C/1961 T1 (Seki)

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C/1961 T1 (Seki)
Comet Seki 1961.jpg
Comet Seki photographed by Elizabeth Roemer on 18 October 1961
Discovery
Discovered by Tsutomu Seki
Discovery date10 October 1961
Designations
1961f
1961 VIII
Orbital characteristics [1]
Epoch 12 November 1961 (JD 2437615.5)
Observation arc 75 days
Number of
observations		15
Aphelion 173 AU
Perihelion 0.681 AU
Semi-major axis 86.8 AU
Eccentricity 0.9921
Orbital period ~810 years
Inclination 155.71°
247.36°
Argument of
periapsis 		126.59°
Last perihelion10 October 1961
TJupiter -0.871
Earth MOID 0.084 AU
Jupiter MOID 0.490 AU
Physical characteristics
4

C/1961 T1 (Seki) is a long-period comet discovered by Tsutomu Seki on 10 October 1961. The comet has been identified as the parent body of the December ρ-Virginids meteor shower.

Contents

Observational history

The comet was discovered on 10 October 1961 by Tsutomu Seki from Kochi, Japan. He used a 9-cm refractor, which had a larger field of view from his previous reflector telescope, to sweep the southeastern sky before the start of the twilight. He quickly spotted the comet 10 degrees above the horizon in the constellation of Leo and estimated its magnitude at 7–8. The comet was then at perihelion and at an elongation of 31 degrees. [2]

The presence of the comet was confirmed by Minoru Honda on 11 October, and described the comet as diffuse with central concentration and a magnitude of 8. The comet reached its northernmost declination on 14 October, at 14° north. [2] On that day the comet was reported by Ahnert to have a tail 4 degrees long while George Alcock estimated the comet to have an apparent magnitude of 7. [3] Elias and Phocas observed the comet from Athens Observatory and noted that the nucleus and had split in three on 17 October and there were bright condensations around the nucleus on 19 October. [4] On the 25 October Elizabeth Roemer estimated using binoculars that the comet had an apparent magnitude of 6.5. [5]

The comet brightened in November, as it approached Earth, and was moving rapidly southwards. The comet was first reported to be visible with naked eye on 11 November, with brightness estimates between 4.5 and 5.5. [2] The comet approached Earth to a distance of 0.102 AU on 15 November 1961. [1] S. Archer from Rhodes University, South Africa, estimated that the comet peaked at an apparent magnitude of 4.3 and its coma was up to 40 arcminutes across. [6] John Caister Bennett estimated the comet had an apparent magnitude of 4 on 13 and 15 November. The comet reached its southernmost declination of 16 November, at -69°. [2] After that the comet faded quickly and on 4 December its magnitude was reported to be 8.4. It was last detected on 29 December 1961. [2]

Meteor showers

The comet approaches Earth to a distance of 0.08 AU and thus it was suggested from 1961 that is could be a source of meteors. Mathematical models indicate that the meteor stream of the comet evolved into two filaments. The shower associated with the first filament was identified as the December ρ-Virginids, while the other shower was identified as the γ-Sagittariids. [7]

Related Research Articles

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C/1975 T2 (Suzuki–Saigusa–Mori) is a long-period comet discovered on 5 October 1975. The comet approached Earth at a distance of 0.1 AU on 31 October 1975 and became visible with naked eye. The comet has been associated with the lambda Ursae Majorids meteor shower.

References

  1. 1 2 "C/1961 T1 (Seki) – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory . Retrieved 25 December 2024.
  2. 1 2 3 4 5 Kronk, Gary W.; Meyer, Maik; Seargent, David Allan John (1999). Cometography: Volume 5, 1960-1982: A Catalog of Comets. Cambridge University Press. pp. 56–60. ISBN   978-0-521-87226-3.
  3. ↑ Thernoe, K. A. (18 October 1961). "Comet Seki (1961f)". International Astronomical Union Circulars. 1776: 1.
  4. ↑ Thernoe, K. A. (27 October 1961). "Comet Seki (1961f)". International Astronomical Union Circulars. 1778: 1.
  5. ↑ Thernoe, K. A. (8 November 1961). "Comet Seki (1961f)". International Astronomical Union Circulars. 1780: 1.
  6. ↑ Thernoe, K. A. (6 December 1961). "Comet Seki (1961f)". International Astronomical Union Circulars. 1783: 1.
  7. ↑ Neslušan, Luboš; Hajduková, Mária (1 July 2021). "Meteoroid Stream of Comet C/1961 T1 (Seki) and Its Relation to the December ρ-Virginids and γ-Sagittariids". The Astronomical Journal. 162 (1): 20. doi: 10.3847/1538-3881/abfdc9 .
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