Photometric studies of comet C/2009 P1 (Garradd) before the perihelion

Abstract

The results of the photometric observations of comet C/2009 P1 (Garradd) performed at the 60-cm Zeiss-600 telescope of the Terskol observatory have been analyzed. During the observations, the comet was at the heliocentric and geocentric distances of 1.7 and 2.0 AU, respectively. The CCD images of the comet were obtained in the standard narrowband interference filters suggested by the International research program for comet Hale-Bopp and correspondingly designated the 'Hale-Bopp (HB) set'. These filters were designed to isolate the BC ($\lambda$4450/67 {\AA}), GC ($\lambda$5260/56 {\AA}) and RC ($\lambda$7128/58 {\AA}) continua and the emission bands of C2 ($\lambda$5141/118 {\AA}), CN ($\lambda$3870/62 {\AA}), and C3 ($\lambda$4062/62 {\AA}). From the photometric data, the dust production rate of the comet and its color index and color excess were determined. The concentration of C2, CN, and C3 molecules and their production rates along the line of sight were estimated. The obtained results show that the physical parameters of the comet are close to the mean characteristics typicalof the dynamically new comets.