A complete set of CRIRES raw calibration frames consists of three dark
exposures, a flat field, a wavelength calibration, and (optionally) a
telluric and/or spectro-photometric standard star. Darks and flats are
measured daily during daytime. Dedicated wavelength calibrations are normally
only necessary for settings below 2500 nm. Standard stars are only observed
on request. In addition to these calibrations, a series of darks and flats
with increasing DIT is measured daily in order to assess detector non-linearities.
These detlin calibrations apply to all settings.
Dark exposures are processed in an elementary way without other calibration
products. The same is true for detlin calibrations. Flat fields need a
master dark product (CALPRO_DARK) with the same DIT and the detlin correction.
The outcome of the flat recipe is a normalised flat (CALPRO_FLAT) and
a bad pixel map (CALPRO_BPM). Both products are used by the wavelength
calibration recipe in order to reduce fixed-pattern noise and to mask
bad pixels which might be misinterpreted as spectral features. The normalised
flat should have the same reference wavelength as the wavelength calibration;
the bad pixel map can be from any setting.
Science and standard star observations are processed with the same recipe.
It uses a master dark, non-linearity correction, a normalised flat, and
a wavelength solution. A dark frame is not necessary for observations
in nodding mode. A wavelength solution can be skipped if enough sky lines
are present in the science/standard exposures.
The calibration scheme for CRIRES is summarised in the map below. It
includes only calibrations that are measured regularly. Static calibration
tables like lines lists and flux tables for standard stars are not included.
CRIRES calibration cascade [click
for full view].
Raw calibration files
are described here.
Calibration products are described here.
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![[click for full view]](../img/CRIRES_cal_map_thumb.png) |
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