A number of factors dictate the choice of field for this survey, ideally including: availability of the deepest data across the entire electromagnetic spectrum, accessibility to major ground-based facilities (e.g. ESO, ALMA, VLA) and an RA which does not clash with the other public UKIDSS surveys (e.g. the Large Area Survey and the Galactic Plane Survey).
One particular field emerges as the clear favourite. The Subaru Deep Field (02h, -05o) is already the focus of a major multiwavelength programme, driven by continually accumulating very deep optical imaging (B,V,R,I) with the Subaru SuprimeCam. This is a unique wide-field instrument, housed on an 8m telescope, which consists of a 8kX10k array giving a 24'X30' field of view. A further 38 nights on Subaru are anticipated over the next two years to complete this programme (a Subaru Key Project). This will readily provide the depth of optical data required to complement the UDS.
This is also the deepest X-ray field covering a ~1 sq. deg. region, with 7 overlapping XMM-Newton observations consisting of one deep 100 ksec in the central (30 arcmin diameter) field and 50 ksec flanking fields. The Subaru field is also a target for SIRTF legacy observations, the proposed SCUBA survey (see above) and the BLAST project (Balloon-borne Large-Aperture Sub-mm Telescope), due for launch in the winter of 2003 (Devlin 2001).