Experimental CCD Positional Observations of the Five Major Uranian Satellites

Two hundred and forty-eight CCD frames, observed by using 1 m telescope at Yunnan Observatories for four consecutive nights, have been reduced to derive the precise positions of the five Uranian major satellites (Ariel, Umbriel, Titania, Oberon, and Miranda). The positions of satellites are measured with respect to the stars in Gaia DR1 (Data Release 1), a newly published star catalogue. Then we make a comparison between the observed and theoretical positions of the satellites. The theoretical positions of the satellites are retrieved from JPL (Jet Propulsion Laboratory) ephemeris (while the position of Uranus is obtained from DE431). Our results show that the mean values of (O-C) (observed values minus calculational values) do not exceed 0.027'' in both right ascension and declination for the five satellites (Ariel: 0.027'' and -0.007''; Umbriel: 0.024'' and -0.003''; Titania: 0.021'' and 0.020''; Oberon: 0.024'' and -0.001''; Miranda: 0.021'' and 0.001''). The dispersion in each direction is better than 0.015'' for the first four Uranian satellites, and 0.030'' for Miranda.