Limits on Short-Term ( ~1000 s) Afterglows from RXTE's All Sky Monitor via Bayes

Wide field of view instruments like RXTE's All-Sky Monitor (RXTE/ASM) have the possibility of tracking fading X-ray emission and any possible resurgences from the start of a gamma-ray burst until ~ thousands of seconds after. Such emssion had been detected serendipitously previously in X-rays (Connors and McConnell 1995 Rome ICRC, 2, 57; Connors and Hueter 1998 ApJ 1998ApJ 501, 307 and references therein); and been tracked at higher energies (Matz et al 1995, 1996, Huntsville Conference Proceedings). Recently, the advent of SWIFT has rekindled theoretical interest in this time frame: it may be possible to descry clues to the slowing and spreading of this high energy, relativistically beamed material; and its progress through its local interstelar matter. However the signal--to--noise ratio could be quite low. Therefore we created a Bayesian tool to map out the likelihood of the intensity of a source of interest, for every 90 s snapshot that it is in the field of view (marginalizing over all ``uninteresting'' parameters such as other sources and the background rates). This is guarenteed to extract all the inforamtion in the data about the flux, but it can be very CPU intensive. We are now applying this to all bursts RXTE/ASM, and will make these Bayes light--curves available for further analysis. This is funded by NASA Grant NAG5-8476.