981 Martina (prov. designation: A917 SW or 1917 Σ92) is a carbonaceous Themistian asteroid from the outer regions of the asteroid belt, approximately 31 kilometers (19 miles) in diameter. It was discovered on 23 September 1917, by Russian astronomer Sergey Belyavsky at the Simeiz Observatory on the Crimean peninsula.[1] The C/B-type asteroid has a rotation period of 11.3 hours.[10] It was named after French historian and revolutionary Henri Martin (1810–1883).[2]

981 Martina
Discovered byS. Belyavskyj
Discovery siteSimeiz Obs.
Discovery date23 September 1917
(981) Martina
Named after
Henri Martin
(French historian)[2]
A917 SW · 1917 Σ92
1906 SD · 1928 TG
1942 EY · 1949 MF
1953 FG · 1959 GF
1959 JF · 1966 QA
A906 SD
main-belt[1][3] · (outer)
Orbital characteristics[3]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc112.98 yr (41,266 d)
Aphelion3.7284 AU
Perihelion2.4685 AU
3.0984 AU
5.45 yr (1,992 d)
0° 10m 50.52s / day
Physical characteristics
Mean diameter
  • 28.87±1.7 km[6]
  • 31.70±1.29 km[7]
  • 32.545±0.124 km[8]
11.267±0.003 h[9][10]

Orbit and classificationEdit

Martina is a core member of the Themis family (602), a very large family of carbonaceous asteroids, named after 24 Themis.[4][5][14]: 23  It orbits the Sun in the outer asteroid belt at a distance of 2.5–3.7 AU once every 5 years and 5 months (1,992 days; semi-major axis of 3.1 AU). Its orbit has an eccentricity of 0.20 and an inclination of 2° with respect to the ecliptic.[3] The body's observation arc begins with its first observation as A906 SD (1906 SD) at Lowell Observatory in August 1906, more than 11 years prior to its official discovery observation at Crimea–Simeis.[1]


This minor planet was named after French historian and revolutionary politician, Henri Martin (1810–1883). The naming was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 94).[2]

Physical characteristicsEdit

In the SDSS-based taxonomy, Martina is a carbonaceous C-type asteroid,[12] while in the classical Tholen classification, it has been classified as a CFU: asteroid, closest to a C-type and somewhat similar to an F-type, though with an unusual (U) and noisy spectra (:).[3] In both the Tholen- and SMASS-like taxonomy of the Small Solar System Objects Spectroscopic Survey (S3OS2), Martina is a B-type asteroid, a "brighter" variant of the more common C-type.[5][13] Members of the Themis family are typically classified as C-types with an albedo of 0.07, a value notably lower than for this asteroid at 0.10–0.13 (see below).[14]: 23 

Rotation periodEdit

In August 2004, a rotational lightcurve of Martina was obtained from photometric observations by David Higgins at the Hunters Hill Observatory (E14) in Australia. Lightcurve analysis gave a rotation period of 28.87±1.7 hours with a brightness variation of 0.20±0.02 magnitude (U=2).[9][10] Astronomers at the Palomar Transient Factory in California also determined the period in the R-band on two occasions, measuring 11.263 and 11.268 hours with an amplitude of 0.24 and 0.15 in 2010 and 2012, respectively (U=2/2).[9][15]

Diameter and albedoEdit

According to the survey carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Franklina measures between 28.8 and 32.5 kilometers in diameter and its surface has an albedo between 0.10 and 0.13.[6][7][8][11] The Collaborative Asteroid Lightcurve Link adopts the results from IRAS, that is, an albedo of 0.1254 and a diameter of 28.87 kilometers, based on an absolute magnitude of 10.9.[9]


  1. ^ a b c d e "981 Martina (A917 SW)". Minor Planet Center. Retrieved 8 February 2020.
  2. ^ a b c Schmadel, Lutz D. (2007). "(981) Martina". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 85. doi:10.1007/978-3-540-29925-7_982. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f g h "JPL Small-Body Database Browser: 981 Martina (A917 SW)" (2019-08-17 last obs.). Jet Propulsion Laboratory. Retrieved 8 February 2020.
  4. ^ a b "Asteroid 981 Martina – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 8 February 2020.
  5. ^ a b c "Asteroid 981 Martina – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 8 February 2020.
  6. ^ a b c Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. 12: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 8 February 2020.
  7. ^ a b c Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
  8. ^ 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.
  9. ^ a b c d "LCDB Data for (981) Martina". Asteroid Lightcurve Database (LCDB). Retrieved 8 February 2020.
  10. ^ a b c Higgins, David J. (March 2005). "Lightcurve periods for 1701 Okavango, 689 Zita, 981 Martina and (14653) 1998 YV11" (PDF). Minor Planet Bulletin. 32 (1): 13–14. Bibcode:2005MPBu...32...13H. ISSN 1052-8091.
  11. ^ a b Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8.
  12. ^ 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 8 February 2020. (PDS data set)
  13. ^ a b Lazzaro, D.; Angeli, C. A.; Carvano, J. M.; Mothé-Diniz, T.; Duffard, R.; Florczak, M. (November 2004). "S3OS2: the visible spectroscopic survey of 820 asteroids" (PDF). Icarus. 172 (1): 179–220. Bibcode:2004Icar..172..179L. doi:10.1016/j.icarus.2004.06.006. Retrieved 8 February 2020.
  14. ^ a b Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
  15. ^ Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal. 150 (3): 35. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75.

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