Properties of the Second Outburst of the Bursting Pulsar (GRO J1744–28) as Observed with BATSE

One year after its discovery, the Bursting Pulsar (GRO J1744(28) went into outburst again, dis- playing the hard X-ray bursts and pulsations that make this source unique. We report on BATSE obser- vations of both the persistent and burst emission for this second outburst and draw comparisons with the —rst. The second outburst was smaller than the —rst in both duration and peak luminosity. The per- sistent —ux, burst peak —ux, and burst —uence were all reduced in amplitude by a factor of D1.7. Despite these diUerences, the two outbursts were very similar with respect to the burst occurrence rate, the dura- tions and spectra of bursts, the absence of spectral evolution during bursts, and the evolution of the ratio a of average persistent to burst luminosity. Although no spectral evolution was found within individual bursts, we —nd evidence for a small (20%) variation of the spectral temperature during the course of the second outburst. Subject headings: pulsars: individual (GRO J1744(28) ¨ X-rays: burstsX-rays: stars