Alice C. Harmon

Precise interplanetary network localization of the bursting pulsar GRO J1744-28

We analyze 426 observations of the bursting pulsar GRO J1744(28 by Ulysses and BATSE. Triangu- lating each burst and statistically combining the triangulation annuli, we obtain a 3 p error ellipse whose area is 532 arcsec2. The accuracy of this statistical method has been independently veri—ed with obser- vations of the soft gamma repeater SGR 1900)14. The ellipse is fully contained within the 1@ radius ASCA error circle of the soft X-ray counterpart and partially overlaps the 10@@ radius ROSAT error circle of a source which may also be the soft X-ray counterpart. A variable source which has been pro- posed as a possible IR counterpart lies at the edge of the 3 p error ellipse, making it unlikely from a purely statistical point of view to be associated with the bursting pulsar. Subject headings: pulsars: individual (GRO J1744(28) ¨ stars: neutronX-rays: stars

Multi-year BATSE earth occultation monitoring of NGC4151

Because the Earth occultation technique allows BATSE to be used as an all-sky monitor, BATSE is uniquely able to provide continuous observations of NGC4151 over the entire lifetime of the Compton GRO mission. Continuous 2154 day light-curves for the Seyfert galaxy NGC4151 have been derived from Earth occultation analysis of CGRO BATSE data. Light-curves for the 20–70 keV and 70–200 keV bands are shown and found to have an average flux of 11×10−3 photons cm−2 s−1 and 2.3×10−3 photons cm−2 s−1 respectively. Evidence for intrinsic source variability is observed in both 20–70 keV and 70–200 keV bands with a fractional variation ratio measured at Fvar=0.2.

Verifying the accuracy of the third interplanetary network: Localization of the bursting pulsar GRO J1744-28 by triangulation

Abstract The bursting pulsar GRO J1744-28 is the first repeating source of intense bursts whose position is accurately known, which has become active since the establishment of the third interplanetary network. We show how observations of this object with Ulysses and BATSE can be used to verify many aspects of the triangulation method. Analysis of the preliminary data indicates that there are no unknown sources of error in this method.