Precise Interplanetary Network Localization of the Bursting Pulsar GRO J1744-28

Abstract

We analyze 426 observations of the bursting pulsar GRO J1744-28 by Ulysses and BATSE. Triangulating each burst, and statistically combining the triangulation annuli, we obtain a 3 sigma error ellipse whose area is 532 sq. arcsec. The accuracy of this statistical method has been independently verified with observations of the soft gamma repeater SGR1900+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 proposed as a possible IR counterpart lies at the edge of the 3 sigma error ellipse, making it unlikely from a purely statistical point of view to be associated with the bursting pulsar.