The calibration processing has been modified since the launch of GOES-8 in 1994 to mitigate the effects of several unexpected instrument performance problems. The noise in these channels is of the order of three counts. The responsivities of the imager visible channels have been decreasing with time. Because of the strong temperature dependence of the Planck function, brightness temperature errors increase rapidly with decreasing scene temperature. Sounder relative errors vary significantly from channel to channel and are of the order of 0.1K at 300K. Solar heating of instrument components occurs in the six hours surrounding midnight when the sun is in the Northern Hemisphere.
Calibration is a necessary step in the observing process.
Stable and accurate calibration is needed for the production of stable and accurate data products. In GOES-8 and Beyond , Edward R. Washwell, Editor, Proc. J.C. J.G. Baucom, H. Vu, M. P. Weinreb and N. Pinkine, 1998. GOES-8 Imager Midnight Effects and Slope Correction. In GOES-8 and Beyond, Edward R. Washwell, Editor, Proc.