Solar Activity Reports

The flare data were compiled primarily from the flare lists of the IAU Quarterly Bulletin and a magnetic tape obtained from the Institute for Telecommunication Sciences and Aeronomy (ITSA). This tape was assembled from the CRPL-F Part B series (1955 through 1964) and included sub-flare reports. Altogether, 84,600 reports were compiled. In preparing the revised tape, tests were made for errors that were introduced at various stages in the handling of the data. Some errors were detected by comparing the entries for flare time, position, and importance of the flare reports found in both the CRPL and IAU flare lists. Only slightly more than one-third of all reports were so compared, but these included practically all flares of importance> or = 1 during the period 1955 through 1962. Errors in reported flare areas were detected by matching reports between the two flare lists and by testing the areas as a function of central distance. This check uncovered flare reports in which the measured and corrected areas were reversed. Other errors were detected by checking for consistency of the information within each flare report. These various tests disclosed a 12.5 percent error in the flare reports of the CRPL-F Part B series, and an 11.2 percent error in the Quarterly Bulletin flare list. After correction of all identified errors, the revised magnetic tape listing may still contain a 5 percent error. Most of these discrepancies are in the sub-flare reports.

This is a summary of the ten years (1955-1964) of observations of solar flares reported by 61 observatories. The flare reports have been published predominantly in the IAU Bulletin and CRPL-F Series Part B. This report summarizes the types of information contained in the flare reports, and the frequency of some parts of these reports as functions of many parameters. The results reflect the need for closer cooperation and coordination of participating observatories in recording and reporting solar flare data.