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GCN: The Gamma-ray Coordinates Network (TAN: Transient Astronomy Network)

14 Feb 2022: There was trouble in printing and processing of Circular #31590.

27 Dec 2021: Earlier today an acciedent in processing caused some old email Notices to be resent. There were 3 intervals of old Notices from short windows of time: Oct 23, Nov 01, and Dec 04, 2021. They were correct Notices of their time and content, but just retransmitted (duration of ~1 hour between 06:40 to 07:40 UT today). This occurred for only those recpients that use the email method. We apologize for the confusion that occurred.

03 Nov 2021: The Time-domain Astronomy Coordination Hub (TACH) project is pleased to announce a
new community tool to access the archive of GCN Notices and Circulars. The GCN Viewer
ingests new notices and circulars in real time, and associates events detected by multiple
facilities, providing useful categorization and searchability. This first public release of the
GCN Viewer provides this functionality, and new features will be added with forthcoming releases.
The new TACH archive of the GCN Notices & Circulars is accesible through the GCN Viewer at

Posted 23 Mar 2020 (last updated 18 Oct 20):
Due to the policies and constraints during the CoronaVirus pandemic,
my response to your requests and questions may not be as fast as normal.
Example: changes to your site_configuration may take up to 7 days (instead of the usual 2-4 days).
Being at home teleworking, requires making the site_config file change a remote operation instead of the normal on-site operation.
Which is doable, but I try to keep that method to a minimum. I will wait longer to do the file change
or I will use a weekly 4-hr pass to do work on-site.

The GCN system distributes:
  1. Locations of GRBs and other Transients (the Notices) detected by spacecraft (most in real-time while the burst is still bursting and others are that delayed due to telemetry down-link delays).
  2. Reports of follow-up observations (the Circulars) made by ground-based and space-based optical, radio, X-ray, TeV, and other particle observers.
These two functions provide a one-stop shopping network for follow-up sites and GRB and transient researchers.

The GCN system can be explored using the links above and below.

Invitation to subscribe to the Notices or Circulars here.    unsubscribe here.
Make a modification to an existing Notices site configuration here.
Invitation to producers to incorporate your events into GCN here.

System Status
System Status: Latest update: 17 Mar 2021 (UT)
What's New
What's New: Latest update: 31 Jul 2020 (UT)

thumbnail of GCN physical network
The physical GCN network. (Click to enlarge.)

Latest Gamma-Ray Bursts

GCN Circulars Archive     Circs by Burst
GCN Reports Archive

The GCN/TAN contact is: Scott Barthelmy,, (301)-286-3106
(or if the Goddard email is down).

A service of the HEASARC at the Astrophysics Science Division (ASD) at NASA's GSFC.

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  • Curator: Teresa Sheets
  • Responsible NASA Official: Phil Newman
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    This file was last modified on Monday, 14-Feb-2022 18:01:05 EST