2.3 New Capabilities for Cycle 29

Although spatial scanning is not a new capability for STIS in Cycle 29, the first actual use of this available-but-unsupported mode was in Cycle 24. For relatively bright targets, spatial scanning can allow many more photons to be collected in a single exposure (without saturating the CCD), better flat fielding, better removal of the fringing in near-IR spectra, and more robust removal of hot pixels and cosmic rays. Signal-to-noise ratios of 600–800 (in the 1D extracted spectra) have been achieved in several programs using this mode. To further explore and encourage the use of spatial scanning with STIS, the STIS team conducted a Cycle 25 special calibration program to better understand and optimize spatial scans; analysis of those data can be found in the STIS September 2020 STAN, and a paper is in progress. For more information about spatial scanning with STIS, see Section 12.12.