CCD STROMGREN PHOTOMETRY OF NGC-6231

We present uvby beta photometry obtained with a CCD for the young open cluster NGC 6231. The distance modulus (V-0-My=11.08) and reddening (E(b-y)=0.325) are determined. We use a recent calibration of effective temperature and bolometric correction to compare the cluster sequence with theoretical models and derive an age of 5 Myr. This cluster has six relatively unevolved beta Cep variables. We conducted a search for more short-period variables, but were unable to add to the number of known beta Cep stars. However, a foreground delta Sct star (S102) in the field of the cluster was discovered as well as several eclipsing binaries (S40, S105 and S224). We did not find any 53 Per variables (slowly pulsating B stars).