1999ApJ...517..431W

One year after its discovery, the Bursting Pulsar (GRO J1744-28) went into outburst again, displaying the hard X-ray bursts and pulsations that make this source unique. We report on BATSE observations of both the persistent and burst emission for this second outburst and draw comparisons with the first. The second outburst was smaller than the first in both duration and peak luminosity. The persistent flux, burst peak flux, and burst fluence were all reduced in amplitude by a factor of ∼1.7. Despite these differences, the two outbursts were very similar with respect to the burst occurrence rate, the durations and spectra of bursts, the absence of spectral evolution during bursts, and the evolution of the ratio α of average persistent to burst luminosity. Although no spectral evolution was found within individual bursts, we find evidence for a small (20%) variation of the spectral temperature during the course of the second outburst.