Provisional designation in astronomy


Provisional designation in astronomy is the naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calculated. In the case of more than 900,000 minor planets, approximately a third remains provisionally designated, as hundreds of thousands have been discovered in the last two decades.

Minor planets

The current system of provisional designation of minor planets has been in place since 1925, and superseded several previous conventions, each of which was rendered obsolete by the increasing numbers of minor planet discoveries. A modern or new-style provisional designation consists of the year of discovery, followed by two letters and, optionally, a suffixed number.

New-style provisional designation

For example, the provisional designation stands for the 3910th body identified during 1–15 March 2016:
Minor planets discovered during the Palomar–Leiden survey including three subsequent Trojan-campaigns, which altogether discovered more than 4,000 asteroids and Jupiter trojans between 1960 and 1977, have custom designations that consist of a number followed by a space and one of the following identifiers:
For example, the asteroid 6344 P-L is the 6344th minor planet in the original Palomar–Leiden survey, while the asteroid 4835 T-1 was discovered during the first Trojan-campaign. The majority of these bodies have since been assigned a number and many are already named.

Historical designations

The first four minor planets 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 minor planets, 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 and 4 Vesta a sacred fire altar.
It soon became apparent, though, that continuing to assign symbols was impractical and provided no assistance when the number of known minor planets was in the tens. Johann Franz Encke introduced a new system in the Berliner Astronomisches Jahrbuch 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 and went through 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.
The new system found popularity among astronomers, and since then, the final designation of a minor planet is a number indicating its order of discovery followed by a name. Even after the adoption of this system, though, several more minor planets 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, four more minor planets 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.

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 in 1892. 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. Under this scheme, 333 Badenia was initially designated, 163 Erigone was, 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 followed 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.
Because a considerable amount of time could sometimes elapse between exposing the photographic plates of an astronomical survey and actually spotting a small Solar System object on them, or even between the actual discovery and the delivery of the message to the central authority, it became necessary to retrofit discoveries into the sequence — to this day, discoveries are still dated based on when the images were taken, and not on when a human realised they were looking at something new. In the double-letter scheme, this was not generally possible once designations had been assigned in a subsequent year. The scheme used to get round this problem was rather clumsy and used a designation consisting of the year and a lower-case letter in a manner similar to the old provisional-designation scheme for comets. For example, , 1917 b. In 1914 designations of the form year plus Greek letter were used in addition.

Temporary minor planet designations

Temporary designations are custom designation given by an observer or discovering observatory prior to the assignment of a provisional designation by the MPC. These intricate designations were used prior to the Digital Age, when communication was slow or even impossible. The listed temporary designations by observatory/observer use uppercase and lowercase letters, digits, numbers and years, as well Roman numerals and Greek letters.
ObservatoryTemp. designationExamples
Algiers Obs.Alger LETTERAlger A, Alger CM
Algiers Obs.Alg LETTERAlg A, Alg CM
Alma-AtaAlma-Ata numberAlma-Ata Nr. 1
Alma-Atayear A number1952 A1, A1
ArequipaArequipa letterArequipa a
ArequipaAreq letterAreq a
ArequipaArequipa numberArequipa 17
ArequipaAreq numberAreq 17
Belgrade Obs.year letter 1956 x, 1956 x
Belgrade Obs.letterx
Lowell Obs.
A numberA0, A7
Heidelberg Obs.Wolf numberWolf Nr. 18, Wolf 18
Heidelberg Obs.Wolf letterWolf u
Heidelberg Obs.Wolf greekWolf alpha
Heidelberg Obs.Heid numberHeid 1, Heid 234
Johannesburg Obs.LETTERA, E
Johannesburg Obs.G numberG 1, G 21
Johannesburg Obs.T numberT 9, T 16
Kyoto-Kwasannumber1, 6
Kyoto-Kwasanletterd
La Plata Obs. year ROMLa Plata 1951 I, 1951 I
La Plata Obs. year LETTERLa Plata 1950 G, 1950 G
Lick LETTERAsteroid B, B
Mount Wilson Obs. LETTERAsteroid A, A
Mount Wilson Obs.LETTERD
Purple Mountain Obs.
P.O. numberP.O. 32, P.O. 189
Purple Mountain Obs.
PO numberPO 32, PO 189
Crimean Astrophysical Obs.
N numberN1
Crimean Astrophysical Obs.
K numberK1, K3423
Simeiz Obs. SIGMA K number1942 SIGMA K1, SIGMA K1
Simeiz Obs. SIG K number1942 SIG K1, SIG K1
Simeiz Obs.sigma numbersigma 1, sigma 229
Taunton Obs.Taunton digitTaunton 83
Tokyo-MitakaTokyo LETTERTokyo B
Tokyo-MitakaTokyo letterTokyo b
Tokyo-MitakaTokyo numberTokyo 20
Tokyo-MitakaTokyo year LETTERTokyo 1954 D
Turku Obs.T- numberT-1, T-774
Uccle Obs.letter p, p
Uccle Obs.letter number x2, x2
Uccle Obs. U number1945 U 12, U 12
Washingtonyear W digit1917 W 15, 1923 W 21
Yerkes Obs.Y.O. numberY.O. 23
Yerkes Obs.YO numberYO 23

