Keyword |
Read |
Write |
CTYPEia |
All coordinate systems and projection types
listed in paper II are supported (note, ``CUBEFACE'' axes are treated as
unknown linear axes). In addition, "-HPX" (HEALPix) is supported. |
Determined by the System attribute
of the SkyFrame and the WcsType attribute of the
WcsMap within the FrameSet. |
CUNITia |
Ignored (assumed to be 'degrees'). |
Not written. |
PVi_ma |
Used to create the pixel to WCS Mapping (values
are stored as attributes of a WcsMap within this Mapping). |
Values are
obtained from the WcsMap in the pixel to WCS Mapping. |
LONPOLEa |
Used to create the pixel to WCS Mapping. Also
stored as a PVi_m attribute for the longitude axis of the WcsMap. |
Only
written if not equal to the default value defined in paper II (see
``Choice of LONPOLE/LATPOLE'' below). |
LATPOLEa |
Used to create the pixel to WCS Mapping. Also
stored as a PV attribute for the longitude axis of the WcsMap. |
Only
written if not equal to the default value defined in paper II (see
``Choice of LONPOLE/LATPOLE'' below). |
RADESYSa |
Used to set the attributes of the SkyFrame. All
values supported except that ecliptic coordinates are currently always
assumed to be FK5. |
Always written. Determined by the System attribute of
the SkyFrame. |
EQUINOXa |
Used to set the Equinox attribute
of the SkyFrame. |
Written if relevant. Determined by the Equinox attribute of
the SkyFrame. |
EPOCH |
Used to set the Equinox attribute of the SkyFrame. |
Only
written if using FITS-AIPS and FITS-AIPS++ encodings. Determined by the Equinox attribute
of the SkyFrame. |
MJD-OBS |
Used to set the Epoch attribute of the
SkyFrame. DATE-OBS is used if MJD-OBS is not present. A default value based on
RADESYS and EQUINOX is used if used if DATE-OBS is not present
either. |
Determined by the Epoch attribute of the SkyFrame. Only written
if this attribute has been set to an explicit value (in which case
DATE-OBS is also written). |