3290 Azabu

3290 Azabu, provisional designation 1973 SZ1, is a dynamical Hildian asteroid from the outermost regions of the asteroid belt, approximately 10–20 kilometers (6–10 miles) in diameter. It was discovered on 19 September 1973, by Dutch astronomers Ingrid and Cornelis van Houten at Leiden, and Tom Gehrels the Palomar Observatory.[1] The asteroid has a rotation period of 7.67 hours.[3] It was named after the former city district of Tokyo, Azabu.[1]

3290 Azabu
Discovery [1]
Discovered byC. J. van Houten
I. van Houten-G.
T. Gehrels
Discovery sitePalomar Obs.
Discovery date19 September 1973
(3290) Azabu
Named after
(City district of Tokyo)
1973 SZ1 · 1982 VX2
main-belt · (outer)[2]
Hilda[1][3] · background[4]
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc63.06 yr (23,034 d)
Aphelion4.4853 AU
Perihelion3.4579 AU
3.9716 AU
7.92 yr (2,891 d)
0° 7m 28.2s / day
Jupiter MOID0.4837 AU
Physical characteristics
Mean diameter
10.185±0.504 km[5]
21.16 km (calculated)[3]
7.670±0.005 h[6][a]
12 h (poor)[7]
0.057 (assumed)[3]
XL (Pan-STARRS)[9]
C (SDSS-MFB)[3][b]

Orbit and classificationEdit

Azabu is a member of the dynamical Hilda group, located beyond the actual core region of the asteroid belt, and locked in a 3:2 orbital resonance with the gas giant Jupiter. This means that for every 2 orbits Jupiter completes around the Sun, a Hildian asteroid will complete 3 orbits.[2] While it belongs to the dynamical Hilda group, Azabu, is not a member of the Hilda family (001), but an asteroid of the background population.[4]

This asteroid orbits the Sun in the outer main-belt at a distance of 3.5–4.5 AU once every 7 years and 11 months (2,891 days; semi-major axis of 3.97 AU). Its orbit has an eccentricity of 0.13 and an inclination of 3° with respect to the ecliptic.[2] The body's observation arc begins with a precovery taken at Palomar in April 1954, or 29 years prior to its official discovery observation.[1]

Palomar–Leiden Trojan surveyEdit

Despite being discovered during the second Palomar–Leiden Trojan survey in 1973, Azabu has not received a provisional survey designation starting with "T-2". This may be related to the swapped naming rights proposed by Tom Gehrels (see below). The survey was a fruitful collaboration between the Palomar and Leiden observatories during the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.[10]

Physical characteristicsEdit

The asteroid has been characterized as an XL-type by Pan-STARRS and in the SDSS-based taxonomy.[8][9] It is also characterized as a carbonaceous C-type asteroid in the SDSS-MFB (Masi Foglia Binzel) taxonomy.[3][b]

Rotation periodEdit

In April 2017, a rotational lightcurve of Azabu was obtained from photometric observations by Brian Warner and Robert Stephens at the Center for Solar System Studies in California. Lightcurve analysis gave a secure rotation period of 7.670 hours with a brightness amplitude of 0.23 magnitude (U=3-),[6][a] superseding a measurement of approximately 12 hours from the 1990s (U=1).[5]

Diameter and albedoEdit

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Azabu measures 10.2 kilometers in diameter and its surface has an albedo between 0.32.[5] The Collaborative Asteroid Lightcurve Link assumes a much lower carbonaceous standard albedo of 0.057 (based on the Masi Foglia Binzel taxonomy) and consequently calculates a much larger diameter of 21.16 kilometers with an absolute magnitude of 12.1.[3]


This minor planet was named after Azabu, a former district of the city of Tokyo, where the Tokyo Astronomical Observatory was previously located.[1] The official naming citation was published by the Minor Planet Center on 16 December 1986 (M.P.C. 11442).[11]

Based on a proposal by the discoverer Tom Gehrels, the naming right for this asteroid were swapped with 3291 Dunlap (discovered by Japanese astronomers), in order to create a quartet of sequentially named asteroids named after Lawrence Dunlap, Bob Sather, Ronald Raylor, and Carl Vesely (numbers 3291–3294).[12]


  1. ^ a b Lightcurve plot of (3290) Azabu, B. D. Warner at the CS3 (April 2017). Rotation period 7.670±0.005 hours with a brightness amplitude of 0.23±0.02 mag. Total of 190 points. Quality code of 3-. Summary figures at the LCDB.
  2. ^ a b Search for Unusual Spectroscopic Candidates Among 40313 minor planets from the 3rd Release of the Sloan Digital Sky Survey Moving Object Catalog (publication). SDSS-MFB (Masi Foglia Binzel) taxonomy (catalog).


  1. ^ a b c d e f g "3290 Azabu (1973 SZ1)". Minor Planet Center. Retrieved 4 May 2018.
  2. ^ a b c d e "JPL Small-Body Database Browser: 3290 Azabu (1973 SZ1)" (2017-05-01 last obs.). Jet Propulsion Laboratory. Retrieved 4 May 2018.
  3. ^ a b c d e f g h "LCDB Data for (3290) Azabu". Asteroid Lightcurve Database (LCDB). Retrieved 4 May 2018.
  4. ^ a b "Asteroid 3290 Azabu – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 29 October 2019.
  5. ^ a b c d e f Grav, T.; Mainzer, A. K.; Bauer, J.; Masiero, J.; Spahr, T.; McMillan, R. S.; et al. (January 2012). "WISE/NEOWISE Observations of the Hilda Population: Preliminary Results". The Astrophysical Journal. 744 (2): 15. arXiv:1110.0283. Bibcode:2012ApJ...744..197G. doi:10.1088/0004-637X/744/2/197. Retrieved 4 May 2018.
  6. ^ a b Warner, Brian D.; Stephens, Robert D. (October 2017). "Lightcurve Analysis of Hilda Asteroids at the Center for Solar System Studies: 2017 April thru July". The Minor Planet Bulletin. 44 (4): 331–334. Bibcode:2017MPBu...44..331W. ISSN 1052-8091. Retrieved 4 May 2018.
  7. ^ Dahlgren, M.; Lahulla, J. F.; Lagerkvist, C.-I.; Lagerros, J.; Mottola, S.; Erikson, A.; et al. (June 1998). "A Study of Hilda Asteroids. V. Lightcurves of 47 Hilda Asteroids". Icarus. 133 (2): 247–285. Bibcode:1998Icar..133..247D. doi:10.1006/icar.1998.5919. Retrieved 4 May 2018.
  8. ^ a b Carvano, J. M.; Hasselmann, P. H.; Lazzaro, D.; Mothé-Diniz, T. (February 2010). "SDSS-based taxonomic classification and orbital distribution of main belt asteroids". Astronomy and Astrophysics. 510: 12. Bibcode:2010A&A...510A..43C. doi:10.1051/0004-6361/200913322. Retrieved 30 October 2019. (PDS data set)
  9. ^ a b c 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. ^ "Minor Planet Discoverers". Minor Planet Center. 2 April 2018. Retrieved 4 May 2018.
  11. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 4 May 2018.
  12. ^ Schmadel, Lutz D. (2007). "(3291) Dunlap". Dictionary of Minor Planet Names – (3291) Dunlap. Springer Berlin Heidelberg. p. 274. doi:10.1007/978-3-540-29925-7_3292. ISBN 978-3-540-00238-3.

External linksEdit