A CCD Search for Variable Stars of Spectral Type B in the Northern Hemisphere Open Clusters. IV. NGC 663

We present results of the variability search in the field of the young open cluster NGC 663. In addition to the one β Cep-type variable known in this cluster, we found another one. It is a mono-periodic pulsator changing brightness with a period of 0.27640 d. In total, 19 new variables were discovered and the variability of 5 other ones was confirmed. Out of all 24 variables in the observed field, 21 are probable cluster members. One SPB candidate and three eclipsing or ellipsoidal variables could be classified. Moreover, ten out of fourteen Be stars we observed vary in brightness. Only one of them shows periodic variations of the λ Eri-type, while the remaining ones exhibit irregular changes with the range up to 0.4 mag in the IC band. We also provide new VIC photometry of 477 stars in the field of the cluster and check the consistence of the present photometry with cluster parameters derived earlier. The average cluster E(V-IC) color excess amounts to about 0.92 mag.