NGC 6569 / C1810-318 (Updated October 2019) 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 -31:49:11.3 R0 0.2674 16.600 0.313 I RR1 2 18:13:31.05 -31:49:40.6 R0 0.5747 16.312 0.611 I RR0 3 18:13:41.84 -31:49:23.0 R0 ---- 8.856 -- K L Note 4 18:13:47.19 -31:46:10.4 R0 0.4525 15.696 0.556 I RR0 f;Note 5 18:13:36.62 -31:49:38.7 R0 ---- -- -- RR? Note 6 18:12:59.48 -31:46:47.3 R0 0.5555 15.446 0.740 I RR0 f;Note 7 18:13:40.55 -31:49:46.9 R0 0.5580 16.273 0.742 I RR0 8 18:13:41.03 -31:49:23.1 R0 0.3034 15.986 0.192 I RR1 9 18:13:24.27 -31:52:09.4 R0 ---- 17.3 0.8 B E? max;Note 10 18:13:24.38 -31:53:26.8 R0 ---- 16.7 0.5 B E? max;Note 11 18:13:28.32 -31:50:32.1 R0 0.3076 16.376 0.265 I RR1 12 18:13:27.38 -31:49:56.0 R0 0.2611 16.319 0.298 I RR1 13 18:13:40.68 -31:57:33.3 R0 ---- 17.55 2.1 B CW? f?;Note 14 18:13:44.73 -31:48:36.9 R0 0.2890 16.494 0.287 I RR1 15 18:13:29.17 -31:39:48.4 R0 212.2177 16.6 2.8 P M: f;Note 16 18:13:37.65 -31:49:13.3 R0 87.5 9.45 0.53 K CW Note 17 18:13:39.22 -31:50:46.4 R0 0.5361 16.369 0.797 I RR0 18 18:13:37.87 -31:49:40.3 R0 0.5011 16.318 0.595 I RR0 19 18:13:39.11 -31:41:39.5 R0 0.2697 15.798 0.292 I RR1 f?;Note 20 18:13:45.97 -31:51:13.4 R0 0.5421 16.332 0.709 I RR0 21 18:13:39.7 -31:49:44 R0 ---- -- -- L Note 22 18:13:36.36 -31:49:31.8 R0 ---- 17.85 0.5 B RR? Note 23 18:13:35.86 -31:50:24.0 R0 ---- 17.9 0.8 B RR? Note 24 18:13:30.79 -31:49:59.8 R0 0.3326 16.428 0.264 I RR1 25 18:13:31.74 -31:49:07.8 R0 0.3128 16.427 0.254 I RR1 26 18:13:36.88 -31:49:17.0 R0 0.6538 16.096 0.346 I RR0 27 18:13:37.03 -31:49:09.6 R0 0.6695 16.176 0.181 I RR0 28 18:13:38.42 -31:48:51.8 R0 0.3061 16.390 0.277 I RR1 29 18:13:38.50 -31:49:45.7 R0 0.6780 15.889 0.391 I RR0 30 18:13:38.60 -31:50:10.8 R0 0.2737 16.498 0.331 I RR1 31 18:13:40.39 -31:49:26.6 R0 0.2552 16.437 0.222 I RR1 32 18:13:41.14 -31:50:38.6 R0 0.3216 16.386 0.260 I RR1 33 18:13:42.48 -31:50:20.7 R0 0.5022 16.325 0.708 I RR0 34 18:13:45.85 -31:52:16.3 R0 0.2887 16.572 0.295 I RR1 35 18:13:29.96 -31:47:21.6 R0 1.4330 17.821 0.954 I E 36 18:13:32.49 -31:51:20.3 R0 0.3017 17.445 0.143 I EC 37 18:13:33.22 -31:50:58.4 R0 0.6316 16.348 0.176 I E 38 18:13:37.57 -31:47:31.5 R0 0.9470 16.297 0.195 I EC 39 18:13:38.53 -31:50:40.4 R0 0.5031 17.100 0.166 I E 40 18:13:39.44 -31:50:45.9 R0 0.3734 17.399 0.169 I E 41 18:13:39.49 -31:47:34.8 R0 0.4204 17.803 0.318 I EC 42 18:13:40.12 -31:48:27.3 R0 0.6565 18.642 1.360 I E 43 18:13:44.51 -31:52:17.3 R0 0.4626 18.567 0.399 I E 44 18:13:48.83 -31:47:35.1 R0 0.4410 17.998 0.433 I EC 45 18:13:50.11 -31:50:42.8 R0 0.9158 17.383 0.379 I E 46 18:13:37.06 -31:51:19.8 R0 1.3428 16.285 0.052 I ELL ====================================================================== Supplementary Notes NGC 6569 is a massive relatively 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. This CMD morphology was confirmed by Cohen et al. (2018) from deep HST imaging and also found in near infrared (JHK) CM diagrams by Valenti et al. (2005) and by Saracino et al. (2019). The first searches for variable stars in this cluster were conducted by Rosino (1962) and by Hazen-Liller (1985). No periods were derived in either study, but they concluded that the cluster has a significant RR Lyrae population. The RR Lyrae variables were subsequently investigated by Kunder et al. (2015) who published a summary, but they did not report results for the individual variables. NGC 6569 was included in the OGLE IV survey of Galactic bulge and numerous RR Lyrae variables and eclipsing binaries were identified. in and around the cluster (Soszynski et al. 2014, 2016, hereafter listed as S14 and S16). Most of the data in the above table are from the OGLE survey. According to the 2010 update to the Harris (1996) catalogue, the cluster has core radius 