1810 Epimetheus

1810 Epimetheus /ɛpɪˈmθəs/, provisional designation 4196 P-L, is a stony Florian asteroid from the inner regions of the asteroid belt, approximately 8 kilometers in diameter.

1810 Epimetheus
Discovery [1]
Discovered byC. J. van Houten
I. van Houten-G.
T. Gehrels
(Palomar–Leiden survey)
Discovery sitePalomar Obs.
Discovery date24 September 1960
(1810) Epimetheus
Named after
(Greek mythology)[2]
4196 P-L · 1942 FS
1950 SC · 1957 WC1
1962 GC · 1970 SS
main-belt · Flora[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc66.21 yr (24,182 days)
Aphelion2.4284 AU
Perihelion2.0198 AU
2.2241 AU
3.32 yr (1,211 days)
0° 17m 49.92s / day
Physical characteristics
Dimensions7.669±0.162 km[4]
8.19 km (calculated)[3]
10.88±0.02 h[5]
28.61±0.01 h[a]
0.24 (assumed)[3]
12.53±0.33[6] · 12.6[1][3][4]

It was discovered on 24 September 1960, by Dutch astronomer couple Ingrid and Cornelis van Houten, and Dutch–American astronomer Tom Gehrels during the Palomar–Leiden survey at Palomar Observatory in California, United States.[7] It was later named after Epimetheus from Greek mythology.[2]

Classification and orbitEdit

The S-type asteroid is a member of the Flora family, one of the largest groups of stony asteroids in the main-belt. It orbits the Sun at a distance of 2.0–2.4 AU once every 3 years and 4 months (1,211 days). Its orbit has an eccentricity of 0.09 and an inclination of 4° with respect to the ecliptic.[1]

The body's observation arc begins with its official discovery observation, as the previous identifications, 1942 FS and 1950 SC, made at Johannesburg and Uccle in 1942 and 1950, respectively, remained unused.[7]

Physical characteristicsEdit

Rotation periodEdit

Two divergent rotational lightcurves of Epimetheus were obtained from photometric observations. They gave a rotation period of 10.9 and 28.6 hours with both having a brightness variation of 0.04 magnitude (U=2/2).[5][a]

Diameter and albedoEdit

According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Epimetheus measures 7.7 kilometers in diameter and its surface has an albedo of 0.27,[4] while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from 8 Flora, the largest member and namesake of its orbital family – and calculates a diameter of 8.2 kilometers, based on an absolute magnitude of 12.6.[3]

Survey designationEdit

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. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.[8]


This minor planet is named for the Titan in Greek mythology, Epimetheus, who opened Pandora's box, which contained all the illnesses and ailments of mankind (also see 55 Pandora). Epimetheus is also a moon of Saturn, which was discovered by Voyager 1 in 1980. Epimetheus is the brother of Prometheus after whom the minor planet 1809 Prometheus was named.[2] The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3935).[9]


  1. ^ a b Pravec 2007, web publication, summary figures given in the Light Curve Data Base – (1810) Epimetheus


  1. ^ a b c d "JPL Small-Body Database Browser: 1810 Epimetheus (4196 P-L)" (2016-11-30 last obs.). Jet Propulsion Laboratory. Retrieved 3 June 2017.
  2. ^ a b c Schmadel, Lutz D. (2007). "(1810) Epimetheus". Dictionary of Minor Planet Names – (1810) Epimetheus. Springer Berlin Heidelberg. p. 145. doi:10.1007/978-3-540-29925-7_1811. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f "LCDB Data for (1810) Epimetheus". Asteroid Lightcurve Database (LCDB). Retrieved 15 December 2016.
  4. ^ a b c d Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 15 December 2016.
  5. ^ a b Brinsfield, James W. (September 2008). "Asteroid Lightcurve Analysis at the Via Capote Observatory: First Quarter 2008". The Minor Planet Bulletin. 35 (3): 119–122. Bibcode:2008MPBu...35..119B. ISSN 1052-8091. Retrieved 15 December 2016.
  6. ^ 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 15 December 2016.
  7. ^ a b "1810 Epimetheus (4196 P-L)". Minor Planet Center. Retrieved 15 December 2016.
  8. ^ "Minor Planet Discoverers". Minor Planet Center. 24 April 2016. Retrieved 15 December 2016.
  9. ^ Schmadel, Lutz D. "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.

External linksEdit