24101 Cassini

24101 Cassini, provisional designation 1999 VA9, is an eccentric background asteroid from the middle region of the asteroid belt, approximately 7 kilometers in diameter. It was discovered on 9 November 1999, by American amateur astronomer Charles Juels at the Fountain Hills Observatory (678) in Arizona, United States.[8] It was named after Italian–French astronomer Giovanni Cassini.

24101 Cassini
Discovery [1]
Discovered byC. W. Juels
Discovery siteFountain Hills Obs.
Discovery date9 November 1999
Designations
(24101) Cassini
Named after
Giovanni Cassini
(Italian astronomer)[2]
1999 VA9 · 1926 XH
1926 YB · 1986 RS16
1986 TM15
main-belt · (middle) [3]
background
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc90.18 yr (32,937 days)
Aphelion3.4620 AU
Perihelion1.8278 AU
2.6449 AU
Eccentricity0.3089
4.30 yr (1,571 days)
29.894°
0° 13m 44.76s / day
Inclination15.474°
176.58°
255.81°
Physical characteristics
Mean diameter
7.051±0.352 km[4][5]
11.05 km (calculated)[3]
3.986±0.001 h[6][lower-alpha 1]
0.10 (assumed)[3]
0.2458±0.0529[4]
0.246±0.053[5]
S/C [3]
12.9[1][3][4] · 13.05±0.23[7]

    Orbit and classification

    Cassini is a non-family from the main belt's background population. It orbits the Sun in the central asteroid belt at a distance of 1.8–3.5 AU once every 4 years and 4 months (1,571 days). Its orbit has an eccentricity of 0.31 and an inclination of 15° with respect to the ecliptic.[1]

    In December 1926, the asteroid was first identified as 1926 XH at Heidelberg Observatory in Germany. The body's observation arc begins 7 years prior to its official discovery observation, with a precovery taken at La Silla Observatory in March 1992.[8]

    Physical characteristics

    Lightcurve

    In February 2009, two rotational lightcurves of Cassini were obtained from photometric observations by Italian astronomer Silvano Casulli, and at the private Shed of Science Observatory (H39) in Minnesota, United States. Lightcurve analysis gave a well-defined, concurring rotation period of 3.986 hours with a brightness variation of 0.12 magnitude (U=3/-3).[6][lower-alpha 1]

    Diameter and albedo

    According to observations carried out by the NEOWISE mission of NASA's space-based Wide-field Infrared Survey Explorer, Cassini measures 7.051 kilometer in diameter and its surface has an albedo of 0.2458.[4]

    The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.10 – a compromise value between the brighter stony (0.20) and darker carbonaceous (0.057) asteroids of the 2.6 to 2.7 AU-region of the asteroid belt – and correspondingly, calculates a larger diameter of 11.05 kilometers, as the lower a body's albedo (reflectivity), the larger its diameter for a given absolute magnitude (brightness).[3]

    Naming

    This minor planet was named in honor of Italian-born French astronomer Giovanni Cassini (1625–1712), who was the first director of the Paris Observatory from 1671 until his death. He discovered the four moons of Saturn – Iapetus, Rhea, Tethys and Dione – the major gap in its rings, known as Cassini Division, and was the first to write down observations of the zodiacal light. The Cassini–Huygens spacecraft is named after him and Christiaan Huygens.[2]

    The lunar and Martian craters Cassini are also named in his honor. The approved naming citation was published by the Minor Planet Center on 21 September 2002 (M.P.C. 46684).[9]

    References
    1. Durkee (2011): rotation period 3.986±0.001 hours with a brightness amplitude of 0.12 mag. Summary figures for (24101) Cassini at Collaborative Asteroid Lightcurve Link (CALL) and at Shed of Science (S.O.S.) Observatory

    References
    1. "JPL Small-Body Database Browser: 24101 Cassini (1999 VA9)" (2017-02-09 last obs.). Jet Propulsion Laboratory. Retrieved 27 June 2017.
    2. Schmadel, Lutz D. (2007). "(24101) Cassini". Dictionary of Minor Planet Names – (24101) Cassini. Springer Berlin Heidelberg. p. 873. doi:10.1007/978-3-540-29925-7_9763. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (24101) Cassini". Asteroid Lightcurve Database (LCDB). Retrieved 17 May 2016.
    4. 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 17 May 2016.
    5. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2): 20. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68. Retrieved 2 December 2016.
    6. Behrend, Raoul. "Asteroids and comets rotation curves – (24101) Cassini". Geneva Observatory. Retrieved 17 May 2016.
    7. 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. Retrieved 17 May 2016.
    8. "24101 Cassini (1999 VA9)". Minor Planet Center. Retrieved 31 January 2016.
    9. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 17 May 2016.

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