Optical modeling of new lifetime positions for the Cosmic Origins Spectrograph (COS)

David Sahnow

doi:10.1117/12.2630389

31 August 2022 Optical modeling of new lifetime positions for the Cosmic Origins Spectrograph (COS)

David Sahnow

Proceedings Volume 12181, Space Telescopes and Instrumentation 2022: Ultraviolet to Gamma Ray; 1218136 (2022) https://doi.org/10.1117/12.2630389
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Conference Poster

Abstract

In order to prolong the life of the detector in the FUV channel of the cosmic origins spectrograph (COS) on the Hubble Space Telescope (HST), the positions of the spectra are adjusted by offsetting targets in the cross-dispersion direction. Since the installation of COS in 2009, five lifetime positions (LPs) have been used, and a sixth is scheduled to be commissioned in late 2022. The location of each LP is chosen based on both the evolving detector gain sag and the optical properties of the spectrograph. The COS optical design was optimized for use at its initial lifetime position (LP1), and offsetting the spectra introduces aberrations which affect the spectral resolution. In order to understand the effects of these aberrations on the data quality, optical models have been constructed in order to predict the performance of the spectrograph over the permissible range of target offsets and grating focus values. This modeling work, and how it is used in combination with on-orbit data when determining where to locate new lifetime positions, is discussed.

Citation Download Citation

David Sahnow "Optical modeling of new lifetime positions for the Cosmic Origins Spectrograph (COS)", Proc. SPIE 12181, Space Telescopes and Instrumentation 2022: Ultraviolet to Gamma Ray, 1218136 (31 August 2022); https://doi.org/10.1117/12.2630389

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available