6344 P-L
Discovery [1][2]
Discovered byC. J. van Houten
I. van Houten-G.
T. Gehrels
Discovery sitePalomar Obs.
Discovery date24 September 1960
Designations
6344 P-L
2007 RR9
Apollo · NEO · PHA [1][2]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc47.36 yr (17,298 days)
Aphelion4.6754 AU
Perihelion0.9332 AU
2.8043 AU
Eccentricity0.6672
4.70 yr (1,715 days)
31.506°
0° 12m 35.64s / day
Inclination4.7249°
183.57°
234.13°
Earth MOID0.0286 AU (11.1 LD)
Physical characteristics
Mean diameter
250 m (generic at 0.20)[3]
460 m (generic at 0.06)[3]
20.4[1]

    6344 P-L is an unnumbered, sub-kilometer asteroid and suspected dormant comet, classified as near-Earth object and potentially hazardous asteroid of the Apollo group that was first observed on 24 September 1960, by astronomers and asteroid searchers Tom Gehrels, Ingrid van Houten-Groeneveld, and Cornelis Johannes van Houten during the Palomar–Leiden survey at Palomar Observatory.[2]

    Description

    Since 6344 P-L is still unnumbered, the discoverers have not yet been officially determined. Last seen in 1960, it was lost, but rediscovered in 2007 as 2007 RR9.[4] In other words, it was a lost asteroid from 1960 until it was recovered and recognized as the same object by Peter Jenniskens in 2007.[5] It was again observed from 19 July 2021 to 4 August 2021 by Astronomical Research Observatory, Westfield, and Calar Alto-Schmidt (see Minor Planet Center MPS 1525704).

    It is either an asteroid or dormant comet nucleus, and it has a 4.7-year orbit around the Sun.[5] The orbit goes out as far as Jupiter's but then back in, passing as close as 0.07 AU to the Earth, making it a collision risk.[5]

    Close approaches

    The minor planet classifies as a potentially hazardous object with an Earth minimum orbit intersection distance of 0.0286 AU (4,280,000 km), equivalent to 11.1 lunar distances.[1] Although it was not outgassing at the time of its recovery, its orbit indicates that it is probably a dormant comet.[5]

    Physical characteristics

    Based on a generic magnitude-to-diameter conversion, 6344 P-L measures between 250 and 460 meters for an assumed albedo between 0.20 and 0.06.[3] As of 2018, no rotational lightcurve has been obtained. The body's rotation period, shape and pole remains unknown.[1][6]

    Palomar–Leiden survey

    The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Tom Gehrels used Palomar's 48-inch Samuel Oschin telescope and shipped the photographic plates to the van Houten's at Leiden Observatory, where astrometry was carried out. The trio are credited with more than 4600 minor planet discoveries.[7]

    Numbering and naming

    As of 2021, this minor planet has neither been numbered nor named and still remains provisionally designated (see list of unnumbered minor planets).

    References

    1. 1 2 3 4 5 6 "JPL Small-Body Database Browser: (6344 P-L)" (2008-02-03 last obs.). Jet Propulsion Laboratory. Retrieved 23 January 2018.
    2. 1 2 3 "6344 P-L". Minor Planet Center. Retrieved 23 January 2018.
    3. 1 2 3 "Asteroid Size Estimator". CNEOS NASA/JPL. Retrieved 12 November 2017.
    4. ↑ Mohit Joshi (10 May 2007). "Long-lost 'Potentially Hazardous Asteroid' re-located". TopNews. Retrieved 20 August 2016.
    5. 1 2 3 4 "Long-Lost, Dangerous Asteroid Is Found Again". ScienceDaily. 15 October 2007. Retrieved 1 June 2016.
    6. ↑ "LCDB Data for (6344)". Asteroid Lightcurve Database (LCDB). Retrieved 23 January 2018.
    7. ↑ "Minor Planet Discoverers". Minor Planet Center. 6 December 2017. Retrieved 23 January 2018.
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