2685 Masursky, provisional designation 1981 JN, is a stony Eunomian asteroid from the central regions of the asteroid belt, approximately 11 kilometers (6.8 miles) in diameter. It was discovered on 3 May 1981, by American astronomer Edward Bowell at the Anderson Mesa Station near Flagstaff, Arizona, and named after American planetary geologist Harold Masursky.[1] In January 2000, the Cassini space probe observed the S-type asteroid from afar during its coast to Saturn.[7]
Masursky is a member of the Eunomia family (502),[3] a prominent family of stony asteroids and the largest one in the intermediate main belt with more than 5,000 members.[8]
It orbits the Sun in the central main-belt at a distance of 2.3–2.9 AU once every 4 years and 1 month (1,505 days; semi-major axis of 2.57 AU). Its orbit has an eccentricity of 0.11 and an inclination of 12° with respect to the ecliptic.[2] The asteroid was first observed as 1950 VOatMcDonald Observatory in November 1950. The body's observation arc begins with its observation as 1973 QFatCerro El Roble Observatory in August 1973, nearly 8 years prior to its official discovery observation at Anderson Mesa.[1]
Little was known about Masursky until the Cassini–Huygens space probe, en route to Jupiter and Saturn, flew past it on 23 January 2000. Because Cassini passed the asteroid at a distance of 1.6 million kilometers (approximately 4 lunar distances), the images it returned showed nothing more than a dot.[7]
Cassini's observations had cast some doubt on its composition,[7] but later ground-based spectroscopy has confirmed its stony S-type spectrum,[6] which is also the Eunomia family's overall spectral type.[8]: 23
During its flyby in January 2000, Cassini–Huygens estimated a mean diameter of approximately 15–20 kilometers, based on an angular diameter of 0.81–1.08 arcseconds just hours before its closest approach.[7] According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Masursky measures 10.744 kilometers in diameter and its surface has an albedo of 0.114.[4][5]
^ abMasiero, 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.
^ abMasiero, 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.
^ abLazzaro, Daniela; Mothé-Diniz, Thaís.; Carvano, Jorge M.; Angeli, Cláudia A.; Betzler, Alberto S.; Florczak, Marcos; et al. (December 1999). "The Eunomia Family: A Visible Spectroscopic Survey". Icarus. 142 (2): 445–453. Bibcode:1999Icar..142..445L. doi:10.1006/icar.1999.6213.
