User Manual
Doc. Number: ESO-323064
Doc. Version: 2
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81 of 82
Document Classification: Public
7.4 Data format and reduction
7.4.1 Format
The SV image and the spectra recorded on the three science detectors are saved in
extended FITS files. Each of the 3 extensions of the science images has a size of 2048 x
2048 pixels (see Figure 6).
7.4.2 Selection of CRIRES FITS header keywords
FITS header keyword
Parameter
OBJECT
Object name
MJD-OBS
Modified Julian Date at start of exposure
HIERARCH ESO DET SEQ1 DIT
Length of sub exposure (DIT) in seconds
HIERARCH ESO DET NDIT
Number of sub exposures (NDIT)
HIERARCH ESO INS WLEN ID
Name of the selected wavelength setting
HIERARCH ESO INS SLIT1 WID
Slit width in arcsec
HIERARCH ESO INS OPTI8 NAME
Decker position for polarimetry
HIERARCH ESO INS1 OPTI1 NAME
Optical element (polarimeter, gas cell, ...)
from the carriage in the light path.
HIERARCH ESO SEQ NODPOS
Nodding position (A or B)
HIERARCH ESO SEQ NODTHROW
Nodding throw along the slit (in arcsec)
HIERARCH ESO AOS RTC LOOP STATE
AO loop state: open or closed
HIERARCH ESO OCS MTRLGY ST
“
T
”
if metrology converged. Keyword only
present if metrology was used.
7.4.3 Pipeline
comes with a new Data Reduction System (DRS) package that is incompatible
with data from the oCRIRES. The DRS follows ESO standards for data reduction pipelines
and uses the usual tools for execution. It calibrates the detector properties and
characterizes the location of the spectral orders on the three detectors for each
wavelength-setting. It further measures the orientation and shape of the spectrograph slit
and uses this information to optimally extract spectra into 1D. Lastly, it calibrates the
wavelength scale and applies the calibrations to the science observations before treating
them in the appropriate way, e.g. combining and pair-wise subtracting nodding
observations.
The naming scheme of DRL recipes indicates their respective role, like this:
