1919 Clemence

Hungaria asteroid and suspected tumbler

1919 ClemenceDiscovery[1]

Discovered by| J. Gibson
C. U. Cesco
Discovery site| El Leoncito
Discovery date| 16 September 1971
Designations

MPC designation

| (1919) Clemence

Named after

| Gerald Clemence
(astronomer)[2]

Alternative designations

| 1971 SA * 1970 EA1
1971 QZ

Minor planet category

| main-belt * (inner)[1]
Hungaria[3][4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc| 46.23 yr (16,884 days)
Aphelion| 2.1200 AU
Perihelion| 1.7522 AU

Semi-major axis

| 1.9361 AU
Eccentricity| 0.0950

Orbital period (sidereal)

| 2.69 yr (984 days)

Mean anomaly

| 286.44°

Mean motion

| 0° 21m 57.24s / day
Inclination| 19.337°

Longitude of ascending node

| 357.00°

Argument of perihelion

| 99.880°
Physical characteristics
Dimensions| 3.238±0.015 km[5]
3.276±0.010[6]
4.95 km (calculated)[4]

Synodic rotation period

| 67.4±0.1 h (revised)[7]
68.5±0.1 h (original)[8]

Geometric albedo

| 0.3 (assumed)[4]
0.686±0.108[6]
0.7103±0.0672[5]

Spectral type

| Tholen = X[1]
X[4] * E[5]
B–V = 0.750[1]
U–B = 0.254[1]

Absolute magnitude (H)

| 13.45[1][4][5]

1919 Clemence, provisional designation 1971 SA, is a bright Hungaria asteroid and suspected tumbler from the inner regions of the asteroid belt, approximately 4 kilometers in diameter. It was discovered on 16 September 1971, by American astronomer James Gibson together with Argentine astronomer Carlos Cesco at the Yale-Columbia Southern Station at Leoncito Astronomical Complex in Argentina.[3] It is named after astronomer Gerald Clemence.[2]

## Orbit and classification

[edit]

Clemence is a member of the Hungaria family, which form the innermost dense concentration of asteroids in the Solar System. It orbits the Sun at a distance of 1.8–2.1 AU once every 2 years and 8 months (984 days). Its orbit has an eccentricity of 0.10 and an inclination of 19° with respect to the ecliptic.[1]

## Physical characteristics

[edit]

In the Tholen taxonomic scheme, Clemence is classified as an X-type asteroid.[1] It has also been characterized as an E-type asteroid by the NEOWISE mission.[5]

### Rotation period

[edit]

In March 2005, a rotational lightcurve was obtained by American astronomer Brian Warner at his Palmer Divide Observatory (716) in Colorado. Lightcurve analysis gave a rotation period of 67.4±0.1 hours and a brightness variation of 0.15 magnitude (U=2, revised analysis).[7] While not being a slow rotator, Clemence has a significantly longer period than most other asteroids, which typically have a spin rate between 2 and 20 hours.

Czech astronomer Petr Pravec from the Ondřejov Observatory believes this may be a tumbling asteroid, yet observations are not sufficient to determine a non-principal axis rotation.[8][9]

### Diameter and albedo

[edit]

According to the surveys carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, the asteroid measures 3.2 kilometers in diameter and its surface has an outstandingly high albedo of 0.71,[5] while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.30 and calculates a somewhat larger diameter of 4.95 kilometers with an absolute magnitude of 13.45.[4]

## Naming

[edit]

This minor planet was named after American astronomer Gerald Maurice Clemence (1908–1974), first scientific director of the United States Naval Observatory and professor of astronomy at the Yale Observatory, known for his work on the theory of the motion of Mars and Mercury, on the system of astronomical constants, and other research in celestial mechanics. He served as president of the American Astronomical Society and of IAU.[2] The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3937).[10]

## References

[edit]

1. ^ a b c d e f g h i "JPL Small-Body Database Browser: 1919 Clemence (1971 SA)" (2016-05-28 last obs.). Jet Propulsion Laboratory. Retrieved 9 June 2017.
2. ^ a b c Schmadel, Lutz D. (2007). "(1919) Clemence". Dictionary of Minor Planet Names – (1919) Clemence. Springer Berlin Heidelberg. p. 154\. doi:10.1007/978-3-540-29925-7_1920. ISBN 978-3-540-00238-3.
3. ^ a b "1919 Clemence (1971 SA)". Minor Planet Center. Retrieved 19 April 2016.
4. ^ a b c d e f "LCDB Data for (1919) Clemence". Asteroid Lightcurve Database (LCDB). Retrieved 19 April 2016.
5. ^ a b c d e f 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. Retrieved 19 April 2016.
6. ^ a b Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 21 March 2017.
7. ^ a b Warner, Brian D.; Stephens, Robert, D.; Harris, Alan W.; Pravec, Petr (October 2009). "A Re-examination of the Lightcurves for Seven Hungaria Asteroids". The Minor Planet Bulletin. 36 (4): 176–179. Bibcode:2009MPBu...36..176W. ISSN 1052-8091. Retrieved 19 April 2016.`{{cite journal}}`: CS1 maint: multiple names: authors list (link)
8. ^ a b Warner, Brian D. (September 2005). "Asteroid lightcurve analysis at the Palmer Divide Observatory - winter 2004-2005". The Minor Planet Bulletin. 32 (3): 54–58. Bibcode:2005MPBu...32...54W. ISSN 1052-8091. Retrieved 19 April 2016.
9. ^ Pravec, P.; Scheirich, P.; Durech, J.; Pollock, J.; Kusnirák, P.; Hornoch, K.; et al. (May 2014). "The tumbling spin state of (99942) Apophis". Icarus. 233: 48–60. Bibcode:2014Icar..233...48P. doi:10.1016/j.icarus.2014.01.026. Retrieved 19 April 2016.
10. ^ Schmadel, Lutz D. "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221\. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.

## External links

[edit]

* The Palmer Divide Observatory: Tour given by Brian Warner on YouTube (time 4:03 min.)
* Lightcurve plot of 1919 Clemence, Palmer Divide Observatory, B. D. Warner (2005)
* Asteroid Lightcurve Database (LCDB), query form (info Archived 21 July 2011 at the Wayback Machine)
* Dictionary of Minor Planet Names, Google books
* Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
* Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
* 1919 Clemence at AstDyS-2, Asteroids—Dynamic Site
* Ephemeris * Observation prediction * Orbital info * Proper elements * Observational info
* 1919 Clemence at the JPL Small-Body Database
* Close approach * Discovery * Ephemeris * Orbit diagram * Orbital elements * Physical parameters

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