1661 Granule

1661 Granule, also designated A916 FA, is a stony Florian asteroid from the inner regions of the asteroid belt, approximately 7 kilometers in diameter. It was discovered on 31 March 1916, by German astronomer Max Wolf at Heidelberg Observatiry in southern Germany, and named for American pathologist Edward Gall.[2][7]

1661 Granule
Discovery [1]
Discovered byM. Wolf
Discovery siteHeidelberg Obs.
Discovery date31 March 1916
Designations
(1661) Granule
Named after
Edward Gall (pathologist)[2][3]
A916 FA · 1936 PM
1949 QG1 · 1949 SJ
1961 DB
main-belt · Flora [4]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc101.07 yr (36,915 days)
Aphelion2.3818 AU
Perihelion1.9857 AU
2.1838 AU
Eccentricity0.0907
3.23 yr (1,179 days)
121.10°
0° 18m 19.44s / day
Inclination3.0353°
261.69°
328.08°
Physical characteristics
Dimensions7.14 km (calculated)[4]
24 h[5]
0.24 (assumed)[4]
S [4][6]
12.9[1][4] · 12.99±0.22[6]

    Classification and orbit

    The S-type asteroid is a member of the Flora family, a large collisional population of stony asteroids in the inner main-belt. It orbits the Sun at a distance of 2.0–2.4 AU once every 3 years and 3 months (1,179 days). Its orbit has an eccentricity of 0.09 and an inclination of 3° with respect to the ecliptic.[1] Granule's observation arc begins with its observation at Bergedorf Observatory, one month after its official discovery observation. (It is unclear whether "HD 17", Message from Heidelberg Observatory #17, is the official discovery observation due to a different time stamp).[7]

    Physical characteristics

    Rotation period

    In January 2006, the first rotational light-curve of Granule was obtained from photometric observations by French amateur astronomer René Roy. It gave a longer-than average rotation period of 24 hours with a brightness variation of 0.15 magnitude (U=2).[5] No other light-curves have been obtained yet.

    Size estimates

    Granule has neither been observed by the Infrared Astronomical Satellite IRAS, nor the Japanese Akari satellite, nor NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission. The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from the family's principal body and namesake, the asteroid 8 Flora – and calculates a diameter of 7.14 kilometers using an absolute magnitude of 12.9.[4]

    Naming

    This minor planet was named in honor of Edward A. Gall, an internationally renowned American pathologist, former director of the University of Cincinnati Academic Health Center and president of USCAP. It was named on the occasion of his retirement to commemorate his career and his discovery of the Gall's granule, a feature of lymphocytes.[2][3] The official naming citation was published by the Minor Planet Center on 20 December 1974 (M.P.C. 3757).[8]

    References
    1. "JPL Small-Body Database Browser: 1661 Granule (A916 FA)" (2017-04-26 last obs.). Jet Propulsion Laboratory. Retrieved 6 June 2017.
    2. Schmadel, Lutz D. (2007). "(1661) Granule". Dictionary of Minor Planet Names – (1661) Granule. Springer Berlin Heidelberg. p. 132. doi:10.1007/978-3-540-29925-7_1662. ISBN 978-3-540-00238-3.
    3. "Past-Presidents – Edward A. Gall". USCAP – The United States and Canadian Academy of Pathology. Archived from the original on 24 December 2016. Retrieved 23 December 2016.
    4. "LCDB Data for (1661) Granule". Asteroid Lightcurve Database (LCDB). Retrieved 23 December 2016.
    5. Behrend, Raoul. "Asteroids and comets rotation curves – (1661) Granule". Geneva Observatory. Retrieved 23 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 23 December 2016.
    7. "1661 Granule (A916 FA)". Minor Planet Center. Retrieved 23 December 2016.
    8. 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.

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