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Because PG 2303+243 had not been observed since 1992, we have arranged the mini-campaign of six observatories on PG 2303+243 in 2004 Sep. 5-21 for the more detailed frequency analysis of variations. The amplitudes of the most frequencies change even during the one night and some frequencies can disappear or appear in one year. Probably it is resonance effect. We have estimated 69 frequencies of pulsations and their amplitudes according the observations from 2004 and 36 frequencies and its amplitudes from 2005. [ABSTRACT FROM PUBLISHER]

High-resolution spectra for all bright (mag) and cooler than F5 spectral class dwarf stars were observed in two fields with radii of 20 degrees (centered at (2000) = 161.03º and (2000) = 86.60º and at (2000) = 265.08º and (2000) = 39.58º) towards the northern ecliptic pole. They coincide with two of the preliminary ESA PLATO fields which also will be targeted by the NASA TESS mission. We use high-resolution spectra obtained with the VUES spectrograph mounted on the 1.65 m telescope at the Moletai Astronomical Observatory of the Institute of Theoretical Physics and Astronomy, Vilnius University. In total we observed 405 stars. Spectroscopic atmospheric parameters and abundances of 23 neutral and ionised atomic species were determined for 261 slowly rotating stars (up to 15 kms-1). 73% of stars were analysed spectroscopically for the first time. We also derived stellar ages and orbital parameters to draw a chemical picture of the Solar vicinity. [ABSTRACT FROM AUTHOR]

The new photometric observations of PG 2303+243 were obtained in 2012 during a campaign carried out with three telescopes. The analysis of these observations is presented in this paper. We identified l = 1 and l = 2 pulsation modes. The pulsation periods were compared with theoretical ones for models of ZZ Ceti stars. This allowed us to estimate the physical parameters of PG 2303+243. The star seems to be cooler and has thicker hydrogen layer than it was thought before. We have derived M*/M⊙ = 0.66, Teff = 11014 K and log(MH/M*)=−4.246 for this star. [ABSTRACT FROM PUBLISHER]