GSC+: software for transferring the Guide Star Catalogue on the FK5 system

Software is developed for selection of star coordinates from the Hubble Space Telescope Guide Star Catalogue (GSC) CD-ROM and for correcting them for three kinds of systematic errors: (1) sky-based errors produced by reference catalogues, (2) plate-based errors produced by telescope optics and by incompleteness of the plate reduction model and (3) plate-based magnitude dependent errors produced by telescope optics and by incompleteness of the plate reduction model. GSC can be used now as a reference catalogue representing the FK5 system on about 0.4 arcsec accuracy level. Further improvement of GSC, including individual plate error correction, is now under development.