VLT-MAN-ESO-14650-4942
P96
24.06.2015
28 of 161
ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
As consequences, in stare mode (object centered in the slit):
-if the observation is conducted at airmass 1.2 with the slit angle at parallactic angle, then the
drift between the blue and red order spectrum will be of ~1.6” in the UVB arm, ~0.6” in the
VIS arm, and ~0.2” in the NIR arm.
--if the observation is conducted at airmass 1.6 with the slit angle at parallactic angle, then
the drift between the blue and red order spectrum will be of ~3.5” in the UVB arm, ~0.8” in
the VIS arm, and ~0.3” in the NIR arm.
Such kind of drifts is important to take into account in case of nodding observations to avoid
too many flux losses even with the slit at the parallactic angle.
It is again more important if the slit angle is different than the parallactic angle.
b) Comparison of ADCs efficiency at different slit angle.
The measure was performed at relatively high airmass (AM=1.8) and compares the flux
between the slit position parallactic+90 degrees and parallactic angles (ratio flux
perpendicular/flux parallactic). The average value corresponds to the average of
measurements for each order, the range gives the min/max values of the ratio and the
standard deviation (std) is given.
Stare mode, AM=1.8
With ADCs ratio perpendicular/parallactic
c) Comparison of observations with/without ADCs
There are 2 sets of measurements comparing the efficiency of observations with/without the
ADCs for the slit angle at parallactic angle or perpendicular to it:
One in stare mode at airmass =1.8 that can be compared to the subsection b.
One in nodding mode at airmass=1.35.
Stare mode, AM=1.8
Ratios no ADCs/with ADCs
To Next Page
Loading...