| Discovery [1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 9 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 arc | 80.17 yr (29,283 d) |
| Aphelion | 2.2851 AU |
| Perihelion | 2.0625 AU |
| 2.1738 AU | |
| Eccentricity | 0.0512 |
| 3.21 yr (1,171 d) | |
| 92.884 ° | |
| 0° 18m 27s / day | |
| Inclination | 3.1320° |
| 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
- ^ a b c d e f "1990 Pilcher (1956 EE)". Minor Planet Center. Retrieved 20 March 2018.
- ^ 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.
- ^ a b "Asteroid (1990) Pilcher". AstDyS-2, Asteroids – Dynamic Site. Retrieved 25 May 2018.
- ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Archived from the original on 2 August 2017. Retrieved 30 May 2018.
- ^ a b c d e f g h "LCDB Data for (1990) Pilcher". Asteroid Lightcurve Database (LCDB). Retrieved 20 March 2018.
- ^ a b "Asteroid 1990 Pilcher". Small Bodies Data Ferret. Retrieved 30 May 2018.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 20 March 2018.
External links
- Minor Planet Lightcurve Data (Frederick Pilcher), Astronomical Society of Las Cruces (ASLC)
- Asteroid Lightcurve Database (LCDB), query form ( info Archived 16 December 2017 at the Wayback Machine)
- Dictionary of Minor Planet Names, Google books
- Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
- 1990 Pilcher at AstDyS-2, Asteroids—Dynamic Site
- 1990 Pilcher at the JPL Small-Body Database
