Investigations of STIS Time Dependent Sensitivity Corrections

The Space Telescope Imaging Spectrograph (STIS) instrument of the Hubble Space Telescope (HST), with wavelength coverage from the far-ultraviolet to the near-infrared, is an essential resource for astronomers. STIS spectrophotometric fluxes provide a basis for all HST and JWST flux calibrations, which makes calibration and monitoring of standard stars especially important. The STIS team monitors the time dependent sensitivity (TDS) of the instrument to ensure the optimal corrections are performed based on the changes of the throughput of each observing mode with time. Here, the STIS team presents new investigations of the TDS accuracies across multiple observing modes. These investigations include the derivation of TDS trends from a new “triad” of standards stars which we compared against the TDS trends derived from the standard stars used to monitor each mode. The newly derived triad TDS trends were found to be within the 2% promised accuracy with respect to the original trends.