Satellites of 2003 AZ_84, (50000), (55637), and (90482)

M. E. Brown and T.-A. Suer, California Institute of Technology, report the discoveries of four satellites of large transneptunian objects from observations with the Hubble Space Telescope High Resolution Camera (+ F606W filter). Observations of (55637) 2002 UX_25 on 2005 Aug. 26.64 UT detected a satellite that was 2.5 +/- 0.2 mag fainter than the primary at a separation of 0".164 +/- 0".003 in p.a. 153 +/- 2 degrees. Observations of (90482) Orcus on 2005 Nov. 13.13 detected a satellite that was 2.7 +/- 1 magnitude fainter than the primary at a separation of 0".25 +/- 0".01 in p.a. 128 +/- 1 deg. Observations of 2003 AZ_84 on 2005 Dec. 2.99 detected a satellite that was 5.0 +/- 0.3 mag fainter than the primary at a separation of 0".22 +/- 0".01 in p.a. 321 +/- 2 deg. Observations of (50000) Quaoar on 2006 Feb. 14.90 detected a satellite that was 5.6 +/- 0.2 mag fainter than the primary at a separation of 0".35 +/- 0".01 in p.a. 110 +/- 1 deg.