An overview of all calibration files present in either the IDPD or in the OSIA system, is given. For each of these files there can be several versions, one for each phase in the mission. Which version is used to process a dataset is defined in the STIMEDEP file.
Not all of these calibration files are actually used in the OLP. Some of them were only for calibration purposes, like Cal-G 8 and Cal-G 16D. Others have become obsolete in the course of the mission, like Cal-G 2B and Cal-G 16E.
In all cases the ISO Data Product Document, [34] should be referred to for the exact file layout. The files are given the names `SCNN_XXX.FITS' in the archive, where `NN' denotes the calibration file number, like `01', `02A', `25_3C' etc, and `XXX' denotes the version number of that file (different versions may be used for different revolutions as already mentioned), and can be `010', `021' etc.
This file is used in Derive-SPD to correct for the effects of electrical cross-talk (see Section 7.2.7).
The file contains 12 records, each 52 integers in length. The first 12 numbers in each record contain the cross-talk for band 1, the next 12 for band 2 etc. Record 1 contains the cross-talk between detector 1 in each band and the other detectors in that band, record 2 contains the cross-talk between detector 2 in each band and the other detectors in that band, etc. Only records 1 and 2 contain information for bands 5 and 6 (the FP bands with only 2 detectors in each).
This file, used in Derive-SPD, contains the time constants for the high pass filter in the amplifier chain (see Section 7.2.5). It contains 52 numbers, the time scales per detectors in seconds.
This file, used in Derive-SPD, contains the `midbit' value for each
detector (see Section 7.2.3). The detector readouts are
between 0 and 4095 (bits) corresponding to 
10 to 
10 Volts. The `midbit'
is the bit value that corresponds to 0 Volts, approximately 2048, and
is different for each detector.
Currently this calibration file is filled with 2047.50.
This is an obsolete calibration file. The pulse shapes are never constant. Consequently they could not be caught into a single calibration file. Since OLP 9 they are corrected for each observation individually. See Section 7.2.6.
This file, used in Derive-SPD, contains the number of 24Hz readouts to ignore after a reset (short circuit of the capacitor) (see Section 7.2.2). It contains 52 numbers, one number per detector.
This file, used in Derive-SPD, contains the limits of the digital data range (see Section 7.2.2). There are 52 records, each of which contains the minimum and maximum values (in bits between 0 and 4095) for the three gains.
This file, used in Derive-SPD, contains the actual gain applied to the signal before AD-conversion (see Section 7.2.10). There are 52 records, one per detector. Each record contains three numbers, one for each gain.
This file, used in Derive-SPD, contains information used to recognise
glitches and reject them (see Section
7.2.8). It contains 52 records, one per detector. Each
record contains four numbers: 
, the signal-to-noise level above
which a point is marked as a glitch; the number of readouts to ignore
before and after a glitch; and the minimum noise level in the signal.
In the glitch detection algorithm of OLP v10 only the -number and
the minimum noise is used. See Section 7.2.8.
For each of the 6 SWS bands noise characteristics are given, split in 3 items: read-noise, dc-noise and signal noise.
Lists for each of the 48 grating detector elements the measured LVDT,
the intensity (
V/s) and the wavelength of the peaks produced
by the grating calibrator source, with the source intensity HIGH for all
bands. This file was used for regular updates of the grating polynome in
the SW section resulting in updates for Cal-G 16E and Cal-G 16ET.
For the LW section Cal-G 8a was used.
Lists for each of the 48 grating detector elements the measured LVDT,
the intensity (V/s) and the wavelength of the peaks produced
by the grating calibrator source, with the source intensity LOW for all
bands. This file was used for regular updates of the grating polynome in
the LW section resulting in updates for Cal-G 16E and Cal-G 16ET. For
the SW section Cal-G 8 was used. The SW section (dets 1 to 24) of Cal-G
8A is still filled with data from an outdated version of Cal-G 8.
This file lists the relation between LVDT and the grating angle, both for the SW and the LW sections. It is not in use any more. It is replaced by the grating polynome using values from Cal-G 16ET.
This file should list the key wavelengths for each of the bands. It has been replaced by Cal-G 13. The file is not present in the archive.
This file contains the fixed FP transmission peak wavelengths for the FM. These peaks are used as reference during the FP wavelength calibration. The peak wavelengths are determined at high accuracy in the laboratory by a Fourier Transform Spectrometer.
This file, used in Derive-SPD, contains information on the gap, current and position relationship of the two FPs (see Sections 7.2.11.2 and 4). Each record contains the FP position (a number calculated from slow housekeeping data) applicable to both FPs, and for each FP the size of the gap. It also contains the main current and two correction currents pertaining to the FP position, but these are not used as the FP position is not obtained from the FP currents.
This file is used in Auto-Analysis for determining key wavelengths and passbands e.g. when normalising the RSRF. There is one row per key wavelength. Each row has the name of the band, the key wavelength, two numbers defining the passband used.
It contains more information which was used in previous versions of the
OLP for the flux calibration. These numbers have been replace by
information from Cal-G 42. This extra information consists of
conversion numbers for each detector in that band (by default 12, with
10 blank for FP bands) in V/s/Jy, 12 internal calibration
signals (in V/s), 12 relative flux calibrations (in Jy), errors
on the conversion numbers (in V/s/Jy), errors on the internal
calibrations (in V/s), errors on the relative flux calibrations
(Jy) and finally the grating start and end position.
The intensity for each of the calibration sources (in both settings, low and high) is given at a specified wavelength. This calibration file has never been in actual use. The file is not available within IA.
For the grating and the FP the maximum wavelength shift is given which is permitted for an observation. This calibration file was never in actual use as the wavelengths were very stable from observation to observation. The file is not available within IA.
