Catalogue format

A catalogue for the telescope computer is a set of User Interface commands, (see chapter ) exactly as typed in at a keyboard. 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 user interface commands are relevant:

• SO(URCE) defines a new catalogue entry. The format is SOURCE name. A source name may have up to 20 alphanumeric characters. Embedded spaces are forbidden, unless the name is enclosed in double quotes.
• R(A) enters the Right Ascension. The format is R hours, minutes, seconds. The last two are optional, but the command must be terminated by a semi-colon if they are omitted. Spaces are not required between the hours, minutes and seconds but it doesn't matter if you put them in.
• D(ECLINATION) enters a declination. The format is D degrees, minutes, seconds. Again, the minutes and seconds may be omitted if the command is terminated by a semi-colon. Spaces are not required between the degrees, minutes and seconds but it doesn't matter if you put them in.
• EQ(UINOX) for mean positions, a leading letter indicates the coordinate system:
  * B implies mean pre-IAU76 or FK4 (default)
  * J implies mean post-IAU76 or FK5

  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 equinox is required.

• P(ROPER-MOTION) sets the proper motions. The corresponding epoch is assumed to be the same as the equinox.
• /R(A) proper motion in RA in sec yr
• /D(ECLINATION) proper motion in Declination in arcsec yr .
• or /B(OTH) both proper motions

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:-

• The file should consist of 80-byte records (i.e. maximum of 80 characters per line).
• The filename must consist of up to 8 alphanumeric characters, starting with a letter, and must have the extension `.CAT'.
• There should be no non-alphanumeric characters such as tabs anywhere in the file.
• A line specifying default parameters and the coordinate type should be given at the beginning of the file, for example:

  .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. These are in fact the default values if DEFAULT is not included.

• The format should be:

  SO OBJECT R hh mm ss.ss D +dd mm ss.s P/R +s.sss P/D +s.sss EQ Byyyy.y

  with the coordinate type, proper motions and equinox omitted if they do not change from the default values.