Electronic Telegram No. 602 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) CBAT@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html PLUTO II (NIX) AND PLUTO III (HYDRA) C. I. Fuentes and M. J. Holman, Harvard-Smithsonian Center for Astrophysics, report on their observations made on June 27 and 28 UT of the recently discovered satellites of Pluto (cf. IAUC 8625, 8676, 8686, 8723) using the Inamori Areal Camera and Spectrograph instrument mounted, with an I filter, on the Magellan I Baade telescope. Positional offsets from Pluto were as follows: June 27.235 UT, Pluto II (Nix), Delta(R.A.) = +1".65, Delta(Decl.) = -1".04; Pluto III (Hydra), Delta(R.A.) = +1".58, Delta(Decl.) = -2".61. June 28.140, Pluto II, Delta(R.A.) = +1".45, Delta(Decl.) = -1".45; Pluto III, Delta(R.A.) = +1".24, Delta(Decl.) = -2".72. These positions agree with predictions based on previous observations, to the accuracy of the observations (0".1 on both nights). The average seeing during the observations was 0".5 on the first night and 0".6 on the second. The total integration times on June 27 and 28 were 13 and 26 min, respectively. The two objects have comparable brightness, with Pluto III being 0.3 mag brighter than Pluto II on the first night and 0.2 mag brighter on the second. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2006 CBAT 2006 August 24 (CBET 602) Daniel W. E. Green