Pushing the limits of the coronagraphic occulters on Hubble Space Telescope/Space Telescope Imaging Spectrograph

John H. Debes, Bin Ren, Glenn Schneider

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph (STIS) contains the only currently operating coronagraph in space that is not trained on the Sun. In an era of extreme-adaptiveoptics-fed coronagraphs, and with the possibility of future space-based coronagraphs, we re-evaluate the contrast performance of the STIS CCD camera. The 50CORON aperture consists of a series of occulting wedges and bars, including the recently commissioned BAR5 occulter. We discuss the latest procedures in obtaining high-contrast imaging of circumstellar disks and faint point sources with STIS. For the first time, we develop a noise model for the coronagraph, including systematic noise due to speckles, which can be used to predict the performance of future coronagraphic observations. Further, we present results from a recent calibration program that demonstrates better than 10-6 point-source contrast at 0.6', ranging to 3 × 10-5 point-source contrast at 0.25'. These results are obtained by a combination of subpixel grid dithers, multiple spacecraft orientations, and postprocessing techniques. Some of these same techniques will be employed by future space-based coronagraphic missions. We discuss the unique aspects of STIS coronagraphy relative to ground-based adaptiveoptics-fed coronagraphs.

Original languageEnglish (US)
Article number035003
JournalJournal of Astronomical Telescopes, Instruments, and Systems
Volume5
Issue number3
DOIs
StatePublished - Jul 1 2019
Externally publishedYes

Keywords

  • Charge-coupled-device imagers
  • Image processing
  • Planets
  • Point spread functions
  • Speckle

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Control and Systems Engineering
  • Instrumentation
  • Astronomy and Astrophysics
  • Mechanical Engineering
  • Space and Planetary Science

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