Ground calibrations
The following pre-processed ascii files contain selected data from ground calibrations.
Labels are contained in the file GROUND.LBL.
- Gain = 1
- Constant mirror position = 0
- Focal plane temperature = -60°C
- Set of 14 x 9 averaged spectra with dark current removed.
The instrument lies on a moving platform and looks at a Glowbar (a black body at about 1400 K with non-uniform temperature, i. e. with a spatial structure). The instrument mirror remains in rest position, but the movement of the platform is used to scan the source laterally (azimuth) and vertically (elevation) so as to acquire an image of the Glowbar. The IDL routine litbidim.pro reconstitutes and plots images of the source in each spectral channel. The shift between images in odd and even channels is due to detectors implementation in the focal plane and is close to 23. The shift between images in channels of identical parity is a measure of channels misregistration, and was used to check and refine correction coefficients in Decal2.dat (see DocISM.pdf). Spectra are averages of several observations with dark current subtracted.
- Gain = 1
- Constant mirror position = 0
- Focal plane temperature = -65°C
Observations of an extended black body at different temperatures (121.5°C and 113°C respectively). Spectra are averaged spectra and dark current is subtracted. The ratio of these two spectra permits to estimate the transfer function in the high wavelength range (no detectable signal is emitted below 1.7 µm). The output signal in the short wavelength range is due to spectral orders overlap only, and actually corresponds to photons with 2 x the nominal wavelength. This ratio was also used to refine the transfer function of first grating order in the short wavelength range. These files can be plotted using IDL routine Affspe.pro.
