New transit observations for HAT-P-30 b, HAT-P-37 b, TrES-5 b, WASP-28   b, WASP-36 b, and WASP-39 b
  We present new transit light curves for planets in six extrasolar planetary systems. They were acquired with 0.4-2.2 m telescopes located in west Asia, Europe, and South America. When combined with literature data, they allowed us to redetermine system parameters in a homogeneous way. Our results for individual systems are in agreement with values reported in previous studies. We refined transit ephemerides and reduced uncertainties of orbital periods by a factor between 2 and 7. No sign of any variations in transit times was detected for the planets studied. 
G. Maciejewski, D. Dimitrov, L. Mancini, J. Southworth, S. Ciceri, G.   D'Ago, I. Bruni, St. Raetz, G. Nowak, J. Ohlert, D. ...
astro-ph.EP