Spectral Characterization of HST Calibration Lamps - New Pt/Ct-Ne Line Catalogues and Ageing Test

Published

June 25, 2004

Author(s)

F Kerber, Michael R. Rosa, Craig J. Sansonetti, Joseph Reader, Gillian Nave, P Bristow, M Fiorentio, G Lercher

Abstract

The Space Telescope European Coordinating Facility's (ST-ECF) lamp project, funded directly by the European Space Agency (ESA), is dedicated to the study of hollow cathode calibration lamps as they are used onboard the Hubble Space Telescope (HST). There are two main objectives: First, we have measured the spectra of Pt/Cr-Ne lamps in order to obtain accurate and reliable wavelengths for all emission lines between 115 and 320 nm. This wavelength range corresponds to the coverage provided by the Space Telescope Imaging Spectrograph (STIS) Echelle modes. Extensive laboratory measurements were performed at the National Institute of Standards and Technology (NIST) usoing the 10.7 m normal incidence spectrograph and a Fourier Transform Spectrograph. Until now no good laboratory wavelengths for Cr had been available and their addition has a najor impact on the wavelength calibration, particularly in the near UV. The new line list is being used in conjunction with the physical instrument model of STIS which is employed to derive an improved wavelength calibration as part of the STIS Calibration Enhancement (STIS-CE) effort. Second, we attempt to gain a better understanding of the performance of such lamps and the physical processes involved in their long term operations. Among the issues studied are the change of the spectrum as a function of current, its change as a function of time and the tolerances of alignment. The bulk of the measurements were performed on flight spares from STIS and on new space qualified lamps for the accelerated aging test. The original flight lamps from the Faint Object Spectrograph (FOS) and the Goddard High Resolution Spectrograph (GHRS) are the only lamps ever to be measured after their return from space. Together with the spectra archived from six years of on-orbit operations they provide a unique data set for studying ageing effects in these lamps. The new Pt/Cr-Ne line list has been successfully applied in the STIS-CE effort. Thereby the ST-ECF's lamp project directly leads to an improvement in the quality of scientific observations of existing HST spectrographs. Our finds also constitute important lessons for the design and operations of future UV and optical spectrographs in space.

Proceedings Title

AS04 Proceedings, SPIE Conference 5488

Conference Dates

June 21-25, 2004

Conference Location

Glascow, 1, SC

Conference Title

Astronomical Telescopes and Instrumentation Conference

Pub Type

Conferences

Keywords

atomic spectra, chromium, Hubble Space Telescope, platinum, Space Telescope Imaging Spectrograph, wavelength standards

Citation

Kerber, F. , Rosa, M. , Sansonetti, C. , Reader, J. , Nave, G. , Bristow, P. , Fiorentio, M. and Lercher, G. (2004), Spectral Characterization of HST Calibration Lamps - New Pt/Ct-Ne Line Catalogues and Ageing Test, AS04 Proceedings, SPIE Conference 5488, Glascow, 1, SC (Accessed November 28, 2024)