User input catalogues are either typed into the TCS (Telescope Control System) computer on line, or loaded via the 1600bpi 9-track tape. A tape in the right format can be prepared and loaded by support staff, given a user catalogue on VMS or Unix. Observation catalogues may be be typed into the telescope computer directly through the user interface or using the OS32 editor. If you have an extensive catalogue this is best done in the afternoon before you start observing. Catalogues can of course be saved to disc, so they are available from night to night, but will normally be deleted at the end of an observing run.
It is possible to select guide stars in advance of an observing run (see Section . on the Guide Star System and Section for allowed positions). Their positions should be entered in the catalogue in the normal way.
A catalogue for the telescope computer is a set of user interface commands, exactly as typed in at a keyboard. The relevant commands are given below. Minimum matching is used, and portions of commands which may be omitted are given in brackets (e.g. the command SOURCE may be shortened to SO). Spaces or semi-colons may be used as separators, the latter being essential if the command is abbreviated (see RA and DECLINATION, below). Anything following an asterisk is treated as a comment and is ignored. The following commands are available:
A number indicates the epoch of the mean equator and equinox of that system (e.g. B1950.0, J1987.5).
The remaining option is APPARENT (abbreviable to A), for which no number is required.
A catalogue may be in free format. For legibility and neatness, however, it is worth adhering to a more rigid tabular format with one object per line of the file. The format should be as follows:
.DEFAULT EQUINOX B1950 P/R 0.0 P/D 0.0
sets the default equinox to 1950 and the default proper motions to zero and specifies mean coordinates. If these parameters are not specified explicitly for objects in the file, then they will take these values.
SO OBJECT R hh mm ss.ss D +dd mm ss.s P/R +s.sss P/D +s.sss EQ B yyyy.y
with the coordinate type, proper motions and equinox omitted if they do not change.