|Discovered by||C. Kowal|
|Discovery site||Palomar Obs.|
|Discovery date||22 October 1976|
|MPC designation||2340 Hathor|
|Pronunciation||ˈhæθ ɔr, -ər (HATH-er)|
|Hathor (Egyptian deity)|
|Aten · NEO · PHA |
|Orbital characteristics |
|Epoch 11 August 2004 (JD 2453228.5)|
|Uncertainty parameter 0|
|Observation arc||38.00 yr (13,878 days)|
|0.78 yr (283 days)|
|1° 16m 17.4s / day|
|Earth MOID||0.0069 AU|
|Dimensions||±0.030 km 0.210
0.3 km (dated)
|B–V = 0.770
U–B = 0.500
Sq (SMASS) · S 
2340 Hathor (HATH-awr; HATH-er), provisional designation 1976 UA, is an eccentric stony asteroid, classified as near-Earth object and potentially hazardous asteroid. It belongs to the Aten group of asteroids and measures approximately 210 meters in diameter. It was discovered on 22 October 1976, by American astronomer Charles Kowal at Palomar Observatory, California, United States. It was independently discovered by Eleanor Helin and is named for the ancient Egyptian deity Hathor.
Being a member of the Aten asteroids, Hathor orbits the Sun at a distance of 0.5–1.2 AU once every 9 months (283 days). Its orbit has an eccentricity of 0.45 and an inclination of 6° with respect to the ecliptic. Its observation arc begins 3 days after its official discovery at Palomar, with no precoveries taken and no prior identifications made. Its orbital solution includes non-gravitational forces.
When it was discovered in 1976, Hathor had one of its closest approaches to Earth at 0.007752 AU (1,160,000 km). On 21 October 2014, when it passed Earth at 0.048 AU, or 18.8 lunar distances, it was observed 22 times by the Goldstone Deep Space Network using radar astronomy over a period of 21 days from 10 to 31 October. Hathor will pass Earth again at 0.00658 AU (984,000 km) on 21 October 2069.
On 25 October 1976, Hathor was independently discovered by Eleanor Helin during the Palomar Planet-Crossing Asteroid Survey (PCAS), and by William Lawrence Sebok, who photographed the same field almost simultaneously using Palomars 1.22-meter Schmidt telescope. On the same day, the official discoverer Charles Kowal found that Hathor had already been imaged three days earlier by Palomars 0.46-meter telescope (the same instrument used by PCAS). A forth independent discovery was made several days later by Nikolai Chernykh at CrAO on the Crimean peninsula. The multiple discoveries were probably due to its very close approach distance to Earth.:20 After 2062 Aten, Hathor was the second discovery of an Aten asteroid. In 1978, the third Aten, 2100 Ra-Shalom was discovered. The Aten 1954 XA was already identified at Palomar in 1954, but its discovery date was later assigned to a 2003-observation at Lincoln Laboratory ETS, and is now known as (363505) 2003 UC20.:21
In the Tholen and SMASS taxonomy, Hathor has a CSU and Sq spectral type, respectively. In the 1990s, Dutch–American astronomer Tom Gehrels estimated Hathor's diameter to measure approximately 300 meters, assuming an albedo of 0.15. During its close approach to Earth in October 2014, a team of astronomer published a revised estimate of ±30 meters for its diameter. 210 The Collaborative Asteroid Lightcurve Link adopts this diameter and derives an albedo of 0.3331 using an absolute magnitude of 20.2.
In November 2014, American astronomer Brian D. Warner obtained a rotational light-curve of Hathor from photometric observations taken at the Palmer Divide Station in Colorado (also see § External links). Light-curve analysis gave a well-defined rotation period of 3.350 hours with a brightness variation of 0.11 magnitude (U=3).
In accordance with the custom to name all members of the Aten group after Ancient Egyptian deities, this minor planet is named for Hathor, sky-goddess and daughter of Ra, who personified the principles of joy, feminine love, and motherhood. The Ancient Greeks sometimes identified Hathor with the goddess Aphrodite. Naming was proposed by Eleanor Helin who also participated in the 1981-recovery. The minor planet 161 Athor is also named for Hathor. Naming citation was published on 1 June 1981 (M.P.C. 6060).
- "JPL Small-Body Database Browser: 2340 Hathor (1976 UA)" (2014-10-24 last obs.). Jet Propulsion Laboratory. Retrieved 6 January 2017.
- Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (2340) Hathor. Springer Berlin Heidelberg. p. 191. ISBN 978-3-540-00238-3. Retrieved 6 January 2017.
- "2340 Hathor (1976 UA)". Minor Planet Center. Retrieved 6 January 2017.
- Giorgini, J. D.; Howell, E. S.; Taylor, P. A.; Richardson, J. E.; Ford, L. A.; Zambrano-Marin, L. F.; et al. (October 2014). "(2340) Hathor". IAU Circ. (9272). Bibcode:2014IAUC.9272....1G. Retrieved 6 January 2017.
- Warner, Brian D. (April 2015). "Near-Earth Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2014 October-December". The Minor Planet Bulletin. 42 (2): 115–127. Bibcode:2015MPBu...42..115W. ISSN 1052-8091. Retrieved 6 January 2017.
- "LCDB Data for (2340) Hathor". Asteroid Lightcurve Database (LCDB). Retrieved 6 January 2017.
- "JPL Close-Approach Data: 2340 Hathor (1976 UA)" (last obs.: 2012-02-03). Retrieved 11 April 2016.
- Lance A. M. Benner (25 October 2014). "Goldstone Radar Observations Planning: 2340 Hathor, 2014 SM143, 2014 RQ17, 2014 TV, and 2014 SC324". NASA/JPL Asteroid Radar Research. Retrieved 6 January 2017.
- Helin, Eleanor F. (September 1984). "Earth-Crossing Asteroids: An Update". The Minor Planet Bulletin. 11: 19–21. Bibcode:1984MPBu...11...19H. Retrieved 7 January 2017.
- "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 6 January 2017.
- Lightcurve plot (i) for (2340) Hathor, 21–22 October 2014, Brian Warner, CS3
- Lightcurve plot (ii) for (2340) Hathor, 30 October to 3 November 2014, Brian Warner, CS3
- Goldstone Asteroid Schedule
- Asteroid Lightcurve Database (LCDB), query form (info)
- Dictionary of Minor Planet Names, Google books
- Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
- Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
- 2340 Hathor at the JPL Small-Body Database