothill, Mark McCaughrean University of

Exeter, UK

Collaborators

This talk...

• Why Antarctica?

• What is PLATO?

• PLATO performance

• Results from Dome A

Altitude: 4093m

Typical wintertime temperature: -70C

Average wind speed: 2.5m/s

Two major problems:

(1) turbulence

(2) absorption

Traditional choices include the west coast of Chile

and Mauna Kea Observatory, Hawaii

Both these sites have relatively smooth airflow and

excellent “seeing”, but can we do better?

+ Dome

F

Observations with a Multi-Aperture Scintillation Sensor and

a SODAR at Dome C showed that the free atmosphere starts

at ~30m, and the seeing is exceptional; confirmed by DIMM and

radiosonde

Cumulative seeing

probability

PILOT telescope

overview

•2.5 metre optical/infrared telescope

•Dual role: pathfinder and unique science

•International project

•Sited at Concordia Station, Dome C, Antarctica

Image: Andrew McGrath

Dome

F

So, where is the best site in Antarctica?

PLATO leaving UNSW, Sydney, Australia, November 2007

Green → the Engine Module (6 diesel engines, 4000 litres Jet-A1)

Yellow → the Instrument Module (experiments that need to be warm)

Pre-HEAT

Gattini SBC

Gattini all-sky

Iridium antennas webcams

Instrument module

spare

ports

CSTAR, SNODAR, Sonics located

externally on snow surface

The 2009 Chinese traverse

570 tonnes

Dome A traverse 2008

Dome C

Dome A

11 Jan 2008

Polar Research Institute of China tractor traverse 2008:

18 expedition members

2 astronomers: Zhou Xu (NAOC), Zhenxi Zhu (PMO)

Images courtesy Li Yuansheng, PRIC

Zhongshan

23 Dec 2007

PLATO on its two week trip to Dome A, December 2007

PLATO at Dome A, January 2010

Things that have

gone wrong •In the first year (2008), we stopped after 204 days due to an exhaust leak. •A solar panel power converter failed in 2008. •Three DC-DC converters have failed. •Various temperature and voltage sensors have failed. •Several alternators have failed catastrophically due to design faults. •The Iridium satellite system is unreliable (typical downtime of 30 minutes/month, with one outage of two days). •Some experiments have had trouble with icing.

Atmospheric turbulence (Snodar x 2 in 2009; Snodar x1 in 2010;

Shabar)

Boundary layer height, distribution and variability.

Sky emission and transparency (CSTAR, Gattini, Nigel, HRCAM)

Visible sky background (BVR and OH filters) versus sun/moon elevation;

auroral intensity and distribution; spectra of the sky background (low-

resolution (2.5nm) 300-900nm); all-sky colour images.

Precision, continuous, optical photometry (CSTAR)

THz sky opacity (Pre-HEAT (2008), FTS (2010))

Transparency and noise in the terahertz region.

Cloud (Gattini, CSTAR, HRCAM, webcams)

• Cloud cover statistics and distribution.

PLATO science

CSTAR: four co-mounted Schmidt telescopes

- 145mm aperture, f/1.2

- 4.5 x 4.5 degree field of view

- g, r, i, and open, filters

- 1K x 1K CCDs

- pointing at the South Celestial Pole, no tracking

- 360GB of data obtained during 2008; over 700GB during 2009

- three papers published in 2010

Pre-HEAT 20cm off-axis parabola

661GHz (450 micron) Schottky diode heterodyne

receiver

Measures sub-mm sky transparency, and hence PWV

(Precipitable Water Vapour)

Gattini wide-field multi-filter

optical camera

PI: Anna Moore, Caltech

> 1.2TB of images have been

obtained in 2009/2010.

Gattini thumbnails

The raw images from

the Gattini camera are

2048x2048 pixels

(8MB).

We transfer 256x256

thumbnails (50KB) of

occasional images.

We send back all the

pixels within small

apertures around 40

stars.

Nigel’s “bob”

Typical spectrum of the twilight sky from Dome A, with approximate flux calibration.

A number of absorption bands are visible: A (759.4 nm) and B (686.7 nm) due to

molecular oxygen, C (656.3 nm) due to hydrogen, and G (430.8 nm) from iron.

It is noteworthy that the water vapour absorption features at 730 and 820 nm normally

quite deep at temperate-latitude observatories are almost entirely absent at Dome A,

due to the exceedingly low water vapour content of the atmosphere.

Gattini-Nigel: a bright aurora

SNODAR

Snodar data; each plot 24 hours;

0-120metres

Cumulative probability distributions of the

boundary layer height over Dome A during

2009 (solid line), and Dome C during 2005

(dashed line). Data for Dome C are from

[10]. Median boundary layer heights for

Dome A and Dome C are 13.9 m and 33 m

respectively.

Cumulative histogram of the boundary layer height

Dome A comparison with Dome C

FTS (Fourier Transform Spectrometer)

Measures the atmospheric transmission from 0.75 to 15 THz, i.e., from 20 microns to

400 microns. Uses ambient temperature DLATGS (deuterated L-anine doped triglycene

suplhate) pyroelectric detectors.

Sheng-Cai Shi, Q. J. Yao, X. X. Li, X. G., Zhang, Z. H. Lin, K. M. Zhou, Q. G. Huang,

J. Yang (PMO); Scott Paine, Q. Z. Zhang (SAO); H. Matsuo (NAOJ)

Webca

ms Moonrise at Dome A April 2008

HRCAM all-sky image, showing

the traverse leaving Dome A,

January 2010

HRCAM images 2010

HRCAM images taken last night, showing the coronal mass

ejection of 2 August 2010 reaching the earth

Where the power came from

Where the power went

Fuel consumption

Atmospheric turbulence (Snodar x 2 in 2009; Snodar x1 in 2010;

Shabar)

Boundary layer height, distribution and variability.

Sky emission and transparency (CSTAR, Gattini, Nigel, HRCAM)

Visible sky background (BVR and OH filters) versus sun/moon elevation;

auroral intensity and distribution; spectra of the sky background (low-

resolution (2.5nm) 300-900nm); all-sky colour images.

Precision, continuous, optical photometry (CSTAR)

THz sky opacity (Pre-HEAT (2008), FTS (2010))

Transparency and noise in the terahertz region.

Cloud (Gattini, CSTAR, HRCAM, webcams)

• Cloud cover statistics and distribution.

PLATO science