The Central Bureau for Astronomical Telegrams (CBAT) has recently celebrated the 125th anniversary since its founding by the editors of Astronomische Nachrichten at Kiel, Germany, in late 1882. The immediate cause was the sudden appearance of the great September sungrazing comet, for which a coordinated worldwide center was seen to be much needed, due to problems in getting proper information circulated quickly to the astronomical community. The CBAT moved to Copenhagen Observatory out of necessity during World War I, where it took on IAU acceptance in 1922 (after an initial 2-year stint of an IAU Central Bureau floundered in Brussels); the IAU's Central Bureau remained at Copenhagen until its transfer to Cambridge at the start of 1965 (where Harvard College Observatory had maintained the western hemisphere's central bureau for astronomical telegrams since 1883). The Smithsonian Astrophysical Observatory (SAO), located on the grounds of HCO, has overseen the Central Bureau -- on behalf of the IAU -- since 1965.
The Kiel Bureau and its IAU continuance has long been recognized as the source of official designations for many astronomical objects, providing a trusted source for early information regarding such discoveries. While wide public access to the Internet in the past 1.5 decades has naturally encouraged many different additional sources -- both professional and amateur -- to produce alerts on various new astronomical discoveries, there is often a lack of oversight to prevent errors from being propagated. The CBAT publications are refereed, and the long history and reputation of the CBAT -- together with its efforts to remain fair and non-political, while simultaneously maintaining constructive dialogue with all interested astronomers -- will ensure that it remains an important part of the astronomical community. Indeed, at a meeting held recently between organizers of the Virtual Observatory and the CBAT/SAO staff, it was acknowledged by the VO members that there will continue to be a strong need for the Central Bureau to highlight the important astronomical discoveries, as automated surveys produce an ever-greater flood of data. The CBAT is working with the astronomical community to aid astronomers with this rapid rise in new data.
The primary subjects of CBAT publications continue to be supernovae, comets, novae and other unusual variable stars, and satellites of minor planets and major planets -- both discovery information and follow-up information. Contributors also send information to the CBAT regarding novae in other galaxies, and while publication is generally made of novae in galaxies other than M31, the CBAT webpage devoted to M31 novae now appears satisfactorily to provide a venue for designating and announcing new novae in that nearby galaxy, with suitable follow-up observations also provided there. Following discussion with IAU Commission 22 in Prague in 2006, reports on new meteor showers also are now routinely published by the CBAT.
The years 2006-2008 continued the marked transition toward the increased issuance of 'Central Bureau Electronic Telegrams' (CBETs) as part of the plan to issue many reports more quickly and to help alleviate the cost of printing the IAU Circulars (IAUCs). For example, a policy was begun to issue all supernova discoveries on CBETs; initially, short summaries of the designations issued and some limited follow-up supernova information were also put on the IAUCs, but even the summaries have ceased on the IAUCs in the last couple of years due to the effort and cost of printing (combined with declining interest in paying line charges for publication of supplemental information). The IAUCs are still used to note the formal issuance of official IAU designations and names of celestial objects other than supernovae. The natural continued evolution worldwide from print to electronic publication is borne out in the Central Bureau's activity as well, although many astronomers still desire that the CBAT continue to maintain its printing of the IAUCs (which are both printed and electronic).
While a total of 137 IAUCs were issued in 2006 -- up from the 130 published in 2005 (see IAU Inf. Bull. No. 98, p. 31) -- this number declined to 117 in 2007 and to 102 in 2008, due to the transferral of most supernova material to CBETs, which saw 446 CBETs issued in 2006, 398 in 2007, and 451 in 2008 (well up from the 243 CBETs that were issued in 2005). As the CBAT announced that there are no line charges levied for items on the electronic-only CBETs, many other follow-up items on unusual variable stars, meteor showers, comets, and supernovae also are submitted specifically for publication therein.
