Catalog of Helios 90 deg Photometer Events
BOSTON COLL CHESTNUT HILL MA INST FOR SPACE RESEARCH
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The two Helios spacecraft were launched into solar orbits in December 1974 and January 1976. Each spacecraft contained three zodiacal light photometers intended to measure the distribution of dust in the interplanetary medium between the Sun and the Earth. Residual brightness variations were evident after the zodiacal light and stellar contributions had been removed from the photometer data. These variations are now known to have been caused primarily by transient plasma clouds propagating through the inner heliosphere. About 23 of these were caused by coronal mass ejections and about 14 by corotating structures. We have used specific criteria to select and identify these plasma events in the data from the Helios photometers which are pointed at the ecliptic poles. This process is now complete and we are making these data available to the scientific community. This document is a catalog of the Helios 90 deg photometer events which we have identified. In the following text we describe the pertinent characteristics of the zodiacal light experiment, the methods used to select, identify and classify the 90 deg events, and the details of the catalog structure. A comprehensive bibliography of all published papers involving analyses of the Helios photometer plasma observations and the zodiacal light calibration is also included.