The Astronomer's Telegram

The Astronomer's Telegram (ATel) is an internet-based short-notice publication service for quickly disseminating information on new astronomical observations. Examples include gamma-ray bursts, gravitational microlensing, supernovae, novae, or X-ray transients, but there are no restrictions on content matter. Telegrams are available instantly on the service's website, and distributed to subscribers via email digest within 24 hours.

The Astronomer's Telegram was launched on 17 December 1997 by Robert E. Rutledge with the goal of rapidly (<1 s) sharing information of interest to astronomers. Telegrams are sent out daily by email, but especially time sensitive events can be transmitted instantly. Since 2013, information is also broadcast over Twitter and Facebook.

To publish, astronomers request credentials. Credentials are issued to professional astronomers and graduate students, after verification by personal contact. Once credentials have been supplied and telegrams authorized, astronomers can publish telegrams directly, with no further editing.

As of August 2019, over 13000 telegrams have been published.