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BATSE Bright Source Report (Pulsed Sources)

The full-sky viewing of the BATSE experiment, required to accomplish it's gamma-ray burst mission, provides the ability to detect pulsed signals from any active source above a detection limit of about 15 mCrab in 20-50 keV, using the DISCLA 1.024s channel 1 data. Large (approximately a factor of 2) variations in the detected counting rate over the CGRO orbit require an elaborate background filtering/fitting and removal process, which greatly improves the sensitivity that would be obtained by epoch-folding the raw data for periods up to about 300s, but removes pulsed signal along with the background for longer period sources.

Data are weighted according to the aspect angle of each detector to a source on the source list, treated to remove the background variations, barycentered, then epoch-folded over a set of grid points in the vicinity of the expected source pulse frequency. The frequency with the greatest Z_n² statistic for a null-signal hypothesis relative to the mean value is stored in a database. If a significant detection is obtained, it will be evident by it's recurrence over successive days. Histories of frequency, peak/median Z_n² and modeled flux are inspected daily for significant detections. The reports available here (either the latest available or from the archive) are produced twice a week.