MPEC 1993-Y05 : EDITORIAL NOTICEThe following Minor Planet Electronic Circular may be linked-to from your own Web pages, but must not otherwise be redistributed electronically.
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M.P.E.C. 1993-Y05 Issued 1993 Dec. 25, 13:59 UT The Minor Planet Electronic Circulars contain information on unusual minor planets and routine data on comets. They are published on behalf of Commission 20 of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. MARSDEN@CFA or WILLIAMS@CFA (.HARVARD.EDU, .SPAN or .BITNET) EDITORIAL NOTICE In response to several requests, we propose to issue in these Circulars monthly lists of the unusual minor planets that are reasonably observable. These will be listings of the objects in order of increasing right ascension from the sun for the "ten-day date" closest to each new moon. Numbered and other multiple-opposition objects will be included, together with objects from the current opposition and from earlier single oppositions for which perturbations were included in the orbit solution. Minor planets will generally be included if they are brighter than magnitude 21 and their elongations from the sun are greater than 90 degrees. At smaller elongations, the brightness limit will be changed by 0.1 mag/deg to a limit of magnitude 18 and elongation 60 degrees for numbered objects and magnitude 15 and elongation 30 degrees for unnumbered objects. Because of their extreme interest and the difficulty of securing adequate observations, the magnitude limit will be ignored for unnumbered objects with perihelia greater than 7 AU and down to a 30-degree elongation. The various columns will give the number and/or provisional designation or name, together with the number of observed oppositions or the observed arclength in days for unnumbered minor planets. Reference will be given to the orbital elements, either in Efemeridy Malykh Planet (EMP) for a specified year (last two digits), the five-digit (or four-digit) number of the Minor Planet Circulars, or (for very recent orbits) the three-character coding for these Minor Planet Electronic Circulars. After the right ascension and declination (J2000.0) in the usual units, five columns (Geo., Hel., El., Ph. and V) will give the geocentric and heliocentric distances (in AU), the solar elongation and phase angle (in deg) and the visual magnitude. In some instances there will be an asterisk following the reference. This will generally indicate unusual numbered objects that are on the critical list, although the opportunity will also be taken to indicate other objects for which observations are particularly desirable, with the reasons given in notes at the end. The appearance of the word "precovered" on MPEC 1993-Y03 necessitates an explanation. In the case of an unnumbered minor planet, the "discovery" refers to the detection that allowed a provisional designation to be given, generally to the first observation on the first of two or more nights. It is possible that an "independent discovery" will be made at the same opposition. It can also happen that one or more "prediscovery", chronologically earlier images will be detected at that opposition by an observer aware of the discovery. Sometimes it will not immediately be appreciated, or it may initially be unclear, that there is an independent discovery of a particular object at the same opposition, in which case a second designation may be applied to the same object; if and when the objects are proven to be the same, there is a "double designation". An "identification" refers to the recognition that the same object has been given provisional designations at different oppositions. In such a case, a "principal discovery" and "principal designation" will be defined, generally to the chronologically earliest opposition for which there was an orbit determination that allowed the identification to be established. The principal discovery is the one of relevance when the minor planet is deemed to have a reliable enough orbit solution that the object can be numbered. Each supporting designation will generally then be of a "rediscovery" of the object. When a single-opposition object is found from a deliberate search on an exposure deliberately made for the object at a future opposition, there is said to be a "recovery", a term that can also apply to a multiple-opposition object found far from its expected place. The term "precovery" refers to the same act on an exposure that was not deliberately made for the object, the exposure generally being at an earlier opposition. It can be noted that, in the case of a comet, a "recovery" generally applies to the first deliberate detection at the first of each sequence of oppositions that observations again become possible--generally as the object next approaches perihelion--and the comet receives a new provisional designation. If a comet is observed at all of its oppositions (or most oppositions, including one near aphelion), the term recovery and a provisional designation are not applied. A new permanent designation is given to a comet at each perihelion passage when observations are made, whether or not a recovery is involved. Brian G. Marsden M.P.E.C. 1993-Y05
- 1997-B01 (the full form)
- J97B01 (the packed version of the full form)
- B01 (the abbreviated form)