CRIRES User Manual
Doc. Number: ESO-254264
Doc. Version: P109.4
Issued on:
2021-12-01
Page:
66 of 99
Document Classification: ESO Internal Use [Confidential for Non-ESO Staff]
guiding star") and the target, respectively. These files can be prepared by using the online
tool available at:
http://www.eso.org/sci/observing/phase2/SMSpecial/MovingTargets.html
In these files, it is important to
make sure that the PAF.NAME is different in both files
,
as otherwise this can lead to problems during target acquisition.
6.3.7 Spectro-Polarimetry
·
Polariziation Stokes Parameter
(TSF:
INS.POL.TYPE
) sets the Stokes parameter (V, Q or
U).
6.4 Science templates
The science observation template sets the instrument, if different from the acquisition, as
well as the detector integration time (DIT) and the number of individual integrations (NDIT)
averaged to create an exposure. In addition, it defines the number of exposures to be taken
in different positions for background subtraction purpose.
As mentioned in §5.4.1.1, the most common observing technique suited for point-source
like targets is the nodding along the slit, where the target is always kept along the slit (i.e.,
no off-slit exposures are possible) and the sky signal is removed from the object spectrum
by subtracting two exposures taken at different slit positions.
On the other hand, when the target is an extended, object nodding along the slit is no longer
a viable strategy because removing the sky signal from the object spectrum requires
necessarily to take exposures off-slit. This can be done with generic offsets.
In addition, CRIRES offers the possibility of using the spectro-astrometry to obtain very high
spatial and spectral resolution line imaging (Beckers, J., 1982, Opt. Acta, 29, 361;; Bailey,
J., 1998, MNRAS 301, 161 and references therein). First results using this technique with
the old CRIRES are described in Pontoppidan et al. (2008).
Table 11: Overview of the available CRIRES observing templates
INSTRUMENT
MODE
TEMPLATE NAME
COMMENT
Spectroscopy
CRIRES_spec_obs_AutoNodOnSlit
Exposures are taken by nodding the
target along the slit (recommended for
point sources)
CRIRES_spec_obs_GenericOffset
Exposures can be taken along and/or off
the slit, depending on the user defined
offsets
pattern
(recommended
for
extended object). Only possible with SKY
derotator mode.
CRIRES_spec_obs_SpectroAstrometry
Exposures are taken by nodding the
target along the slit and repeated at any
user-defined
position
angle.
Not
compatible with differential tracking. Only
on-slit guiding / AO NGS possible.