0.35' (arcminutes), half light radius 0.80' and tidal radius 7.15'. However, the vector point diagrams published by Saracino et al. (2019) show that, even at distances less than 0.75 arcminutes from the cluster centre, there is contamination from field stars. The new variables (V24-V46) listed in the above table were all announced in the OGLE IV survey. They are all less than 3.2' from the cluster centre because this was the radius adopted by S14. ==================================================================== Notes on individual stars V3: JHK photometry published by Valenti et al. (2005) shows that this star is located near the RG tip on the CM diagram, the location expected for a long period variable. This confirms the classification by Hazen-Liller (1985). The RA and dec are from Samus et al. (2009) V4, V6: According to Samus et al. (2009), these stars are V2711 Sgr and NSV 10364 respectively. The data listed for these stars in the above table are from the OGLE IV survey (S14). These variables were also detected by Cseresnjes et al. (2000): V4=vd9f612 and V6=vd301f640. V5: Hazen-Liller (1985) classified V5 as a possible RR Lyrae variable, but it was not listed in the RR Lyrae catalogues of Cseresnjes et al. (2000) or S14. This might be due to the fact that the star is located in a crowded region near the cluster centre. The RA and dec are from Samus et al. (2009). V9, V10: These are stars that Hazen-Liller (1985) tentatively classified as eclipsing binaries, but neither star was identified as eclipsing in the OGLE IV bulge survey (S16). With radial distances of 4.0 and 4.9 respectively, it is possible that they belong to the rich field surrounding the cluster. The RA and dec listed for these two stars are from Samus et al. (2009). V13: Hazen-Liller (1985) tentatively classified this as a type II Cepheid. However, it is not included among the Galactic bulge type II Cepheids listed by Soszynski et al. (2017). With a radial distance of 7.95', it is located beyond the tidal radius and may not belong to the cluster. Its JHK magnitudes from 2MASS indicate that it is brighter than the brightest stars in NGC 6569. The RA and dec are from Samus et al. (2009). V15: According to Samus et al. (2009), this star is V2698 Sgr. The RA, dec, magnitudes and classification in the above table are from the GCVS. The period is from Watson et al. (2006). With r~10', the star is well beyond the tidal radius and probably a field star. V16: The RA and dec are from Samus et al. (2009). The remaining data are from Matsunaga et al. (2006). V16 was not included among the Galactic bulge type II Cepheids listed by Soszynski et al. (2017). V19: With a radial distance of about 8 arcminutes from the cluster centre, V19 is beyond the tidal radus. Since it is at least 0.5 mag brighter than the other RR Lyrae in the cluster, it probably belongs to the rich field surrounding the cluster. V21: JHK photometry published by Valenti et al. (2005) shows that this star is located near the RG tip on the CM diagram, the location expected for a long period variable. This confirms the classification by Hazen-Liller (1985). The RA and dec are from Samus et al. (2009) V22, V23: Hazen-Liller (1985) classified these two stars as RR Lyrae variables, but they were not listed in the RR Lyrae catalogues of Cseresnjes et al. (2000) or S14. Their RR Lyrae classification is uncertain. The RA and dec are from Samus et al. (2009). =================================================================== 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 her assumed (600 arcsecond) tidal radius. V7-23: Hazen-Liller (1985) with x,y coordinates and an ID chart. NOTE: Many of the above variables were identified by S14: