1990 Pilcher

1990 Pilcher
Discovery[1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date9 March 1956
Designations
(1990) Pilcher
Named after
Frederick Pilcher[1]
(American photometrist)
1956 EE · 1937 JL
1940 FA · 1959 CE1
1964 VS2 · 1972 EC
1972 GO · 1973 QM
main-belt[1][2] · (inner)
background[3][4] · Flora[5][6]
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc80.17 yr (29,283 d)
Aphelion2.2851 AU
Perihelion2.0625 AU
2.1738 AU
Eccentricity0.0512
3.21 yr (1,171 d)
92.884°
0° 18m 27s / day
Inclination3.1320°
193.63°
11.957°
Physical characteristics
6.39 km (calculated)[5]
6.754±0.167 km[7]
7.273±0.064 km[8]
2.842±0.001 h[9]
0.1864±0.0254[8]
0.215±0.039[7]
0.24 (assumed)[5]
Tholen = S[2]
S (assumed)[5]
B–V = 0.850[2]
U–B = 0.504[2]
13.14[2][5][8]

1990 Pilcher, provisional designation 1956 EE, is a stony background asteroid from the Florian region of the inner asteroid belt, approximately 7 kilometers (4.3 miles) in diameter. It was discovered on 9 March 1956, by German astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in Heidelberg, Germany. In 1982, it was named by the MPC for American physicist and photometrist Frederick Pilcher.[1] The S-type asteroid has a short rotation period of 2.8 hours.[5]

Orbit and classification

Pilcher is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method (HCM) to its proper orbital elements (Nesvorný, Milani and Knežević).[3][4] In a previous HCM-analysis (Zappalà) and based on osculating Keplerian orbital elements, the asteroid has also been classified as a member of the Flora family (402), a giant asteroid family and the largest family of stony asteroids in the main-belt.[5][6]

It orbits the Sun in the Florian region of the inner asteroid belt at a distance of 2.1–2.3 AU once every 3 years and 3 months (1,171 days; semi-major axis of 2.17 AU). Its orbit has an eccentricity of 0.05 and an inclination of 3° with respect to the ecliptic.[2]

The asteroid was first observed as 1937 JL at Nice Observatory in May 1937. The body's observation arc begins with a precovery taken at Palomar Observatory in June 1950, or six years prior to its official discovery observation at Heidelberg.[1]

Physical characteristics

In the Tholen classification, Pilcher is a common, stony S-type asteroid.[2]

Rotation period

In March 2017, a first rotational lightcurve of Pilcher was obtained from photometric observations at the Flarestar Observatory on the island of Malta. Lightcurve analysis gave a short rotation period of 2.842 hours with a brightness amplitude of 0.10 magnitude, indicative for a rather spherical shape (U=2+).[9]

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Pilcher measures between 6.754 and 7.273 kilometers in diameter and its surface has an albedo between 0.1864 and 0.215.[7][8]

The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from 8 Flora, the Flora family's parent body and namesake – and calculates a diameter of 6.39 kilometers based on an absolute magnitude of 13.14.[5]

Naming

This minor planet was named after American astronomer Frederick Pilcher, a retired professor of Physics at Illinois College and prolific lightcurve photometrist at his Organ Mesa Observatory (G50) in New Mexico.[1] The official naming citation was published by the Minor Planet Center on 8 April 1982 (M.P.C. 6833).[10]

References

  1. ^ a b c d e f "1990 Pilcher (1956 EE)". Minor Planet Center. Retrieved 20 March 2018.
  2. ^ a b c d e f g h "JPL Small-Body Database Browser: 1990 Pilcher (1956 EE)" (2017-07-05 last obs.). Jet Propulsion Laboratory. Retrieved 20 March 2018.
  3. ^ a b "Asteroid (1990) Pilcher". AstDyS-2, Asteroids – Dynamic Site. Retrieved 25 May 2018.
  4. ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Archived from the original on 2 August 2017. Retrieved 30 May 2018.
  5. ^ a b c d e f g h "LCDB Data for (1990) Pilcher". Asteroid Lightcurve Database (LCDB). Retrieved 20 March 2018.
  6. ^ a b "Asteroid 1990 Pilcher". Small Bodies Data Ferret. Retrieved 30 May 2018.
  7. ^ a b c Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121.
  8. ^ a b c d Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90.
  9. ^ a b Brincat, Stephen M.; Grech, Winston (October 2017). "Photometric Observations of Main-belt Asteroids 1990 Pilcher and 8443 Svecica". The Minor Planet Bulletin. 44 (4): 287–288. Bibcode:2017MPBu...44..287B. ISSN 1052-8091.
  10. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 20 March 2018.