64P/Swift–Gehrels
{{Short description|Periodic comet with 9 year orbit}}
{{Use dmy dates|date=May 2025}}
{{For|other comets discovered by Lewis A. Swift|Comet Swift}}
{{Infobox comet
| name = 64P/Swift-Gehrels
| image = Comet 64P Swift-Gehrels.jpg
| caption = Comet Swift–Gehrels photographed by Alexander Vasenin from Moscow, Russia on 11 October 2018
| discoverer = Lewis A. Swift
Tom Gehrels
| discovery_date = 17 November 1889
8 February 1973
| mpc_name = P/1889 W1
P/1973 C1
| designations = Swift 1
1889f, 1973d, 1981j, 1991c
1889 VI, 1972 VII, 1981 XIX, 1991 II{{r|ICQ1}}
| orbit_ref = {{r|jpl}}
| epoch = 9 December 2017 (JD 2458096.5)
| observation_arc = 6,707 days (18.36 years)
| obs = 3,436
| perihelion = 1.393 AU
| aphelion = 7.518 AU
| semimajor = 4.456 AU
| period = 9.407 years
| eccentricity = 0.687
| inclination = 8.948°
| asc_node = 300.00°
| arg_peri = 97.144°
| tjup = 2.496
| Earth_moid = 0.4401 AU
| Jupiter_moid = 0.6491 AU
| physical_ref = {{r|jpl}}
| dimensions = {{cvt|3.2|km|mi}}
| M1 = 14.5
| M2 =
| magnitude = 9.0
(2018 apparition)
| last_p = 3 November 2018
| next_p = 31 March 2028{{r|Yoshida_2023}}
}}
64P/Swift–Gehrels is a periodic comet in the Solar System which has a current orbital period of 9.23 years.
Observational history
It was originally discovered on 17 November 1889 by Lewis A. Swift at the Warner Observatory, Rochester, New York, and was described by Swift as being pretty faint. It was rediscovered after it became a lost comet on 8 February 1973 by Tom Gehrels at the Palomar Observatory, California who estimated its brightness as a very low magnitude 19.{{r|cometography}}
It was also observed in 1981, 1991, 2000, 2009 and 2018. The 2018 apparition was the most favourable, with the comet reaching a peak magnitude of 9. It had its closest approach to the Earth on 28 October 2018, at a distance of 0.445 au.{{r|Biver_2021}} The comet had four outbursts. The brightest was on 14 August, during which the comet brightened 2.7 magnitudes.{{r|Kelley_2019}}
See also
References
{{Reflist|refs=
| author1= N. Biver
| author2= D. Bockelée-Morvan
| author3= D. C. Lis
| author4= D. Despois
| author5= R. Moreno
| author6= J. Crovisier
| author7= P. Colom
| author8= J. Boissier
| author9= N. Dello Russo
| author10= R. J. Vervack
| author11= M. Cordiner
| author12= S. Milam
| author13= N. X. Roth
| author14= B. P. Bonev
| author15= M. A. DiSanti
| author16= J. K. Davies
| author17= H. Kawakita
| display-authors= 5
| title= Molecular composition of short-period comets from millimetre-wave spectroscopy: 21P/Giacobini-Zinner, 38P/Stephan-Oterma, 41P/Tuttle-Giacobini-Kresák, and 64P/Swift-Gehrels
| url= https://www.aanda.org/articles/aa/pdf/2021/07/aa40765-21.pdf
| journal= Astronomy & Astrophysics
| year= 2021
| volume= 651
| pages= A25
| bibcode= 2021A&A...651A..25B
| s2cid= 236361791
| doi= 10.1051/0004-6361/202140765
| doi-access= free }}
| author1= G. W. Kronk
| title= 64P/Swift–Gehrels
| url= https://cometography.com/pcomets/064p.html
| website= Cometography.com
| access-date= 26 November 2014 }}
| title= Comet Names and Designations
| url= http://www.icq.eps.harvard.edu/names1.html
| website= International Comet Quarterly
| access-date= 31 December 2024 }}
| title= 64P/Swift–Gehrels – JPL Small-Body Database Lookup
| url= https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=64P
| website= ssd.jpl.nasa.gov
| publisher= Jet Propulsion Laboratory
| access-date= 31 December 2024 }}
| author1= M. S. P. Kelley
| author2= D. Bodewits
| author3= Q. Ye
| author4= T. Ahumada
| author5= J. Cromer
| author6= R. Dekany
| author7= G. Helou
| author8= R. R. Laher
| author9= F. J. Masci
| author10= C-C. Ngeow
| author11= B. Rusholme
| author12= D. L. Shupe
| display-authors= 5
| title= Outbursts at Comets 46P/Wirtanen, 64P/Swift-Gehrels, and 78P/Gehrels 2 in 2018
| url= https://iopscience.iop.org/article/10.3847/2515-5172/ab3fb4/ampdf
| journal= Research Notes of the AAS
| year= 2019
| volume= 3
| issue= 9
| pages= 126
| bibcode= 2019RNAAS...3..126K
| s2cid= 203040145
| issn= 2515-5172
| doi= 10.3847/2515-5172/ab3fb4
| doi-access= free }}
| author1= S. Yoshida
| title= 64P/Swift–Gehrels
| url= http://www.aerith.net/comet/catalog/0064P/index.html
| website= www.aerith.net
| access-date= 31 December 2024 }}
}}