Pushing the limits of the coronagraphic occulters on Hubble Space Telescope/Space Telescope Imaging Spectrograph
AffiliationUniv Arizona, Steward Observ
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CitationJohn H. Debes, Bin Ren, and Glenn Schneider "Pushing the limits of the coronagraphic occulters on Hubble Space Telescope/Space Telescope Imaging Spectrograph," Journal of Astronomical Telescopes, Instruments, and Systems 5(3), 035003 (13 June 2019). https://doi.org/10.1117/1.JATIS.5.3.035003
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AbstractThe 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-adaptive-optics-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 adaptive-optics-fed coronagraphs.
NoteOpen access article
VersionFinal published version
SponsorsHST GO program [13786, 15219]; State of Maryland grant through the Institute for Data Intensive Engineering and Science (IDIES)