NIRSpec auto-cals (auto-calibrations) are internal calibration exposures that can be acquired with lamps within the NIRSpec calibration assembly (CAA). These auto-cals can be acquired for flat fields, wavelength reference exposures, and broad line peaks measured for dispersion verification.
It is not recommended for users to acquire NIRSpec auto-cals with their science for two reasons:
- Acquiring auto-cals can cause moderate overheads, ~5 minutes or more per exposure.
- Acquiring auto-cals with lamp illumination may cause low levels persistence in subsequent science that could effect very deep sky exposures on faint objects.
NIRSpec auto-cals have been added to the science templates for FS, IFU, and MOS observing modes to make it possible to acquire lamp exposures at the same time as on-sky external exposures. It is expected this capability will primarily be used for instrument commissioning and observatory calibration observations.