21795 Masi
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| Discovery[1] | |
|---|---|
| Discovered by | F. Mallia |
| Discovery site | Campo Catino Obs. |
| Discovery date | 29 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 | |
| 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]
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]
