ESO CRIRES+, Руководство пользователя

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User Manual
Doc. Number: ESO-323064
Doc. Version: 2
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38 of 82
Document Classification: Public
The new adopted naming convention is given by the central wavelength of the
corresponding setting (see column 1 of Table 13). Depending on the science template and
the observing strategy, observations are carried out before moving to a new fixed setting
(e.g., all nodding positions will be done per setting first; a full polarimetric sequence is
carried out before moving to a new setting). A total of 29 different settings is required to
cover the full operating range of CRIRES. Further details on the offered wavelength settings
can be found in §7.2
Some small wavelength gaps cannot be probed with CRIRES due to design decisions to
optimise the throughput in the regions of interest. The ranges include the following: 1356-
1423nm, 1854-1908nm, and 2527-2725nm (the gaps are larger if full slit illumination is
considered). These regions are dominated by telluric lines and are not of general interest
for most science cases.
Table 3: Approximate spectral coverage achieved within different photometric bands.
Spectral coverage of
photometric band
Spectral coverage of
point source (middle
of slit)
Spectral coverage for
full slit
Band
Starting λ
(nm)
Ending λ
(nm)
Starting λ
(nm)
Ending λ
(nm)
Starting λ
(nm)
Ending λ
(nm)
Y 955 1120 948 1120 948 1120
J 1100 1400 1116 1356 1116 1331*
H 1500 1800 1423 1854 1461 1796
K 2000 2400 1908 2527 1946 2472**
L 3200 3700 2810 4150 2840 4100
M 4600 5000 3340 5800*** 3360 5600***
*1356nm 85% of slit; **2501nm 75% of slit; *** The detector cut off is 5300nm
4.4.4 Wavelength calibration
The problem of wavelength calibration can be approached by using different methods
according to the required accuracy. For an accuracy corresponding to ~3 pixels, the start
and end wavelengths and the derived dispersion for each detector is sufficient.
If present in the raw data (i.e., settings below 2500 nm), either emission or absorption sky
lines can be used to improve the absolute wavelength calibration. The presence of sky lines
in the desired wavelength setting can be checked by using the ETC.
The density of lines provided by arc lamps is usually small in the IR regime, However,
Uranium-Neon lamp can provide a large number of lines up to ~2500 nm.
Alternatively, the use of gas cells (i.e., SGC or N
2
O, see 3.2.3.1) should be considered for
high precision wavelength calibration.
4.4.5 Flat Field
Flats field exposures are taken with the Halogen lamp. Once the user specifies the required
NDIT and the maximum flux, the DIT and NDIT is automatically determined by the template.