NGC 6569 / C1810-318 (Updated August 2015) RA: 18:13:38.88 DEC: -31:49:35.2 (J2000) ============================================================ Bytes Format Explanation 1-8 A8 Star ID 10-32 A11,1x,A11 Position 34-35 A2 Units for position R0 denotes RA, DEC in the J2000 coordinates R5 denotes RA, DEC in the 1950 coordinates XA denotes X, Y in arcseconds XP denotes X, Y in pixels 37-44 F8.4 Period (days) 46-51 F6.3 Mean magnitude (or maximum magnitude if "max" is indicated in the remarks column) 53-57 F5.3 Light amplitude (range of variability) 59 A1 Colour for mean magnitude and amplitude e.g. B, V, R, I, J, K or P (for photographic). 61-65 A5 Type of variable (draft 2006 GCVS classifications) CST denotes non variable stars previously designated as variables 67-80 A19 Notes and Remarks (f denotes field star) "--" or "----" indicates no data available ========================================================================= ID Position Period ampl C Type Notes/ RA/X Dec/Y Units Remarks ========================================================================= 1 18:13:30.72 -31:49:11.0 R0 ---- 17.95 0.5 B RR 2 18:13:31.03 -31:49:40.1 R0 ---- 17.95 1.1 B RR 3 18:13:41.84 -31:49:23.0 R0 ---- -- -- B L 4 18:13:47.16 -31:46:10.1 R0 ---- 17.3 1.0 B RR f?;Note 5 18:13:36.62 -31:49:38.7 R0 ---- -- -- B RR? 6 18:12:59.48 -31:46:47.2 R0 ---- 17.15 1.30 B RR f?;Note 7 18:13:40.57 -31:49:47.4 R0 ---- 17.4 0.80 B RR 8 18:13:41.04 -31:49:22.3 R0 ---- 17.6 0.40 B RR 9 18:13:24.27 -31:52:09.4 R0 ---- 17.3 0.8 B E max 10 18:13:24.38 -31:53:26.8 R0 ---- 16.7 0.5 B E max 11 18:13:28.37 -31:50:32.1 R0 ---- 17.7 0.6 B RR? 12 18:13:27.37 -31:49:56.1 R0 ---- 17.45 0.7 B RR? f? 13 18:13:40.68 -31:57:33.3 R0 ---- 17.55 2.1 B CW? 14 18:13:44.70 -31:48:37.1 R0 ---- 17.95 0.50 B RR 15 18:13:29.17 -31:39:48.4 R0 ---- 16.90 3.4 B L Note 16 18:13:37.65 -31:49:13.3 R0 ---- 16.55 1.5 B CW? 17 18:13:39.17 -31:50:46.0 R0 ---- 18.05 1.1 B RR 18 18:13:37.9 -31:49:39 R0 ---- 17.95 0.5 B RR 19 18:13:39.11 -31:41:39.5 R0 ---- 17.25 0.7 B RR f? 20 18:13:45.98 -31:51:13.7 R0 ---- 17.85 0.7 B RR 21 18:13:39.7 -31:49:44 R0 ---- 17.4 1.6 B LPV 22 18:13:36.36 -31:49:31.8 R0 ---- 17.85 0.5 B RR 23 18:13:35.86 -31:50:24.0 R0 ---- 17.9 0.8 B RR ====================================================================== Supplementary Notes The RA and dec in the above table are from Samus et al. (2009). The remaining data are from Hazen-Liller (1985). NGC 6569 is a massive metal-rich cluster located in the Galactic bulge. A CM diagram based on BVI data by Ortolani et al. (2001) showed that the HB is predominantly red, but some bluer stars may be present. They plotted the positions of the variable stars on the CM diagram and found that the magnitudes and colours of most of them were consistent with cluster membership. A subsequent study by Mauro et al. (2012), based on JK photometry showed that that the cluster's HB is split into two distinct clumps separated by ~0.1 mag in the K_s band. A study of the RR Lyrae variables in NGC 6569 has been undertaken by Kunder et al. (2015) who published a preliminary report. They identified 27 RR Lyrae variables, of which 15 were new discoveries. ==================================================================== Notes on individual stars V4, V6, V15: According to Samus et al. (2009), these stars are V2711 Sgr, NSV 10364 and V2698 Sgr respectively. =================================================================== Discovery of the variable stars in NGC 6569: V1-5: Rosino (1962) with x,y coordinates and ID charts Rosino discovered 3 additional variables V6-8 which were considered to be field stars. V6 = Rosino's V7 The number V6 was assigned by Hazen-Liller (1985) who noted that this star was within the tidal radius. V7-23: Hazen-Liller (1985) with x,y coordinates and an ID chart. Hazen-Liller also discovered 20 new field variables (F3-F22) and published their 1950 RA and dec, along with an ID chart. She listed Rosino's V6 and V8 as F1 and F2. ===================================================================== References Hazen-Liller, M. L. 1985, AJ, 90, 1807 Kunder, A., Stetson, P. B., Catelan, M., Walker, A., Cassisi, S., Johnson, C., Soto, M. 2015, in Fifty Years of Wide Field Studies in the Southern Hemisphere, ed. S. Points and A. Kunder, ASP Conf., 491, 104 Mauro, F., Moni Bidin, C., Cohen, R., Geisler, D., Minniti, D., Catelan, M., Chene, A.-N., Villanova, S. 2012, ApJ, 761, L29 Ortolani, S., Bica, E., Barbuy, B. 2001, A&A, 374, 564 Rosino, L. 1962, Mem. SAI, 33, 351 = Asiago Contr. 132 Samus, N. N., Kazarovets, E. V., Pastukhova, E. N., Tsvetkova, T. M., Durlevich, O. V. 2009, PASP, 121, 1378 =================================================================