The COS calibration pipeline and verification process

Mary Elizabeth Kaiser; Philip E. Hodge; Charles Keyes; David Sahnow; Thomas Ake; Alessandra Aloisi; Stephane Béland; Rosa Diaz; Scott Friedman; Cynthia Froning; Parviz Ghavamian; James Green; Jason McPhate; Cristina Oliveira; Steve Osterman; Steve Penton; Brittany Shaw; Erik Wilkinson

doi:10.1117/12.790239

23 July 2008 The COS calibration pipeline and verification process

Mary Elizabeth Kaiser, Philip E. Hodge, Charles Keyes, David Sahnow, Thomas Ake, Alessandra Aloisi, Stephane Béland, Rosa Diaz, Scott Friedman, Cynthia Froning, Parviz Ghavamian, James Green, Jason McPhate, Cristina Oliveira, Steve Osterman, Steve Penton, Brittany Shaw, Erik Wilkinson

Author Affiliations +

Proceedings Volume 7014, Ground-based and Airborne Instrumentation for Astronomy II; 70146G (2008) https://doi.org/10.1117/12.790239
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

Abstract

The Cosmic Origins Spectrograph,1 COS, will be installed in the Hubble Space Telescope (HST) during the next servicing mission. This will be the most sensitive ultraviolet spectrograph ever flown aboard the HST. The calibration pipeline (CALCOS), written in Python, has been developed by the Space Telescope Science Institute (STScI) to support the calibration of HST/COS data. As with other HST pipelines, CALCOS uses an association table to specify the data files to be included, and employs header keywords to specify the calibration steps to be performed and the reference files to be used. CALCOS is designed with a common underlying structure for processing far ultraviolet (FUV) and near ultraviolet (NUV) channels which, respectively, use a cross delay line and a Multi Anode Microchannel Array (MAMA) detector. The pipeline basics and channel dependent specifics are presented. The generation and application of the current reference files, derived from ground-based calibration data, is described, along with the pipeline verification process and results. The CALCOS calibration includes pulse-height filtering and geometric correction for the FUV channel; flat-field, deadtime, and Doppler correction for both channels. Methods for obtaining an accurate wavelength calibra-tion using the on-board spectral line lamp are described. The instrument sensitivity is applied to the background corrected spectrum to produce the final flux calibrated spectrum.

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Mary Elizabeth Kaiser, Philip E. Hodge, Charles Keyes, David Sahnow, Thomas Ake, Alessandra Aloisi, Stephane Béland, Rosa Diaz, Scott Friedman, Cynthia Froning, Parviz Ghavamian, James Green, Jason McPhate, Cristina Oliveira, Steve Osterman, Steve Penton, Brittany Shaw, and Erik Wilkinson "The COS calibration pipeline and verification process", Proc. SPIE 7014, Ground-based and Airborne Instrumentation for Astronomy II, 70146G (23 July 2008); https://doi.org/10.1117/12.790239

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KEYWORDS

Calibration

Sensors

Doppler effect

Switches

Space telescopes

Data archive systems

Data conversion

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