21795 Masi

21795 Masi
Discovery [1]
Discovered by F. Mallia
Discovery site Campo Catino Obs.
Discovery date 29 September 1999
Designations
MPC designation (21795) Masi
Named after
 Gianluca Masi [1]
(Italian astronomer)
1999 SN9 · 1988 UE
1993 BZ1
main-belt [1][2] · (inner)
Nysa [3]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc 64.45 yr (23,541 d)
Aphelion 2.8409 AU
Perihelion 1.9222 AU
2.3815 AU
Eccentricity 0.1929
3.68 yr (1,342 d)
337.35°
0° 16m 5.52s / day
Inclination 1.8376°
337.09°
81.681°
Physical characteristics
Mean diameter
 2.45 km (calculated)[4]
3.150±0.164 km[5][6]
13.862±0.0121 h[7]
0.20 (assumed)[4]
0.235±0.037[5][6]
S (assumed)[4]
14.7[6]
14.9[2]
14.970±0.004 (R)[7]
15.41±0.14[8]
15.42[4]

    21795 Masi, provisional designation 1999 SN9, is a Nysian asteroid from the inner regions of the asteroid belt, approximately 3 kilometers (2 miles) in diameter. It was discovered on 29 September 1999, by Italian amateur astronomer Franco Mallia at the Campo Catino Astronomical Observatory in Lazio, Italy.[1] The likely S-type asteroid has a rotation period of 13.86 hours.[4] It was named for Italian astronomer Gianluca Masi.[1]

    Orbit and classification

    Masi is member of the Nysa family (405),[3] located in the Nysa–Polana complex and one of the largest asteroid families of the asteroid belt, named after 44 Nysa.[9] It orbits the Sun in the inner main-belt at a distance of 1.9–2.8 AU once every 3 years and 8 months (1,342 days; semi-major axis of 2.38 AU). Its orbit has an eccentricity of 0.19 and an inclination of 2° with respect to the ecliptic.[2] The body's observation arc begins with a precovery published by the Digitized Sky Survey and taken at the Palomar Observatory in April 1954, more than 45 years prior to its official discovery observation at Campo Catino.[1]

    Physical characteristics

    Masi is an assumed, stony S-type asteroid,[4] which is also the overall spectral type for members of the Nysa family of asteroids.[9]:23

    Rotation period

    In September 2010, a rotational lightcurve of Masi was obtained from photometric observations in the R-band by astronomers at the Palomar Transient Factory in California. Lightcurve analysis gave a rotation period of 13.862 hours with a relatively high brightness amplitude of 0.68 magnitude (U=2).[7]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Masi measures 3.150 kilometers in diameter and its surface has an albedo of 0.235,[5][6] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20, and calculates a diameter of 2.45 kilometers based on an absolute magnitude of 15.42.[4]

    Naming

    This minor planet was named after Italian astrophysicist and astronomer, Gianluca Masi (born 1972), a researcher and discoverer of minor planets and variable stars, who became an avid amateur astronomer when he was 8 years old.[1] The official naming citation was published by the Minor Planet Center on 9 May 2001 (M.P.C. 42679).[10]

    References

    1. 1 2 3 4 5 6 7 "21795 Masi (1999 SN9)". Minor Planet Center. Retrieved 29 May 2018.
    2. 1 2 3 4 "JPL Small-Body Database Browser: 21795 Masi (1999 SN9)" (2017-09-27 last obs.). Jet Propulsion Laboratory. Retrieved 29 May 2018.
    3. 1 2 "Asteroid 21795 Masi". Small Bodies Data Ferret. Retrieved 29 May 2018.
    4. 1 2 3 4 5 6 7 "LCDB Data for (21795) Masi". Asteroid Lightcurve Database (LCDB). Retrieved 29 May 2018.
    5. 1 2 3 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 29 May 2018.
    6. 1 2 3 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" (PDF). The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 29 May 2018. (catalog)
    7. 1 2 3 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" (PDF). The Astronomical Journal. 150 (3): 35. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75. Retrieved 29 May 2018.
    8. ↑ 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" (PDF). Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 29 May 2018.
    9. 1 2 Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families" (PDF). Asteroids IV: 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. Retrieved 29 May 2018.
    10. ↑ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 29 May 2018.

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