Presentation on theme: "Small Body Provisional Designation AS3141 Benda Kecil dalam Tata Surya Prodi Astronomi 2007/2008 B. Dermawan."— Presentation transcript:
Small Body Provisional Designation AS3141 Benda Kecil dalam Tata Surya Prodi Astronomi 2007/2008 B. Dermawan
How are Small Bodies Named? 1. The assignment of a particular name to a particular small body is the end of a long process that can take many decades 2. It begins with the discovery of a minor planet that cannot be identified with any already-known multiple-opposition or recent single-opposition object At this stage, it is possible to search for identifications with previously-discovered provisionally-designated objects observed at only one opposition in the past. If an identification is made, one of the provisional designations is defined to be the principal designation If no identifications are forthcoming, further observations of the new object are obtained and an orbit is computed If no identifications are found and the observed arc reaches two or three months, it is likely that the object may be found as a result of a direct search at the next opposition
How are Small Bodies Named? 3. Further observations are made of the object at later oppositions. When there are observations at four or more oppositions the object may receive a permanent designation, a number The discoverer of the numbered object is defined to be the same as the discoverer of the principal designation This discoverer is accorded the privilege of suggesting a name for his/her discovery. The discoverer has the privilege for a period of ten years following the numbering of the object The discoverer writes a short citation explaining the reasons for assigning the name
How are Small Bodies Named? 4. Names are judged by the fifteen-person Committee for Small-Body Nomenclature (formerly the Small Bodies Names Committee) of the International Astronomical Union, comprised of professional astronomers (with research interests connected with small bodies) from around the world Proposed names should be: 16 characters or less in length (including any spaces or punctuation), preferably one word, pronounceable (in some language), non-offensive, not too similar to an existing name of a minor planet or natural planetary satellite Names for persons or events known primarily for their military or political activities are acceptable only after 100 years elapsed since the person died or the event occurred Names of pet animals are discouraged Names of a purely or principally commercial nature are not allowed 5. Accepted names become official when they are published, along with their accompanying citations, in the Minor Planet Circulars, issued monthly by the Minor Planet Center (an official service of IAU Commission 20)
Asteroids The first element is the year of discovery, followed by two letters and, optionally, a number The first letter indicates the half-month of the object's discovery within that year —"A" denotes discovery in the first half of January, "D" is for the second half of February, "J" is for the first half of May ("I" is not used), and so on until "Y" for the second half of December. The first half is always the 1st through the 15th of the month, regardless of the numbers of days in the second "half". The second letter and the number indicate the order or discovery within that half-month. The 8th asteroid discovered in the second half of March 1950, for example, would be provisionally designated 1950 FH. But since modern techniques typically yield far more than 25 objects (again, "I" is not used) in a half-month, a subscript number is appended to indicate the number of times that the letters have cycled through. Thus, the 28th asteroid discovered in the second half of March 1950 would be 1950 FC 1. For technical reasons, such as ASCII limitations, the subscript is sometimes "flattened out", so that this could be written 1950 FC1. The subscripts were first used with 1926 GA 1
Asteroids In the year 2004, the first asteroid discovery of January 1 would be named 2004 AA. Then the naming continues to 2004 AZ, followed by 2004 AA 1. The next discovery is 2004 AB 1, then 2004 AC 1, etc. Eventually one could get to something like 2004 AA 276. Following the end of the half-month, the next asteroid to be discovered would receive the provisional designation 2004 BA The large outer solar system object 90377 Sedna had the provisional designation 2003 VB 12, meaning it was discovered in the first half of November 2003, and that it was the 302 nd object (B 2 + 12*25 = 302) discovered during that time. 28978 Ixion, originally 2001 KX 76, was discovered in the latter half of May 2001, and was the (X 23 + 76*25 = 1923) 1,923 rd object discovered during that time As of April 13, 2007, the busiest half-month has been the second half of October 2005. During those 16 days, 12,875 asteroids were observed and provisionally discovered, and the last one was thus named 2005 UW 512.
