| Discovery[1] | |
|---|---|
| Discovered by | LONEOS |
| Discovery site | Anderson Mesa Stn. |
| Discovery date | 11 April 1999 |
| Designations | |
| (12923) Zephyr | |
| Pronunciation | /ˈzɛfər/[2] |
Named after | Zephyrus[3] (Greek mythology) |
| 1999 GK4 | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 61.75 yr (22,554 days) |
| Earliestprecovery date | 21 April 1955 |
| Aphelion | 2.9267 AU |
| Perihelion | 0.9964 AU |
| 1.9615 AU | |
| Eccentricity | 0.4920 |
| 2.75 yr (1,003 days) | |
| 199.23° | |
| 0° 21m 31.68s / day | |
| Inclination | 5.3045° |
| 168.21° | |
| 147.06° | |
| Earth MOID | 0.0211 AU (8.2 LD) |
| Physical characteristics | |
| 3.891 h[a] | |
12923 Zephyr (prov. designation:1999 GK4) is a stonyasteroid, classified aspotentially hazardous asteroid andnear-Earth object of theApollo group, approximately 2 kilometers (1.2 miles) in diameter. It was discovered on 11 April 1999, by astronomers of theLowell Observatory Near-Earth Object Search atAnderson Mesa Station near Flagstaff, Arizona.[4] The asteroid was named after the deityZephyrus from Greek mythology.[3]
Zephyr orbits the Sun at a distance of 1.0–2.9 AU once every 2 years and 9 months (1,003 days). Its orbit has aneccentricity of 0.49 and aninclination of 5° with respect to theecliptic.[1] The body'sobservation arc begins with aprecovery taken atPalomar Observatory in April 1955, almost 44 years prior to its official discovery observation at Anderson Mesa.[4]
Thisnear-Earth asteroid has an Earthminimum orbital intersection distance of 0.0211 AU (3,160,000 km), which corresponds to 8.2lunar distances.[1] This short distance as well as its sufficiently large size makes it apotentially hazardous asteroid. In September 2010, the asteroid approached Earth at 0.2546 AU (38,100,000 km); it will make close encounters with Earth again in 2021, 2032 and 2043.[1]
Thisminor planet was named after the god of the west wind,Zephyrus, fromGreek mythology. The name was suggested by M. Smitherman.[3] The official naming citation was published by theMinor Planet Center on 28 September 2004 (M.P.C. 52768).[13]
In theSMASS classification,Zephyr is a commonS-type asteroid.[1] The body is also characterized as a stony asteroid by theInfrared Telescope Facility,[10] and in theTholen classification (noisy spectrum).[11]
In April 1999, a rotationallightcurve ofZephyr was obtained from photometric observations by Czech astronomerPetr Pravec atOndřejov Observatory. Lightcurve analysis gave a well-definedrotation period of 3.891 hours with a brightness amplitude of 0.18magnitude (U=3).[a]
According to the survey carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer and the ExploreNEOs survey of theSpitzer Space Telescope,Zephyr measures between 1.86 and 2.062 kilometers in diameter and its surface has analbedo between 0.1764 and 0.21.[5][6][7][8][9]
TheCollaborative Asteroid Lightcurve Link adopts Petr Pravec's revised WISE data, with albedo of 0.1764 and a diameter of 2.06 kilometers based on anabsolute magnitude of 15.93.[11]
