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Proceedings Paper

On-orbit modulation transfer function characterization of terra MODIS using the moon
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Paper Abstract

The on-orbit Modulation Transfer Function (MTF) of MODIS instrument can be accurately measured by its on-board SpectroRadiometirc Calibration Assembly (SRCA). For other Earth observing instruments without calibrators similar to SRCA, the sharp edge of moon provides a reasonable high-contrast target for their on-orbit MTF characterization. In this paper, we propose a procedure to measure MODIS on-orbit MTF from the moon image. For Terra MODIS, lunar calibration was performed nearly every month since its launch in 2000. For each lunar calibration, the images of the moon from multiple scans are taken and traced across the right edge to form an edge spread function (ESF). The ESF is used to calculate a line spread function (LSF) through differentiation. The MTF in along-scan direction is then derived through the Fourier Transform of the LSF. The same procedure can also be applied to MTF calculation in along-track direction. The results are compared with SRCA measured MTF, and the long-term trending of both MTF agrees. Lunar MTF characterization appears noisier mainly because of the non-uniformity of the moon surface and moderate spatial resolution of the moon image, which makes it difficult to accurately locate the circular lunar edge in sub-pixel level. Improvement of the current method is discussed in the end.

Paper Details

Date Published: 13 September 2011
PDF: 10 pages
Proc. SPIE 8153, Earth Observing Systems XVI, 81531N (13 September 2011); doi: 10.1117/12.892118
Show Author Affiliations
Zhipeng Wang, Sigma Space Corp. (United States)
Taeyoung Choi, Sigma Space Corp. (United States)
Xiaoxiong Xiong, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 8153:
Earth Observing Systems XVI
James J. Butler; Xiaoxiong Xiong; Xingfa Gu, Editor(s)

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