TITLE: GCN CIRCULAR NUMBER: 7504 SUBJECT: GRB 080319B: Optical observation (Brno, CZ) DATE: 08/03/21 21:58:31 GMT FROM: Rudolf Novak at N.Copernicus Obs/Czech Rep We observed GRB 080319B using 40cm Newtonian telescope, SBIG ST-7XMEi CCD camera and R-band Kron-Cousins filter. We found afterglow to be R=20.0+-0.3 mag at 2008.03.20 0.125 UT. Given time is mid-exposure (total exposure: 6.7h). Weather conditions were poor because of clouds and Moon. We used 13 nearby USNO-B1.0 stars to get R magnitude. An aperture photometry package Munipack (http://adsabs.harvard.edu/abs/1998stel.conf...30H) was used for data reduction. Rudolf Novak Nicholas Copernicus Observatory & Planetarium in Brno, Czech Republic (http://ccd.astronomy.cz) Filip Hroch Masaryk University, Brno (http://monteboo.blogspot.com)