V1=OGLE-BLG-RRLYR-34946, V2=OGLE-BLG-RRLYR-34949, V4=OGLE-BLG-RRLYR-35016, V6=OGLE-BLG-RRLYR-15630, V7=OGLE-BLG-RRLYR-34989, V8=OGLE-BLG-RRLYR-34991, V11=OGLE-BLG-RRLYR-34939, V12=OGLE-BLG-RRLYR-34936, V14=OGLE-BLG-RRLYR-35002, V17=OGLE-BLG-RRLYR-34982, V18=OGLE-BLG-RRLYR-34973, V19=OGLE-BLG-RRLYR-34981, V20=OGLE-BLG-RRLYR-35010 Hazen-Liller (1985) also discovered 20 new field variables (F3-F22) and published their 1950 RA and dec, along with an ID chart. Hazen-Liller's field stars F1 = Rosino V6 = V2675 Sgr = ASAS 181304-3157.2 (Pojmanski 2002) F2 = Rosino V8 = NSV 10351 = OGLE-BLG-RRLYR-34690 F3 = V4127 Sgr = OGLE-BLG-RRLYR-35201 F4 = V4123 Sgr = OGLE-BLG-RRLYR-15591 F5 = V4126 Sgr = OGLE-BLG-RRLYR-35153 F6 = V4125 Sgr = OGLE-BLG-RRLYR-35000 F7 = NSV 24332 = OGLE-BLG-ECL-369452 F8 = V4124 Sgr = OGLE-BLG-RRLYR-15617 F9 = V4122 Sgr = OGLE-BLG-RRLYR-15546 F10 = V2684 Sgr = OGLE-BLG-RRLYR-34898 F11 = V2759 Sgr = OGLE-BLG-RRLYR-35222 F12 = NSV 24337 F13 = V2653 Sgr F14 = (no ID in the GCVS) F15 = V2674 Sgr = OGLE-BLG-RRLYR-34844 F16 = V2681 Sgr F17 = NSV 24331 F18 = V2709 Sgr F19 = V2740 Sgr F20 = V2658 Sgr = OGLE-BLG-RRLYR-15585 F21 = V2659 Sgr = OGLE-BLG-RRLYR-15603 F22 = V2736 Sgr = vd11f610 (Cseresnjes et al. 2000) When she carried out her investigation, Hazen-Liller assumed that the tidal radius for the cluster was 10' (arcminutes). Therefore all variables within that radius were assigned numbers and the variables beyond were listed as field stars. Since the tidal radius listed in the 2010 update to the Harris (1996) catalogue is 7.15', some of variables (V1-23) are now considered to be field stars. V24-34: These are RR Lyrae variables identified by S14 who published their RA and dec (J2000). All of them are located less than 3.2' from the cluster centre, the cluster radius they adopted: V24= OGLE-BLG-RRLYR-34947, V25= OGLE-BLG-RRLYR-34953, V26= OGLE-BLG-RRLYR-34968, V27= OGLE-BLG-RRLYR-34970, V28= OGLE-BLG-RRLYR-34976, V29= OGLE-BLG-RRLYR-34977, V30= OGLE-BLG-RRLYR-34978, V31= OGLE-BLG-RRLYR-34987, V32= OGLE-BLG-RRLYR-34993, V33= OGLE-BLG-RRLYR-34996, V34= OGLE-BLG-RRLYR-35009 V25 (=vd3f640) was also detected by Cseresnjes et al. (2000). S14 announced 3 other RR Lyrae variables with r greater than 3.2', but less than the tidal radius 7.15': OGLE-BLG-RRLYR-34907, OGLE-BLG-RRLYR-34961, OGLE-BLG-RRLYR-35012. #34907 (=vd20f640) and #35012 (=vd12f612) were also detected by Cseresnjes et al. (2000). Some of these stars have VI magnitudes appropriate for cluster membership and could also be cluster members. V35-46: These are eclipsing binaries identified by S16 who published their RA and dec (J2000). All of them are located less than 3.2' from the cluster centre, the cluster radius adopted by S14: V35=OGLE-BLG-ECL-369233, V36=OGLE-BLG-ECL-369587, V37=OGLE-BLG-ECL-369682, V38=OGLE-BLG-ECL-370166, V39=OGLE-BLG-ECL-370288, V40=OGLE-BLG-ECL-370431, V41=OGLE-BLG-ECL-370437, V42=OGLE-BLG-ECL-370518, V43=OGLE-BLG-ECL-371056, V44=OGLE-BLG-ECL-371617, V45=OGLE-BLG-ECL-371778, V46=OGLE-BLG-ELL-023030 S16 announced 25 other eclipsing binaries with r greater than 3.2', but less than the tidal radius 7.15': OGLE-BLG-ECL-000185, OGLE-BLG- ECL-366792 OGLE-BLG- ECL-369268, OGLE-BLG- ECL-369403, OGLE-BLG- ECL-369691, OGLE-BLG- ECL-369727, OGLE-BLG- ECL-370191, OGLE-BLG- ECL-370539, OGLE-BLG- ECL-370751, OGLE-BLG- ECL-371443, OGLE-BLG- ECL-372469, OGLE-BLG- ECL-372661, OGLE-BLG- ECL-372709, OGLE-BLG- ECL-372728, OGLE-BLG- ECL-372888, OGLE-BLG- ECL-372923, OGLE-BLG- ECL-372990, OGLE-BLG- ECL-373362, OGLE-BLG- ECL-373436, OGLE-BLG- ECL-373686, OGLE-BLG- ECL-373864, OGLE-BLG- ECL-373883, OGLE-BLG- ECL-373992, OGLE-BLG- ECL-374060, OGLE-BLG- ELL-023083. ===================================================================== References Cohen, R. 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