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10.3. IAU Circulars, Minor Planets, ATEL, and Ephemerides

Information about time-critical phenomena has been distributed by the IAU ``Central Bureau for Astronomical Telegrams'' (CBAT; via ``IAU Circulars'' since October 1922. The IAU ``Minor Planet Center'' (MPC; is responsible for the collection and dissemination of astrometric observations and orbits for minor planets and comets, via the ``Minor Planet Electronic Circulars'' (MPEC;, distributed on paper as the ``Minor Planet Circulars'' since before 1947. Through collaboration with CBAT and MPC, the ADS Abstract Service includes electronic circulars of these two sites. The title, author, and object names are freely available through the ADS, and the whole text of each circular is indexed by ADS so that it is found on searches. The references returned from the ADS include an on-line link to the full circular at CBAT and MPC.

In December 1997 the ``Astronomer's Telegram'' (ATEL; [Rutledge (1998)]) was released. It is a web-based publication system for short notices on time-critical information and is available at Submission of telegrams is restricted to professional astronomers and requires special permission. The potential authors are given a special authentication code to be used at the time of submission, which is entirely automated and unmoderated, without any human intervention. Readers can freely access the telegrams or ask to be on a mailing list to receive telegrams within minutes of their submission. During the first six months of its existence about five telegrams per month were received.

Ephemerides and orbital elements of comets and minor planets can be consulted e.g. at or at JPL's HORIZONS system ( A free, interactive program for fancy calculations of ephemeris, visibility curves from any site on Earth, and graphical displays of finding charts based on the HST Guide Star Catalogue, orbits of solar system bodies, views of Earth and Moon, and much more is available (for X-Windows systems with Motif) for download at

The ``Astronomy Calculator'', available at, aspires to provide general information about the phases of the moon, lunar eclipse, next annual meteor shower and planets.

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