The shift map provides the distorsion and dispersion calibration laws. The measurement is made using plastic foils which provides a good estimate of the WL to pixel relation at low spectral resolution. For higher resolution, this measurement is not accurate enough and the fine spectral calibration is performed by means of sky measurements which are systematically recorded during the scientific observations.
The input
data contains a series of images containing the laboratory background for
each pinehole and for the slit (DISTOR_HOTDARK and SPECTRA_HOTDARK), a
serie of images of the three pinholes (DISTOR_IMAGES), a serie of
spectral images (SPECTRA_IMAGES), the static bad pixel map (BADPIX),
the static nonlinearity map (NONLINEARITY) and the observation specific
flatfield map (OBS_FLATFIELD).
Due to the different optical paths, the photometrics and interferometric channels are not aligned in spectral and spatial directions. The optical elements produce different distorsions in the different channels.
This plugin calculates the distorsion coefficients of the photometric
and interferometric channels, and it determines the relative shifts
between each photometric channel and the interferometric one.
The input
data are:
a series of images containing the laboratory background for
each pinehole and for the slit (DISTOR_HOTDARK and SPECTRA_HOTDARK),
a
series of images of the three pinholes (DISTOR_IMAGES),
a series of
spectral images (SPECTRA_IMAGES),
the observation specific
flatfield map (OBS_FLATFIELD),