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Description
This catalogue was prepared during the study of proper motions (Platais 1991A&AS...87...69P) in and around the open cluster NGC 752 (C0154+374) which belongs to the poorly-populated open cluster class. Relative proper motions of 1777 stars have been determined from the PDS measurements of 11 Pulkovo normal astrograph plates (scale is 59.57"/mm) in a 110'-diameter circle around the cluster. The catalogue of proper motions is complete down to mpg=15.0m, the limiting value is 15.4m. The average standard error of the catalogue proper motions varies from 0.75mas/yr (milliarcseconds per year) for stars with mpg<14.0m to 1.1mas/yr for the rest. These errors refer to the highest weight group (the star is present on all or nearly all plate pairs). In order to calculate the standard error of a star belonging to the lower weight group, it is necessary to use a unit weight error of 3.7 mas/yr and the appropriate weights from Table I for the plate pairs used in the determination of the star's proper motion, as given in the Catalogue. For stars located far from the field centre as well for fainter stars, an additional factor proportional to the accuracy degradation should be applied. Table I. Assigned weights. ------------------------------------------------------------------- | Pair No.| 1 | 2 | 3 | 4 | 5 | 6 | 7 | |---------|-------|-------|-------|-------|-------|-------|-------| | Weight | 7.0 | 7.0 | 2.5 | 2.3 | 2.8 | 3.0 | 1.0 | ------------------------------------------------------------------- Example: For the star No. 40 the weighted standard error of the proper motion is as follows: 3.7/sqrt(2.3+2.8)*1.5=2.5 mas/yr. The degradation factor of 1.5 comes from the decreased accuracy for the faint stars located at the edge of the field investigated. More detailed information on measured plates, standard errors, assigned weights, membership probabilities etc. is given in Platais (1991A&AS...87...69P). The membership probabilities were calculated assuming that on the vector-point diagram the distribution of field stars is essentially flat within a limited area around the centroid of the cluster member proper motion distribution. A clear separation of field and cluster stars is achieved.
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