TY - JOUR
T1 - Calibration of ShadowCam
AU - Humm, David Carl
AU - Kinczyk, Mallory Janet
AU - Brylow, Scott Michael
AU - Wagner, Robert Vernon
AU - Speyerer, Emerson Jacob
AU - Estes, Nicholas Michael
AU - Mahanti, Prasun
AU - Boyd, Aaron Kyle
AU - Robinson, Mark
N1 - Publisher Copyright:
Copyright © The Korean Space Science Society
PY - 2023
Y1 - 2023
N2 - ShadowCam is a high-sensitivity, high-resolution imager provided by NASA for the Danuri (KPLO) lunar mission. ShadowCam calibration shows that it is well suited for its purpose, to image permanently shadowed regions (PSRs) that occur near the lunar poles. It is 205 times as sensitive as the Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC). The signal to noise ratio (SNR) is greater than 100 over a large part of the dynamic range, and the top of the dynamic range is high enough to accommodate most brighter PSR pixels. The optical performance is good enough to take full advantage of the 1.7 meter/pixel image scale, and calibrated images have uniform response. We describe some instrument artifacts that are amenable to future corrections, making it possible to improve performance further. Stray light control is very challenging for this mission. In many cases, ShadowCam can image shadowed areas with directly illuminated terrain in or near the field of view (FOV). We include thorough qualitative descriptions of circumstances under which lunar brightness levels far higher than the top of the dynamic range cause detector or stray light artifacts and the size and extent of the artifact signal under those circumstances.
AB - ShadowCam is a high-sensitivity, high-resolution imager provided by NASA for the Danuri (KPLO) lunar mission. ShadowCam calibration shows that it is well suited for its purpose, to image permanently shadowed regions (PSRs) that occur near the lunar poles. It is 205 times as sensitive as the Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC). The signal to noise ratio (SNR) is greater than 100 over a large part of the dynamic range, and the top of the dynamic range is high enough to accommodate most brighter PSR pixels. The optical performance is good enough to take full advantage of the 1.7 meter/pixel image scale, and calibrated images have uniform response. We describe some instrument artifacts that are amenable to future corrections, making it possible to improve performance further. Stray light control is very challenging for this mission. In many cases, ShadowCam can image shadowed areas with directly illuminated terrain in or near the field of view (FOV). We include thorough qualitative descriptions of circumstances under which lunar brightness levels far higher than the top of the dynamic range cause detector or stray light artifacts and the size and extent of the artifact signal under those circumstances.
KW - calibration
KW - Korea Pathfinder Lunar Orbiter (KPLO)
KW - lunar
KW - permanently shadowed regions
KW - radiometric
KW - ShadowCam
KW - stray light
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U2 - 10.5140/JASS.2023.40.4.173
DO - 10.5140/JASS.2023.40.4.173
M3 - Article
AN - SCOPUS:85189450561
SN - 2093-5587
VL - 40
SP - 173
EP - 197
JO - Journal of Astronomy and Space Sciences
JF - Journal of Astronomy and Space Sciences
IS - 4
ER -