This file, used in Derive-SPD, contains the angles, in degrees, from the optical axis to the entrance or calibration source used, as seen from the SW and LW collimators (see Section 7.2.11.1).
This file, used in Derive-SPD, contains the angles, in degrees, from the optical axis to each of the detectors (see Section 7.2.11.1).
This file, used in Derive-SPD, contains two grating constants, in m, for
the SW and LW gratings (see Section 7.2.11.1).
This file contains the size of the telescope area, in m
. It is
nowhere used in the data processing.
This file contains the scanner curve coefficients derived at several time intervals during the mission. It is not used anymore in Derive-SPD, where it has been replaced by Cal-G 16ET (see Section 4).
This contains the scanner curve coefficients needed to transform the LVDT values into incidence angles. The values are presented at a number of intervals suited for linear interpolation in time within Derive-SPD (see Section 7.2.11.1).
This file, used in Derive-SPD, contains information of the effective gap
correction. For each possible FP wavelength there is a gap correction
for each of the two FPs. All units are m.
Cal-G 19 is used in the processing of all speed SWS01s. It contains the factors needed to smooth the RSRFs of each band down to the spectral resolution of the SWS01 being processed and hence match the resolutions.
These 4 files, Cal-G 21_1, Cal-G 21_2, Cal-G 21_4 and Cal-G 21_8
contain information on the dark current. There is one file per reset
interval. Each file contains 52 records, each containing the detector
number, the average measured dark current (from ground and PV phase
tests), the noise in the dark current and finally the minimum and
maximum valid dark currents. Dark currents are measured in V/s.
They are used in Derive-AAR to check whether the observed dark currents
are within the bounds. If not a warning is issued (and subsequently
completely ignored).
This file, used in Derive-SPD, contains information on the wavelength
limits for the six detector bands. There is one row for each band, and
each row contains the lower and upper wavelength limits in m.
See also the next entry, Cal-G 24.
This file, used in Derive-SPD, contains information on the wavelength
limits for the three apertures. There are five rows, one row for each
aperture plus two for calibrators, and each row contains the lower and
upper limit wavelength limit for the two subsystems, in m.
Together with Cal-G 23 they determine which order is seen for all
grating settings by each of the bands, essentially which band is seen.
These files, Cal-G 25_1A, Cal-G 25_1B, Cal-G 25_1D, Cal-G 25_1E, Cal-G 25_2A, Cal-G 25_2B, Cal-G 25_2C, Cal-G 25_3A, Cal-G 25_3C, Cal-G 25_3D, Cal-G 25_3E, Cal-G 25_4, Cal-G 25_4a, Cal-G 25_4c, Cal-G 25_4d, Cal-G 25_5A, Cal-G 25_5B, Cal-G 25_5C, Cal-G 25_5D and Cal-G 25_6, contain the spectral responsivity information (RSRF) for each band.
Each is composed of the number of detectors in that band (twelve for
grating, two for the FP files Cal-G 25_5x and 25_6) times three
numbers. These are the wavelengths at which the responsivity is
measured (in m), the responsivity and the error on it, both in
.
Files Cal-G 25_4A, Cal-G 25_4B and Cal-G 25_4C are used for off-band data. They are not in the OLP products but can only be reached with OSIA.
These files, Cal-G 35_1A, Cal-G 35_1B, Cal-G 35_1D, Cal-G 35_1E,
Cal-G 35_2A, Cal-G 35_2B, Cal-G 35_2C, Cal-G 35_3A, Cal-G 35_3C,
Cal-G 35_3D, Cal-G 35_3E, Cal-G 35_4,
Cal-G 35_5A, Cal-G 35_5B, Cal-G 35_5C, Cal-G 35_5D
and Cal-G 35_6, contain the beam profile
information for pointing and jitter
correction. There is one file for each of the bands. The beam
profile is given at a sampling of 0.1 arcsec in the y-axis (cross
dispersion) and z-axis (dispersion) for the key wavelength over an area of 
10 arcsec. In some bands the beam
profile is given at two key wavelengths.
These files, Cal-G 36_1A, Cal-G 36_1B, Cal-G 36_1D, Cal-G 36_1E,
Cal-G 36_2A, Cal-G 36_2B, Cal-G 36_2C, Cal-G 36_3A, Cal-G 36_3C,
Cal-G 36_3D, Cal-G 36_3E, Cal-G 36_4,
Cal-G 36_5A, Cal-G 36_5B, Cal-G 36_5C, Cal-G 36_5D
and Cal-G 36_6, contain beam profile information
for extended source flux correction information. There is one file for
each of the bands. The beam profile is given at a sampling of 1
arcsec in the y-axis (cross dispersion) and z-axis (dispersion) for the
key wavelength over an area of 6 arcmin.
In some bands the beam profile is given at two key wavelengths.
Cal-G 40 contains the extreme positions in LVDT for both scanners. It was used for deriving uplink tables for SWS01 observations, and also to monitor the instrument. It has no use in data processing.
Cal-G 41 contains for every detector the average flux at each of the 22 grating positions that were used during a photometric check. These fluxes are compared bandwise with the observed fluxes to determine the relative sensitivity of the band. See Section 7.3.5.2.
This contains the factors used in converting from signal, in V/s,
to flux, in Jy. The errors in the flux conversion are also stated. It is
used in the flux calibration stage, see Section 7.3.5.3.
Cal-G 43 contains the flat-fielding factors for all detectors within each of the bands. Flat-field errors are also given. It used in pipeline Section 7.3.5.1.
The Time Dependency file defines which version of the Cal-G files is used to process an observation. It lists the file (or files) which are valid for what observations.
