Flat-fielding and wavelength calibration observations of GNIRS are done with the facility calibration unit, GCAL. Basic calibrations for GNIRS (i.e. 1-3 or 3-5 µm spectroscopic calibrations) are needed for all observations, queue or classical. These baseline" calibrations are summarized in the context of all Gemini Near-IR instrument calibrations (i.e. 1-5 µm imaging and spectroscopy).

Flats, arcs and pinhole calibrations for many of the GNIRS science modes can be carried out during morning or evening twilight. Exceptions include GNIRS IFU and R=18,000 (long slit with long camera) modes, which must be executed right before or after the science observation. In the case where twilight calibrations are taken, we recommend that an arc lamp be taken at the time of the science data, to account for any small shifts caused when re-positioning the grating, though tests show that the grating can be re-positioned to within a few pixels in these modes. Whether these calibrations are completed during the night or during twilight, they will not be charged to the program, though nightime calibrations will be charged to the partner country. Check the NIR baseline calibrations page for more details. Additional calibrations beyond the baseline set are charged to the program, except for twilight flats when needed in rare cases. Recommended flatfield and arc lamp configurations and exposure times are available, and also included in the OT library templates available for your phase II. Additional links to photometric and spectroscopic standards along with wavelength calibration are available in the NIR Resources section for planning.

All calibrations, including baseline tellurics, flatfields and arcs, must be specified in the Phase II definition.