Precision photometric calibration with alternating incoherent satellite speckles

Ananya Sahoo, Olivier Guyon, Julien Lozi, Jeffery Chilcote, Timothy Brandt, Nemanja Jovanovic, Tyler Groff, Frantz Martinache, Sebastien Vievard, Yosuke Minowa

Research output: Contribution to conferencePaperpeer-review

Abstract

Exoplanet characterization relies on extracting precision astrometry (orbits) and photometry (spectra, time variation) measurements from high contrast images. Obtaining such measurements is challenging due to residual starlight speckles and the fact that the central stellar PSF core is blocked by the coronagraph. In post coronagraphic images it becomes quite difficult to measure the relative position and intensity of companion with respect to the stellar as it is blocked by the coronagraph. This issue has been addressed by imposing a periodic phase grid on the Deformable Mirror of SCExAO system to generate satellite speckles which are incoherent with underlying speckle halo for calibration. We report on-sky measurements of the photometric stability of such incoherent speckles over a 15 minute period time. We demonstrate that for relatively fainter speckles, unknown background noise (speckles) creates a bias in the photometric measurement. We show that, by subtracting two frames with two different speckle patterns, we address this issue and obtain unbiased measurements. This technique will be beneficial for future large telescopes where they have the potential to obtain diffraction limited images.

Original languageEnglish (US)
StatePublished - Jan 1 2019
Externally publishedYes
Event6th International Conference on Adaptive Optics for Extremely Large Telescopes, AO4ELT 2019 - Quebec City, Canada
Duration: Jun 9 2019Jun 14 2019

Conference

Conference6th International Conference on Adaptive Optics for Extremely Large Telescopes, AO4ELT 2019
CountryCanada
CityQuebec City
Period6/9/196/14/19

Keywords

  • Adaptive optics
  • Coronagraphy
  • High contrast imaging
  • Instrumentation
  • Photometry
  • Satellite speckles

ASJC Scopus subject areas

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

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