| Discovery [1] | |
|---|---|
| Discovered by | E. F. Helin |
| Discovery site | Palomar Obs. |
| Discovery date | 4 July 1973 |
| Designations | |
| (5496) 1973 NA | |
| 1973 NA ·1992 OA | |
| Apollo · NEO [2] | |
| Orbital characteristics [1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 41.30 yr (15,086 days) |
| Aphelion | 3.9837 AU |
| Perihelion | 0.8865 AU |
| 2.4351 AU | |
| Eccentricity | 0.6360 |
| 3.80 yr (1,388 days) | |
| 240.93° | |
| 0° 15m 33.84s / day | |
| Inclination | 68.006° |
| 101.04° | |
| 118.02° | |
| Earth MOID | 0.0904 AU |
| Physical characteristics | |
| 1.88 km (calculated) [3] | |
| 2.855±0.001 h [a] | |
| 0.20 (assumed) [3] | |
| C/X [4] · S [3] | |
| 16.0 [1] [3] | |
(5496) 1973 NA, is a very eccentric and heavily tilted asteroid, classified as near-Earth object of the Apollo group, approximately 2 kilometers in diameter. It was discovered on 4 July 1973, by American astronomer Eleanor Helin at the U.S. Palomar Observatory in California. [2] At the time of its discovery, it was the most highly inclined minor planet known to exist. It may be the parent body of the Quadrantids.
1973 NA is a possible parent body of the Quadrantids, a major meteor shower that occurs every January. It may also be just a fragment of the parent or the dormant remains of the parent. Other possible parent bodies are Comet 1491 I and comet 96P/Machholz, [5] as well as (196256) 2003 EH1 . [6] [7]
The asteroid orbits the Sun at a distance of 0.9–4.0 AU once every 3 years and 10 months (1,388 days). Its orbit has an eccentricity of 0.64 and an inclination of 68° with respect to the ecliptic. [1] No precoveries were taken. The asteroid's observation arc even begins 2 days after its discovery. [2]
The body was also one of the first known near-Earth asteroids. Its discovery happened just two days after it had passed 0.07984 AU (11,900,000 km) from Earth on one of its closest approaches ever computed. [8] It was then tracked for more than a month, but was not seen again until its next close approach in 1992, when it was recovered by the Siding Spring Observatory in Australia. [2] Its minimum orbit intersection distance with Earth is now 0.0904 AU (13,500,000 km). [1]
The stony S-type asteroid is also classified as a transitional C/X-type according to observations by the NASA IRTF telescope. [4] A rotational lightcurve for this asteroid was obtained by American astronomer Brian Skiff from photometric observations made in June 2011. Lightcurve analysis gave a well-defined rotation period of 2.855±0.001 hours with a brightness variation of 0.15 magnitude ( U=3 ). [a] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 1.88 kilometers with an absolute magnitude of 16.0. [3]
