C/1999 J6 (SOHO)

C/1999 J6 (SOHO) is a small comet, notable for being among those that made a close approach to the Earth.^[2][3][4][5] It was first observed by the space-based Solar and Heliospheric Observatory (SOHO) on 10 May 1995.^[6][7] It is next expected to come to perihelion (closest approach to the Sun) in June 2026 at 0.044 AU (6.6 million km).^[1]

C/1999 J6 (SOHO)

Discovery
Discovered by	SOHO Mike Oates
Discovery date	May 10, 1995 first observed only
Orbital characteristics
Epoch	2007-Jan-19
Observation arc	10.95 Years
Number of observations	267
Aphelion	6.15 AU
Perihelion	0.049 AU
Semi-major axis	3.10 AU
Eccentricity	0.984
Orbital period	5.46 years
Max. orbital speed	200 km/s (2026)[lower-alpha 1]
Inclination	26.6
Next perihelion	2026-Jun-18?[1]
TJupiter	1.923
Earth MOID	0.0099 AU (1,480,000 km; 3.9 LD)

The most notable Earth approach was on June 12, 1999 when it passed between 357,000 km (222,000 mi) to 3.3 million kilometres (2,100,000 mi) from Earth.^[3] The uncertainty is a result of the large number of observations at roughly the same time as there were around 50 observations on April 19, 2010. The discovery was made on March 20, 2000, during a review of previously captured images.^[8]

It next came to perihelion in November 2004, when it was known as "C/2004 V9",^[9] and then on April 19, 2010 when it was known as "C/2010 H3".^[10][11] On August 15, 2015 it should have been 0.56 AU from Earth.^[12]

Notes

1. v = 42.1219 √1/r − 0.5/a, where r is the distance from the Sun, and a is the major semi-axis.

References

1. "Horizons Batch for C/1999 J6 (SOHO) on 2026-Jun-18" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Retrieved August 29, 2022. (JPL#7/Soln.date: 2021-Apr-16)
2. "What are the closest comet encounters with Earth?". University of Maryland. Archived from the original on May 2, 2018. Retrieved December 15, 2018.
3. "JPL Close-Approach Data: P/1999 J6 (SOHO)". NASA (2010-04-22 last obs (arc=10.9 yr; JFC)). June 28, 2012. Archived from the original on January 11, 2017. Retrieved August 29, 2022.
4. Zdenek Sekanina; Paul W. Chodas (December 2005). "Origin of the Marsden and Kracht Groups of Sunskirting Comets. I. Association with Comet 96P/Machholz and Its Interplanetary Complex" (PDF). The Astrophysical Journal Supplement Series. 151 (2): 551–586. Bibcode:2005ApJS..161..551S. doi:10.1086/497374. S2CID 85442034. Archived from the original (PDF) on December 16, 2018. Retrieved January 11, 2018.
5. "P/1999 J6 (SOHO). Close-Approach Data". NASA/JPL. May 7, 2012. Archived from the original on August 4, 2020. Retrieved November 10, 2017.
6. "C/1999 J6 (SOHO)". Minor Planet Center. Retrieved December 16, 2018.
7. "MPEC 2000-F30: COMET C/1999 J6 (SOHO)". Minor Planet Electronic Circular. Retrieved December 17, 2018.
8. Mike Oates (January 17, 2005). "Mike's SOHO Comet Hunt: Non-Sungrazing Comets". Archived from the original on March 6, 2017. Retrieved December 15, 2018. Found on the evening of March 21 2000 while searching archive data from the LASCO C3 instrument on FITS images taken on May 11 1999. The comet was seen moving away from the Sun, getting brighter then fading, it could be followed on the May 12th images as well. Doug Biesecker also located the comet on C2 frames on the 10th.
9. Matthew M. Knight. "Studies of SOHO Comets" (PDF). p. 167. Archived (PDF) from the original on October 26, 2017. Retrieved December 15, 2018. The only comet which was observed well enough to compare the lightcurve shapes was C/1999 J6 which returned as C/2004 V9.
10. "Return of Marsden Comet 1999 J6 = 2004 V9 = 2010 H3". University of Maryland. Archived from the original on December 16, 2018. Retrieved December 15, 2018.
11. "The Return of C/1999 J6 = C/2004 V9". Archived from the original on October 25, 2018. Retrieved December 15, 2018. The two brightest Marsden group comets C/1999 J6 and C/2004 V9 were linked by Brian Marsden (MPEC 2004-X73) and Z. Sekanina and P. W. Chodas, an orbit for the 2010 return by S. Nakano is here.
12. Ron Baalke (August 15, 2015). "Sun grazer comet P/1999 J6 (SOHO) makes its closest approach to Earth today. Orbital period: 5.5 years". Archived from the original on December 16, 2018. Retrieved December 16, 2018.