The APM Sky Catalogues: Overview

Over the last few years we have used the APM facility to measure the first epoch Palomar O and E sky survey plates, with the aim of constructing a readily accessible Northern sky optical catalogue (see Gemini No. 37 and Spectrum No. 2 for more details). We now have available an on-line catalogue which includes fields to within tex2html_wrap_inline34 of the Galactic Plane. Most of the on-line catalogue covers the North Galactic cap, centred at tex2html_wrap_inline36 , whilst the South Galactic cap appears in two regions located at around tex2html_wrap_inline38 and tex2html_wrap_inline40 . The catalogue is based on digitised scans of both the blue O plates and red E plates covering some 15000 square degrees of sky and with parameters for well over 150 million images recorded. Both B1950 and J2000 astrometry is available and was calibrated by using the appropriate 200+ PPM astrometric standards per Palomar field. More details of the accuracy of astrometry derived from Schmidt plates are given in an article published in the Working Group on Wide Field Imaging - Newsletter 5 p25-30.

A similar catalogue is in the process of being constructed for the Southern hemisphere based on UKST sky survey IIIaJ and IIIaF plates. This is being put on-line in a similar manner to the Palomar survey as it becomes available. The main limitation in construction of the Southern catalogue is the limited number of SES R survey plates in the high latitude fields south of tex2html_wrap_inline42 .

Mike Irwin