Astrometric and photometric studies of the 2009 WZ104 asteroid as it approached the earth

The astrometric and photometric observations of the potentially hazardous 2009 WZ104 asteroid were carried out at the MTM-500M and ZA-320M automatic telescopes of the Pulkovo Observatory in December 2009. A total of 686 observations were performed in the integral band and 146 observations with B, V, R, and I filters on an arc of the orbit of 17°; these accounted for about 77% of all worldwide observations (). On the basis of the obtained data, the orbit was improved and an estimation of the physical parameters of the asteroid was made. Estimates of the absolute stellar magnitude of the asteroid, H = (20.52 ± 0.04) ^m , as well as its size and mass, were obtained. The taxonomic class of the 2009 WZ104 asteroid (R or Q) was determined. A frequency analysis of the series of observations was carried out; periodicities in the asteroid’s light variation were revealed using this method.