Reference Files

WCS Reference files are in the Advanced Scientific Data Format (ASDF). The best way to create the file is to programmatically create the model and then save it to a file. A tutorial on creating reference files in ASDF format is available here.

Transforms are 0-indexed. The forward direction is from detector to sky.

Reference file types used by assign_wcs

REFTYPE	Description	Instruments
CAMERA	NIRSpec Camera model	NIRSpec
COLLIMATOR	NIRSpec Collimator Model	NIRSpec
DISPERSER	Disperser parameters	NIRSpec
DISTORTION	Spatial distortion model	FGS, MIRI, NIRCam, NIRISS
FILTEROFFSET	MIRI Imager filter offsets	MIRI, NIRCAM, NIRISS
FORE	Transform through the NIRSpec FORE optics	NIRSpec
FPA	Transform in the NIRSpec FPA plane	NIRSpec
IFUFORE	Transform from the IFU slicer to the IFU entrance	NIRSpec
IFUPOST	Transform from the IFU slicer to the back of the IFU	NIRSpec
IFUSLICER	IFU Slicer geometric description	NIRSpec
MSA	Transform in the NIRSpec MSA plane	NIRSpec
OTE	Transform through the Optical Telescope Element	NIRSpec
SPECWCS	Wavelength calibration models	MIRI, NIRCam, NIRISS
REGIONS	Stores location of the regions on the detector	MIRI
WAVELENGTHRANGE	Typical wavelength ranges	MIRI, NIRCam, NIRISS, NIRSpec