| 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 | 64.45yr (23,541 d) |
| Aphelion | 2.8409AU |
| 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 designation1999 SN9) is aNysian asteroid from the inner regions of theasteroid belt, approximately 3 kilometers (2 miles) in diameter. It was discovered on 29 September 1999, by Italian amateur astronomerFranco Mallia at theCampo Catino Astronomical Observatory in Lazio, Italy.[1] The likelyS-type asteroid has arotation period of 13.86 hours.[4] It was named for Italian astronomerGianluca Masi.[1]
Masi is member of theNysa family (405),[3] located in the Nysa–Polana complex and one of the largestasteroid families of the asteroid belt, named after44 Nysa.[9] It orbits the Sun in theinner 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 aneccentricity of 0.19 and aninclination of 2° with respect to theecliptic.[2] The body'sobservation arc begins with aprecovery published by theDigitized Sky Survey and taken at thePalomar Observatory in April 1954, more than 45 years prior to its official discovery observation at Campo Catino.[1]
Masi is an assumed, stonyS-type asteroid,[4] which is also the overallspectral type for members of the Nysa family of asteroids.[9]: 23
In September 2010, a rotationallightcurve of Masi was obtained fromphotometric observations in the R-band by astronomers at thePalomar Transient Factory in California. Lightcurve analysis gave arotation period of 13.862 hours with a relatively high brightness amplitude of 0.68magnitude (U=2).[7]
According to the survey carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer, Masi measures 3.150 kilometers in diameter and its surface has analbedo of 0.235,[5][6] while theCollaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20, and calculates a diameter of 2.45 kilometers based on anabsolute magnitude of 15.42.[4]
Thisminor planet was named after Italianastrophysicist and astronomer,Gianluca Masi (born 1972), a researcher anddiscoverer of minor planets andvariable stars, who became an avidamateur astronomer when he was 8 years old.[1] The official naming citation was published by theMinor Planet Center on 9 May 2001 (M.P.C. 42679).[10]
