Inter-calibration of the OSIRIS-REx NavCams with earth-viewing imagers

David Doelling, Konstantin Khlopenkov, Conor Haney, Rajendra Bhatt, Brent Bos, Benjamin Scarino, Arun Gopalan, Dante S. Lauretta

Research output: Contribution to journalArticle

Abstract

The Earth-viewed images acquired by the space probe OSIRIS-REx during its Earth gravity assist flyby maneuver on 22 September 2017 provided an opportunity to radiometrically calibrate the onboard NavCam imagers. Spatially-, temporally-, and angularly-matched radiances from the Earth viewing GOES-15 and DSCOVR-EPIC imagers were used as references for deriving the calibration gain of the NavCam sensors. An optimized all-sky tropical ocean ray-matching (ATO-RM) calibration approach that accounts for the spectral band differences, navigation errors, and angular geometry differences between NavCam and the reference imagers is formulated in this paper. Prior to ray-matching, the GOES-15 and EPIC pixel level radiances were mapped into the NavCam field of view. The NavCam 1 ATO-RM gain is found to be 9.874 × 10-2 Wm-2sr-1μm-1DN-1 with an uncertainty of 3.7%. The ATO-RM approach predicted an offset of 164, which is close to the true space DN of 170. The pre-launch NavCam 1 and 2 gains were compared with the ATO-RM gain and were found to be within 2.1% and 2.8%, respectively, suggesting that sensor performance is stable in space. The ATO-RM calibration was found to be consistent within 3.9% over a factor of ±2 NavCam 2 exposure times. This approach can easily be adapted to inter-calibrate other space probe cameras given the current constellation of geostationary imagers.

Original languageEnglish (US)
Article number2717
JournalRemote Sensing
Volume11
Issue number22
DOIs
StatePublished - Nov 1 2019

Keywords

  • Calibration
  • DSCOVR-EPIC
  • GOES-15
  • NavCam
  • OSIRIS-REx
  • Ray-matching
  • SBAF

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

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    Doelling, D., Khlopenkov, K., Haney, C., Bhatt, R., Bos, B., Scarino, B., Gopalan, A., & Lauretta, D. S. (2019). Inter-calibration of the OSIRIS-REx NavCams with earth-viewing imagers. Remote Sensing, 11(22), [2717]. https://doi.org/10.3390/rs11222717