In 2006, two notable astronomical objects were the source of a larger-than-usual number of textual items contributed to the Central Bureau: the recurrent nova RS Oph, which experience an outburst to visual mag 4.5 in February; and comet 73P/Schwassmann-Wachmann, which was making its long-awaited close approach to the earth, reaching total visual mag 5 and observed to split into scores of individual pieces. In 2007, again two astronomical objects produced a larger-than-usual number of CBAT-published items: comet C/2006 P1 (McNaught), the brightest comet since 1965, which was visible to the naked eye in broad daylight in January when near perihelion; and comet 17P/Holmes, which experienced an outburst of some 13 magnitudes over two days in October, to total visual mag 2.5. V1280 Sco (Nova Sco 2007) also produced numerous CBAT-published reports, as it became one of the brighter novae in recent years, at peak visual mag ≈ 4 in February (curiously, the nova V598 Pup -- announced in November 2007 -- was found on archival images also to have peaked near visual mag ≈ 4 in June, but it wasn't detected in real time).
The IAUCs continue to have multiple titles (regarding multiple objects) on most issued Circulars, whereas the CBETs contain only one title (one object/subject) per issue. During 2006-2008, the number of IAUC titles regarding supernova discoveries decreased from 74 in 2006 to 20 in 2007, and to only two in 2008 -- reflecting the move of supernova items to CBETs; the last IAU Circular with supernova designations summarized was No. 8875 in late September 2007. Meanwhile, the number of items on IAU Circulars pertaining to discoveries of novae (≈ 10 items/yr), other variables including follow-up text on novae (≈ 35/yr), natural solar-system satellites and rings (≈ 15/yr), major and minor planets (several per year), comet discovery (≈ 90/yr), and cometary follow-up text (≈ 50/yr) remained rather steady over the past triennium. Some 1017 CBETs were devoted to supernovae during 2006-2008, with another 162 pertaining to other variable objects outside the solar system, while 53 CBETs concerned minor planets (including satellites), 33 CBETs were issued regarding comets, 26 regarding meteor showers, and two dealt with major planetary satellites and rings.
Milky-Way novae (and occasional other unusual variable stars announced by the Central Bureau) have formal IAU/GCVS designations announced in CBAT publications, after they have been assigned by the GCVS staff in Moscow (via an on-going collaboration between the Central Bureau and the GCVS staff). The Central Bureau has initiated a designation scheme for novae in other nearby galaxies, beginning with M31 (and extended now also to M33 and M81), which is now widely used in the astronomical community; these lists are maintained at the CBAT website, along with lists of novae, supernovae, comets, and solar-system satellites announced by the Bureau.
The Central Bureau issued 1380 new designations for supernova discoveries announced during 2006-2008, including nine designations for belated discovery reports for objects found in images from 1985, 1996, 2004, and 2005. The type-II supernova 2007it, which peaked at red mag ≈ 12, appears to have been the brightest supernova detected in the past three years. The Central Bureau has continued to report occasional supernova linkages with observed gamma-ray outbursts, as with objects that were given the supernova designations 2008D and 2008hw. The CBAT also began a new designation scheme (labelled 'PSN') for (generally fainter) possible supernovae that are unconfirmed spectroscopically, and it maintains a website list with these objects.
The Central Bureau issues designations and names of comets, and during 2006-2008 it announced 176 designations of new and recovered comets observed from the ground, plus 469 designations for presumed comets found by solar-imaging spacecraft (six by STEREO, the rest by SOHO -- none of which were observed from the ground). Presumed comets discovered via SOHO spacecraft images are found primarily by amateur astronomers looking at images at the SOHO website, and the SOHO comets reported in the past three years include many objects found from the mid-1990s through 2005 (though the majority were from 2006 onwards). The last three years also saw a large increase (by ≈ 50-60 percent) over the previous five years in the number of satellites of minor planets reported -- continuing the trend that started around 2000; a large portion of this increase involves transneptunian objects, which has naturally created much excitement and investigation in recent years. The Central Bureau also announced the annual recipients of the Edgar Wilson Award for the discoveries of comets by amateur astronomers (three recipients each in 2006 and 2007, and two in 2008).
