Applying weighted image coaddition to observations of GRB optical afterglows at the D50 telescope in Ondřejov

One of the primary observational objectives of the 0.5 m robotic telescope of Ondřejov observatory is the ground-based follow-up of gamma-ray burst triggers. This independent robotic observatory has been in operation since 2008 and has followed up more than a hundred events localized by the Swift or INTEGRAL satellites. We describe the use of the weighted coaddition of astronomical images while applying this method to observations of GRB optical afterglows. We present optical photometric observations of the detected optical afterglows. The collection contains several faint optical afterglows, in some cases a lightcurve is available, in some cases only a single point detection has been achieved. A brief collection of available information is presented for each of the events together with our fitting and analysis. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim