Correction: Gamma-Ray Observations of Orbiting Nuclear Reactors

Abstract

The Perspective "Gamma-ray observations of orbiting nuclear reactors" by Joel R. Primack (28 Apr., p. 407) incorrectly identified the Gamma-Ray Spectrometer on the Solar Maximum Mission satellite as having been blinded by radiation from Soviet satellites. The seventh paragraph should have read, in part, "Gamma-ray detectors are surrounded by charged-particle detectors, so that events initiated by gamma rays can be distinguished from background events initiated by electrons. But positrons can annihilate on other parts of the gamma-ray detector spacecraft such as the SMM shield, and the resulting 511-keV gamma rays can appear to be astronomical gamma-ray signals. The SMM-GRS picked up such signals an average of eight times per day for much of 1987 and early 1988, each time causing brief interference with astronomical observations. The data storage capacity of the Gamma-ray Burst Detector (GBD) on the Japanese Ginga satellite was sometimes saturated by such events, so that it could take no more data until the next pass over its ground station (which could be on the same orbit or as many as 14 orbits later); this effectively blinded the GBD about 20% of the time. The sensitive detectors aboard Gamma Ray Observatory ...." [The remainder of this paragraph is as published.]