EPOXI instrument calibration

Abstract

NASA’s EPOXI mission used the Deep Impact (DI) Flyby spacecraft to deliver a payload of three scientific instruments, two visible cameras and an IR spectrometer, to a close flyby of Comet 103P/Hartley 2 in November 2010. Interpretation of the scientific measurements made using these instruments depends on accurate calibration of the instruments’ performance. Updates to the instrument calibrations achieved during the Deep Impact primary mission and results of continued monitoring of their performance during EPOXI are reported here. The instruments’ performance has remained remarkably stable over the nearly 7years of flight. Significant improvements in the understanding and calibration of the IR spectrometer response non-linearity, time-varying background level, flat field, wavelength map, and absolute spectral response have been achieved. Techniques for reducing some semi-coherent horizontal noise stripes in the visible cameras’ readouts were developed, and some adjustments have been made to their absolute radiometric conversion constants. The data processing pipeline has been updated to incorporate the improvements in the instrument calibrations.