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FITS Keywords
Eric E Palmer edited this page Oct 23, 2026
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| Category B | Version 3.0.1 |
|---|
This list shows the keyword that process-fits reads, the SPC variable it sets and a description explaining the setting.
| FITS Keyword | Levels | SPC Variable | Description |
|---|---|---|---|
| BITPIX | 0/1 | BITPIX | This sets the flag in SPC for how many bits to treat the data. Everything is eventually converted into unsigned integer. For ORex, the level 0 data is 16. The camera is a 14-bit imager, but the SPOC will pad the leading bits to 0 to make it a simple unsigned 16-bit integer. IF a LUT (look-up-table) is used, the SPOC will convert the 8-bit LUT into the standard 16-bit integers. For level 1, it is set to -32, which is 32-bit signed. |
| DATE_OBS | 0/1 | UTC0 | The UTC time of the observation. This is converted within SPC via SPICE into ET, setting both ET0 and ET. |
| EXPTIME | 0/1 | EXP | The duration of the exposure. It is used to calculate the midpoint of the exposure. This is _ used for OREx. |
| SCLK_STR | 0/1 | CLK0 and CKLUSE | This is the spacecraft clock. If this value is set in the FITS headers, it is the primary time used to calculate the midpoint of the exposure. |
| NAXIS1 | 0/1 | NPX | Number of pixels wide (the x value) |
| NAXIS2 | 0/1 | NLN | Number of pixels tall (the y value) |
| CAMERAID | 0/1 | CAM | Which camera is being used. Values are 0-Map, 1-Sam, 2-Poly |
| MTR_POS | 0/1 | FLT | Defines the position of the PolyCam motor, which is used to calculate its focal position. For MapCam and SamCam, it provides the position of the filter wheel in degrees. |
| LUT | 0 | LUT | If LUT is defined, this tells what LUT was used on the spacecraft. No processing is done via SPC because the SPOC has already done it. This variable isn't used |
| MCFWHTMP | 0/1 | NTX (1,1) | MapCam temperature. The final algorithm has not been decided yet. However, the weighting of each temperature can be adjusted in the file DN2TEMP.TXT. This assumes a linear mixing of the four camera temperatures. Level 0 is in DN. Level 1 is in degrees C |
| MCFWMTMP | 0/1 | NTX (1,2) | see above |
| MCLENTMP | 0/1 | NTX (1,3) | see above |
| MCROETMP | 0/1 | NTX (1,4) | see above |
| SCFWHTMP | 0/1 | NTX (2,1) | SamCam temperature. The final algorithm has not been decided yet. However, the weighting of each temperature can be adjusted in the file DN2TEMP.TXT. This assumes a linear mixing of the four camera temperatures. Level 0 is in DN. Level 1 is in degrees C |
| SCFWMTMP | 0/1 | NTX (2,2) | see above |
| SCLENTMP | 0/1 | NTX (2,3) | see above |
| SCROETMP | 0/1 | NTX (2,4) | see above |
| PCFWHTMP | 0/1 | NTX (3,1) | PolyCam temperature. The final algorithm has not been decided yet. However, the weighting of each temperature can be adjusted in the file DN2TEMP.TXT. This assumes a linear mixing of the four camera temperatures. Level 0 is in DN. Level 1 is in degrees C |
| PCFWMTMP | 0/1 | NTX (3,2) | see above |
| PCLENTMP | 0/1 | NTX (3,3) | see above |
| PCROETMP | 0/1 | NTX (3,4) | see above |
| NCCHTEMP | 0 | NTX (4,0) and NTX (4,1) | NavCam temperature. |
| TCCHTEMP | 0 | NTX (5,0) and NTX (5,1) | TAGCam temperature |
| SC_QA | 0/1 | QT(0) | Quadterians. OREx will write the spacecraft pointing information, as of when the image was taken, into the FITS header. process_fits will output them in the file quaternions.txt in the format PICNM, QT(I), I=0,3 |
| SC_QX | 0/1 | QT(1) | see above |
| SC_QY | 0/1 | QT(2) | see above |
| SC_QZ | 0/1 | QT(3) | see above |
| BZERO | 0 | DDN and SIGNED | FORTRAN reads all integers as signed. Because the data is unsigned, then the DN values less than zero are converted into high-bit values. |
| INSTRUME | 0/1 | INAME and NC | Level 0 has OCAMS, so NC is set via CAMERAID-1. This is the name of the instrument in human-readable form. It sets the variable NC as follows: |
| INSTRUME | NC | Comment |
|---|---|---|
| MAP | N/A Because INSTRUME will be OCAMS | |
| SAM | N/A Because INSTRUME will be OCAMS | |
| POL | N/A Because INSTRUME will be OCAMS | |
| NCM | 4 | |
| NFT | 5 | |
| OCAMS | CAMERAID+1 |
. /!\ The order of this is important because the camera number is the reference that SPC uses for camera ID within the configuration files make_sumfiles.txt, DN2TEMP, and FLATFIELD.TXT.