COLOR-INDEX DETERMINATION OF LEO SATELLITES USING COLOR IP-CAMERAS

Abstract

The study is devoted to determining the color characteristics of the structural surfaces of artificial satellites. Observations of satellites were carried out in automatic mode using software for detection fast moving object, developed at RI “MAO”. The satellite observations equipment consists of Canon EF 85mm f/1.8 USM photographic lens and professional VIVOTEK IP816A-HP network camera. The camera is directed to the zenith and has a field of view (4.9°х2.8°). The camera has progressive CMOS sensor with Bayer color filter⁰₀ array for producing RGB color image. Coordinate and photometric processing of saved images is carried out using SExtractor and Astrometry.net software along with additional Python scripts. In this paper, we present first results of our LEO satellites observations using network IP-cameras with RGB Bayer filter. To convert the instrumental magnitudes from RGB Bayer system into standard bp/rp magnitudes of the Gaia EDR3 photometric system, a system of equations was solved, where the calculated magnitudes in the bp/rp photometric system were represented as functions of magnitudes and colors in the instrumental RGB system. The mean differences between the calculated magnitudes and the catalog magnitudes are (0.03±0.15)mag and (0.01±0.16)mag for bp and rp band, respectively. The calculated Brjb_bp and Rrjb_rp magnitudes using obtained transformation coefficients show a good linear correlation with the bp and rp Gaia EDR3 magnitudes. Only main sequence’s stars in the range of (5-13)mag were used as reference stars for determining the transformation coefficients. The results of determining the color indexes (Brjb_bp - Rrjb_rp) for 8 LEO satellites with the obtained transformation coefficients were received. The average accuracy of the obtained values of color indexes is about 0.2mag.