WFCAM Instrument Overview

The WFCAM is an ambitious instrument which will give the UK and ESO the most capable IR survey facility in the world. The instrument consists not only of a cryogenic camera holding four state-of-the-art detectors, associated electronics and computing, but also large fore-optics including a new f/9 secondary and a complete autoguiding system. A substantial data centre and archive will be established within the UK wide-field astronomy groups.

Top-level specifications

• Four 2048 x 2048 Rockwell detectors spaced by 94%
• 1-2.5 microns operation (JHKY, narrowband and Z band filters)
• 0.4" pixels giving single-exposure area coverage of 0.19 sq. degrees
• tip-tilt secondary platform to give best possible image quality
• microstepping to ensure proper sampling of the psf

Optical Design

• Forward-Cassegrain quasi-Schmidt camera design
• includes re-imaged pupil and cold stop for maximum K-band sensitivity
• optical rms image quality <0.26 arcseconds rms.
• 1 degree diameter field

Detectors

• Four Rockwell 2048 x 2048 detectors
• PACE technology rather than MBE for lower cost, less risk.

Electronics and computing

• array-limited read-out times (1-2 seconds).
• design uses four completely parallel channels - one per detector
• 128 channel SDSU system to be used
• will handle 120 GBytes/night (3 Tbyte on-line tape systems currently available)

Software

• real-time data pipeline processing to fully reduced frames
• object extraction, precision astrometry and photometry to be done off-line. This will be handled by UK Wide Field Astronomy groups and is not part of the instrument project.

Focal plane layout