11409 Horkheimer

11409 Horkheimer, provisional designation 1999 FD9, is a Themistian asteroid from the outer regions of the asteroid belt, approximately 15 kilometers (9.3 miles) in diameter. It was discovered on 19 March 1999, by astronomers of the Lowell Observatory Near-Earth Object Search at Anderson Mesa Station near Flagstaff, Arizona. The likely C-type asteroid was named for American science communicator Jack Horkheimer.[1]

11409 Horkheimer
Discovery [1]
Discovered byLONEOS
Discovery siteAnderson Mesa Stn.
Discovery date19 March 1999
Designations
(11409) Horkheimer
Named after
Jack Horkheimer [1]
(American science communicator)
1999 FD9 · 1988 HY
1990 RH15
main-belt [1][2] · (outer)
Themis [3]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc29.11 yr (10,632 d)
Aphelion3.5587 AU
Perihelion2.8167 AU
3.1877 AU
Eccentricity0.1164
5.69 yr (2,079 d)
109.84°
0° 10m 23.52s / day
Inclination2.2984°
115.92°
74.973°
Physical characteristics
Mean diameter
15.355±0.100 km[4]
0.053±0.005[4]
C (Themis family)
12.8[1][2]

    Orbit and classification

    Horkheimer is a core member of the Themis family (602),[3] a very large family of carbonaceous asteroids, named after 24 Themis.[5] It orbits the Sun in the outer asteroid belt at a distance of 2.8–3.6 AU once every 5 years and 8 months (2,079 days; semi-major axis of 3.19 AU). Its orbit has an eccentricity of 0.12 and an inclination of 2° with respect to the ecliptic.[2] The body's observation arc begins with its first observation as 1988 HY at the Leoncito Astronomical Complex in April 1988, or 11 years prior to its official discovery observation at Anderson Mesa.[1]

    Physical characteristics

    Horkheimer has an absolute magnitude of 12.8.[1][2] While its spectral type has not been determined, it is likely a carbonaceous C-type asteroid, typical for members of the Themis family.[5]:23 As of 2018, no rotational lightcurve has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.[2]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Horkheimer measures 15.355 kilometers in diameter and its surface has an albedo of 0.053, typical for carbonaceous asteroids.[4]

    Naming

    This minor planet was named after Jack F. Horkheimer (1938–2010), director of the Planetarium at the former Miami Science Museum, who was the creator and host of the television program Jack Horkheimer: Star Gazer. The official naming citation was published by the Minor Planet Center on 9 January 2001 (M.P.C. 41938).[6]

    References
    1. "11409 Horkheimer (1999 FD9)". Minor Planet Center. Retrieved 28 May 2018.
    2. "JPL Small-Body Database Browser: 11409 Horkheimer (1999 FD9)" (2017-06-02 last obs.). Jet Propulsion Laboratory. Retrieved 28 May 2018.
    3. "Asteroid 11409 Horkheimer". Small Bodies Data Ferret. Retrieved 28 May 2018.
    4. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2): 20. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68.
    5. Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
    6. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 28 May 2018.

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