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13P/Olbers
	13P/Olbers on 11 August 2024
Discovery
Discovered by	Heinrich Olbers
Discovery date	March 6, 1815
Designations
Alternative designations	1815 E1; 1887 Q1;; 1887 V; 1887f;; 1956 A1; 1956 IV;; 1956a
Orbital characteristics
Epoch	2024-06-19; (JD 2460480.5)
Aphelion	32.56 AU
Perihelion	1.175 AU
Semi-major axis	16.87 AU
Eccentricity	0.9303
Orbital period	69.3 yr; 68y 11d (perihelion to perihelion)
Inclination	44.67°
Longitude of; ascending node	85.8°
Argument of; periapsis	64.4°
Last perihelion	June 30, 2024; June 19, 1956
Next perihelion	March 20, 2094
Earth MOID	0.466 AU
Jupiter MOID	0.692 AU
Comet total; magnitude (M1)	6.9

13P/Olbers is a periodic comet with an orbital period of 69 years. It fits the classical definition of a Halley-type comet with a period between 20 and 200 years.^[5] The comet last passed perihelion 30 June 2024 and it was previously seen in 1956. The next perihelion is in 2094.

Observational history

Discovery

Heinrich Wilhelm Matthias Olbers discovered the comet on 6 March 1815 and described it as small. The comet came to perihelion on 26 April 1815 and reached an apparent magnitude of about 5,^[6] and was faintly visible by naked eye.^[7] Its orbit was first computed by Carl Friedrich Gauss on March 31 as parabolic, and Friedrich Bessel calculated an orbital period of 73.9 years using observations from June. Calculations by other astronomers during that era resulted anywhere between 72 and 77 years.^[6] Modern solutions give an orbital period of 74.9 years for the 1815 epoch.^[1]

1887

Epoch	Orbital period (years)
Orbital period at different epochs^[8]
1887	72.37
1956	69.54
2024	69.25
2094	70.72

There were unsuccessful searches for the comet throughout 1887, until it was accidentally found by William Robert Brooks on 25 August 1887.^[6] He described as an easy object to see through a 9-inch reflector, with a brightish nucleus and a faint tail; it continued to brighten for a few days after passing perihelion.^[9] The comet brightened to an apparent magnitude of about 9.^[7] On 28 July 1887 the comet passed 0.081 AU (12.1 million km) from Mars and then passed perihelion on 8 October 1887.^[8]

1956

The comet was recovered on 4 January 1956 by Antonín Mrkos. The comet was then located in Eridanus and its apparent magnitude was estimated to be 16. He then found the comet in plates obtained by the McDonald Observatory on 12 November 1955.^[7] The comet passed perihelion on 19 June 1956 and reached an apparent magnitude of 6.5, while its tail was about one degree long.^[6]

2024

The comet was recovered on 24 August 2023 by Alan Hale with the Las Cumbres Observatory at Siding Spring, and then additional pre-recovery images from August 13 were located. The comet then had an estimated apparent magntitude of about 22.^[8]^[1] On 16 November 2023 the comet came to opposition 139 degrees from the Sun. On 14 January 2024 the comet had an estimated magnitude of 15.3, was reported to have a strongly condensed coma measuring 0.9 arcminutes across and a faint tail one arcminute. By 10 March 2024 the comet had brightened to a magnitude of 11.4 and the coma was 4 arcminutes across. The comet was observed visually on April 12 to have a magnitude of 9.2, being a magnitude brighter than the ephemeris.^[10] It came to perihelion on June 30, 2024,^[2] when it was 1.18 AU from the Sun and 1.94 AU from Earth.^[2] It was expected to brighten to about apparent magnitude 7−8 but peaked at 6–7.^[3]

Earth close approach
Date	Distance (AU)	Solar elongation
2024-Jul-20^[11]	1.895 AU (283.5 million km)	35°
2094-Jan-09^[12]	0.676 AU (101.1 million km)	134°

2094

Before the 2023 recovery, while the last observation was in 1956, Kinoshita calculated that the comet would come to a future perihelion passage (closest approach to the Sun) on 22 March 2094.^[13] Accounting for observations in 2023–4, the nominal time of perihelion passage is now calculated to be 20 March 2094.^[4]

Meteor showers

There is some speculation that 13P/Olbers has an associated annual meteor shower on Mars coming from the direction of Beta Canis Majoris.^[14] The minimum orbit intersection distance of the orbits of comet Olbers and Mars is 0.0266 AU (3.98 million km) and the meteors impact the planet with a velocity of 27 km/s. An intersection distance of less than 0.1 AU and an impact speed high enough for the meteors to become ablaze are considered good predictors for a potential meteor shower.^[15]

References

^ ^a ^b ^c ^d MPC
^ ^a ^b ^c "Horizons Batch for 13P/Olbers (90000226) on 2024-Jun-30" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Archived from the original on 2022-06-15. Retrieved 2023-08-28. (JPL#11 Soln.date: 2023-Aug-28)
^ ^a ^b ^c Seiichi Yoshida (2004-07-31). "13P/Olbers". Seiichi Yoshida's Comet Catalog. Retrieved 2010-02-24.
^ ^a ^b "Horizons Batch for 13P/Olbers (90000226) for March 2094" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Archived from the original on 2023-08-29. Retrieved 2024-06-25.
^ ^a ^b "JPL Small-Body Database Browser: 13P/Olbers". Jet Propulsion Laboratory. Retrieved 2012-07-26.
^ ^a ^b ^c ^d Kronk, Gary W. (2001–2005). "13P/Olbers". Retrieved 2012-02-22. (Cometography Home Page)
^ ^a ^b ^c Roemer, Elizabeth (1956). "Comet Notes". Publications of the Astronomical Society of the Pacific. 68 (401): 171–172. Bibcode:1956PASP...68..171R. doi:10.1086/126910. ISSN 0004-6280. JSTOR 40673045.
^ ^a ^b ^c "CBET 5289 : COMET 13P/OLBERS". Central Bureau for Astronomical Telegrams. 2023-08-28. Retrieved 2023-08-29.
^ Brooks, W. R. (1 January 1888). "The Olbers-Brooks Comet". The Observatory. 11: 90–91. Bibcode:1888Obs....11...90B. ISSN 0029-7704.
^ Green, Daniel (29 April 2024). "COMET 13P/OLBERS". Central Bureau for Astronomical Telegrams. 5389.
^ "Closest Approach to Earth around 20 July 2024" (Closest Earth approach occurs when deldot flips from negative to positive). JPL Horizons. Retrieved 2023-08-28.
^ "Closest Approach to Earth around 9 January 2094" (Closest Earth approach occurs when deldot flips from negative to positive). JPL Horizons. Retrieved 2023-08-28.
^ Kinoshita, Kazuo (2003-02-25). "13P/Olbers past, present and future orbital elements". Comet Orbit. Retrieved 2023-08-28.
^ "Meteor Showers And Their Parent Bodies". Archived from the original on 2008-10-03. Retrieved 2006-12-30.
^ Christou, Apostolos A. (December 2004). "Predicting Martian and Venusian Meteor Shower Activity". Earth, Moon, and Planets. 95 (1–4): 425–431. doi:10.1007/s11038-005-9023-0.