1345 Potomac

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1345 Potomac
Discovery [1]
Discovered by J. H. Metcalf
Discovery site Taunton Obs.
Discovery date 4 February 1908
MPC designation (1345) Potomac
Pronunciation /pəˈtmək/ (About this sound listen)
Named after
Potomac River[2]
(U.S. Mid-Atlantic river)
1908 CG · 1932 CF
1932 EA · 1932 FB
1971 DE2
main-belt · (outer)
Hilda[3] · background [4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 109.69 yr (40,063 days)
Aphelion 4.7166 AU
Perihelion 3.2611 AU
3.9888 AU
Eccentricity 0.1824
7.97 yr (2,910 days)
0° 7m 25.32s / day
Inclination 11.399°
Jupiter MOID 0.4561 AU
Physical characteristics
Dimensions 71.82±3.0 km[5]
72.975±0.463 km[6]
76.72±2.34 km[7]
11.40 h[8]
11.41±0.01 h[9]
Tholen = X[1] · C[3][10]
B–V = 0.719 [1]
U–B = 0.286 [1]
9.59±0.53[10] · 9.73[1][3][5][7]

1345 Potomac (/pəˈtmək/ (About this sound listen)), provisional designation 1908 CG, is a dark Hildian asteroid from the outermost regions of the asteroid belt, approximately 73 kilometers in diameter. It was discovered on 4 February 1908, by American astronomer Joel Metcalf at the Taunton Observatory (803) in Massachusetts, United States.[11] The asteroid was named for the Potomac River on which Washington, D.C. is located.[2]

Orbit and classification[edit]

Potomac is member of the dynamical Hilda group, which stays in a 3:2 orbital resonance with Jupiter.[3] 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.[4]

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.[1]

The body's observation arc begins at the United States Naval Observatory, three weeks after its official discovery observation at Taunton.[11]

Physical characteristics[edit]

In the Tholen classification, Potomac is an X-type asteroid.[1] It has also been characterized as a carbonaceous C-type asteroid by Pan-STARRS photometric survey.[10]

Rotation period[edit]

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).[8][9]

Diameter and albedo[edit]

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.[5][6][7]

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.[3]


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]


  1. ^ a b c d e f g h "JPL Small-Body Database Browser: 1345 Potomac (1908 CG)" (2017-11-02 last obs.). Jet Propulsion Laboratory. Retrieved 17 November 2017. 
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1345) Potomac. Springer Berlin Heidelberg. p. 109. ISBN 978-3-540-00238-3. Retrieved 17 November 2017. 
  3. ^ a b c d e "LCDB Data for (1345) Potomac". Asteroid Lightcurve Database (LCDB). Retrieved 17 November 2017. 
  4. ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Retrieved 17 November 2017. 
  5. ^ a b c d Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. Bibcode:2004PDSS...12.....T. Archived from the original on 2016-06-03. Retrieved 17 November 2017. 
  6. ^ a b c 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:1110.0283Freely accessible. Bibcode:2012ApJ...744..197G. doi:10.1088/0004-637X/744/2/197. Retrieved 17 November 2017. 
  7. ^ a b c d 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 November 2017. 
  8. ^ a b 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. 
  9. ^ a b 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. ^ a b c 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:1506.00762Freely accessible. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 17 November 2017. 
  11. ^ a b "1345 Potomac (1908 CG)". Minor Planet Center. Retrieved 17 November 2017. 

External links[edit]