Provisional designation in astronomy

Provisional designation 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 The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calculated., approximately 47% of the more than 1,100,000 known minor planets remain provisionally designated, as hundreds of thousands have been discovered in the last two decades. The modern system is overseen by the Minor Planet Center of the International Astronomical Union.

Minor planets

The current system of provisional designation of minor planets has been in place since 1925. It superseded several previous conventions, each of which was in turn rendered obsolete by the increasing numbers of minor planet discoveries.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, possibly, a suffixed number.

New-style provisional designation

For example, the provisional designation stands for the 27th body identified during 16–31 Aug 1992:

1992 – the first element indicates the year of discovery.
Q – the first letter indicates the half-month of the object's discovery within that year and ranges from A to Y, while the letters I and Z are not used '. The first half is always the 1st through to the 15th of the month, regardless of the numbers of days in the second "half". Thus, Q indicates the period from Aug 16 to 31.
B₁ – the second letter and a numerical suffix indicate the order of discovery within that half-month. The first 25 discoveries of the half-month only receive a letter without a suffix, while the letter I is not used. Because modern techniques typically yield hundreds if not thousands of discoveries per half-month, the subscript number is appended to indicate the number of times that the letters from A to Z have cycled through. The suffix 1 indicates one completed cycle, while B is the 2nd position in the current cycle. Thus, B₁ stands for the 27th minor planet discovered in a half-month.
The [|packed form] of is written as.

This scheme is now also used retrospectively for pre-1925 discoveries. For these, the first digit of the year is replaced by an A. For example, A'''801 AA indicates the first object discovered in the first half of January 1801.

Further explanations

During the first half-month of January 2014, the first minor planet identification was assigned the provisional designation. Then the assignment continued to the end of the cycle at, which was in turn followed by the first identification of the second cycle,. The assignment in this second cycle continued with,,... until, and then was continued with the first item in the third cycle. With the beginning of a new half-month on 16 January 2014, the first letter changed to "B", and the series started with.
An idiosyncrasy of this system is that the second letter is listed before the number, even though the second letter is considered "least-significant". This is in contrast to most of the world's numbering systems. This idiosyncrasy is not seen, however, in the so-called packed form.
A [|packed designation] has no spaces. It may also use letters to codify for the designation's year and subscript number. It is frequently used in online and electronic documents. For example, the provisional designation is written as K07Tf8A in the packed form, where "K07" stands for the year 2007, and "f8" for the subscript number 418.
90377 Sedna, a large trans-Neptunian object, had the provisional designation, meaning it was identified in the first half of November 2003, and that it was the 302nd object identified during that time, as 12 cycles of 25 letters give 300, and the letter "B" is the second position in the current cycle.
[|Survey designations] do not follow the rules for new-style provisional designations.
For technical reasons, such as ASCII limitations, the numerical suffix is not always subscripted, but sometimes "flattened out", so that can also be written as.
A very busy half month was the second half of January 2015, which saw a total of 15,502 new minor planet identifications. One of the last assignments in this period was and corresponds to the 15,502nd position in the sequence.
Survey designations

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:

P-L Palomar–Leiden survey
T-1 Palomar–Leiden Trojan survey
T-2 Palomar–Leiden Trojan survey
T-3 Palomar–Leiden Trojan survey

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 stylized lance or spear, 3 Juno a scepter, and 4 Vesta an altar with a sacred fire. All had various graphic forms, some of considerable complexity.
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 dozens. 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 Astraea 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 morning star and lance of Mars's 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.
134340 Pluto is an exception: it is a high-numbered minor planet that received a graphical symbol with significant astronomical use, because it was considered a major planet on its discovery, and did not receive a minor planet number until 2006.
Graphical symbols continue to be used for some minor planets, and assigned for some recently discovered larger ones, mostly by astrologers. Three centaurs – 2060 Chiron, 5145 Pholus, and 7066 Nessus – and the largest trans-Neptunian objects – 50000 Quaoar, 90377 Sedna, 90482 Orcus, 136108 Haumea, 136199 Eris, 136472 Makemake, and 225088 Gonggong – have relatively standard symbols among astrologers: the symbols for Haumea, Makemake, and Eris have even been occasionally used in astronomy. However, such symbols are generally not in use among astronomers.

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 around 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 designations 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 or observer use uppercase and lowercase letters, digits, numbers and years, as well Roman numerals and Greek letters.

Observatory	Temp. designation	Examples
Algiers Obs.	Alger `LETTER`	Alger A, Alger CM
Algiers Obs.	Alg `LETTER`	Alg A, Alg CM
Alma-Ata	Alma-Ata `number`	Alma-Ata Nr. 1
Alma-Ata	`year` A `number`	1952 A1, A1
Arequipa	Arequipa `letter`	Arequipa a
Arequipa	Areq `letter`	Areq a
Arequipa	Arequipa `number`	Arequipa 17
Arequipa	Areq `number`	Areq 17
Belgrade Obs.	`year` `letter`	1956 x, 1956 x
Belgrade Obs.	`letter`	x
Lowell Obs.	A `number`	A0, A7
Heidelberg Obs.	Wolf `number`	Wolf Nr. 18, Wolf 18
Heidelberg Obs.	Wolf `letter`	Wolf u
Heidelberg Obs.	Wolf `greek`	Wolf alpha
Heidelberg Obs.	Heid `number`	Heid 1, Heid 234
Johannesburg Obs.	`LETTER`	A, E
Johannesburg Obs.	G `number`	G 1, G 21
Johannesburg Obs.	T `number`	T 9, T 16
Kyoto-Kwasan	`number`	1, 6
Kyoto-Kwasan	`letter`	d
La Plata Obs.	`year` `ROM`	La Plata 1951 I, 1951 I
La Plata Obs.	`year` `LETTER`	La Plata 1950 G, 1950 G
Lick	`LETTER`	Asteroid B, B
Mount Wilson Obs.	`LETTER`	Asteroid A, A
Mount Wilson Obs.	`LETTER`	D
Purple Mountain Obs.	P.O. `number`	P.O. 32, P.O. 189
Purple Mountain Obs.	PO `number`	PO 32, PO 189
Crimean Astrophysical Obs.	N `number`	N1
Crimean Astrophysical Obs.	K `number`	K1, K3423
Simeiz Obs.	SIGMA K `number`	1942 SIGMA K1, SIGMA K1
Simeiz Obs.	SIG K `number`	1942 SIG K1, SIG K1
Simeiz Obs.	sigma `number`	sigma 1, sigma 229
Taunton Obs.	Taunton `digit`	Taunton 83
Tokyo-Mitaka	Tokyo `LETTER`	Tokyo B
Tokyo-Mitaka	Tokyo `letter`	Tokyo b
Tokyo-Mitaka	Tokyo `number`	Tokyo 20
Tokyo-Mitaka	Tokyo `year` `LETTER`	Tokyo 1954 D
Turku Obs.	T- `number`	T-1, T-774
Uccle Obs.	`letter`	p, p
Uccle Obs.	`letter` `number`	x2, x2
Uccle Obs.	U `number`	1945 U 12, U 12
Washington	`year` W `digit`	1917 W 15, 1923 W 21
Yerkes Obs.	Y.O. `number`	Y.O. 23
Yerkes Obs.	YO `number`	YO 23