Central Bureau for Astronomical Telegrams

Central Bureau for Astronomical Telegrams -- Image credits

International Astronomical Union Circulars Archive

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. 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.]

      On-line IAUCs are generally available, though older IAUCs are still being scanned in gradually. Below are jpeg images of many of the older IAUCs published at the Royal Observatory of Uccle (where Nos. 1-31 of the first series were issued) and at the Copenhagen Observatory (where Nos. 1-1883 of the second series were issued), as well as some of those older IAUCs published in Cambridge (beginning in 1965). The 31 Circulars that were published by the IAU's Uccle office of the Central Bureau during 1920-1922 were printed on regular-sized paper. When Elis Strömgren at the Copenhagen Observatory assumed publication of the IAUCs in 1922, they started over again at No. 1 and continued printing their circulars on cards for easier mailing. (The IAU was actually formed in 1919.) The postcard concept goes back to 1914, when Strömgren began issuing urgent astronomical information on postal cards because of disruptions incurred by the first world war that affected the CBAT at Kiel; when the IAU moved its CBAT to Strömgren's direction at Copenhagen in 1922, Strömgren naturally transformed his early postcard system into the new version of the IAUCs.

      The current CBAT collection of physical IAUC cards includes those collected over the decades by the three Cambridge CBAT Directors (Gingerich, Marsden, Green), as well as collections from Fred Whipple (for many years the official HAC Editor) and his assistant Francis Wright, and from the AAVSO (donated recently to the CBAT at the time of their move away from Bay State Rd. in Cambridge). [It is speculated that no Harvard astronomers had individual subscriptions to the Copenhagen IAUCs because they got the in-house-produced Harvard Announcement Cards (HACs) that were generally considered the western-hemisphere equivalent to the European-printed IAUCs, and the HCO/SAO astronomers simply relied on the Harvard College Observatory (HCO) Library (= Phillips Library) subscription to the Copenhagen-produced IAUCs.] But, unfortunately (and very surprisingly), a complete set of physical IAUCs was never sent from Copenhagen to Cambridge when the CBAT moved to Cambridge in 1965, so early IAUCs are missing from the CBAT collection, and any libraries who would like to consider donating any IAUC cards prior to those printed in July 1958 (specifically, any IAUCs prior to No. 1651) to the Central Bureau are encouraged to do so (and the CBAT will pay for shipping costs). [Note: the CBAT is still missing the following postcard versions of IAUCs in the range of Nos. 1651-2100: 1715, 1873-1875, 1877, 1878 (for which photocopies only are on hand).]

      We have been assisted by other libraries (including especially the U.S. Naval Observatory Library in Washington, and the Copenhagen Observatory Library) in obtaining better copies of older IAUCs where Phillips (HCO) Library copy is inferior (by way of torn cards or text-imposing postage marks). We thank Sally Bosken (USNO Librarian) and her assistants and Lone Gross (Astronomical Observatory Library, University of Copenhagen) for their time and effort in helping to augment the HCO/SAO collection of older IAUCs. Emma Palmqvist (Librarian, Neils Bohr Institute, Copenhagen) also kindly sent photocopies of early Copenhagen circulars beginning in 1914 that we did not have (and which are rare in North America, if existent at all) -- circulars that the Copenhagen Observatory began issuing during World War 1 due to disruptions at the Central Bureau in Kiel, Germany. [Note that the HCO library (known as the Wolbach Library in recent decades, after the Smithsonian Astrophysical Observatory (SAO) library combined with the HCO library in the 1970s, and the Phillips Library of HCO before that) was sadly dismantled in March 2024 (due to lack of use, according to the CfA Director in January 2024) and no longer exists. The supplementary SAO library was also dismantled at the same time to make way for more office space.] Also presented here are hundreds of jpeg scans from Konkoly Observatory from their original card collection (courtesy of Krisztian Sarneczky) -- namely, most of IAUCs here in the range 1224-2200; scanned IAUCs in this range that are posted here are from the Konkoly collection except when noted otherwise. The goal is to have all of IAUCs 1-2999 available here as jpeg (or .png) images by the end of 2025. Meanwhile, researchers can send requests to the Bureau for specific missing IAUCs to be scanned and posted quickly here. IAUCs 3000 to the present are available as plain-ASCII-text files at this website (enter the individual IAUC number in the current-IAUCs "Display" box). A simple, plain-ASCII-text index of IAUC item titles for IAUCs 1-8000 is available here.

      The CBAT began in Kiel, Germany, in 1882, where the world's most preeminent astronomical journal (Astronomische Nachrichten) was published (not a coincidence!). The A.N. was published approximately once a week for many years in the 19th century, and it was considered a primary source for announcing new discoveries of astronomical objects, but it was a journal format (and thus larger than the announcement bulletins and circulars that would follow in the 20th century). Telegrams were issued from Kiel (and HCO, and soon also Copenhagen), but these were generally coded to avoid mistakes (and thus not generally readable), and copies of old telegrams are exceedingly rare -- the printed versions being the sole surviving form of most older discoveries. The A.N. staff began its own version of the HCO Bulletins in 1919, which the Kiel editors named the Beobachtungs-Zirkulars. The B.Z. were typeset onto paper that was smaller than that of the parent A.N. publication, and it focussed on reports of new discoveries and follow-up information for such objects as minor planets, variable stars, novae, and comets. The B.Z., which was produced more irregularly than the A.N. (but which could be produced more quickly due to its smaller size), continued publication until 1944 (from Berlin), when the War forced a permanent end to its production.

      Scans of "pre- and non-IAU/CBAT" postcard circulars that were published at Copenhagen beginning in 1914 are available here, as well. Another important task (with no time goal yet) will be to ensure that the HCO Announcement Cards and the HCO Bulletins are also available via the web; these HCO publications served as the mailed output from the western-hemisphere's version of the CBAT during 1895-1964 (with the HCO Circulars during 1895-1898), while western-hemisphere "central bureau" unprinted astronomical telegrams also were issued from HCO beginning in 1883 after transferral of this task was completed from the Smithsonian Institution in Washington, DC. The HCO Circulars were another related publication with more expanded information, and they have been scanned in and posted on the ADS website here (but note that they are merely Circulars with no volume numbers, despite what ADS says).

Note, of course, that any older addresses in the old IAUCs given here are no longer valid. Since 2010, the Central Bureau has been located at EPS/Harvard (and has no ties left to SAO, where it had been based from 1965 until 2010). It has been considered the best policy to leave the contemporary addresses on all IAUCs posted here, for proper historical context.

Various Older IAUCs

Various older IAUCs are available, with additional issues posted here as time permits.

IMPORTANT NOTE: When looking at the IAUCs below, please note that the older postal and telegram addresses have been discontinued.

Series 1 (Uccle, 1920-1922)

Series 2 (Copenhagen/Cambridge, 1922-present)

Please ensure that you have read this policy statement on the availability of IAUCs. Details on how to subscribe to the IAUCs are available.

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