ATL_WCSPX

Create a WCS FrameSet from a SPECX file

Description:

This returns a pointer to a FrameSet describing the WCS information in a SPECX file. The current Frame is a 3D Frame with RA on axis 1, DEC on axis 2, and frequency on axis 3. The base Frame is a 3D GRID Frame. The parameters defining the axes are read from two supplied AST KeyMaps, which should contain values for various items read from a SPECX and SPECX_MAP extensions in a SPECX map (the observatory location are provided separately by the caller).

Invocation

CALL ATL_WCSPX( KM1, KM2, CRPIX, OBSLON, OBSLAT, IWCS, STATUS )

Arguments

KM1 = INTEGER (Given)
Pointer to an AST KeyMap holding items read from the SPECX extension in the required SPECX map file. The key for each entry is identicial to the name of the item in the SPECX extension. It should contain entries with the following keys (the data type with which each entry is accessed is also shown):

" JFREST(1)" - _INTEGER " RA_DEC(1)" - _DOUBLE " RA_DEC(2)" - _DOUBLE " DPOS(1)" - _DOUBLE " DPOS(2)" - _DOUBLE " IDATE" - _CHAR " ITIME" - _CHAR " LSRFLG" - _INTEGER " V_SETL(4)" - _DOUBLE " JFCEN(1)" - _INTEGER " JFINC(1)" - _INTEGER " IFFREQ(1)" - _DOUBLE

In addition, the KeyMap may contain an item " CENTRECODE" (_INTEGER) that specifies the co-ordinate system to which the RA_DEC and DPOS values refer. It may take any of the following values:

1 : AZEL 4 : RD (geocentric apparent RA and Dec) 6 : RB (FK4 1950 RA and Dec) 7 : RJ (FK5 2000 RA and Dec) 8 : GA (galactic longitude and latitude)

An error is reported if any other value is supplied for CENTRECODE. If CENTRECODE is missing a value of 6 (FK4 B1950) is assumed.

KM2 = INTEGER (Given)
Pointer to an AST KeyMap holding items read from the SPECX_MAP extension in the required SPECX map file. The value AST__NULL should be provided if the SPECX file does not have a SPECX_MAP extension. If supplied, it should contain entries with the following keys:

" CELLSIZE(1)" - _DOUBLE " CELLSIZE(2)" - _DOUBLE " POSANGLE" - _DOUBLE

In addition, the KeyMap may contain an item " CELLCODE" (_INTEGER) that specifies the co-ordinate system to which the CELLSIZE and POSANGLE values refer. It may take any of the values listed for CENTRECODE in the " KM1" argument description above. If CELLCODE is missing a value of 6 (FK4 B1950) is assumed.

CRPIX( 3 ) = DOUBLE PRECISION (Given)
The pixel co-ordinates at the reference point. The spatial position of the reference point is given by RA_DEC(1) and RA_DEC(2) offset by the DPOS(1) and DPOS(2) values (all these are in the KM1 KeyMap). The spectral reference value is given by the JFCEN item in KM1.
OBSLON = DOUBLE PRECISION (Given)
The geodetic longitude of the observatory. Radians, positive east.
OBSLAT = DOUBLE PRECISION (Given)
The geodetic latitude of the observatory. Radians, positive north.
IWCS = INTEGER (Returned)
The returned FrameSet.
STATUS = INTEGER (Given and Returned)
The global status.

Notes: