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Scattered light in the STIS echelle modesThe Space Telescope Imaging Spectrograph (STIS) echelle spectra obtained during the Early Release Observations have non-zero residuals in the cores of saturated interstellar lines, indicating the need for a scattered light correction. A rough measure of the magnitude of the needed correction shows the ratio of the interorder to the in-order flux in different echelle modes in both pre-launch calibration images of a continuum lamp source and in post-launch images of stellar continuum sources. The interorder and in-order fluxes are computed by averaging the central 200 pixels in the dispersion direction. The amount of scattered light in the interorder region rises toward shorter wavelengths for two reasons: (1) the order separation decreases toward shorter wavelengths; and (2) the amount of echelle scattering is expected to have an inverse dependence on wavelength. At the shortest wavelengths the fraction of light scattered into the interorder region can be 10% for the Near-ultraviolet-Multi-Anode Microchannel Array (NUV-MAMA) and 15% for the Far-ultraviolet-Multi-Anode Microchannel Array (FUV-MAMA).
Document ID
19980202046
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Landsman, W.
(Hughes STX, Inc. Greenbelt, MD United States)
Bowers, C.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
August 18, 2013
Publication Date
January 1, 1997
Publication Information
Publication: The 1997 HST Calibration Workshop with a New Generation of Instruments
Subject Category
Optics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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