All burst detections are announced via the GCN. The GCN system distributes location information for gamma-ray bursts to the community as it is obtained from various spacecraft. The network also reports follow-up observations to rapidly inform the community of the evolution of a GRB and the need for further observations.
The GCN forwards the BAT localization of a transient detection to the community. This process is usually started within 20 seconds of the initial detection. This localization is accurate to 1-3 arcminutes at the 90% confidence level. The accuracy of the BAT localization depends on the significance of the detection. The XRT localization, which is to within 5 arcseconds, is available to the GCN within 100 seconds of the burst. The TDRSS finding chart is made available to the GCN within 270 seconds of the initial detection. These times assume normal operations of the satellite, TDRSS, and the ground system. Events such as Earth occultation can delay a localization.
The amount of time required for the GCN to distribute Swift localizations to the community will depend on the individual user's choice of distribution method. Distribution times are expected to be less than two seconds for socket connections and between 5 and 30 seconds for network connections. Pager notifications require between 1 and 3 minutes. These times may vary due to circumstances beyond anyone's control and should be considered to be guide lines and not definitive.