Survey Designation Asteroids discovered during four special past surveys have designations that consist of a number (order in the survey) followed by a space and one of the identifiers: P-L Palomar-Leiden Survey (1960) T-1 First Trojan Survey (1971) T-2 Second Trojan Survey (1973) T-3 Third Trojan Survey (1977) For example, the 2040th asteroid in the Palomar-Leiden Survey is 2040 P-L. The majority of these bodies have since been assigned a number
Comets The system used previous to 1995 was complex. The year was followed by a space and then a Roman numeral (indicating the sequence of discovery) in most cases, but difficulties always arose when an object needed to be placed between previous discoveries. For example, after Comet 1881 III and Comet 1881 IV might be reported, an object discovered in between the discovery dates but reported much later couldn't be designated "Comet 1881 III 1/2" The system since 1995 is similar to the provisional designation of asteroids. For comets, the provisional designation consists of the year of discovery, a space, ONE letter (unlike the asteroids with two) indicating the half-month of discovery within that year (A first half of January, B second half of January, etc. skipping I and not reaching Z), and finally a number (not subscripted as with asteroids), indicating the sequence of discovery. Thus, the eighth comet discovered in the second half of March 2006 would be given the provisional designation 2006 F8, whilst the tenth comet of late March would be 2006 F10
Comets If a comet splits, its segments are given the same provisional designation with a suffixed letter A, B, C,..., Z, a, b, c..., z. One presumes that tracking beyond 52 fragments is unlikely If an object is originally found asteroidal, and later develops a cometary tail, it retains its asteroidal designation. For example, asteroid 1954 PC turned out to be Comet Faye, and we thus have "4P/1954 PC" as one of the designations of said comet. Similarly, minor planet 1999 RE 70 was reclassified as a comet, and because it was discovered by LINEAR, it is now known as 176P/LINEAR (LINEAR 52) and (118401) LINEAR Comets are assigned one of four possible prefixes in order to give them a rough classification. The prefix "P" designates a periodic comet (as in, for example, P/1997 C1, a.k.a. Comet Gehrels 4), one which has an orbital period of less than 200 years or which has been observed during more than a single perihelion passage (e.g. 153P/Ikeya-Zhang, whose period is 367 years). They receive a permanent number prefix after their second observed perihelion passage (183 such comets as of January 2007)
Comets Comets which do not fulfill the "periodic" requirements receive the "C" prefix (e.g. C/2006 P1, the Great Comet of 2007), but it should be noted that such comets may switch to "P" if they later fulfill the requirements. Comets which have been lost or have disintegrated are prefixed "D" (e.g. D/1993 F2, Comet Shoemaker-Levy 9). Finally, comets known from historical records but for which no reliable orbit could be calculated are prefixed "X" (e.g. X/1106 C1) Provisional designations for comets are given condensed or "packed form" in the same manner as asteroids. 2006 F8, if a periodic comet, would be listed in the IAU Minor Planet Database as PK06F080. The last character is purposely a zero, as that allows comet and asteroid designations not to overlap
Satellites & Rings When satellites or rings are first discovered, they are given provisional designations such as "S/2000 J 11" (the 11th new satellite of Jupiter discovered in 2000), "S/2005 P 1" (the first new satellite of Pluto discovered in 2005), or "R/2004 S 2" (the second new ring of Saturn discovered in 2004). The initial "S/" or "R/" stands for "satellite" or "ring", respectively, distinguishing the designation from the prefixes "A/", "C/", "D/", "P/", and "X/" used for comets. These designations are sometimes written as "S/2005 P1", dropping the second space The prefix "S/" indicates a natural satellite, and is followed by a year (using the year when the discovery image was acquired, not necessarily the date of discovery). A one letter code identifies the planet (J, S, U, N, P for Jupiter, Saturn, Uranus, Neptune, and Pluto, respectively, and then a number identifies sequentially the observation. For example, Naiad, the innermost moon of Neptune, was at first designated "S/1989 N 6". Later, once its existence and orbit were confirmed, it received its full designation, "Neptune III Naiad"
Satellites & Rings The Roman numbering system arose with the very first discovery of natural satellites other than Earth's Moon: Galileo referred to the Galilean moons as I through IV (counting from Jupiter outward), in part to spite his rival Simon Marius, who had proposed the names now adopted. Similar numbering schemes naturally arose with the discovery of moons around Saturn and Mars. Although the numbers initially designated the moons in orbital sequence, new discoveries soon failed to conform with this scheme (e.g. "Jupiter V" is Amalthea, which orbits closer to Jupiter than does Io). The unstated convention then became, at the close of the 19th century, that the numbers more or less reflected the order of discovery, except for prior historical exceptions. The convention has been extended to natural satellites of asteroids, such as "(87) Sylvia I Romulus"
Asteroid Moons The provisional designation system for asteroid moons follows that established for the satellites of the major planets. With asteroids, the planet letter code is replaced by the asteroid number in parentheses. Thus, the moon of 87 Sylvia, discovered in 1998, was at first designated S/2001 (87) 1, later receiving its permanent designation of (87) Sylvia I Romulus. Where more than one moon has been discovered, Roman numerals specify the discovery sequence, so that Sylvia's second moon is designated (87) Sylvia II Remus