Started by Sich, August 13, 2006, 02:21:58 pm
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Iz MPC 57381-57382,This is the last batch of Minor Planet Circulars to be published duringmy directorship of the Minor Planet Center: I shall retire at the end of theIAU General Assembly in Prague later this month. When I took over the reinsin 1978 from Paul Herget, the first director of the Minor Planet Center, therewere just 2060 numbered minor planets (of which about 20 were lost), andthe observation file amounted to some 200,000 entries. Now there are 134,339numbered minor planets (all of which are very precisely predictable) and atotal of almost 40,000,000 observations. In 1978, (1566) Icarus was famousfor having an orbit that took it to within 0.19 AU of the sun; now there arefour numbered minor planets that go in closer, and two multiple-oppositionobjects have just under half the perihelion distance of Icarus. Then, (2060)Chiron, the sole centaur, was by far the most distant of the numberedobjects, ranging from near Saturn at perihelion to near Uranus at aphelion;now the number of known centaurs is dwarfed by the wealth of transneptunianobjects that have been found, one of them, (90377) Sedna, notably havingperihelion and aphelion distances of 75 and 900 AU. More than 100multiple-opposition objects have orbits showing the same 2:3 mean-motionresonance with Neptune that is characteristic of Pluto. Two of these``plutinos'' have diameters that are more or less half that of Pluto, raisinganew the question of why Pluto was catalogued as the ``ninth planet''---aproblem now brought to a head with the recognition last year of 2003 EL61,2003 UB313 and 2005 FY9, more esoteric transneptunian objects that areindeed very comparable to Pluto in size.The Minor Planet Center could not have succeeded during the past 28 yearswithout the two people who have served as associate directors, and I wish topay tribute to them here. Conrad Bardwell moved with the Minor Planet Centerto Cambridge from its previous home in Cincinnati. As the first person tocomputerize the search for identifications between minor planets having shortobserved arcs at their discovery oppositions and objects generally observed ontwo nights at a different opposition, he had already in Cincinnati been ablesignificantly to increase the production of multiple-opposition minor planetsbeyond the efforts of astronomers who had attempted such work by hand; hispursuit of this activity in both Cincinnati and Cambridge very specificallyresulted in the recovery of numerous lost numbered minor planets, many ofwhich had previously only been definitely recorded at their discoveryoppositions. Thanks also to his meticulous involvement in the preparation ofthe MPC's, this allowed an increase in numberings from (2061) to(4295)---with only two of the earlier ones still lost---and the number ofcompleted pages of the MPC's from 4391 to 15,600 by the time he retiredat the end of 1989. Bardwell has also maintained a subsequent interest inminor planets, a noteworthy contribution by him being the identification 1950DA = 2000 YK66, which led to the numbering of this near-earth object as(29075) and the recognition that there is a 1-in-300 probability that itwill strike the earth in 2880. Bardwell still visits the MPC for a couple ofhours most Saturday afternoons and will be celebrating his eightieth birthdayon Aug.\ 11.On succeeding to the position of associate director, Gareth Williams continuedand considerably extended the automation of MPC activities, something thatwas becoming very necessary as the CCD succeeded the photographic plate, anda new era of sky surveys began with the specific aim of dramaticallyincreasing the rate of discoveries of near-earth objects. The deep searchesnecessary for making substantial numbers of discoveries in the outer solarsystem also began. The combination made it desirable to introduce theseries of Minor Planet Electronic Circulars} in 1993. To ensure therapid follow-up of candidate near-earth objects, ``The NEO Confirmation Page''was developed in 1996, another service that quickly proved highly successful.Although the MPC's themselves continued to be published monthly, theconcomitant increase in observations of main-belt minor planets resultingfrom the use of the CCD made it necessary to transfer the publication ofthe observations themselves to a supplement series in 1997 that hasonly electronic distribution. The computer software necessary for arrangingthese new features was conceived and developed by Williams, who also in1997 arranged for the automatic preparation and distribution, at 2 a.m.\ localtime, of the ``Daily Orbit Update'' MPEC} containing all theorbits computed during the previous 24 hours. By 2000 it became necessaryto transfer the monthly MPC publication of orbits to another electronicsupplement. By 2001 the observations supplement was appearing morefrequently than monthly, and since mid-2003 Williams has single-handedly beenensuring that it appears weekly. Although the number of basic MPC'spublished is still only some 57,000, there have been more than 175,000 pages ofobservation supplements, more than 100,000 pages of orbit supplements andwell over 12,000 MPEC.s. Williams' impressive efforts at automationalso include the checking of observations directly from e-mail messages as theyreach the MPC's computers and in most cases the actual computation of orbits.He has also attended to the difficult task of the automatic coherentextraction of information about the observers and instrumentation used, sothat the actual publication of this information (which is very necessary inorder to give credit where it is due) can be made after very limited furthermanual editing. Williams also found the last two of the lost numbered minorplanets, (878) Mildred and (719) Albert, in 1991 and 2000, respective Brian G. Marsden