Experimental Astrometry of Himalia using Gaia DR1

Himalia is the largest member of Jovian irregular satellites. In order to obtain its high-precision observed positions, all the astrometric effects in data reduction should be taken into account, especially for the star catalogue used. In this paper, the newly published star catalogue Gaia Data Release 1 (Gaia DR1) was used to math reference stars in all CCD frames. In order to make comparisons, the catalogue UCAC4 was also used in data reduction. A total of 185 CCD observations of Himalia were processed. Our results showed that the positional precision of Himalia is estimated at about 0.02″ in both right ascension and declination, after catalogue Gaia DR1 was used. This precision is significantly improved than the results by using catalogue UCAC4.