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P. R. Kesten (Santa Clara Univ.), J. K. Davies (JAC Hawaii), D. P. Cruikshank, T. L. Roush (NASA Ames)
We report photometric measurements of Uranian satellites Miranda, Ariel, Umbriel, and Titania (10.4 Aug. 1995), and Neptune's satellite Triton (21.2 Sept. 1995) with the infrared camera (IRCAM) and standard J (1.13-1.42 \mum), H (1.53-1.81 \mum), and K (2.00-2.41 \mum) filters at the 3.8-m UKIRT telescope on Mauna Kea. The individual image frames are 256 x 256 pixels with an image scale of 0.286 arcsec/pixel, resulting in a 1.22 arcmin field of view. The standard star used for airmass correction and flux calibration was UKIRT FS 34 (EG141). The photometric information for the Uranian satellites was derived from 5-image mosaics created after dark frame and flat-field corrections; a circular aperture approximation based on DAOPHOT/aper-irtf (P. B. Stetson, PASP 99, 191, 1987) was used except in the case of Miranda, in which a linear fit to the strong background light gradient from the nearby image of Uranus was applied. The center of Uranus was 9.7 arcsec (measured on the images) from Miranda. Triton data were extracted from individual images (not mosaics) with an 8-arcsec aperture and a sky anulus 10-15 arcsec. The phase angle of the Uranian satellites was \alpha=1.0o, and that of Triton was \alpha=1.7o. The resulting magnitudes are as follows: Miranda J = 15.30 ±.05, H = 15.14 ±.05, K = 15.40 ±.06; Ariel J = 12.96 ±.04, H = 12.86 ±.04, K = 13.04 ±.04; Umbriel J = 13.60 ±.04, H = 13.37 ±.04, K = 13.44 ±.04; Titania J = 12.58 ±.04, H = 12.44 ±.04, K = 12.60 ±.04; Triton J = 12.26 ±.04, H = 12.14 ±.04, K = 12.31 ±.04. Other reports of Uranian satellite photometry are: P. D. Nicholson and T. J. Jones (Icarus 42, 54, 1980), D. P. Cruikshank (Icarus 41, 246, 1980), and K. H. Baines et al. (Icarus 132, 266, 1998).