Telluric standard stars should be taken within +/- 2 hours and within an airmass difference of +/- 0.2 of the SCIENCE observation.
The airmass constraint is set to 0.22.
A telluric standard violating the airmass constraint is not found by calChecker and marked as MISS.
Please consult the tellTracker page in these cases to see if additional telluric standard stars are needed
calChecker accepts VIS telluric standard stars with smaller binning than the SCIENCE (e.g. SCIENCE 1x2 accepts telluric with 1x1 and 1x2), but tellTracker checks only for identical binning.
calChecker accepts VIS and NIR telluric standard stars with the same slit as the SCIENCE (SLIT != 5.0x11) and telluric standard stars of any slit for SCIENCE acquired with the wide slit (5.0x11).
The following keys are used to define a SCIENCE XSHOOTER setup: ins.opti2.name (= IFU/SLOT) ins.opti3/4/5.name (= slit width for different arms) (since 2011-12-07: not for 5 arcsec slits) det.win1.binx/y (= binning along x/y axis; UVB and VIS only) det.read.clock (= readout mode; UVB and VIS only) det.dit (= exposure time, NIR only) det.ndit (= number of averaged exposures, NIR only)