133 Cyrene

A 3D lightcurve-derived model of 133 Cyrene.

Discovery[1]
Discovered by| James Craig Watson
Discovery site| Ann Arbor, Michigan, United States
Discovery date| 16 August 1873
Designations

MPC designation

| (133) Cyrene
Pronunciation| /saɪˈriːniː/[3]
Named after| Cyrene (nymph)

Alternative designations

| A873 QA * A910 NB * 1936 HO * 1948 QC * 1959 UR[2][lower-alpha 1]
Minor planet category| Main belt
Adjectives| Cyrenean /saɪrɪˈniːən/, Cyrenian /saɪˈriːniən/[4]
Orbital characteristics[2]
Epoch 21 November 2025 (JD 2461000.5)
Uncertainty parameter 0
Observation arc| 152.13 yr (55566 d)
|{{{apsis}}}|helion}}| 7.2245 AU (1,080.77 Gm)
|{{{apsis}}}|helion}}| 2.6736 AU (399.96 Gm)

Semi-major axis

| 3.0742 AU (459.89 Gm)
Eccentricity| 0.1303
Orbital period| 5.3902 yr (1968.77 d)
Average Orbital speed| 17.03 km/s
Mean anomaly| 219.02°
Mean motion| 0° 10m 58.26s / day
Inclination| 7.2245°
Longitude of ascending node| 318.67°

|{{{apsis}}}|helion}}

| 291.65°
Earth MOID| 1.6686 AU (249.62 Gm)
Jupiter MOID| 1.6595 AU (248.26 Gm)
TJupiter| 3.205
Physical characteristics
Dimensions| 66.57±6.0 km
Mass| 3.1 × 1017 kg
Mean density| 2.0? g/cm3

Equatorial surface gravity

| 0.0186 m/s²

Equatorial escape velocity

| 0.0352 km/s
Rotation period| 12.708 h (0.5295 d)[2]
12.707 h (0.5295 d)[5]
Geometric albedo| 0.2563±0.053[2]
0.2563[6]
Physics| ~133 K

Spectral type

| S[6]
Absolute magnitude (H)| 7.98,[2] 7.990[7]

133 Cyrene is a fairly large and very bright main-belt asteroid that was discovered by J. C. Watson on 16 August 1873 in Ann Arbor, Michigan, and named after Cyrene, a nymph, daughter of king Hypseus and beloved of Apollo in Greek mythology.[8] It is classified as an S-type asteroid based upon its spectrum. It is listed as a member of the Hecuba group of asteroids that orbit near the 2:1 mean-motion resonance with Jupiter.[9]

## Contents

* 1 Discovery and naming
* 2 Orbit
* 3 Physical characteristics
* 4 See also
* 5 Notes
* 6 References
* 7 External links

## Discovery and naming

Cyrene was discovered on 16 August 1873 by astronomer James Craig Watson at Ann Arbor, Michigan, United States.[1] Its discovery, alongside that of 132 Aethra, was announced in the journal Astronomische Nachrichten on 30 August.[10] The asteroid was given the name Cyrene after the Greek mythological figure Cyrene, daughter of the Lapithian king Hypseus. With the god Apollo, she bore her two sons Aristaeus and Idmon.[11]: 25

## Orbit

An orbital diagram of 133 Cyrene. The ecliptic grid and the orbits of the inner planets and Jupiter are also shown.

Cyrene is a main belt asteroid, orbiting the Sun at an average distance—its semi-major axis—of 3.07 astronomical units (AU). Along its 5.39 year long orbit, its distance from the Sun varies from 2.67 AU at perihelion to 3.47 AU at aphelion due to its orbital eccentricity of 0.13. It has an orbital inclination of 7.22° with respect to the ecliptic plane.[2]

## Physical characteristics

In the Tholen classification system, it is categorized as a stony SR-type asteroid.[12] Photometric observations of this asteroid at the Altimira Observatory in 1985 gave a light curve with a period of 12.707 ± 0.015 hours and a brightness variation of 0.22 in magnitude. This result matches previous measurements reported in 1984 and 2005.[5]

