The observed uvby and H-beta indices of member stars of the Hyades and Praesepe clusters are analyzed in detail for rotation. The slopes of the rotation effects observed are utilized to determine the zero rotation main ...

The colour-magnitude diagram for NGC 1851 is presented to a limit of V = 21.0 mag, approximately 2 mag below the main-sequence turn-off point, on the basis of UBV photoelectric photometry and electronographic BV photometry. ...