It's official, Pluto now has 5 moons.
Breaking News.....NEW SATELLITE OF PLUTO: P5 - new Moon
M. R. Showalter (SETI Institute), H. A. Weaver (Applied Physics Laboratory,
Johns Hopkins University), S. A. Stern, A. J. Steffl, M. W. Buie, W. J. Merline
(Southwest Research Institute), M. J. Mutchler, R. Soummer (Space Telescope
... Science Institute) and H. B. Throop (NASA Headquarters) report the discovery of
a fifth satellite of Pluto. The object, provisionally designated S/2012 (134340)
1 and referred to as "P5", was detected in 14 separate sets of images taken by
the Hubble Space Telescope WFC3/UVIS. Each image set comprises 11-12
three-minute exposures. Upon co-adding, S/N = 5-8 in five sets and S/N = 3-5 in
nine sets where the detection was somewhat degraded by P5's close proximity of
Pluto II (Nix). Times and positions are as follows:
June 26.51-26.67 UT, 3 sets, 1".99 from Pluto at p.a. 158 deg
June 27.78-27.94 UT, 3 sets, 1".71 from Pluto at p.a. 182 deg
June 29.64-29.80 UT, 3 sets, 1".44 from Pluto at p.a. 219 deg
July 7.42- 7.58 UT, 3 sets, 1".76 from Pluto at p.a. 352 deg
July 9.41- 9.51 UT, 2 sets, 1".42 from Pluto at p.a. 31 deg
The satellite's mean magnitude is V = 27.0 +/- 0.3, making it 4 percent as
bright as Pluto II (Nix) and half as bright as S/2011 (134340) 1. The diameter
depends on the assumed geometric albedo: 10 km if p_v = 0.35, or 25 km if p_v =
0.04. The motion is consistent with a body traveling on a near-circular orbit
coplanar with the other satellites. The inferred mean motion is 17.8 +/- 0.1
degrees per day (P = 20.2 +/- 0.1 days), and the projected radial distance from
Pluto is 42000 +/- 2000 km, placing P5 interior to Pluto II (Nix) and close to
the 1:3 mean motion resonance with Pluto I (Charon).