## See also

Minor planets named after figures related to Cyrene:

* 1862 Apollo – A near-Earth asteroid (NEA) named after Cyrene's lover
* 2135 Aristaeus – An NEA named after Cyrene's son

## Notes

1. ↑ The MPC notates Aethra's retroactive new-style designations as 1873 QA and 1910 NB.[1]

## References

1. ↑ 1.0 1.1 1.2 "(133) Cyrene = 1873 QA = 1910 NB = 1936 HO = 1948 QC = 1959 UR". Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?utf8=✓&object_id=133. Retrieved 5 November 2025.
2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Yeomans, Donald K., "133 Cyrene", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=133, retrieved 12 May 2016.
3. ↑ Noah Webster (1884) A Practical Dictionary of the English Language
4. ↑ Cyrenean (3rd ed.), Oxford University Press, September 2005, http://oed.com/search?searchType=dictionary&q=Cyrenean (Subscription or UK public library membership required.)
5. ↑ 5.0 5.1 Buchheim, Robert K. (June 2006), "Photometry of asteroids 133 Cyrene, 454 Mathesis, 477 Italia, and 2264 Sabrina", Astronomy and Astrophysics Supplement Series 33 (2): pp. 29–30, Bibcode: 2006MPBu...33...29B.
6. ↑ 6.0 6.1 Richmond, Michael (1 March 2001), "Asteroid Lightcurve Data File", Astronomy and Astrophysics Supplement Series, http://spiff.rit.edu/richmond/parallax/phot/LCSUMPUB.TXT, retrieved 2013-03-29.
7. ↑ Pravec, P. et al. (May 2012), "Absolute Magnitudes of Asteroids and a Revision of Asteroid Albedo Estimates from WISE Thermal Observations", Asteroids, Comets, Meteors 2012, Proceedings of the conference held May 16–20, 2012 in Niigata, Japan (1667), Bibcode: 2012LPICo1667.6089P.
8. ↑ Schmadel, Lutz D.; International Astronomical Union (2003), Dictionary of minor planet names, Berlin; New York: Springer-Verlag, p. 27, ISBN 978-3-540-00238-3, https://books.google.com/books?id=VoJ5nUyIzCsC&pg=PA27.
9. ↑ McDonald, Sophia Levy (June 1948), "General perturbations and mean elements, with representations of 35 minor planets of the Hecuba group", Astronomical Journal 53: p. 199, doi:10.1086/106097, Bibcode: 1948AJ.....53..199M, http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1948AJ.....53..199M&link_type=ARTICLE&db_key=AST&high=.
10. ↑ Watson, James Craig (30 August 1873). "Correspondence - Discovery of Two New Planets". Astronomical Register 11: 284. Bibcode: 1873AReg...11..284W.
11. ↑ Schmadel, Lutz (2003), Dictionary of minor planet names, 1, Springer, p. 68, ISBN 9783540002383, https://books.google.com/books?id=VoJ5nUyIzCsC&pg=PA68.
12. ↑ DeMeo, Francesca E. et al. (July 2009), "An extension of the Bus asteroid taxonomy into the near-infrared", Icarus 202 (1): pp. 160–180, doi:10.1016/j.icarus.2009.02.005, Bibcode: 2009Icar..202..160D, archived from the original on 2014-03-17, https://web.archive.org/web/20140317200310/https://www.tara.tcd.ie/bitstream/2262/43276/1/PEER_stage2_10.1016/j.icarus.2009.02.005.pdf, retrieved 2013-04-08. See appendix A.

## External links

* 133 Cyrene at AstDyS-2, Asteroids—Dynamic Site
* Ephemeris * Observation prediction * Orbital info * Proper elements * Observational info
* 133 Cyrene at the JPL Small-Body Database
* Close approach * Discovery * Ephemeris * Orbit diagram * Orbital elements * Physical parameters

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