On 1965 Jan. 1, the CBAT moved from Copenhagen to Cambridge, Massachusetts, where the Harvard College Observatory had been acting as the western hemisphere's astronomy information center also since 1883 (an arrangement several years earlier between the Royal Astronomer in England and the Secretary of the Smithsonian Institution in the U.S.A. allowed for several astronomical telegrams per year to be sent back and forth via the new cable laid under the Atlantic Ocean, and this began the astronomical-discovery announcement service for the western hemisphere that was soon transferred from Washington, DC, to Harvard). While telegrams were issued (often as preliminary supplements to printed-and-mailed circulars) by the Kiel, HCO, Copenhagen, and SAO Bureaus for 110 years starting in 1882, telegrams ceased to be used when the computer-communications era opened up (just prior to the existence of the WWW); nonetheless, given the long history of the Bureau's name, the word "Telegram" has not been dropped (and, indeed, a new electronic-only publication, the Central Bureau Electronic Telegrams, are now the most prolific venue for announcing news of new discoveries by the CBAT).
The CBAT has operated in Cambridge since 1965 under the successive directorships of Prof. Owen Gingerich (1965-1968), Dr. Brian G. Marsden (1968-2000), and Dr. Daniel W. E. Green (2000-present).
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.
The first IAUCs were published at the Royal Observatory of Uccle (where Nos. 1-31 of the first series were issued), and later at the Copenhagen Observatory (where Nos. 1-1883 of the second series were issued). 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 the 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 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.
"Pre- and non-IAU/CBAT" postcard circulars were published at Copenhagen beginning in 1914. The HCO Announcement Cards and the HCO Bulletins were Harvard publications that 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.