8026 Johnmckay

8026 Johnmckay
Discovery [1]
Discovered byE. F. Helin
Discovery sitePalomar Obs.
Discovery date8 May 1991
(8026) Johnmckay
Named after
John B. McKay (test pilot)[2]
1991 JA1 · 1989 UF2
main-belt · (inner)[1]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc27.33 yr (9,981 days)
Aphelion2.0697 AU
Perihelion1.7809 AU
1.9253 AU
2.67 yr (976 days)
0° 22m 8.04s / day
Known satellites1 [4]
Physical characteristics
Dimensions1.690±0.239 km[5][6]
2.54 km (calculated)[3]
355±5 h[7]
372±5 h[8]
0.30 (assumed)[3]
14.60±0.44[9] · 14.7[5] · 14.9[1][3]

8026 Johnmckay, provisional designation 1991 JA1, is a binary[4] Hungaria asteroid and very slow rotator from the inner regions of the asteroid belt, approximately 2 kilometers in diameter. It was discovered on 8 May 1991, by American astronomer Eleanor Helin at the U.S. Palomar Observatory, California, and later named for NASA test pilot John B. McKay.[2]

Classification and orbit[]

The bright E-type asteroid is a member of the Hungaria family, which form the innermost dense concentration of asteroids in the Solar System. Johnmckay orbits the Sun in the inner main-belt at a distance of 1.8–2.1 AU once every 2 years and 8 months (976 days). Its orbit has an eccentricity of 0.08 and an inclination of 20° with respect to the ecliptic.[1] The first observation was made at the discovering observatory in 1989, extending the asteroid's observation arc by almost 2 years prior to its discovery.[2]

Diameter estimates[]

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Johnmckay measures 1.7 kilometers in diameter and its surface has an exceptionally high albedo of 0.81, while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for Hungaria asteroids of 0.30, and calculates a diameter of 2.5 kilometers, based on an absolute magnitude of 14.9.[3][5][6]



Two rotational lightcurves of Johnmckay were obtained for this asteroid from photometric observations by U.S. astronomer Brian D. Warner at the Palmer Divide Station (PDO), Colorado. In August 2010, the first lightcurve gave a long rotation period of 372±5 hours with a brightness variation of 1.0 in magnitude (U=3).[8] The second lightcurve from June 2015, gave a similar period of 355±5 with an amplitude of 0.66 in magnitude (U=2).[7]

This makes Johnmckay one of the Top 100+ slowest rotators known to exist.


In 2010 a small asteroid moon was discovered around this asteroid. It has an orbital period of 2.300±0.001 hours,[4] while observations at the PDO gave it a period of 2.2981 and 14.93 hours, respectively.[3][7][8]


This minor planet was named in memory of NASA test pilot John B. McKay (1922–1975), one of the first pilots assigned to fly the North American X-15. He was also assigned to the X-1E and to the D-558-II. He died in 1975, from injuries he had sustained during a X-15 crash. In 2005, he received posthumous the astronaut badge for a reached peak-altitude of 89,900 metres (295,000 feet).[2] The approved naming citation was published by the Minor Planet Center on 7 February 2012 (M.P.C. 78269).[10]


  1. ^ a b c d e "JPL Small-Body Database Browser: 8026 Johnmckay (1991 JA1)" (2017-02-23 last obs.). Jet Propulsion Laboratory. Retrieved 4 July 2017.
  2. ^ a b c d e "8026 Johnmckay (1991 JA1)". Minor Planet Center. Retrieved 11 August 2016.
  3. ^ a b c d e f g "LCDB Data for (8026) Johnmckay". Asteroid Lightcurve Database (LCDB). Retrieved 11 August 2016.
  4. ^ a b c Johnston, Robert. "(8026) Johnmckay". johnstonsarchive.net. Retrieved 29 May 2015.
  5. ^ a b c d Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90.
  6. ^ a b c 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:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68.
  7. ^ a b c Warner, Brian D. (October 2015). "Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2015 March-June". The Minor Planet Bulletin. 42 (4): 267–276. Bibcode:2015MPBu...42..267W. ISSN 1052-8091.
  8. ^ a b c Warner, Brian D. (January 2011). "A Quartet of Known and Suspected Hungaria Binary Asteroids". The Minor Planet Bulletin. 38 (1): 33–36. Bibcode:2011MPBu...38...33W. ISSN 1052-8091.
  9. ^ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007.
  10. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 11 August 2016.

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