Last revision December 4, 1995 TJD 8670 = February 18, 1992 Because of a growing artifact in Spectroscopy Detector No. 1, the spectral calibration for TJDs 8670 - ? is bad. Most of the time, especially on TJD 8670, the channel number for the centroid of the 511 keV line is smaller than it really should be by perhaps approximately 120 linear channels.