Onboard dynamic image exposure control for the Star–Planet Activity Research CubeSat (SPARCS)

Tahina Ramiaramanantsoa, Judd D. Bowman, Evgenya L. Shkolnik, R. O.Parke Loyd, David R. Ardila, April Jewell, Travis Barman, Christophe Basset, Matthew Beasley, Samuel Cheng, Johnathan Gamaunt, Varoujan Gorjian, John Hennessy, Daniel Jacobs, Logan Jensen, Mary Knapp, Joe Llama, Victoria Meadows, Shouleh Nikzad, Sarah PeacockPaul Scowen, Mark R. Swain

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


The Star–Planet Activity Research CubeSat (SPARCS) is a 6U CubeSat under development to monitor the flaring and chromospheric activity of M dwarfs at near-ultraviolet (NUV) and far-ultraviolet (FUV) wavelengths. The spacecraft hosts two UV-optimized delta-doped charge-coupled devices fed by a 9-cm telescope and a dichroic beam splitter. A dedicated science payload processor performs near-real-time onboard science image processing to dynamically change detector integration times and gains to reduce the occurrence of pixel saturation during strong M dwarf flaring events and provide adequate flare light-curve structure resolution while enabling the detection of low-amplitude rotational modulation. The processor independently controls the NUV and FUV detectors. For each detector, it derives control updates from the most recent completed exposure and applies them to the next exposure. The detection of a flare event in the NUV channel resets the exposure in the FUV channel with new exposure parameters. Implementation testing of the control algorithm using simulated light curves and full-frame images demonstrates a robust response to the quiescent and flaring levels expected for the stars to be monitored by the mission. The SPARCS onboard autonomous exposure control algorithm is adaptable for operation in future point source-targeting space-based and ground-based observatories geared towards the monitoring of extreme transient astrophysics phenomena.

Original languageEnglish (US)
Pages (from-to)5702-5712
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Feb 1 2022


  • space vehicles: instruments
  • stars: flare
  • stars: low-mass
  • stars: rotation
  • techniques: image processing
  • techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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