21795 Masi

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21795 Masi
Discovery [1]
Discovered by F. Mallia
Discovery site Campo Catino Obs.
Discovery date29 September 1999
Designations
(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]

    Contents

    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]

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    References

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    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.
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