Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
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Preflight Calibration Results of Wide-Angle Polarimetric Camera (PolCam) onboard Korean Lunar Orbiter, Danuri

  • Minsup Jeong (Exploration Science Project Group, Korea Astronomy and Space Science Institute) ;
  • Young-Jun Choi (Exploration Science Project Group, Korea Astronomy and Space Science Institute) ;
  • Kyung-In Kang (Satellite Technology Research Center, Korea Advanced Institute of Science and Technology) ;
  • Bongkon Moon (Exploration Science Project Group, Korea Astronomy and Space Science Institute) ;
  • Bonju Gu (Satellite Technology Research Center, Korea Advanced Institute of Science and Technology) ;
  • Sungsoo S. Kim (Humanitas College, Kyung Hee University) ;
  • Chae Kyung Sim (Exploration Science Project Group, Korea Astronomy and Space Science Institute) ;
  • Dukhang Lee (Exploration Science Project Group, Korea Astronomy and Space Science Institute) ;
  • Yuriy G. Shkuratov (Astronomical Institute of Kharkiv, V.N. Karazin National University) ;
  • Gorden Videen (Space Science Institute) ;
  • Vadym Kaydash (Astronomical Institute of Kharkiv, V.N. Karazin National University)
  • Received : 2023.08.28
  • Accepted : 2023.12.18
  • Published : 2023.12.30
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Abstract

The Wide-Angle Polarimetric Camera (PolCam) is installed on the Korea's lunar orbiter, Danuri, which launched on August 5, 2022. The mission objectives of PolCam are to construct photometric maps at a wavelength of 336 nm and polarization maps at 461 and 748 nm, with a phase angle range of 0°-135° and a spatial resolution of less than 100 m. PolCam is an imager using the push-broom method and has two cameras, Cam 1 and Cam 2, with a viewing angle of 45° to the right and left of the spacecraft's direction of orbit. We conducted performance tests in a laboratory setting before installing PolCam's flight model on the spacecraft. We analyzed the CCD's dark current, flat-field frame, spot size, and light flux. The dark current was obtained during thermal / vacuum test with various temperatures and the flat-field frame data was also obtained with an integrating sphere and tungsten light bulb. We describe the calibration method and results in this study.

Keywords

Acknowledgement

The work by SSK was supported by the National Research Foundation of Korea (2019R1A2C1009004) and by the Korea Astronomy and Space Science Institute under the R&D program (2023-1-850-09) supervised by the the Ministry of Science and ICT. GV was supported by the NASA KPLO Participating Scientist Program NNH18ZDA001N-KPLOPSP, grant 80NSSC21K0755.

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