The following diagram illustrates the operation of the BATSE RBR system from the detection of a burst by BATSE on-board software to the computation and dissemation of the burst location through the Gamma-Ray Coordinates Network (GCN). While data downloading and location dissemenation are automated, human operators are a valuable part of the procedure for estimation of source/ background time-intervals and efficient rejection of non-GRB triggers.

While the BATSE RBR system uses the same LOCBURST algorithm employed for all "best-and-final" BATSE burst locations, it cannot make use of the full BATSE dataset (most burst data are stored in memory and are thus not available in the real-time telemetry at the time of a burst). We have therefore independently assessed the location errors from the BATSE RBR system. As a comparison sample, we use 70 of the most recent bursts located to single annuli by BATSE/Ulysses IPN timing analysis. The shortest angular separation rho between BATSE locations and IPN annuli yields a statistical estimate of the total BATSE location error (a combination of measured statistical error and an unknown systematic contribution).

The following figure shows the cumulative distribution of BATSE-RBR/IPN separations. The procedure has been repeated for the BACODINE locations and the official BATSE locations from the 4B catalog. It is evident that the BATSE RBR locations are consistent with the 4B locations, whereas they are significantly more accurate (factor of ~3, on average) than BACODINE.

Through Monte Carlo simulations, we have found that a constant systematic error of ~2 deg is required in addition to the measured statistical errors to explain the BATSE RBR/IPN distribution. The following table shows the fraction of BATSE RBR bursts expected as a function of total location error (assuming 2 deg systematic error).

A more detailed analysis of the BATSE-RBR location errors is explained in a paper presented at the 4th Huntsville GRB symposium. Follow THIS LINK to read a web-version of the paper, or go back to the RBR home page and select "publications" to download a printable version.