J/AJ/111/1205 J/AJ/111/1205 Proper-Motion Membership of Open Cluster NGC 188 D I Dinescu T M Girard W F van Altena T Yang Y -W Lee Astron. Journ. 111 1205 1996 1996AJ....111.1205D Clusters, open Proper motions Relative proper motions have been determined for 1127 stars in the field of the open cluster NGC 188 from plates spanning a 60-year interval, taken with the 76-cm Thaw refractor of the Allegheny Observatory. Special attention has been paid to the corrections for systematic errors as a function of magnitude and color. The study is complete to a magnitude B = 16.2. Also some stars brighter than B = 12.5 were eliminated from the study because of the large uncertainty in estimating the magnitude equation at the bright end. The final relative proper motions have an accuracy of 0.5 mas/yr for well-exposed stars. From the cluster membership probabilities based on proper motions we obtain 360 cluster members, enabling us to better define the color-magnitude diagram. We provide a list of highly probable candidate blue stragglers in addition to the sample proposed by Eggen & Sandage (1969).

ID identification number (AJ 111, 1205) --- IDUP identification number (Upgren at al. AJ 77, 74) --- IDS identification number (Sandage ApJ 135, 333) --- V V magnitudes (calibrated photographic magnitudes) mag B-V B-V colors mag X X coordinate mm Y Y coordinate mm RAh Right Ascension J2000 (h); mean epoch 1983.91 h RAm Right Ascension J2000 (minutes) min RAs Right Ascension J2000 (seconds) s DE- Declination sign --- DEd Declination J2000 (degrees) deg DEm Declination J2000 (arcminutes) arcmin DEs Declination J2000 (arcseconds) arcsec pmX Proper Motion in X (milliarcseconds/yr) mas/yr pmY Proper Motion in Y mas/yr e_pmX Proper-motion error in X mas/yr e_pmY Proper-motion error in Y mas/yr Pc Proper-motion membership probability % Pcx Proper-motion and spatial (combined) membership probability % N Number of plates on which the object was measured --- Notes Explained at the end of the table 1 - photoelectric standards used in the photometric calibration (Sandage 77, 74) 2 - photometry from McClure and Twarog ApJ 214, 111 3 - photometry replaced from Caputo et al. AJ 99, 261 4 - stars with no magnitudes estimates from Lick plates which were used for the photometry 5 - stars with only V magnitudes from the Lick plates BS - blue stragglers (Eggen and Sandage ApJ 158, 669) ER Cep, ES Cep, V5, V8, V9 - short-period variables (Kaluzny and Shara ApJ 314, 585) --- Paul Kuin NASA/ADC 1997May19 J_AJ_111_1205.xml