Performance of the spectropolarimeter for the space telescope faint object spectrograph

R. G. Allen, J. R.P. Angel

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The Faint Object Spectrograph of the Space Telescope will be able to obtain spectro-polarimetric data on faint astronomical objects. This is done by introducing a Wollaston prism and rotating waveplate behind the spectrograph entrance apertures. Fabrication of the polarimeter assembly has now been completed at the Martin Marietta Aerospace Co. in Denver, Colorado. Recent tests of the polarimeter and its optics have demonstrated that the device is capable of excellent performance. The magnesium flouride optical components of the polarimeter permit measurements of linear and circular polarization throughout the ultraviolet, down to Lyman a at 1216 Å. The mechanical stability and repeatability of the mechanism are demonstrated to yield position angles of the incoming plane of polarization to better than ± 0.5°, and we anticipate that measurements of the degree of polarization could be made to an accuracy of at least 0.1%. The accuracy for faint objects will depend on the integration times available for the observations, because of noise from photoelectron statistics. A 20-minute integration at 15th magnitude gives typically errors of 1% in each 100 Å wide spectral band.

Original languageEnglish (US)
Pages (from-to)259-267
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - Nov 16 1982

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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