|Discovery site||Anderson Mesa Stn.|
|Discovery date||19 March 1999|
|MPC designation||(11409) Horkheimer|
|Jack Horkheimer 
(American science communicator)
|1999 FD9 · 1988 HY
|main-belt  · (outer)
|Orbital characteristics |
|Epoch 23 March 2018 (JD 2458200.5)|
|Uncertainty parameter 0|
|Observation arc||29.11 yr (10,632 d)|
|5.69 yr (2,079 d)|
|0° 10m 23.52s / day|
|C (Themis family)|
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.
Orbit and classification
Horkheimer is a core member of the Themis family (602), a very large family of carbonaceous asteroids, named after 24 Themis. 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. 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.
Horkheimer has an absolute magnitude of 12.8. While its spectral type has not been determined, it is likely a carbonaceous C-type asteroid, typical for members of the Themis family.:23 As of 2018, no rotational lightcurve has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.
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.
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).
- "11409 Horkheimer (1999 FD9)". Minor Planet Center. Retrieved 28 May 2018.
- "JPL Small-Body Database Browser: 11409 Horkheimer (1999 FD9)" (2017-06-02 last obs.). Jet Propulsion Laboratory. Retrieved 28 May 2018.
- "Asteroid 11409 Horkheimer". Small Bodies Data Ferret. Retrieved 28 May 2018.
- 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: . Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68. Retrieved 28 May 2018.
- Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families" (PDF). Asteroids IV: 297–321. arXiv: . Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. Retrieved 28 May 2018.
- "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 28 May 2018.
- Congressional Record of the Asteroid Naming in Honor of Jack "Star Hustler" Horkheimer
- Dictionary of Minor Planet Names, Google books
- Discovery Circumstances: Numbered Minor Planets (10001)-(15000) – Minor Planet Center
- 11409 Horkheimer at AstDyS-2, Asteroids—Dynamic Site
- 11409 Horkheimer at the JPL Small-Body Database