Comets

The system used for comets was complex previous to 1995. Originally, 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 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 III½". More commonly comets were known by the discoverer's name and the year. An alternate scheme also listed comets in order of time of perihelion passage, using lower-case letters; thus "Comet Faye" was both Comet 1881 I and Comet 1880c.
The system since 1995 is similar to the provisional designation of minor planets. For comets, the provisional designation consists of the year of discovery, a space, ONE letter indicating the half-month of discovery within that year, and finally a number, indicating the sequence of discovery within the half-month. 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.
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, minor planet 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 was reclassified as a comet, and because it was discovered by LINEAR, it is now known as 176P/LINEAR and LINEAR.
Provisional designations for comets are given condensed or "packed form" in the same manner as minor planets. 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 minor planet designations not to overlap.

Periodic comets

Comets are assigned one of four possible prefixes as a rough classification. The prefix "P" designates a "periodic comet", one which has an orbital period of less than 200 years or which has been observed during more than a single perihelion passage. They receive a permanent number prefix after their second observed perihelion passage .

Non-periodic comets

Comets which do not fulfill the "periodic" requirements receive the "C" prefix. Comets initially labeled as "non-periodic" may, however, switch to "P" if they later fulfill the requirements.
Comets which have been lost or have disintegrated are prefixed "D".
Finally, comets for which no reliable orbit could be calculated, but are known from historical records, are prefixed "X" as in, for example, X/1106 C1.

Satellites and rings of planets

When satellites or rings are first discovered, they are given provisional designations such as "", "", or "". The initial "S/" or "R/" stands for "satellite" or "ring", respectively, distinguishing the designation from the prefixes "C/", "D/", "P/", and "X/" used for comets. These designations are sometimes written as "", dropping the second space.
The prefix "S/" indicates a natural satellite, and is followed by a year. A one-letter code written in upper case identifies the planet such as J and S for Jupiter and Saturn, respectively ', and then a number identifies sequentially the observation. For example, Naiad, the innermost moon of Neptune, was at first designated "". Later, once its existence and orbit were confirmed, it received its full designation, "".
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, 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. 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 minor planets, such as "".

Moons of minor planets

The provisional designation system for minor planet satellites, such as 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 first observed moon of 87 Sylvia, discovered in 2001, was at first designated S/2001 1, later receiving its permanent designation of 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 Sylvia II Remus.

Packed designation

Packed designations are used in online and electronic documents as well as databases.

Packed minor planet designation

The Orbit Database of the Minor Planet Center uses the "packed form" to refer to all provisionally designated minor planets. The idiosyncrasy found in the new-style provisional designations, no longer exists in this packed-notation system, as the second letter is now listed after the subscript number, or its equivalent 2-digit code. For an introduction on provisional minor planet designations in the "un-packed" form, see.

Provisional packed designations

The system of packed provisional minor planet designations:
Contrary to the new-style system, the letter "i" is used in the packed form both for the year and the numeric suffix. The compacting system provides upper and lowercase letters to encode up to 619 "cycles". This means that 15,500 designations within a half-month can be packed, which is a few times more than the designations assigned monthly in recent years.
; Examples:
  1. is written as J95X00A
  2. is written as J95X01L
  3. is written as K16EF6K
  4. is written as K07Tf8A
; Description
  1. The year 1995 is compacted to J95. As it has no subscript number, 00 is used as placeholder instead, and directly placed after the half-month letter "X".
  2. The year 1995 is compacted to J95. Subscript number "1" is padded to 01 to maintain the length of 7 characters, and placed after the first letter.
  3. The year 2016 is compacted to K16. The subscript number "156" exceeds 2 digits and is converted to F6, '
  4. The year 2007 is compacted to K07. The subscript number "418" exceeds 2 digits and is converted to f8,
; Conversion tables

Packed survey designations

used during the Palomar–Leiden Survey have a simpler packed form, as for example:
Note that the survey designations are distinguished from provisional designations by having the letter S in the third character, which contains a decimal digit in provisional designations and permanent numbers.

Permanent packed designations

A packed form for permanent designations also exists. In this case, only the designation's number is used and converted to a 5-character string. The rest of the permanent designation is ignored. Minor planet numbers below 100,000 are simply zero-padded to 5 digits from the left side. For minor planet above 100,000, a single letter is used, similar as for the provisional subscript number :
; Examples:
This system permits compression of numbers up to 619,999. the list of minor planets already contains more than half a million numbered bodies. For minor planets numbered 620,000 or higher, a tilde "~" will be used as the first character. The subsequent 4 characters encoded in Base62 are used to store the difference of the object's number minus 620,000. This extended system will allow for the encoding of more than 15 million minor planet numbers. For example: