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GHRS Instrument Science Report 073

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GHRS Instrument Science Report 073:
Short-Term Variations in GHRS Response: An Investigation into an Apparent Anomaly

D. Soderblom, J. Eisenhamer, S. Hulbert, C. Leitherer,
M. McGrath, L. Sherbert, and J. Skapik
May 07, 1996

Abstract

This is a report on an unusual phenomenon seen in a long series of ACCUM observations of a star and of the wavelength calibration lamp. The phenomenon is described, our initial hypotheses are explained and rejected, and further investigations are presented. Our current best hypothesis is that the changes seen in the lamp and star are independent of one another and are due to known effects.


Short-Term Variations in GHRS Response: An Investigation into an Apparent Anomaly
Abstract
1. - Introduction
2. - A Description of the Phenomenon
3. - Initial Hypotheses
Image Motion at the Spectrograph Aperture
Variations in Lamp Output
Spectrum Drift within the Detector
Lyman-alpha Background
Bright Earth Background
4. - Further Investigations
Orbital Phasing of Sensitivity Monitors
Engineering Parameters
Detector Hysteresis
5. - Independent Phenomena
Acknowledgments

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