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D.J. Stys, N.R. Walborn, I. Busko, P. Goudfrooij, C. Proffitt, K. Sahu (STScI)
The analysis of the STIS Sensitivity Monitor observations from 1997 through 2002 continues to show sensitivity trends correlated with time for all first-order modes, as well as temperature dependence in the FUV. The mean wavelength-averaged rate of sensitivity loss for the low-resolution (L) modes is ~1%/yr, with individual losses ranging from ~0%/yr (G430L, G750L) to ~2%/yr (G140L). Selected wavelength settings of the medium-resolution (M) gratings G140M, G230M, G230MB, G430M, and G750M have also been followed by this monitoring program. The lower exposure levels in the CCD M-mode observations result in significantly larger effects from charge transfer efficiency (CTE) losses, than is the case for the L-mode observations. In general, the sensitivity losses are found to be wavelength dependent. The limited MAMA M-mode wavelength coverage is consistent with the same sensitivity trends observed in the L modes at the corresponding wavelengths. On this basis, the STIS pipeline processing software is currently being revised to correct the extracted fluxes for these sensitivity changes in both the MAMA L and M modes. The CCD sensitivity losses due to CTE depend on the exposure level and detector location, and so require tailored corrections.
The author(s) of this abstract have provided an email address for comments about the abstract: stys@stsci.edu
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.