Remarks of Gaia DR1 magnitude using ground-based optical monitoring of QSOs

Since September 2016, the first release (DR1) of the Gaia catalogue was appeared. The optical Gaia positions of sources will be linked to the ICRF (VLBI radio positions of mostly quasars, QSOs). For high accurate link we need to investigate variations of optical flux of QSOs via their magnitude variations using data of ground-based telescopes. To do that, from 2013 we observed 47 QSOs and other sources; nine optical telescopes were used for that monitoring. To increase the total number of objects for the link, after a first set of 70 objects (Bourda et al. 2008), Bourda et al. (2011) established a second set of 47 objects. It is necessary to investigate the photometry and morphology of these objects. We collected ground-based data of QSOs (B, V and R mag) and compared with G mag of Gaia DR1; some results are presented here.