Lacerta OB1 Revisited

This investigation utilizes precise uvby beta photometry and the recently recalculated Hipparcos data to provide an improved homogeneous distance scale for the apparent groups of young stars in Lacerta. All existing uvby beta photometry for stars earlier than A0-type in a 20 degrees x 20 degrees field centered at l = 100 degrees, b = -15 degrees is collated and the individual stellar distances and color excesses are obtained. The association Lac OB1 is reliably identified as a very compact young group of 12 bright stars at an average distance of 520 +/- 20(s.e.) pc. The available radial velocity and proper motion measurements strongly support the impression that the group is real. The stars in the northeast part of Lacerta seem not to represent a physical group, but rather a layer of field stars spread between 140 and 400 pc and extending farther than that toward l similar to 104 degrees. An estimate of 678 +/- 50(s.e.) pc of the distance to the open cluster NGC 7243 is obtained based on the brightest cluster members. The calculated distances are based on a well-tested procedure, and thus represent a clarification over the range of distance existing in the literature for the bright stars in the Lacerta field. Although a better agreement is now evident between the photometric distances and the recalculated Hipparcos parallaxes in comparison to the original Hipparcos data, discrepancies still exist for this particular field.