Verifying the STIS Time Dependent Sensitivity Trends with the Primary CALSPEC Standards

Verifying the STIS Time Dependent Sensitivity Trends with the Primary CALSPEC Standards
Daniel Stapleton, Svea Hernandez
arXiv:2604.21966v1 Announce Type: new
Abstract: The STIS team monitors the time dependent sensitivity (TDS) of each grating with one from a set of three secondary CALSPEC standard stars: GRW+70D5824, AGK+81D266, and BD+28D4211. Here, we use the three primary CALSPEC White Dwarf standard stars, dubbed the standard star “triad” (GD71, GD153, G191B2B), as an independent set of standards to verify the accuracy of STIS TDS corrections derived from the TDS monitoring stars, increasing the sample for each STIS L-mode from one up to three or four standard stars. We focus on triad star observations using the STIS L-mode gratings (e.g., G140L, G230L, etc.) with the same configuration as our standard TDS monitoring programs, and compare the triad observations to the TDS pipeline trends. Our analysis indicates the relative net count rates inferred from the triad standards agree with the TDS trends derived from the TDS monitoring stars with average residuals $arXiv:2604.21966v1 Announce Type: new
Abstract: The STIS team monitors the time dependent sensitivity (TDS) of each grating with one from a set of three secondary CALSPEC standard stars: GRW+70D5824, AGK+81D266, and BD+28D4211. Here, we use the three primary CALSPEC White Dwarf standard stars, dubbed the standard star “triad” (GD71, GD153, G191B2B), as an independent set of standards to verify the accuracy of STIS TDS corrections derived from the TDS monitoring stars, increasing the sample for each STIS L-mode from one up to three or four standard stars. We focus on triad star observations using the STIS L-mode gratings (e.g., G140L, G230L, etc.) with the same configuration as our standard TDS monitoring programs, and compare the triad observations to the TDS pipeline trends. Our analysis indicates the relative net count rates inferred from the triad standards agree with the TDS trends derived from the TDS monitoring stars with average residuals $