CRIRES User Manual
Doc. Number: ESO-254264
Doc. Version: P109.4
Issued on:
2021-12-01
Page:
76 of 99
Document Classification: ESO Internal Use [Confidential for Non-ESO Staff]
Most of the parameters to be defined in this template are described in §6.3 and §6.6.2;; we
describe the following template-specific parameters and settings here.
·
Wavelength calibration source
(TSF:
INS.LAMP
) selects the wavelength calibration
source. Possible choices are:
•
FPET
for wavelength calibration <2500 nm. Keep in mind that the FPET alone does
not serve as absolute wavelength reference (see UNE+FPET).
•
UNE
for the Uranium Neon lamp (<2500 nm), which provides an absolute
wavelength reference.
•
UNE+FPET
takes two exposures, the first one with the UNE lamp and the second
one with the Fabry-Perot Etalon (<2500 nm). The UNE lamp is taken to establish
the zero-point of the FPET (recommended setup for wavelength calibration).
•
HALOGEN
in combination with any of the
gas cells
(
INS.OPTI1.NAME
= GAS_SGC
or GAS_N2O).
·
Optical Element
(TSF:
INS.OPTI1.NAME
) allows to insert any gas cell (GAS_SGC or
GAS_N2O) into the light path. If the wavelength calibration source is "UNE" or
"UNE+FPET", then
INS.OPTI1.NAME
must be "FREE".
·
Maximum Flux
(TSF:
SEQ.MAXFLUX
) sets the flux level of the calibration sources. It should
be set to 20'000 ADU for all calibration sources except for the UNE, which should be set to
100'000 ADU.
Maximum Flux2
(TSF:
SEQ.MAXFLUX2
) is only relevant if
INS.LAMP
=
UNE+FPET, as it allows to individually set the flux level of the FPET following the UNE.
·
Number of cleaning darks
(TSF:
SEQ.NCD
): if set >0, then the specified number of
cleaning darks will be taken, with the goal to remove persistence from the detector after the
use of the UNE lamp (we recommend to set
SEQ.NCD
= 6). The DIT of the cleaning darks is
hardcoded (20s), and they are not stored in the archive. Note that if
INS.LAMP
= UNE+FPET,
then cleaning darks are taken after the UNE calibrations and additionally after the FPET
calibrations. If
SEQ.NCD
= 0, then no cleaning darks will be taken.
6.6.4 Sky observations
Observed sky lines which can be identified by HITRAN have the advantage that wavelength
calibration is done from the science observations themselves. Observers are strongly
advised to use the ETC
with the output options Sky Emission Spectrum and Sky Absorption
Spectrum and to check for themselves if enough unsaturated telluric lines are available for
a proper wavelength calibration in the spectral range of interest.
In addition, the template
CRIRES_spec_cal_SkyObs
template allows to take a spectrum
of the sky at the current telescope location without slit viewer guiding and with the AO loop
open;; it is unlikely to be needed in any science OB. All parameters to be defined in this
template have already been described in § 6.3 and §6.4.
6.6.5 Polarimetric standard stars
Any OB for a polarimetric standard star must consist of an acquisition template (see Table
10) and of the calibration template
CRIRES_pol_cal_AutoNodOnSlit
. The latter is very
similar to the observing template CRIRES_pol_obs_AutoNodOnSlit described in §6.4.5.
