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5.7 Calibration Files

5.7.1 Calibration-G files

The instrument characteristics required for the processing of the ISOPHOT raw data into calibrated products are stored in calibration files which are referred to as general calibration products: `Calibration-G' or `Cal-G' files. All Cal-G files are in FITS format. The Cal-G files are updated depending on the outcome of the dedicated calibration observations.

In Table 5.1 the types of Cal-G information mentioned in this chapter are listed together with references to the full descriptions elsewhere in this manual. A complete description of all Cal-G files can be found in Chapter 14.

Table 5.1: Cal-G files related to the parameters described in this chapter.
parameter Description full description
$H(S)$ Correction for signal non-linearities Section 14.8
$\zeta(S_{src},\,det,\,t_{dwell})$ Correction for chopped signal losses Section 14.10
$c_{chop}(f,i,\theta)$ Correction for chopper vignetting/offset Section 14.11
$P_{fcs}^{f}(h)$ FCS power calibration tables Section 14.12
$S^{det}_{dark}$ Orbit dependent dark signals Section 14.7
$R_{det}$ Default detector responsivities Section 14.13
$A(a)$ Area of the aperture in mm$^2$ (hardcoded) Section A.1.2
$f^f_{PSF}$ Point Spread Function factors Section 14.18
${\alpha}^f(a)$ Inhomogeneous FCS illumination of PHT-P Section 14.15
${\Gamma}^{f}(i)$ Array Illumination by FCS Section 14.14
${\chi}^{f}(i) $ Wavelength dependent detector flat-fields Section 14.17
$\varphi(i,S,t)$ Conversion from staring PHT-S signal to flux density Section 14.9
$g(i,S,t)$ Weight factors related to correction $\varphi(i,S,t)$ Section 14.9
${\Omega}_{eff}^{f}$ Effective solid angles of apertures and pixels Section 14.21
$\lambda(i)$, $C^{c,p}_{ave}(i)$, $C^{s,p}_{ave}(i)$ PHT-S wavelength and average spectral response functions Section 14.19
$A_0(i)$, $A_1(i)$ First order signal corrections for PHT-S chopped Section 14.19
$k_f$ Colour corrections Section 14.22

5.7.2 Calibration-A files

In contrast to the general calibration files applicable per instrument mode, there are calibration products per observation. These are related to the FCS measurements which are part of all PHT AOTs except PHT40. The resulting products are called `Calibration-A' or `Cal-A' files. Cal-A files are generated at the SPD processing level. Among other data items the Cal-A products contain the signal per chopper plateau of the FCS measurement. The FCS heating power as well as the expected in-band power is provided so that the responsivity of the detector close to the time of the target measurement can be obtained. The derived responsivity together with its uncertainty for each detector pixel has been included in the FITS header of the related SPD product.

See also Sections 13.3.7 and 13.3.8.

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ISO Handbook Volume IV (PHT), Version 2.0.1, SAI/1999-069/Dc