1345 Potomac

1345 Potomac (/pəˈtoʊmək/ (listen)), provisional designation 1908 CG, is a dark Hildian asteroid from the outermost regions of the asteroid belt, approximately 73 kilometers (45 mi) in diameter. It was discovered on 4 February 1908, by American astronomer Joel Metcalf at the Taunton Observatory (803) in Massachusetts, United States.[1] The X-type asteroid has a rotation period of 11.4 hours.[4] It was named for the Potomac River on which Washington, D.C. is located.[2]

1345 Potomac
Discovery [1]
Discovered byJ. H. Metcalf
Discovery siteTaunton Obs.
Discovery date4 February 1908
Designations
(1345) Potomac
Pronunciation/pəˈtoʊmək/ (listen)
Named after
Potomac River [2]
(U.S. Mid-Atlantic river)
1908 CG · 1932 CF
1932 EA · 1932 FB
1971 DE2
main-belt · (outer)[3]
Hilda [1][4] · background [5]
Orbital characteristics [3]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 0
Observation arc111.20 yr (40,617 d)
Aphelion4.7100 AU
Perihelion3.2611 AU
3.9856 AU
Eccentricity0.1818
7.96 yr (2,906 d)
31.380°
0° 7m 26.04s / day
Inclination11.402°
137.43°
333.12°
Jupiter MOID0.4592 AU
TJupiter2.9930
Physical characteristics
Mean diameter
71.82±3.0 km[6]
72.975±0.463 km[7]
76.72±2.34 km[8]
11.41±0.01 h[9]
0.039±0.003[8]
0.043±0.008[7]
0.0439±0.004[6]
Tholen = X [3] · C [4][10]
B–V = 0.719 [3]
U–B = 0.286 [3]
9.73[3][4][6][8]
9.9[1]

    Orbit and classification

    Potomac is member of the dynamical Hilda group, which stays in a 3:2 orbital resonance with Jupiter.[1][4] It is, however, not a member of the Hilda family but a non-family asteroid of the main belt's background population when applying the Hierarchical Clustering Method to its proper orbital elements.[5]

    It orbits the Sun in the outermost asteroid belt at a distance of 3.3–4.7 AU once every 7 years and 12 months (2,910 days; semi-major axis of 3.99 AU). Its orbit has an eccentricity of 0.18 and an inclination of 11° with respect to the ecliptic.[3] The body's observation arc begins at the United States Naval Observatory, three weeks after its official discovery observation at Taunton.[1]

    Naming

    This minor planet was named after the U.S. Potomac River in the Mid-Atlantic region of the United States, on which Washington, D.C. is located. The river flows from West Virginia into the Chesapeake Bay and forms the southern boundary of Maryland. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 122).[2]

    Physical characteristics

    In the Tholen classification, Potomac is an X-type asteroid.[3] It has also been characterized as a carbonaceous C-type asteroid by Pan-STARRS photometric survey.[10]

    Rotation period

    Two rotational lightcurves of Potomac was obtained from photometric observations. Lightcurve analysis gave a rotation period of 11.40 and 11.41 hours with a brightness amplitude of 0.22 and 0.24 magnitude, respectively (U=2/3).[11][9]

    Diameter and albedo

    According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Potomac measures between 71.82 and 76.72 kilometers in diameter and its surface has an albedo between 0.039 and 0.0439.[6][7][8]

    The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0439 and a diameter of 71.82 kilometers based on an absolute magnitude of 9.73.[4]

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    References
    1. "1345 Potomac (A908 CE)". Minor Planet Center. Retrieved 29 October 2019.
    2. Schmadel, Lutz D. (2007). "(1345) Potomac". Dictionary of Minor Planet Names – (1345) Potomac. Springer Berlin Heidelberg. p. 109. doi:10.1007/978-3-540-29925-7_1346. ISBN 978-3-540-00238-3.
    3. "JPL Small-Body Database Browser: 1345 Potomac (A908 CE)" (2019-05-10 last obs.). Jet Propulsion Laboratory. Retrieved 29 October 2019.
    4. "LCDB Data for (1345) Potomac". Asteroid Lightcurve Database (LCDB). Retrieved 17 November 2017.
    5. "Asteroid 1345 Potomac – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 29 October 2019.
    6. Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. 12: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 22 October 2019.
    7. Grav, T.; Mainzer, A. K.; Bauer, J.; Masiero, J.; Spahr, T.; McMillan, R. S.; et al. (January 2012). "WISE/NEOWISE Observations of the Hilda Population: Preliminary Results". The Astrophysical Journal. 744 (2): 15. arXiv:1110.0283. Bibcode:2012ApJ...744..197G. doi:10.1088/0004-637X/744/2/197. Retrieved 17 November 2017.
    8. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 17 October 2019. (online, AcuA catalog p. 153)
    9. Brinsfield, James W. (April 2010). "Asteroid Lightcurve Analysis at Via Capote Observatory: 4th Quarter 2009". The Minor Planet Bulletin. 37 (2): 50–53. Bibcode:2010MPBu...37...50B. ISSN 1052-8091. Retrieved 17 November 2017.
    10. Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 17 November 2017.
    11. Dahlgren, M.; Lahulla, J. F.; Lagerkvist, C.-I.; Lagerros, J.; Mottola, S.; Erikson, A.; et al. (June 1998). "A Study of Hilda Asteroids. V. Lightcurves of 47 Hilda Asteroids". Icarus. 133 (2): 247–285. Bibcode:1998Icar..133..247D. doi:10.1006/icar.1998.5919. Retrieved 17 November 2017.

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