Astronomy:1990 Pilcher

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1990 Pilcher
Discovery[1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date9 March 1956
Designations
(1990) Pilcher
Named afterFrederick Pilcher[1]
(American photometrist)
1956 EE · 1937 JL
1940 FA · 1959 CE1
1964 VS2 · 1972 EC
1972 GO · 1973 QM
Minor planet categorymain-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)
|{{{apsis}}}|helion}}2.2851 AU
|{{{apsis}}}|helion}}2.0625 AU
2.1738 AU
Eccentricity0.0512
Orbital period3.21 yr (1,171 d)
Mean anomaly92.884°
Mean motion0° 18m 27s / day
Inclination3.1320°
Longitude of ascending node193.63°
11.957°
Physical characteristics
Mean diameter6.39 km (calculated)[5]
6.754±0.167 km[7]
7.273±0.064 km[8]
Rotation period2.842±0.001 h[9]
Geometric albedo0.1864±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]
Absolute magnitude (H)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 ({{{1}}}).[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. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 "1990 Pilcher (1956 EE)". Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=1990. Retrieved 20 March 2018. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 "JPL Small-Body Database Browser: 1990 Pilcher (1956 EE)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2001990. Retrieved 20 March 2018. 
  3. ↑ 3.0 3.1 "Asteroid (1990) Pilcher". AstDyS-2, Asteroids – Dynamic Site. https://newton.spacedys.com/astdys/index.php?n=1990&pc=1.1.6. Retrieved 25 May 2018. 
  4. ↑ 4.0 4.1 "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. https://sbntools.psi.edu/ferret/PropertySearch/familyForm.action. Retrieved 30 May 2018. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 "LCDB Data for (1990) Pilcher". Asteroid Lightcurve Database (LCDB). http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=1990%7CPilcher. Retrieved 20 March 2018. 
  6. ↑ 6.0 6.1 "Asteroid 1990 Pilcher". Small Bodies Data Ferret. https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=1990+Pilcher. Retrieved 30 May 2018. 
  7. ↑ 7.0 7.1 7.2 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. doi:10.1088/0004-637X/791/2/121. Bibcode: 2014ApJ...791..121M. 
  8. ↑ 8.0 8.1 8.2 8.3 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. doi:10.1088/0004-637X/741/2/90. Bibcode: 2011ApJ...741...90M. 
  9. ↑ 9.0 9.1 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. ISSN 1052-8091. Bibcode: 2017MPBu...44..287B. 
  10. ↑ "MPC/MPO/MPS Archive". Minor Planet Center. https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html. Retrieved 20 March 2018. 

External links



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