This CCF contains the wavelength and flux calibrations for the two OM grisms, GRISM1 (or UV grism) and GRISM2 (or Visible grism). It is used by the SAS.
The wavelength calibration is provided in two tables, one per grism, containing the value of the wavelength corresponding to each pixel in the extracted spectrum, counted from the centroid of the spectrum zero order in the undistorted and rotated image.
The flux calibration is also provided in two tables, one per grism. They define the Inverse Sensitivity Function (ISF) in three columns containing wavelength, value of the ISF and its percentage error. The ISF's are defined in the intervals 1800 - 3600 A for GRISM1, and 3000 - 6000 A for GRISM2. The sampling of the ISF's is 40 A.
When applying the flux calibration, the ISF has to be interpolated for each wavelength in the extracted net spectrum, within the calibrated range. Points outside this range are zeroed.
A header keyword ALGOID has been introduced to prevent the usage of the CCF Version 4 (the latest one) with SAS versions earlier than 7.
The format of the Grism calibration CCF component is described in detail below.
Binary table: FLUX_GRISM1
| column name | column type | column unit | comment |
| WAVELENGTH | E | Angstrom | |
| ISF | E | erg/cm2/count | Inverse Sensitivity Function |
| ISF_error | E | % | Error on ISF |
Binary table: FLUX_GRISM2
| column name | column type | column unit | comment |
| WAVELENGTH | E | Angstrom | |
| ISF | E | erg/cm2/count | Inverse Sensitivity Function |
| ISF_error | E | % | Error on ISF |
Binary table: WAVELENGTH_GRISM1
| column name | column type | column unit | comment |
| WAVELENGTH | E | Angstrom |
Binary table: WAVELENGTH_GRISM2
| column name | column type | column unit | comment |
| WAVELENGTH | E | Angstrom |