Table 22
Reserved WCS keywords.
| Keyword | Primary | BINTABLE vector | Pixel List | ||
| itemize | Array | primary | alternative | primary | alternative |
|
|
|||||
| Coordinate dimensionality | WCSAXESa | WCAXna | ... | ||
| Axis type | CTYPEia | iCTYPn | iCTYna | TCTYPn | TCTYna |
| Axis units | CUNITia | iCUNIn | iCUNna | TCUNIn | TCUNna |
| Reference value | CRVALia | iCRVLn | iCRVna | TCRVLn | TCRVna |
| Coordinate increment | CDELTia | iCDLTn | iCDEna | TCDLTn | TCDEna |
| Reference point | CRPIXja | jCRPXn | jCRPna | TCRPXn | TCRPna |
| Coordinate rotation1 | CROTAi | iCROTn | TCROTn | ||
| Transformation matrix2 | PCi_ja | ijPCna | TPCn_ka or TPn_ka | ||
| Transformation matrix2 | CDi_ja | ijCDna | TCDn_ka or TCn_ka | ||
| Coordinate parameter | PVi_ma | iPVn_ma or iVn_ma | TPVn_ma or TVn_ma | ||
| Coordinate parameter array | ... | iVn_Xa | ... | ||
| Coordinate parameter | PSi_ma | iPSn_ma or iSn_ma | TPSn_ma or TSn_ma | ||
| Coordinate name | WCSNAMEa | WCSNna | WCSna or TWCSna | ||
| Coordinate axis name | CNAMEia | iCNAna | TCNAna | ||
| Random error | CRDERia | iCRDna | TCRDna | ||
| Systematic error | CSYERia | iCSYna | TCSYna | ||
| WCS cross-reference target | ... | WCSTna | ... | ||
| WCS cross reference | ... | WCSXna | ... | ||
| Coordinate rotation | LONPOLEa | LONPna | LONPna | ||
| Coordinate rotation | LATPOLEa | LATPna | LATPna | ||
| Coordinate epoch | EQUINOXa | EQUIna | EQUIna | ||
| Coordinate epoch3 | EPOCH | EPOCH | EPOCH | ||
| Date of observation | MJD-OBS | MJDOBn | MJDOBn | ||
| Average date of observation | MJD-AVG | MJDAn | MJDAn | ||
| Date/time of observation | DATE-OBS | DOBSn | DOBSn | ||
| Average date/time of obs | DATE-AVG | DAVGn | DAVGn | ||
| Reference frame | RADESYSa or | RADEna | RADEna | ||
| RADECSYS4 | |||||
| Line rest frequency (Hz) | RESTFRQa or | RFRQna | RFRQna | ||
| RESTFREQ4 | ... | ... | |||
| Line rest vacuum wavelength (m) | RESTWAVa | RWAVna | RWAVna | ||
| Spectral reference frame | SPECSYSa | SPECna | SPECna | ||
| Spectral reference frame | SSYSOBSa | SOBSna | SOBSna | ||
| Spectral reference frame | SSYSSRCa | SSRCna | SSRCna | ||
| Observation X (m) | OBSGEO-X | OBSGXn | OBSGXn | ||
| Observation Y (m) | OBSGEO-Y | OBSGYn | OBSGYn | ||
| Observation Z (m) | OBSGEO-Z | OBSGZn | OBSGZn | ||
| Radial velocity (m s-1) | VELOSYSa | VSYSna | VSYSna | ||
| Redshift of source | ZSOURCEa | ZSOUna | ZSOUna | ||
| Angle of true velocity | VELANGLa | VANGna | VANGna | ||
Notes. The indexes j and i are pixel and intermediate world coordinate axis numbers, respectively. Within a table, the index n refers to a column number, and m refers to a coordinate parameter number. The index k also refers to a column number. The indicator a is either blank (for the primary coordinate description) or a character A through Z that specifies the coordinate version. See text.
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