84P/Giclas

84P/Giclas
Comet Giclas photographed from the Zwicky Transient Facility on 14 August 2020
Discovery[1]
Discovered byHenry L. Giclas
Discovery siteLowell Observatory, USA
Discovery date8 September 1978
Designations
  • D/1931 R1,[2] P/1978 R2
  • P/1985 M1
  • 1978 XXII, 1985 XV
  • 1992 XXV, 1978k, 1985g
  • 1992l
Orbital characteristics[5][6]
Epoch21 November 2025 (JD 2461000.5)
Observation arc89.43 years
Earliest precovery date12 September 1931[3]
Number of
observations		1,792
Aphelion5.381 AU
Perihelion1.719 AU
Semi-major axis3.550 AU
Eccentricity0.51562
Orbital period6.689 years
Inclination7.553°
108.08°
Argument of
periapsis		281.74°
Mean anomaly293.89°
Last perihelion3 June 2020
Next perihelion12 February 2027[4]
TJupiter2.872
Earth MOID0.862 AU
Jupiter MOID0.555 AU
Physical characteristics[5]
Mean radius
0.90 ± 0.05 km (0.559 ± 0.031 mi)[7]
0.04 (assumed)
(V–R) = 0.32±0.03[7]
Comet total
magnitude (M1)		14.2

84P/Giclas is a Jupiter-family comet with a 6.69-year orbit around the Sun. It is the only comet discovered by American astronomer, Henry L. Giclas.

Observational history

1931 apparition

It was announced in 1995 that Clyde W. Tombaugh had observed a previously unknown comet for three nights in September 1931.[3] Designated as D/1931 R1,[2] it was later confirmed to be an earlier apparition of 84P/Giclas upon reconstructing its orbit using non-gravitational accelerations in a 1996 study by Grzegorz Sitarski.[8]

1979 apparition

The comet was discovered by Henry L. Giclas from the Lowell Observatory on 8 September 1978.[1] At the time it was a diffuse 15th-magnitude object within the constellation Cetus.[a] He confirmed his discovery about two days later,[10] where Brian G. Marsden soon determined that it follows a 6.74-year periodic orbit around the Sun.[11] Throughout its 1978–1979 apparition, it remained mostly a photographic object.[9]

Follow-up observations

During the 2020 apparition, it was not more than 60 degrees from the Sun until September 2020. On 11 June 2033, the comet will pass 0.0387 AU (5.79 million km; 3.60 million mi) from the asteroid 4 Vesta.[5]

Physical characteristics

Based on observations by the Hubble Space Telescope in 1999–2000, the nucleus of the comet has a radius of 0.90±0.05 km, assuming a geometric albedo of 0.04.[7]

Notes

  1. ^ Reported initial position upon discovery was: α = 0h 08m 14s, δ = –8° 59′ 48″[9]

References

  1. ^ a b H. L. Giclas; M. L. Kantz (13 September 1978). B. G. Marsden (ed.). "Comet Giclas (1978k)". IAU Circular. 3264 (2). Bibcode:1978IAUC.3264....2G.
  2. ^ a b B. A. Skiff; D. H. Levy (13 April 1995). D. W. Green (ed.). "Comet D/1931 R1". IAU Circular. 6161 (3). ISSN 0081-0304.
  3. ^ a b R. J. Bouma (5 May 1995). D. W. Green (ed.). "Comet 84P/Giclas". IAU Circular. 6168 (4). ISSN 0081-0304.
  4. ^ "Horizons Batch for 84P/Giclas (90000868) on 2027-Feb-12" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Retrieved 19 June 2022. (JPL#49 Soln.date: 2021-Mar-29)
  5. ^ a b c "84P/Giclas – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 18 February 2012.
  6. ^ "84P/Giclas Orbit". Minor Planet Center. Retrieved 16 June 2014.
  7. ^ a b c P. L. Lamy; I. Toth; H. A. Weaver; M. F. A'Hearn; L. Jorda (2009). "Properties of the nuclei and comae of 13 ecliptic comets from Hubble Space Telescope snapshot observations" (PDF). Astronomy & Astrophysics. 508 (2): 1045–1056. Bibcode:2009A&A...508.1045L. doi:10.1051/0004-6361/200811462. S2CID 125249770.
  8. ^ G. Sitarski (1996). "On the Identity of the Periodic Comets 84P/Giclas and D/1931 R1" (PDF). Acta Astronomica. 46 (1): 47–49. Bibcode:1996AcA....46...47S.
  9. ^ a b G. W. Kronk; M. Meyer (2010). Cometography: A Catalog of Comets. Vol. 5: 1960–1982. Cambridge University Press. pp. 613–614. ISBN 978-0-521-87226-3.
  10. ^ H. L. Giclas; M. L. Kantz (14 September 1978). B. G. Marsden (ed.). "Comet Giclas (1978k)". IAU Circular. 3266 (1). Bibcode:1978IAUC.3266....1G.
  11. ^ C. Y. Shao (18 September 1978). B. G. Marsden (ed.). "Periodic Comet Giclas (1978k)". IAU Circular. 3269 (2). Bibcode:1978IAUC.3269....2S.


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