(5496) 1973 NA

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(5496) 1973 NA
Discovery [1]
Discovered by E. F. Helin
Discovery site Palomar Obs.
Discovery date 4 July 1973
MPC designation (5496) 1973 NA
1973 NA · 1992 OA
Apollo · NEO
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc 41.30 yr (15,086 days)
Aphelion 3.9838 AU
Perihelion 0.8866 AU
2.4352 AU
Eccentricity 0.6359
3.80 yr (1,388 days)
0° 15m 33.84s / day
Inclination 67.993°
Earth MOID 0.0902 AU
Physical characteristics
Dimensions 1.88 km (calculated)[2]
2.855±0.001 h[a]
0.20 (assumed)[2]
C/X[3] · S[2]

(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.[4] At the time of its discovery, it was the most highly inclined minor planet known to exist.

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 a high eccentricity of 0.64 and an exceptionally high 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.[4]

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.[5] 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.[4] Its minimum orbit intersection distance with Earth is now 0.0902 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.[3] A rotational light-curve for this asteroid was obtained by American astronomer Brian Skiff from photometric observations made in June 2011. The light-curve gave a rotation period of 2.855±0.001 hours with a brightness variation of 0.15 in 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, based on an absolute magnitude of 16.0.[2]

The asteroid is expected to be related to the Quadrantids January meteor shower.[6]


  1. ^ a b Skiff (2011) web: rotation period 2.855±0.001 hours with a brightness amplitude of 0.15 mag. Observation rated Quality Code (U) of 3. Summary figures at Collaborative Asteroid Lightcurve Link (CALL) for (5496) 1973 NA
  1. ^ a b c d e "JPL Small-Body Database Browser: 5496 (1973 NA)" (2014-10-25 last obs.). Jet Propulsion Laboratory. Retrieved 1 March 2016. 
  2. ^ a b c d e "LCDB Data for (5496)". Asteroid Lightcurve Database (LCDB). Retrieved 24 May 2016. 
  3. ^ a b Thomas, Cristina A.; Emery, Joshua P.; Trilling, David E.; Delbó, Marco; Hora, Joseph L.; Mueller, Michael (January 2014). "Physical characterization of Warm Spitzer-observed near-Earth objects". Icarus. 228: 217–246. arXiv:1310.2000free to read. Bibcode:2014Icar..228..217T. doi:10.1016/j.icarus.2013.10.004. Retrieved 24 May 2016. 
  4. ^ a b c "5496 (1973 NA)". Minor Planet Center. Retrieved 1 March 2016. 
  5. ^ "JPL Small-Body Database Browser: 5496 (1973 NA) – Close-Approach Data". Jet Propulsion Laboratory. Retrieved 1 March 2016. 
  6. ^ Williams, Iwan P.; Collander-Brown, S. J. (February 1998). "The parent of the Quadrantid meteoroid stream". Monthly Notices of the Royal Astronomical Society. 294: 127. Bibcode:1998MNRAS.294..127W. doi:10.1046/j.1365-8711.1998.01168.x. Retrieved 1 March 2016. 

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