MOST observations of the young open cluster NGC 2264

Context. Photometric time series obtained from space are one of the best ways to study pulsations in pre-main sequence (PMS) stars, especially as the corresponding amplitudes are at the millimagnitude level or below. We present high-precision time-series photometry of stars in the field of NGC2264 obtained with the MOST (Microvariability & Oscillations of STars) satellite. Aims. A search for pulsating A and F type members of NGC 2264 with ultra-precise MOST photometry was conducted. Methods. 68 stars in the field of NGC2264 were observed simultaneously with the MOST satellite, 34 of which were previously identified as potential targets to search for PMS pulsation. The routines SigSpec and Period04 were used for the frequency analysis. Results. We discovered pulsation in 4 potential A and F type PMS members of NGC2264 with frequencies between 2.7 h and 23 min. For one of the PMS pulsators identified with MOST after the first days of observation, simultaneous ground-based Stromgren photometry was obtained with the OSN 0.9 m telescope and confirms the highest frequency identified in the MOST photometry. 26 stars with other (i.e., hotter and cooler) spectral types show clear variability: SPB and gamma Doradus pulsation, red giant oscillations, eclipsing binaries and variability caused by rotational modulation.