Discontinued Support Services within GCN/TAN

COMPTEL Data Transfer: The same hardware and software that captures and processes the BATSE instrument data also captures the CGRO-COMPTEL instrument data when there is a GRB in the COMPTEL FOV. Using a ring buffer, with 120 seconds of pre-trigger data and 230 seconds of post-trigger, the data are captured and automatically ftp-ed to a COMPTEL computer at U. of New Hampshire. There, the data are automatically analyzed and if the GRB was bright enough for the COMPTEL instrument, a location is available 10-15 minutes after the GRB. This is particularly useful because the COMPTEL error boxes (1-3 deg) are smaller than the BATSE-Original/-Final/-MAXBC locations. They are comparable in size to the BATSE-LOCBURST locations and provide and independent check on the LOCBURST algorithm. This rapid analysis program and the UNH COMPTEL GRB webpage are managed by Alanna Conners (UNH). The COMPTEL Rapid Response Network (RRN) distributes these locations and is managed by Bernie McNamara (NMSU). No longer available since the de-orbit of CGRO.

BATSE Data Transfer: Since the GCN hardware and software captures (and processes) the BATSE instrument data, it can send it to the BATSE team in Huntsville, where they can process it in near-real time (20-25 min) with their locburst algorithm to produce GRB locations with improved error boxes. This procedure (see LOCBURST Notices is only performed for the brighter bursts (>2000 c/s). A ring buffer, with 143 seconds of pre-trigger data and 369 seconds of post-trigger, is used to captured the data. After fill the ring-buffer it is automatically ftp-ed to a BATSE computer at MSFC. No longer available since the de-orbit of CGRO.

Combined BATSE Position & IPN Annuli: The GCN system captures and automatically transfers to Kevin Hurley (UC Berkeley) the BATSE light curve for each GRB. This gets the appropriate data to UCB a couple days before the Huntsville BATSE team could do so, thus eliminating a couple days from the total time delay. At Berkeley a daemon program monitors for incoming light curves, and upon receipt waits for the appropriate time segment of data to be downlinked from the Ulysses spacecraft via the DSN. When the Ulysses data has been transferred from JPL, it is searched for a matching GRB and when a significant enough match is found, an IPN annulus is calculated and sent back to GSFC. This annulus is combined with the BATSE-Original/-Final/-MAXBC/-LOCBURST error circle and an a GCN/IPN_SEGMENT Notice is composed and sent to all GCN sites (this is the human-in-the-loop part). No longer available since the de-orbit of CGRO.

Heads-up: GCN also provides a "heads-up" service to the EGRET, OSSE, ALEXIS, TGRS, IPN, COMPTEL-RRN, SAX, and several optical & radio sites so that they can perform quick-look analysis of their instruments' data and/or be ready to observe when smaller error boxes become available at a later time (T+hours). EGRET has detected 5 GRBs and their error boxes are quite small (1-3 deg) (Dingus, 1995). This heads-up notification helps the EGRET team analyze their data in a timely fashion. No longer available since the de-orbit of CGRO.

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The GCN/TAN contact is: Scott Barthelmy, scott@lheamail.gsfc.nasa.gov, (301)-286-3106

This file was last modified on 16-Apr-12.