Overgangsnamn
Frå Wikipedia – det frie oppslagsverket
Overgangsnamn er den astronomiske namnekonvensjonen som blir brukt for astronomiske objekt rett etter at dei er oppdaga. Det provisoriske namnet blir som regel erstatta med eit permanent namn så snart forskarane har vorte i stand til å rekne ut omløpet nøyaktig. For asteroidar er det funne så mange, at mange av dei vil aldri få namn av dei som oppdaga dei.
Innhaldsliste |
[endre] Asteroids
Dagens overgangsnamnesystem for asteroidar har vore i bruk sidan 1925. Det erstatta fleire tidlegare system som var blitt ubrukbare på grunn av stadig nye asteroideoppdagingar.
| Denne artikkelen er ikkje (ferdig) omsett frå engelsk enno.
Hjelp oss gjerne med å gjera omsetjinga ferdig! |
[endre] Historical designations
The first four asteroids were discovered in the early 19th century, after which there was a lengthy gap before the discovery of the fifth. Astronomers initially had no reason to believe that there would be countless thousands of asteroids, and strove to assign a symbol to each new discovery, in the tradition of the symbols used for the major planets. For example, 1 Ceres was assigned a stylized sickle, 2 Pallas a lozenge with a crossed handle, 3 Juno a Venus mirror crowned by a star (later became a star with a crossed handle) and 4 Vesta a sacred fire altar [1].
It soon became apparent, though, that continuing to assign symbols was impractical and provided no assistance when the number of known asteroids was in the tens. Johann Franz Encke introduced a new system in the Berliner Astronomisches Jahrbuch (BAJ) for 1854, published in 1851, in which he used encircled numbers instead of symbols. Encke's system began the numbering with Astrea which was given the number (1) and went through (11) Eunomia, while Ceres, Pallas, Juno and Vesta continued to be denoted by symbols, but in the following year's BAJ, the numbering was changed so that Astraea was number (5).
The new system found popularity among astronomers, and since then, the final designation of an asteroid is a number indicating its order of discovery followed by a name. Even after the adoption of this system, though, several more asteroids received symbols, including 28 Bellona the whip and lance of Mars' martial sister, 35 Leukothea an ancient lighthouse and 37 Fides a latin cross. According to Webster's A Dictionary of the English Language, G. & C. Merriam & Co., Springfield (Ma), USA, p. 1780 (1884), four more asteroids were also given symbols: 16 Psyche, 17 Thetis, 26 Proserpina, and 29 Amphitrite. However, there is no evidence that these symbols were ever used outside of their initial publication in the Astronomische Nachrichten.
[endre] Genesis of the current system
Several different notation and symbolic schemes were used during the latter half of the nineteenth century, but the present form first appeared in the journal Astronomische Nachrichten (AN) in 1911. New numbers were assigned by the AN on receipt of a discovery announcement, and a permanent designation was then assigned once an orbit had been calculated for the new object.
At first, the provisional designation consisted of the year of discovery followed by a letter indicating the sequence of the discovery, but omitting the letter I (sometimes J was omitted instead). Under this scheme, 333 Badenia was initially designated 1892 A, 163 Erigone was 1892 B, etc. In 1893, though, increasing numbers of discoveries forced the revision of the system to use double letters instead, in the sequence AA, AB...AZ, BA and so on. The sequence of double letters was not restarted each year, so that 1894 AQ followed 1893 AP and so on. In 1916, the letters reached ZZ and, rather than starting a series of triple-letter designations, the double-letter series was restarted with 1916 AA.
[endre] Later refinements
1925 saw the adoption of a more structured lettering system, in which the provisional designation consisted of the year of discovery, followed by two letters indicating the order of the object's discovery within that year. The first letter indicated the half-month (A=first half of January, B=second half of January, etc), while the second letter indicated the sequence of the discovery. So, the 8th asteroid discovered in the second half of March 1950 would be provisionally designated 1950 FH. If more than 25 objects are discovered in a given half-month (The letter I is not used), the lettering restarts with a subscript 1
[endre] Examples
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 AA1 (partly for technological reasons (ASCII limitations), the subscript may be "flattened out", so that 2004 AA1 is written 2004 AA1). The next discovery is 2004 AB1, then 2004 AC1, etc. Eventually one could get to something like 2004 AA276. 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 VB12, meaning it was discovered in the first half of November 2003, and that it was the 302nd object (B->2 + 12*25 = 302) discovered during that time. 28978 Ixion, originally 2001 KX76, was discovered in the latter half of May 2001, and was the (X->23 + 76*25 = 1923) 1,923rd object discovered during that time.
[endre] Survey designations
Minor planets 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.
[endre] Comets
The system used previous to 1995 was complex. The year was followed by a space and then a Roman numeral in most cases, but difficulties always arose when an object needed to be placed between previous discoveries. For example, after Comet 1990 III and Comet 1990 IV might be reported, an object discovered in between the discovery dates couldn't be designated Comet 1990 III 1/2. More commonly comets were known by the discoverer's name and the year.
The system since 1995 follows the provisional designation of asteroids. For comets, the provisional designation consists of the year of discovery, followed by ONE letter (unlike the asteroids with two) indicating the order of the object's discovery within that year. The first letter indicates the half-month (A=first half of January, B=second half of January, etc. skipping I and not reaching Z), while the next character, an on-the-line-digit, indicates the sequence of the discovery. So, the 8th comet discovered in the second half of March 2006 would be given a provisional designation 2006 F8. The tenth comet of late March would thus be 2006 F10.
This method contrasts with asteroids, which use subscripted numerals. 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.
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.
Further detail is found at [2]
[endre] Satellites of planets
When satellites are first discovered, they are given provisional designations such as "S/2000 J 11" (the 11th new satellite of Jupiter discovered in 2000) or "S/2005 P 1" (the 1st new satellite of Pluto discovered in 2005). The initial "S/" stands for "satellite", and distinguishes from such prefixes as "D/", "C/", and "P/", 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.
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 (see the Timeline of discovery of Solar System planets and their natural satellites).
[endre] Asteroid moons
The provisional designation system for asteroid moons follows that established for the satellites of the major planets. With minor planets, the planet letter code is replaced by the minor planet 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.
[endre] References
- Mal:Cite journal
[endre] See also
- Astronomical naming conventions
- Naming of natural satellites
[endre] External links
- When Did the Asteroids Become Minor Planets?
- New- And Old-Style Minor Planet Designations (Minor Planet Center)
