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UKIDSS SV

UKIDSS SV. operational aspects, archives, flat & sky properties. Marco Riello CASU - IoA mriello@ast.cam.ac.uk. Outline. Operational aspects WFCAM archives & status pages Flats fields and skies properties. Operations: overview. Life cycle of WFCAM data at CASU:

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UKIDSS SV

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  1. UKIDSS SV • operational aspects, archives, • flat & sky properties Marco Riello CASU - IoA mriello@ast.cam.ac.uk

  2. Outline • Operational aspects • WFCAM archives & status pages • Flats fields and skies properties

  3. Operations: overview • Life cycle of WFCAM data at CASU: • Raw data arrive at CASU: dump LTO tapes to disk. • MEF creation + detection/logging of missing files. • Pipeline processing. • DQC information generation. • Transfer processed data to Edinburgh. • Raw MEF transfer to ESO (UKIDSS + calibrations only).

  4. Operations: some figures • Data volume (½ UKIDSS, ½ Private P.I.): • ~13 (3.3) Tb of raw data • ~21 (5.8) Tb of processed data • Transfers to ESO fairly slow: 0.5-0.7 Mb/sec. Only UKIDSS and calibration data, 7 nights left to transfer. • Pipeline processing is keeping up well: • ~2000-3500 images per night. Typically ~24 hr/night • 8 nights simultaneously processed (1 CPU/night). • GPS data challenging: 120000-250000 detections/MSB

  5. Pipeline processing • Reduction is group-based. • Dark and flat field correction + de-curtaining. • Creation of “sky” frames: correct for residual patterns (e.g. crud on chip #1) and reset anomaly rather than removing the sky. • Interleaving (if required) • Stacking • Catalogue creation & astrometry • Photometry

  6. Public WFCAM facilities at CASU • WFCAM raw data archive: data availability for registered users according to UKIDSS policy. Private P.I. data. • WFCAM Reduction progress monitor. • Documents and information.

  7. http://www.ast.cam.ac.uk/~mike/casu

  8. http://apm15.ast.cam.ac.uk

  9. Information organised per semester

  10. K H J Y Z K H J Y Z DQC Plots 1

  11. chip #1 #2 #3 #4 chip #1 #2 #3 #4 DQC Plots 2

  12. K H J Y Z DQC Plots 3

  13. Flat Properties The stability of the flat fields have been checked over the period April-June 2005 in all the broad-band filters: • The noise properties are stable within 0.3% in JHKYZ. • Large scale variations (corner-to-corner gradients) are presents between different flats: • Variations over a 15-20 days period usually less than 0.5% • Variations over a ~1 month period usually less than 1% • Variations over a >1 month period can be usually ~1% but can be > 2% • Conclusion: take sky-flats twice a month or, at least not less than every 20 days

  14. H June 19th April 7th

  15. Y April 12th April 7th

  16. Sky Properties • Algorithm similar to fringing correction: combine 4-12 science frames with minimum separation of 0.1 arcmin. • We have several sky frames per filter per night: each MSB is corrected using the closest sky frame in time. • The CRUD feature on chip #1: • It appears as a diffuse patch of light with some brighter spots. It is possibly due to scattered light. • It is due to the presence of dirt/dust on some of the camera lenses. Will disappear from semester 2005B.

  17. CRUD on chip #1 K 100 px/40”

  18. K NM FM

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