Precovery
In
Orbit determination requires measuring an object's position on multiple occasions. The longer the interval between observations, the more accurately the orbit can be calculated; however, for a newly discovered object, only a few days' or weeks' worth of measured positions may be available, sufficient only for a preliminary (imprecise) orbit calculation.
When an object is of particular interest (such as asteroids with a chance of impacting Earth), researchers begin a search for precovery images. Using the preliminary orbit calculation to predict where the object might appear on old archival images, those images (sometimes decades old) are searched to see if it had in fact already been photographed. If so, a far longer observation arc can allow a far more precise orbital calculation.
Until fast computers were widely available, it was impractical to analyze and measure images for possible minor planet discoveries because this required much human labor. Usually, such images were made years or decades earlier for other purposes (studies of
Examples
In an extreme case of precovery, an object was discovered on December 31, 2000, designated
The asteroid
Another noteworthy case of precovery concerns
One of the most exceptional suggested instances is related to the discovery of Ganymede. This again involved Galileo, who is usually stated to have discovered it in 1610. It has been postulated by Xi Zezong that Ganymede was discovered by the Chinese astronomer Gan De in 365 B.C., when he catalogued it as a small red star next to Jupiter during naked eye observation.[6]
Dwarf planets
Discovery and precovery dates for well-known dwarf planets, minor planets and probable dwarf planets:
Index | Object | Discovery Year |
Precovery Year |
Years Elapsed | Absolute Magnitude |
---|---|---|---|---|---|
2 | Pallas | 1802 | 1779[7] | 23 | 4.13 |
134340 | Pluto | 1930 | 1909[8] | 21 | -0.7 |
19521 | Chaos | 1998 | 1991 [9] | 7 | 5.0 |
20000 | Varuna | 2000 | 1954[10] | 46 | 3.76 |
38628 | Huya | 2000 | 1996[11] | 4 | 5.04 |
78799 | 2002 XW93 | 2002 | 1989 [12] | 13 | 5.5 |
28978 | Ixion | 2001 | 1982[13] | 19 | 3.6 |
55637 | 2002 UX25 | 2002 | 1991 [14] | 11 | 3.87 |
50000 | Quaoar | 2002 | 1954[15] | 48 | 2.82 |
307261 | 2002 MS4 | 2002 | 1954[16] | 48 | 3.7 |
55565 | 2002 AW197 | 2002 | 1997 [17] | 5 | 3.5 |
2002 XV93 |
2002 | 1990 [18] | 12 | 5.42 | |
174567 | Varda | 2003 | 1980 [19] | 23 | 3.1 |
84922 | 2003 VS2 | 2003 | 1991 [20] | 12 | 4.1 |
208996 | 2003 AZ84 | 2003 | 1996 [21] | 7 | 3.54 |
455502 | 2003 UZ413 | 2003 | 1954 [22] | 49 | 4.38 |
90377 | Sedna | 2003 | 1990[23] | 13 | 1.83 |
444030 | 2004 NT33 | 2004 | 1982 [24] | 22 | 4.4 |
230965 | 2004 XA192 | 2004 | 1989 [25] | 15 | 4.1 |
90568 | 2004 GV9 | 2004 | 1954 [26] | 50 | 4.25 |
90482 | Orcus | 2004 | 1951[27] | 53 | 2.2 |
175113 | 2004 PF115 | 2004 | 1992 [28] | 12 | 4.54 |
120347 | Salacia | 2004 | 1982 [29] | 22 | 4.36 |
120348 | 2004 TY364 | 2004 | 1983 [30] | 21 | 4.52 |
136108 | Haumea |
2004 | 1955[31] | 49 | 0.2 |
145451 | 2005 RM43 | 2005 | 1976 [32] | 29 | 4.4 |
145452 | 2005 RN43 | 2005 | 1954 [33] | 51 | 3.89 |
202421 | 2005 UQ513 | 2005 | 1990 [34] | 15 | 3.4 |
136199 | Eris | 2005 | 1954[35] | 51 | -1.17 |
136472 | Makemake |
2005 | 1955[36] | 50 | -0.3 |
470308 | 2007 JH43 | 2007 | 1984 [37] | 23 | 4.49 |
229762 | Gǃkúnǁʼhòmdímà | 2007 | 1982 [38] | 25 | 3.69 |
225088 | Gonggong | 2007 | 1985[39] | 22 | 1.8 |
523671 | 2013 FZ27 | 2013 | 2001[40] | 12 | 4.1 |
472271 | 2014 UM33 | 2014 | 2003 [41] | 11 | 5.2 |
523794 | 2015 RR245 | 2015 | 2004[42] | 11 | 3.6 |
2018 VG18 | 2018 | 2003 [43] | 15 | 3.5 |
Oort cloud comets
Oort cloud comets can take 10+ years going from
Comet | Discovery date |
Precovery date |
Discovery distance from Sun (AU) |
Precovery distance from Sun (AU) |
Ref |
---|---|---|---|---|---|
C/2010 U3 (Boattini) | 2010-10-31 | 2005-11-05 | 18.4 | 25.8 | JPL |
C/2012 S1 (ISON) |
2012-09-21 | 2011-09-30 | 6.3 | 9.4 | JPL |
C/2013 A1 (Siding Spring) | 2013-01-03 | 2012-10-04 | 7.2 | 7.9 | JPL |
C/2017 K2 (PANSTARRS) |
2017-05-21 | 2013-05-12 | 16.1 | 23.7 | JPL |
See also
- Discovery image
- DANEOPS
References
- Bibcode:1995ASPC...84..170M.
- ^ D.I. Steel, R.H. McNaught, G.J. Garradd, D.J. Asher and K.S. Russell (25 March 1997). "AANEAS: A Valedictory Report". Archived from the original on 2012-07-28.
{{cite web}}
: CS1 maint: multiple names: authors list (link) - ^ Villard, Ray; Lafreniere, David (April 1, 2009). "Hubble Finds Hidden Exoplanet in Archival Data". HubbleSite NewsCenter. NASA. Archived from the original on April 5, 2009. Retrieved 2009-04-03.
- ^ "JPL Small-Body Database Browser: 2060 Chiron (1977 UB)" (2009-09-17 last obs). Archived from the original on 2011-06-09. Retrieved 2010-02-08.
- ISBN 9780521789813. Retrieved 2009-09-11.
- ^ "Galilean Moons– Gan De". Archived from the original on 2017-12-01. Retrieved 27 November 2017.
- ^ "Charles Messier, premier observateur de l'astéroïde Pallas". cieletespace.fr. Archived from the original on 16 March 2016. Retrieved 7 May 2018.
- Bibcode:1998DPS....30.5514W.
- ^ "JPL Small-Body Database Browser".
- ^ Chamberlin, Alan. "JPL Small-Body Database Browser". ssd.jpl.nasa.gov. Archived from the original on 7 May 2018. Retrieved 7 May 2018.
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- ^ "JPL Small-Body Database Browser: 50000 Quaoar (2002 LM60)" (2009-09-12 last obs). Archived from the original on 2011-06-11. Retrieved 2010-02-08.
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- ^ "JPL Small-Body Database Browser: 136472 Makemake (2005 FY9)" (2010-01-26 last obs). Archived from the original on 2011-08-30. Retrieved 2010-02-08.
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- ^ "JPL Small-Body Database Browser: 2015 RR245)" (2016-06-08 last obs). Archived from the original on 2016-12-27. Retrieved 2016-12-26.
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