Baseline Calibrations

For all queue observations, a set of standard calibrations (the "baseline calibrations") will be taken by Gemini Staff to ensure the long-term utility of data in the archive. The baseline calibration set varies from instrument to instrument and from mode to mode.

Applicants should not include time for baseline calibrations in their proposals. If additional calibrations are deemed necessary by applicants, for example to achieve a precision beyond that achievable via the baseline set, then these must be included explicitly as part of the Phase I proposal and Phase II science program. Baseline calibrations (i.e photometric standards, spectroscopic calibration stars) must be defined by the PI in the Phase II program (as described below), for ease of observing and to ensure that appropriate "standard" stars are selected.

Baseline calibration data may be shared between programs and will be distributed to the users as part of their dataset. Any time used between the hours of nautical sunset and sunrise to obtain baseline calibrations will not be explicitly charged to the program but will be charged to the partner country whose NTAC recommended time (i.e. it is part of the time accounting used to balance partner usage). The time will be charged in proportion to the number of programs that receive the calibration data. Any time required for additional calibrations requested by the PI will be charged to that particular program.

Starting in semester 2005B, all Phase II (OT) files must include observations for all baseline calibrations: photometric standards and/or spectroscopic calibration stars. See table below for details.

Measurement Type	Notes
Bad pixel mask	Not included as part of the baseline calibration set.
Flat field	Not included as part of the baseline calibration set.
Dark	Not applicable. Because of the chopped nature of all T-ReCS observations, Darks are not needed to reduce science data.
Wavelength calibration	Transmission curves are available for all T-ReCS filters.
Telluric standard star	Not applicable.
Flux standard star	The PI must specify two photometric standards for each science target in the Phase II Science Program, one that would match the airmass of the target if observed before it and one that would match it if observed after. The PI should try to choose stars such that the airmass matches with the science target is good, taking into account the amount of time spent observing the science target. If the time on the target is very short (i.e. less than 30 minutes of real time), then one photometric standard at a similar airmass to the science target will be sufficient. More information and a list of mid-infrared photometric standards is available.
Atmospheric extinction	Not included; however choosing of photometric standard star at an airmass matching the science target should minimize problems. Please include additional and specific photometric standard observations in your proposal if extinction corrections to better than ~10% are required.
Point Spread Function star	The approximate PSF can usually be derived from the photometric standard star baseline observations, but special PSF-reference images are not included as part of the baseline calibration set.
World coordinate system	Automatically included for each T-ReCS image. The default accuracy is of order 1-2 arcsec. Please include special observations of a nearby astrometric standard if higher accuracy is required.
Focal plane mask image	Focal plane mask images are not included as part of the baseline calibration, but will be taken periodically for engineering purposes.
Special standards	Not applicable.

Measurement Type	Notes
Bad pixel mask	Not included as part of the baseline calibration set.
Flat field	Not included as part of the baseline calibration set.
Dark	Not applicable. Because of the chopped nature of all T-ReCS observations, Darks are not needed to reduce science data.
Wavelength calibration	The dispersions of the Low-Resolution and High-Resolution spectra were precisely measured during commissioning. The wavelength calibration of individual spectra can be derived from the telluric ozone and water features in the 10 and 20 micron bands.
Telluric standard star	The PI must specify two spectroscopic calibration stars in the Phase II Science Program, one that would match the airmass of the target if observed before it and one that would match it if observed after. The PI should try to choose stars such that the airmass matches with the science target is good, taking into account the amount of time spent observing the science target. More information and a list of mid-infrared spectroscopic calibration stars is available.
Flux standard star	Not included; as part of the baseline calibration set. Absolute flux calibration through narrow slits is very unreliable. Please include imaging observations at a similar wavelength in your proposal if absolute flux calibration is important.
Atmospheric extinction	Not included; however a good choice of spectroscopic calibration star at matching airmass should minimize problems.
Point Spread Function star	The approximate PSF can usually be derived from the photometric standard star baseline observations, but special PSF-reference images are not included as part of the baseline calibration set.
World coordinate system	Automatically included for each T-ReCS spectrum. The default accuracy is 1-2 arcsec. Please include special observations of a nearby astrometric standard in your proposal if higher accuracy is required.
Focal plane mask image	Not applicable.
Special standards	Not applicable.

T-ReCS Baseline Calibrations

Imaging Mode

Spectroscopic Modes (Lo-Res10, Lo-Res20, Hi-Res)