The continuing close collaboration of the CBAT with the Minor Planet Center resulted in near-simultaneous announcements on IAU Circulars and Minor Planet Electronic Circulars of most of the professional-survey comets, many of which are initially reported as asteroidal but found to show cometary appearance elsewhere by follow-up observers (many of whom again are amateurs) who monitor the MPC's 'Near-Earth-Object Confirmation' webpage. Some initial information on comet discoveries and recoveries appears also on CBETs, which can be prepared and issued more rapidly than the IAUCS.
The Central Bureau is working hard to get all its older IAUCs available online. Plain-ASCII-text versions of Circulars from about No. 1600 onwards should be available at the CBAT website by the end of 2010, and most of the earlier Circulars should also be available at the CBAT website in jpeg image form (from scans) by year's end; they are being added to nearly every week. We thank Sally Bosken (U.S. Naval Observatory Librarian), 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 (which suffered from damage).
Assistant Director G. V. Williams has continued to serve as joint MPC/CBAT webmaster (and has been responsible for the Web CS dissemination of the IAUCs). All of the year's Circulars were prepared by the undersigned, with very helpful editorial backup by Director Emeritus B. G. Marsden, who prepared some CBETs during the Director's absence from Cambridge during the year (and helped to proofread and referee many IAUCs prior to issuance and to discuss many CBAT matters from his decades of experience as CBAT Director).
Numerous referees worldwide, especially some who are Commission 6 members, are also to be thanked for their great help with many items published on Circulars in the past triennium. Correspondence with scientists, the general public, and the news media occupies much of the Director's time, with thousands of e-mails and many phone calls relating to CBAT science arriving each year. At SAO, Muazzez Lohmiller has continued to handle the accounts, addressing of envelopes, and other administrative matters. Dan Wooldridge continues, as he has for years, with the fine printing of the IAUC cards.
The CBAT has continued its notable presence on the World Wide Web, with those Circulars and CBETs older than about one year being posted freely. The number of paid subscribers to the printed edition of the IAU Circulars continued to fall, from 146 at the end of 2005 to 103 at the end of 2008. However, the subscriptions to the printed IAUCs do pay for the cost of printing and mailing, and there clearly is a continued interest in printing the IAUCs -- both from the subscribers and from contributors who perceive a certain prestige for a publication with a very long history in print, despite the simultaneous online presence. In addition, there were 14 free (complimentary or exchange) subscriptions to the printed IAUCs at the end of 2005. The printed IAUCs go to 43 addresses within North America and 74 outside of North America. The number of subscribers to the Computer Service (shared by the CBAT with the MPC, and which includes web access to all CBAT publications plus eligibility for e-mail delivery) remained very stable, at around 460.
Until 2000, the Director's salary was paid by SAO, with two additional CBAT employees paid entirely by subscriptions to the Bureau's publications. The tremendous growth of the World Wide Web has eaten into the subscription revenues of the CBAT, just as it has with magazines and newspapers worldwide: people have come to expect information to be freely available on the Web, expecting that "somebody else" will pay for whatever professional expertise is necessary to make that information available. Thus, the total number of recipients of CBAT publications (both printed and electronic) is down by roughly 50 percent from the pre-Web era.
The Central Bureau is grateful to the U.S. National Science Foundation for funding half of the Director's salary during 2008-2010, and to the IAU for its small-but-helpful annual subvention that helps to pay for supplying CBAT publications to astronomers in countries with poor financial support. As noted in recent reports, the subscription and line-charge income is no longer sufficient to sustain fully the salary of the current CBAT Director, as it had done for decades, together with secretarial help. While there are likely sufficient funds through the existing sources to pay the Director's and secretary's salaries into 2010, additional funding is needed for the long-term health of the CBAT. The Director continues actively to seek alternate sources of income to maintain the CBAT. It is hoped that individual countries may help with small contributions to ensure that the important work of the Bureau in serving the astronomical community can continue.
Daniel W. E. Green
Director of the Bureau