New Gapless COS G140L Mode Proposed for Background-Limited Far-UV Observations

TL;DR

This paper introduces a new G140L mode for the COS instrument on HST that improves far-UV observations by simplifying calibration and reducing astigmatism, enabling more efficient and precise scientific studies.

Contribution

It proposes a novel G140L mode (CENWAV=800) that fully utilizes the Segment A detector for far-UV observations, enhancing calibration and image quality.

Findings

Mode moves the far-UV band onto Segment A detector

Calibration management is simplified

Astigmatism in the wavelength region is reduced

Abstract

Here we describe the observation and calibration procedure for a new G140L observing mode for the Cosmic Origins Spectrograph (COS) aboard the Hubble Space Telescope (HST). This mode, CENWAV = 800, is designed to move the far-UV band fully onto the Segment A detector, allowing for more e cient ob- servation and analysis by simplifying calibration management between the two channels, and reducing the astigmatism in this wavelength region. We also de- scribe some of the areas of scientific interest for which this new mode will be especially suited.