WFCAM (Wide Field Camera) is a wide-field infrared camera on the UK Infrared Telescope (UKIRT) on Mauna Kea, Hawaii, and one of the most capable infrared survey instruments in the northern hemisphere. CASU processed all WFCAM data, for surveys including UKIDSS, UHS and the Galactic Clusters Survey.
WFCAM is a wide-field infrared camera on the UK Infrared Telescope (UKIRT) on Mauna Kea, and one of the most capable infrared survey imagers in the northern hemisphere. It has four Rockwell Hawaii-II detectors of 2048×2048 pixels, each pixel 18 microns across, giving a pixel scale of 0.4″ (f/2.4) and 0.21 square degrees of sky per exposure.
Each detector is split into quadrants, and each quadrant into eight channels of 128×1024 pixels. The detectors are spaced 94% of a detector width apart, so four exposures are needed to cover a continuous area (a tile) of 0.8 square degrees.
WFCAM has eight filter slots, holding the broadband Z, Y, J, H and K filters and two narrow-band filters, H2 and Brγ. On an average night it produces about 140 GB of data (2,200 images), and up to 230 GB on the busiest nights.
Instrument characteristics
| Detectors | 4 Rockwell Hawaii-II (HgCdTe 2048×2048) |
|---|---|
| Pixel scale | 0.4″ per pixel |
| Field of view | 0.8 sq. deg. (4 pointings per tile) |
| Grasp | 2.38 m² deg² |
| Data volume | About 140 GB per night |
| Filters | Z Y J H K H2 Brγ |
UKIDSS and other surveys
WFCAM was used mainly for the UKIRT Infrared Deep Sky Survey (UKIDSS), which was made up of five surveys covering everything from the Galactic Plane to deep extragalactic fields. CASU did all the primary data processing: bias subtraction, dark correction, flat-fielding, sky subtraction, astrometric and photometric calibration, and making the source catalogues.
Data processing
CASU processed all the data taken with WFCAM. The data arrived in Cambridge on LTO-I tapes as single-extension FITS files. They were copied to RAID disks and converted to multi-extension FITS, with one file holding the images from all four detectors. The calibrated images and catalogues were then made available through the WFCAM Science Archive (WSA), run by WFAU in Edinburgh.
