15 December 2008 Science from UKIDSS II

WFCAM Science Pipeline WFCAM Science Pipeline UpdateUpdate

Jim Lewis, Mike Irwin & Marco RielloJim Lewis, Mike Irwin & Marco Riello

Cambridge Astronomy Survey UnitCambridge Astronomy Survey Unit

15 December 2008 Science from UKIDSS II

WFCAM processing summaryWFCAM processing summary

SemestersSemesters 05A05A 05B05B 06A06A 06B06B 07A07A 07B07B 08A08A 08B08B

NightsNights 8181 166166 9595 157157 5050 125125 132132 7575

► an average of 70% of telescope timean average of 70% of telescope time► 115 TB Raw Data (30 TB compressed)115 TB Raw Data (30 TB compressed)► 200 TB processed Data (50 TB compressed)200 TB processed Data (50 TB compressed)► 4 million 2k x 2k images4 million 2k x 2k images

15 December 2008 Science from UKIDSS II

Processing steps reminderProcessing steps reminder► Internet raw data transfer -> Cambridge Internet raw data transfer -> Cambridge ► Ingest and verify, record OMP MSB status -> tape backupIngest and verify, record OMP MSB status -> tape backup► Dark and reset anomaly correction <- master darksDark and reset anomaly correction <- master darks► Flat field correction <- master twilight flatsFlat field correction <- master twilight flats► Decurtaining - remove variable pattern noiseDecurtaining - remove variable pattern noise► Detector crosstalk removal - channels within quadrantsDetector crosstalk removal - channels within quadrants► Sky background estimation and subtraction -> sky imagesSky background estimation and subtraction -> sky images► Interleaving 1x1, 2x2 or 3x3Interleaving 1x1, 2x2 or 3x3► Dither/jitter stacking -> science product imageDither/jitter stacking -> science product image► Catalogue generation Catalogue generation ► Astrometric and photometric calibrationAstrometric and photometric calibration► Quality control checksQuality control checks

15 December 2008 Science from UKIDSS II

Why Do Background Correction ?Why Do Background Correction ?typical before and after background correction #1typical before and after background correction #1

15 December 2008 Science from UKIDSS II

Update since 07BUpdate since 07B

extra processing to remove parquet floor patternextra processing to remove parquet floor pattern

monthly photometric recalibration (Hodgkin et al. 2008)monthly photometric recalibration (Hodgkin et al. 2008)

MSBTid logs available immediately after stage I MSBTid logs available immediately after stage I

processingprocessing

nebulosity filtering post-processing option nebulosity filtering post-processing option

new observing and reduction strategies for improved new observing and reduction strategies for improved

background subtraction for large extended objectsbackground subtraction for large extended objects

bug fixes/workarounds including a long-standing one bug fixes/workarounds including a long-standing one

15 December 2008 Science from UKIDSS II

problems with detectors #2,3problems with detectors #2,3K-band sky #3 stacked final imageK-band sky #3 stacked final image

15 December 2008 Science from UKIDSS II

Parquet floor processingParquet floor processing

LAS Y-bandLAS Y-band

detector #2detector #2

15 December 2008 Science from UKIDSS II

Sky flipping/offsetsSky flipping/offsets

► extended objects observed on a given detectorextended objects observed on a given detector

► objects are then ‘flipped’ to a different detector objects are then ‘flipped’ to a different detector

► background for ‘object’ detector in one jitter background for ‘object’ detector in one jitter determined from compliment observation jitterdetermined from compliment observation jitter

► objects of interest are observed at all times objects of interest are observed at all times (advantage over offset sky strategy)(advantage over offset sky strategy)

► offset skies only for large objects, e.g. M101, clusters, offset skies only for large objects, e.g. M101, clusters, which cover more than 1 detectorwhich cover more than 1 detector

15 December 2008 Science from UKIDSS II

Bugs: Bugs:

indexing bug in catalogue Petrosian routineindexing bug in catalogue Petrosian routine only affects deblended objects and is now fixedonly affects deblended objects and is now fixed fundamental problem with circular aperturesfundamental problem with circular apertures workaround found that can be applied retrospectivelyworkaround found that can be applied retrospectively all catalogues will be repaired at end of 08B all catalogues will be repaired at end of 08B

processingprocessing

deblended objects Petrosian fluxes and radiideblended objects Petrosian fluxes and radii

Photometry in regions of high nebulosity - M17 K-band Photometry in regions of high nebulosity - M17 K-band WFCAM WFCAM