Global Information757 Portlandia information
| Discovery | |
|---|---|
| Discovered by | Joel Hastings Metcalf |
| Discovery site | Taunton, Massachusetts |
| Discovery date | 30 September 1908 |
| Designations | |
MPC designation | (757) Portlandia |
Alternative designations | 1908 EJ |
| Orbital characteristics[1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 99.16 yr (36218 d) |
| Aphelion | 2.6327 AU (393.85 Gm) |
| Perihelion | 2.1142 AU (316.28 Gm) |
Semi-major axis | 2.3734 AU (355.06 Gm) |
| Eccentricity | 0.10922 |
Orbital period (sidereal) | 3.66 yr (1335.6 d) |
Mean anomaly | 133.453° |
Mean motion | 0° 16m 10.38s / day |
| Inclination | 8.1694° |
Longitude of ascending node | 22.515° |
Argument of perihelion | 44.204° |
| Physical characteristics | |
Mean radius | 16.045±0.7 km |
Synodic rotation period | 6.5837 h (0.27432 d)[1] |
Geometric albedo | 0.1427±0.014[1] |
Spectral type | M |
Apparent magnitude | 12.3 to 15.7 |
Absolute magnitude (H) | 10.20[1] |
757 Portlandia is a main-belt asteroid 32 km in diameter.[1] It was discovered on 30 September 1908 from Taunton, Massachusetts by the amateur American astronomer Joel E. Metcalf. The asteroid was named for the city of Portland, Maine, where Hastings was a church minister at the time.[2] In November 2015, amateur astronomers captured it with images of comet 67P/Churyumov–Gerasimenko.[3] Portlandia came to opposition in March 2016 at apparent magnitude 13.2.[citation needed]
This body is orbiting at a distance of 2.37 AU with a period of 3.66 years and an eccentricity of 0.109. The orbital plane is inclined at an angle of 8.2° to the plane of the ecliptic.[1] 757 Portlandia is classified as an X-type asteroid and is a core member of the proposed Athor asteroid family, named after 161 Athor. This asteroid spans a girth of 32.89±0.24 km and is rotating with a period of 6.58 hours.[4] During 2003, the asteroid was observed occulting a star. The resulting chords were used to determine a diameter estimate of 36.7 km.[5]
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