Ersa (moon)

Ersa
Precovery image of Ersa taken by the Canada-France-Hawaii Telescope in February 2003
Discovery[1][2]
Discovered byScott S. Sheppard
Discovery siteCerro Tololo Obs.
Discovery date11 May 2018
Designations
Designation
Jupiter LXXI
Pronunciation/ˈɜːrsə/
Named after
Ἔρσα Ersa
S/2018 J 1
Orbital characteristics
Epoch 1 January 2000 (JD 2451545.0)
Observation arc21.08 yr (7,701 d)
Earliest precovery date6 August 2000[3]
Satellite ofJupiter
GroupHimalia group
Proper orbital elements[4]
11,401,000 km (0.07621 AU) AU
0.116
29.1° (to ecliptic)
527.587231 deg / yr
0.68235 yr
(249.229 d)
Precession of perihelion
8994.503 arcsec / yr
Precession of the ascending node
4232.058 arcsec / yr
Physical characteristics
≈3 km[5]
Albedo0.04 (assumed)[5]
22.9[5]
15.9[1]

Ersa /ˈɜːrsə/, also designated Jupiter LXXI, is a small outer natural satellite of Jupiter discovered by Scott S. Sheppard on 11 May 2018, using the 4.0-meter Víctor M. Blanco Telescope at Cerro Tololo Observatory, Chile. It was announced alongside nine other Jovian moons on 17 July 2018 and was provisionally designated S/2018 J 1 by the Minor Planet Center, after observations were collected over a long enough time span to confirm the satellite's orbit.[1] The satellite has been found in precovery observations as early as 6 August 2000.[3]

Ersa is part of the Himalia group, a tight cluster of prograde irregular moons of Jupiter that follow similar orbits to Himalia at semi-major axes between 11–12 million km (6.8–7.5 million mi) and inclinations between 26–31°.[5] With an estimated diameter of 3 km (1.9 mi) for an absolute magnitude of 15.9, it is one of the smallest known members of the Himalia group.[5]

  1. ^ a b c Cite error: The named reference MPEC-2018-O18 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference jplsats-disc was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference MPC141872 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference jplsats-elem was invoked but never defined (see the help page).
  5. ^ a b c d e Cite error: The named reference SheppardMoons was invoked but never defined (see the help page).