Some preliminary results from current observational programs with the new 23-cm zone astrograph

The quality of images obtained with a zone astrograph having a focal length of 2053 mm, a focal ratio of 1:9, and operating in the spectral range from 5200 to 5800 A is discussed. It is noted that when this instrument is combined with a 6-mag objective grating, the mean error in the position of a single FK4 star on one plate is 0.12 arcsec. From the reduction of about 80 plates taken in a proper-motion study of some 2000 stars down to 14th magnitude, it is found that the mean positional error is 0.13 arcsec. Results of a study undertaken to obtain new epoch positions and the absolute proper motions of open clusters are presented which show that the mean error in epoch position is 0.07 arcsec, while cluster proper motions can be obtained with an accuracy of better than 0.001 arcsec/a. The use of this astrograph in the AGK4 project is pointed out.