Types of Calibration Files

Arclamp or Domearc: Spectrum of one or more standard lamps used for wavelength calibration of a given instrument configuration.

Bias: Short (often zero-second) unilluminated image used to measure the electronic baseline of the detector. (Does not depend on instrument configuration.) Generally for optical instruments.

Contbars: (KCWI only) Continuum bars used for geometry reconstruction.

Dark: Non-illuminated images taken at longer exposure times to measure dark current in the detector. (Does not depend on instrument configuration.)

Eng Calib: (NIRC2 only) Engineering files for Adaptive Optics calibration. OSIRIS: Enginering files for Adaptive Optics calibration and engineering files used in the creation of the OSIRIS rectification matrices (RECMATS). KOA users who wish to create data cubes from raw OSIRIS data will not need these ENG Calib files and will use the RECMATS (available on the download page) instead. Note: the value for the header keyword KOAIMTYP is calib for these types of files.

Fcscal: (DEIMOS only) Image file obtained by the DEIMOS flexure compensation system (FSC) that can be used as a reference frame to match the instrument spectroscopic settings to those of a previous night or run. The setup alignment can be made to within a fraction of a pixel.

Flatlamp or Domeflat or Flatlampoff: Flat-field spectra taken with a continuous spectrum source (usually a quartz halogen lamp) at a given instrument configuration. Flat fields can be used for a variety of purposes, such as: calibrating pixel-to-pixel sensitivity, calibrating global illumination gradients, and determining the edges of spectral orders.

For some instruments (usually infrared instruments), images are also taken with the identical configuration, but with the continuum source turned off. These flatlampoff images are subtracted from the flatlamp images, in order to remove various sources of stray background light, such as the thermal emission from the calibration unit.

Fpc: (KCWI only) Focal plane camera exposure.

Focus: Spectra taken with a given instrument configuration to optimize focus, usually by measuring arc-line widths as a function of instrument focus. Generally for optical instruments.

Polcal: (LRIS only) A polarimetry calibration file, for either the "polarizance" (the efficiency at which the instrument measures 100% polarized light) or the position angle zero-point (angle vs. wavelength in spectroscopic mode).

Solar: (KPF only) Calibration observations of the Sun. Note for searching for Solar data in the More options of the user interface, select other modes as well (green, red, ca_hk) either when searching on solar via the instrument modes or when doing a calibration file only search. If you do not want solar data returned, either uncheck the solar mode or uncheck solar when doing a calibration files only search.

Svc: (KCWI only) Calibration file using a focal plane to look down at the slicer.

Trace: Spectra of a continuum source and a pinhole to provide a trace spectrum for order extraction. Note: this purpose is often fulfilled with standard stars or the program stars if sufficiently bright; in either of these cases the file will be saved with KOAIMTYP 'object' (i.e., it's identified as a science file), not 'trace.'

Undefined: This is used when the image data type cannot be determined and does not fit any of the defined calibration types.