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7816 Hanoi, provisional designation 1987 YA, is an eccentric stony asteroid and Mars-crosser from the inner regions of the asteroid belt, approximately 3 kilometers in diameter. It was discovered on 18 December 1987, by Japanese astronomer Masahiro Koishikawa at the Ayashi Station (391) of the Sendai Astronomical Observatory, Japan, and later named after the Vietnamese capital of Hanoi.[2][7]

7816 Hanoi
Discovery [1]
Discovered byM. Koishikawa
Discovery siteAyashi Station (391)
Sendai Obs.
Discovery date18 December 1987
MPC designation(7816) Hanoi
Named after
(Vietnamese capital)[2]
1987 YA · 1994 VB1
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc29.37 yr (10,728 days)
Aphelion2.9970 AU
Perihelion1.6341 AU
2.3156 AU
3.52 yr (1,287 days)
0° 16m 46.92s / day
Physical characteristics
Dimensions2.97 km (calculated)[3]
5.17±0.01 h[4]
5.18±0.02 h[5]
0.20 (assumed)[3]
15.0[1][3] · 15.18±0.30[6]

Orbit and classificationEdit

Hanoi orbits the Sun in the inner main-belt at a distance of 1.6–3.0 AU once every 3 years and 6 months (1,287 days). Its orbit has an eccentricity of 0.29 and an inclination of 2° with respect to the ecliptic.[1] No precoveries were taken. The asteroid's observation arc begins with its official discovery observation.[7]

Physical characteristicsEdit


In November 2011, a rotational lightcurve of Hanoi was obtained from photometric observations made American astronomer by Brian Warner at his Palmer Divide Observatory in Colorado. The lightcurve gave a rotation period of 5.18±0.02 hours with a brightness variation of 0.72 magnitude (U=2+).[5] Ten years later, remeasurements of the original images rendered a slightly refined period of 5.17±0.01 and an amplitude of 0.77 (U=3-).[4]

Diameter and albedoEdit

The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20, and calculates a diameter of 3.0 kilometers with an absolute magnitude of 15.0.[3]


This minor planet was named after the city of Hanoi, capital of Vietnam, which the discoverer visited in 1997. Together with astronomer Yoshihide Kozai, after whom the minor planet 3040 Kozai is named, he assisted local astronomers install a Schmidt-Cassegrain and a refracting telescope at HNUE. The installed instrumentation was funded by the Japanese Sumitomo Foundation, with the intention to foster Vietnamese astronomical research.[2] The official naming citation was published by the Minor Planet Center on 2 February 1999 (M.P.C. 33790).[8]

See alsoEdit


  1. ^ a b c d e "JPL Small-Body Database Browser: 7816 Hanoi (1987 YA)" (2017-05-02 last obs.). Jet Propulsion Laboratory. Retrieved 22 June 2017.
  2. ^ a b c Schmadel, Lutz D. (2007). "(7816) Hanoi". Dictionary of Minor Planet Names – (7816) Hanoi. Springer Berlin Heidelberg. p. 617. doi:10.1007/978-3-540-29925-7_6690. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f "LCDB Data for (7816) Hanoi". Asteroid Lightcurve Database (LCDB). Retrieved 26 May 2016.
  4. ^ a b Warner, Brian D. (January 2011). "Upon Further Review: V. An Examination of Previous Lightcurve Analysis from the Palmer Divide Observatory". The Minor Planet Bulletin. 38 (1): 63–65. Bibcode:2011MPBu...38...63W. ISSN 1052-8091. Retrieved 26 May 2016.
  5. ^ a b Warner, B. D. (June 2002). "Asteroid Photometry at the Palmer Divide Observatory: Results for 620 Drakonia, 3447 Burkhalter, and 7816 Hanoi". The Minor Planet Bulletin. 29: 27–28. Bibcode:2002MPBu...29...27W. Retrieved 26 May 2016.
  6. ^ 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. Retrieved 26 May 2016.
  7. ^ a b "7816 Hanoi (1987 YA)". Minor Planet Center. Retrieved 26 May 2016.
  8. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 26 May 2016.

External linksEdit