Central Bureau for Astronomical Telegrams

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International Astronomical Union Circulars

Central Bureau for Astronomical Telegrams

The International Astronomical Union Circulars (IAUCs) are a series of postcard notices giving information about astronomical phenomena requiring prompt dissemination, particularly the discovery and follow-up of novae, supernovae and comets, which were pubished continuously from 1920 until 2017; the electronic-only CBETs, which started in 2002 as a supplement to the printed IAUCs, gradually became the main CBAT publication during the following decade, due to the extra effort and cost in printing and mailing IAUCs and due to the lessening demand amongst subscribers for printed publications. Note that the IAUCs were published up until 2017 (the final printed postcard Circular, IAUC 9287, was published on 2017 May 2); all additional CBAT publications since then have been via CBETs (as of 2024 April 18), though the use of IAUCs could be revived in the future.

The IAUCs are also available in electronic form via e-mail or through the CBAT/MPC Computer Service. [Note that the printed IAUCs are considered "official" and final; the e-mailed versions are officially issued but are not the final version, because they are issued in ASCII form (and do not entail diacritical marks, Greek letters, and other aspects). Official citing should always be to the printed IAUCs, not the electronic versions. Scans of the printed IAUCs on this website are also official.]

On-line IAUCs are available, the newer ones by paid subscription only, and many (but not yet all) older ones freely available. Please ensure that you have read this policy statement on the availability of IAUCs.

Sample IAUCs

Sample IAUCs are available showing a range of the material covered. The sample Circulars are available in two forms:
  • A in ASCII format as used in the e-mail version
  • D in .dvi format as used in the printed version

IMPORTANT NOTE: When looking at the sample IAUCs below, please note that the CBAT TWX number has been discontinued.

The available sample Circulars are:

  • IAUC 6123 A A
  • IAUC 6124 A A
  • IAUC 6125 A A
  • IAUC 6126 A A
  • IAUC 6127 A A
  • IAUC 6128 A A

Details on how to subscribe to the IAUCs are available.

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