Plaskett 1.8 metre Observations of Starlink Satellites

Abstract: We present observations of 23 Starlink satellites in the $g'$ bandpass, obtained from the Dominion Astrophysical Observatory's Plaskett 1.8 metre telescope. The targets include a mixture of satellites with and without brightness mitigation measures (i.e., visors). At the time of the observations (16 July 2021), Starlink satellites were sunlight throughout the night, and even with strict elevation and azimuth limits, there were over 800 candidate Starlink arcs. The satellites altogether have a median absolute brightness (550 km) of $\overline{H}_g^{550} =5.3$ mag. Dividing the targets into those without and with visors, their median absolute magnitudes are $\overline{H}_g^{550}(no~visor)=5.1$ and $\overline{H}^{550}_g(visor)=5.7$ mag, respectively. While the visor sample is dimmer in aggregate, the absolute brightness distribution ranged from $H_g^{550}=4.3$ mag to 9.4 mag, with the brightest being a visored satellite and the dimmest a satellite with no mitigation. The intrinsic brightness dispersion among the full sample is $\sigma_g = 0.5$ mag.