K-type star GSC3488-819 in Ursa Major constallation has an exoplanet named HAT-P-3b. Its diameter is 0.89 Rjup and it diminishes light of its host star about 0.015 magnitude and its distance is 456 ly. This exoplanet was discovered last spring and now it is observed first time at Taurus Hill Observatory Varkaus at 30th/31st of August. So after observing period of a little over one year we have measured successfully ten different exoplanet transit. We detected that transit time of this exoplanet was as in prediction. We used GSC 3466-1226 (C1) and GSC 3466-663 (C2) as check stars. The exposure time was 120 sec with photometric R-filter. Observing conditions were not ideal. The object was only 30 – 20 degrees above the horizon in the northwest sky. The end of the transit was not observed because the object moved behind tall trees. Temperature was 5 degrees and humidity over 80 %. There were many light clouds in the sky all the observing period and the full Moon was shining in the southeast sky. Observing team: Veli-Pekka Hentunen and Markku Nissinen.