IRA_GETEQ - Extracts the epoch of the reference equinox from a string specifying a Sky Co-ordinate System

Description:

If, on entry, the argument SCS contains an explicit equinox specifier (see routine IRA_ISCS), the epoch contained within it is returned in argument EQU as a double precision value, and argument BJ is returned equal to the character "B" or "J" depending on whether the epoch is Besselian or Julian. If there is no equinox specifier in argument SCS on entry, then the default of B1950 is returned.

If the sky co-ordinate system specified by SCS is not referred to the equinox (e.g. GALACTIC) then EQU is returned equal to the Starlink "BAD" value VAL__BADD, and BJ is returned blank.

The argument NAME is returned holding the full (unabbreviated) name of the sky co-ordinate system without any equinox specifier. On exit, the argument SCS holds the full name plus an explicit equinox specifier (for systems which are referred to the equinox). Thus, if SCS contained "EQUAT" on entry, it would contain "EQUATORIAL(B1950)" on exit.

Invocation:

CALL IRA_GETEQ( SCS, EQU, BJ, NAME, STATUS )

Arguments:

SCS = CHARACTER $*$ ( $*$ ) (Given and Returned)

On entry this should contain an SCS name (or any unambiguous abbreviation), with or without an equinox specifier. On exit, it contains the full SCS name with an explicit equinox specifier (for those sky co-ordinate systems which are referred to the equinox). If no equinox specifier is present on entry, then a value of B1950 is used (if required). This variable should have a declared length given by the symbolic constant IRA__SZSCS.

EQU = DOUBLE PRECISION (Returned)

The epoch of the reference equinox. This is extracted from any explicit equinox specifier contained in SCS on entry. If there is no equinox specifier in SCS, a value of 1950.0 is returned. If the sky co-ordinate system is not referred to the equinox (e.g. GALACTIC) the Starlink "BAD" value (VAL__BADD) is returned, irrespective of any equinox specifier in SCS.

BJ = CHARACTER $*$ ( $*$ ) (Returned)

Returned holding either the character B or J. Indicates if argument EQU gives a Besselian or Julian epoch. Returned blank if the sky co-ordinate system is not referred to the equinox.

NAME = CHARACTER $*$ ( $*$ ) (Returned)

The full name of the sky co-ordinate system without any equinox specifier. This variable should have a declared length given by the symbolic constant IRA__SZSCS.

STATUS = INTEGER (Given and Returned)

The global status.