385571 Otrera

385571 Otrera, provisional designation 2004 UP10, is a Neptune trojan leading Neptune's orbit in the outer Solar System. It was discovered by American astronomers Scott Sheppard and Chad Trujillo at Las Campanas Observatory on 16 October 2004.[2] It measures approximately 100 kilometers in diameter and was the second such body to be discovered after 2001 QR322.[3]

385571 Otrera
Discovery [1][2]
Discovered byS. S. Sheppard
C. Trujillo
Discovery siteLas Campanas Obs.
Discovery date16 October 2004
(385571) Otrera
Named after
Otrera (Greek mythology)[2]
2004 UP10
Neptune trojan · L4[3]
centaur[1] · distant[2]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 4
Observation arc8.97 yr (3,277 days)
Aphelion30.727 AU
Perihelion29.327 AU
30.027 AU
164.54 yr (60,099 days)
0° 0m 21.6s / day
Physical characteristics
Dimensions74 km (est. at 0.10)[4]
100 km[5]

Orbit and classificationEdit

Neptune trojans are resonant trans-Neptunian objects in a 1:1 mean-motion orbital resonance with Neptune. These Trojans have a semi-major axis and an orbital period very similar to Neptune's (30.10 AU; 164.8 years).

Otrera belongs to the L4 group, which leads 60° ahead Neptune's orbit. It orbits the Sun with a semi-major axis of 30.027 AU at a distance of 29.3–30.7 AU once every 164 years and 6 months (60,099 days). Its orbit has an eccentricity of 0.02 and an inclination of 1° with respect to the ecliptic.[1]

Physical characteristicsEdit

The discoverers estimate that the body has a mean-diameter of 100 kilometers based on a magnitude of 23.3.[5] Based on a generic magnitude-to-diameter conversion, it measures approximately 74 kilometers in diameter using an absolute magnitude of 8.8 and an assumed albedo of 0.10.[4]


This minor planet was the first Neptune trojan to be named in November 2015. It was named after Otrera, the first Amazonian queen in Greek mythology.[2] The naming scheme is to name these objects after figures related to the Amazons, which was an all-female warrior tribe that fought in the Trojan War on the side of the Trojans against the Greeks.[6]


  1. ^ a b c d e "JPL Small-Body Database Browser: 385571 Otrera (2004 UP10)" (2013-10-06 last obs.). Jet Propulsion Laboratory. Retrieved 4 August 2017.
  2. ^ a b c d e "385571 Otrera (2004 UP10)". Minor Planet Center. Retrieved 4 August 2017.
  3. ^ a b "List Of Neptune Trojans". Minor Planet Center. 10 July 2017. Retrieved 4 August 2017.
  4. ^ a b "Asteroid Size Estimator". CNEOS/JPL. Retrieved 2 August 2017.
  5. ^ a b c Lakdawalla, Emily (13 August 2010). "2008 LC15, the first Trojan asteroid discovered in Neptune's L5 point". The Planetary Society. Retrieved 4 August 2017.
  6. ^ Ticha, J.; et al. (10 April 2018). "DIVISION F / Working Group for Small Body Nomenclature Working Group for Small Body Nomenclature. THE TRIENNIAL REPORT (2015 Sept 1 - 2018 Feb 15)" (PDF). IAU. Retrieved 25 August 2018.

External linksEdit