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Description of FITS catalogues

 

FITS tables containing source lists are produced for each image by Mike Irwin. There is one source list for each CCD in a given image. They can be found at the same location as the images.

A typical header indicating the nature of fields in the FITS table can be found in Appendix 3. Source positions are given as RA and DEC and as X- and Y- coordinates relative to a reference point; the projection used is Zenithal Polynomial (ZPN). Further information on the contents of the headers anf the definition of each column is available in [4]. The highest magnitude detected varies according to the exposure time but never exceeds 29 and the g--band isusually the deepest, although the i--band will be used for XID purposes because it is consistently available for every field with WFC data. The shallowest band is usually the U--band. Number densities vary between 20000 and 75000 per square degree depending on the depth and on each field's galactic latitude, as can be seen on Fig. gif(d).



Richard McMahon
Tue Feb 27 19:50:01 GMT 2001