125P/Spacewatch

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125P/Spacewatch
125P 2024-06-03 image ZTF-sso-442-zr-size-8.5arcmin.png
Comet 125P/Spacewatch photographed from the Zwicky Transient Facility on 3 June 2024
Discovery [1]
Discovered by Spacewatch
Tom Gehrels
Discovery site Kitt Peak Observatory
Discovery date8 September 1991
Designations
P/1991 R2, P/1996 F1
1990 XXIX, 1991x
Orbital characteristics [2] [3]
Epoch 11 August 2015 (JD 2457245.5)
Observation arc 33.12 years
Number of
observations		1,297
Aphelion 4.728 AU
Perihelion 1.523 AU
Semi-major axis 3.126 AU
Eccentricity 0.51269
Orbital period 5.526 years
Inclination 9.988°
153.19°
Argument of
periapsis 		87.145°
Mean anomaly 161.39°
Last perihelion7 March 2024 [4]
TJupiter 2.975
Earth MOID 0.554 AU
Jupiter MOID 0.810 AU
Physical characteristics [2]
Mean radius
0.83 km (0.52 mi) [5]
Comet total
magnitude (M1)		12.9
Comet nuclear
magnitude (M2)		16.7

125P/Spacewatch is a Jupiter-family comet with a 5.53-year orbit around the Sun. It was discovered on 8 September 1991 by Tom Gehrels using the 0.91 m Spacewatch telescope at the Kitt Peak National Observatory. [6] It was the first comet discovered with the use of a CCD, [7] and also the faintest comet upon discovery up to that point. [6] Its nucleus has a diameter of 1.66 km (1.03 mi). [5]

Contents

Observational history

The comet was discovered in images taken by the 0.91 m Spacewatch telescope at the Kitt Peak National Observatory by Tom Gehrels on September 8, 1991 as an essentially stellar object with an apparent magnitude of 21, with a tail more than 5 arcminutes long. [1] Brian G. Marsden calculated a parabolic and an elliptical orbit, with the elliptical orbit suggesting an orbital period of 5.58 years and a perihelion date on 18 December 1990. [8]

The comet was recovered on 21 March 1996 by the Spacewatch telescope from James V. Scotti and J. Montani, with an apparent magnitude of 17.6, a tail measuring 0.66 arcminutes long and a coma measuring 15 arcseconds across. The orbit calculated after the recovery indicates an orbital period of 5.56 years. [9] During that apparition the comet experienced an outburst in late July 1996 and brightened to a magnitude of 14.5. [6] During the 2002 apparition the comet brightened to a magnitude of 18. [6]

References

  1. 1 2 J. V. Scotti; T. Gehrels (10 September 1991). B. G. Marsden (ed.). "Comet Spacewatch (1991x)". IAU Circular. 5341 (1). Bibcode:1991IAUC.5341....1S. ISSN   0081-0304.
  2. 1 2 "125P/Spacewatch – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory . Retrieved 2 June 2013.
  3. ↑ "125P/Spacewatch Orbit". Minor Planet Center . Retrieved 17 June 2014.
  4. ↑ "Horizons Batch for 125P/Spacewatch (90001024) on 2024-Mar-07" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons . Retrieved 6 July 2023. (JPL#32 Soln.date: 2019-May-15)
  5. 1 2 G. Tancredi; J. A. Fernández; H. Rickman; J. Licandro (2006). "Nuclear magnitudes and the size distribution of Jupiter family comets". Icarus. 182 (2): 527–549. Bibcode:2006Icar..182..527T. doi:10.1016/j.icarus.2006.01.007.
  6. 1 2 3 4 G. W. Kronk. "125P/Spacewatch". Cometography.com. Retrieved 2 June 2013.
  7. ↑ "SPACEWATCH® News and History". spacewatch.lpl.arizona.edu. Retrieved 11 August 2024.
  8. ↑ J. V. Scotti; T. Gehrels (12 September 1991). B. G. Marsden (ed.). "Comet Spacewatch (1991x)". IAU Circular. 5343 (1). Bibcode:1991IAUC.5343....1S. ISSN   0081-0304.
  9. ↑ J. V. Scotti; J. Montani; S. Nakano (22 March 1996). B. G. Marsden (ed.). "Comet P/1996 F1 (Spacewatch)". IAU Circular. 6349 (1). Bibcode:1996IAUC.6349....1S. ISSN   0081-0304.
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