87P/Bus

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87P/Bus
Comet 87P Bus u65z1f02r.fits.gz sci.jpg
Comet 87P/Bus photographed by the Hubble Space Telescope on 7 June 2001
Discovery [1]
Discovered by Schelte J. Bus
Discovery site Siding Spring Observatory
(UK Schmidt Telescope)
Discovery date2 March 1981
Designations
P/1981 E1, P/1987 B4
  • 1981 XI, 1987 XXXIV
  • 1994 XVI
  • 1981b, 1987f, 1993b
Orbital characteristics [2] [3]
Epoch 31 May 2025 (JD 2459000.5)
Observation arc 39.57 years
Earliest precovery date9 February 1981
Number of
observations		801
Aphelion 4.776 AU
Perihelion 2.099 AU
Semi-major axis 3.438 AU
Eccentricity 0.38918
Orbital period 6.374 years
Inclination 2.603°
181.87°
Argument of
periapsis 		24.932°
Mean anomaly 3.356°
Last perihelion9 May 2020
Next perihelion7 June 2029 [4]
TJupiter 3.009
Earth MOID 1.098 AU
Jupiter MOID 0.181 AU
Physical characteristics [5]
Mean radius
0.27±0.01 km
32.0±9.0 hours
Comet total
magnitude (M1)		12.7
Comet nuclear
magnitude (M2)		16.1

87P/Bus is an Encke-type comet with a current orbital period of 6.37 years around the Sun. It is the only comet discovered by Australian astronomer, Schelte J. Bus.

Contents

Observational history

It was discovered by Schelte J. Bus on the night of 2 March 1981 from a photographic plate taken with the 1.2m UK Schmidt telescope at the Siding Spring Observatory. [1] Additional observations by Kenneth S. Russell noticed a faint tail about 20 arcseconds in length to the northwest, estimated to be 17.5 in apparent magnitude. [6] Preliminary orbital calculations in 9 March 1981 had Brian G. Marsden to conclude that the comet may be a short-periodic one, [7] which was later confirmed after Bus was able to find precovery images as early as 9–13 February 1981. [8]

It has been observed on each of its subsequent apparitions, most recently in 2020. [9]

Physical characteristics

Preliminary CCD photometry from the La Palma Observatory in December 1998 obtained an upper limit value of around 0.6–0.8 km (0.37–0.50 mi) for the comet's nuclear radius. [10] Later observations from the Hubble Space Telescope in 2009 revised the size of its nucleus, which is now estimated to be 0.27±0.01 km in radius. [5] Hubble data also showed the comet to be elongated in shape, with an a/b ratio greater than 2.2. [5] Its rotational period is estimated to be around 32.0±9.0 hours in length. [5]

Orbit

Perihelion distance
at different epochs [11]
Epoch Perihelion
(AU)
19424.43
19552.13
20293.69

A close approach to Jupiter on 13 May 1952, at a distance of 0.0668 AU (9.99 million km), lowered the orbital period from 12.46 years and the perihelion distance from 4.43 AU to 6.43 years and 2.13 AU respectively. Another close approach to Jupiter on 24 February 2023, at a distance of 0.182 AU (27.2 million km), raised the perihelion to 3.62 AU and the orbital period to 9.58 years. [11]

References

  1. 1 2 S. J. Bus; K. S. Russell (4 March 1981). D. W. Green (ed.). "Comet Bus (1981b)". IAU Circular. 3578 (1). Bibcode:1981IAUC.3578....1B. ISSN   0081-0304.
  2. ↑ "87P/Bus – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory . Retrieved 20 March 2016.
  3. ↑ "87P/Bus Orbit". Minor Planet Center . Retrieved 16 June 2014.
  4. ↑ "Horizons Batch for 87P/Bus (90000883) on 2029-Jun-07" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons . Retrieved 27 June 2022. (JPL#K203/18 Soln.date: 2020-Sep-28)
  5. 1 2 3 4 P. L. Lamy; I. Toth; H. A. Weaver; M. F. A'Hearn; L. Jorda (2011). "Properties of the nuclei and comae of 10 ecliptic comets from Hubble Space Telescope multi-orbit observations" (PDF). Monthly Notices of the Royal Astronomical Society. 412 (3): 1573–1590. doi: 10.1111/j.1365-2966.2010.17934.x .
  6. ↑ S. J. Bus; K. S. Russell (5 March 1981). B. G. Marsden (ed.). "Comet Bus (1981b)". IAU Circular. 3579 (1). Bibcode:1981IAUC.3579....1B. ISSN   0081-0304.
  7. ↑ C. Y. Shao; G. Schwartz; T. Seki (9 March 1981). B. G. Marsden (ed.). "Comet Bus (1981b)". IAU Circular. 3581 (2). Bibcode:1981IAUC.3581....2S. ISSN   0081-0304.
  8. ↑ S. J. Bus; K. S. Russell; M. Hartley (10 March 1981). B. G. Marsden (ed.). "Periodic Comet Bus (1981b)". IAU Circular. 3582 (1). Bibcode:1981IAUC.3582....1B. ISSN   0081-0304.
  9. ↑ S. Yoshida. "87P/Bus". www.aerith.net. Retrieved 15 May 2015.
  10. ↑ S. C. Lowry; A. Fitzsimmons (1999). "CCD photometry of distant comets II" (PDF). Astronomy & Astrophysics. 365: 204–213. Bibcode:1999A&A...349..649L. doi: 10.1051/0004-6361:20000180 .
  11. 1 2 K. Kinoshita (13 February 2014). "87P/Bus: Past, Present and Future orbital elements". Comet Orbit. Retrieved 13 November 2024.

Bibliography

Numbered comets
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