Djorg 2 / ESO 456-SC38 / C1758-278 (Upated February 2016) RA: 18:01:49.1 DEC: -27:49:33 (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 18:01:40.87 -27:49:56.1 R0 0.5151 16.325 0.658 I RR0 11141 2 18:01:46.91 -27:49:28.2 R0 0.5638 16.269 0.492 I RR0 11190 3 18:01:49.37 -27:49:29.7 R0 0.5086 16.304 0.825 I RR0 11215 4 18:01:49.68 -27:49:13.1 R0 0.6346 16.348 0.126 I RR0 11218 5 18:01:50.40 -27:49:29.8 R0 0.5172 16.280 0.558 I RR0 11223 6 18:01:50.76 -27:49:31.5 R0 0.3026 16.496 0.253 I RR1 11225 7 18:01:53.96 -27:48:30.8 R0 0.3170 16.519 0.229 I RR1 11257 ======================================================= Supplementary Notes The "IAU nomenclature" name for this cluster was assigned by Clement et al. (2001) based on its 1950 position. This cluster lies in a crowded field near the Galactic centre. Valenti et al. (2010) published a near IR (K, J-K) CM diagram and estimated [Fe/H] = -0.65, based on the slope of the RGB. Harris (1996) listed V(HB)=17.60 in the 2010 update to his catalogue. He estimated this value from the paper by Valenti et al. The data for all the variables listed in the above table are from Soszynski et al. (2014). These stars are all located within 2 arcminutes of the cluster centre, well within the tidal radius, 10.5 arcminutes, according to the 2010 update to the Harris (1996) catalogue. Harris listed half-light radius = 0.83 arcminutes. These 7 variables have mean = 17.954 according to Soszynski et al. (2014). In view of the uncertainties involved in Harris's estimate of V(HB), it is reasonable to assume that they belong to the cluster. ================================================================ Notes on individual stars The numbers in the remarks column are the numbers assigned by Soszynski et al. (2011): OGLE-BLG-RRLYR-NNNNN. ================================================================= Discovery of the variable stars in Djorg 2 V1-7 = OGLE-BLG-RRLYR-11141, OGLE-BLG-RRLYR-11190, OGLE-BLG-RRLYR-11215, OGLE-BLG-RRLYR-11218, OGLE-BLG-RRLYR-11223, OGLE-BLG-RRLYR-11125, OGLE-BLG-RRLYR-11257 Soszynski et al. (2011) in the OGLE III Catalogue of RR Lyrae variables in the Galactic Bulge Their RA and dec are listed by the Vizier Service. These variables have mean =16.363 and mean =17.954 mag. Soszynski et al. (2014) identified 10 additional RR Lyrae variables that are located within 5 arcminutes of the cluster centre: BLG-RRLYR-11044, 11049, 11060, 11075, 11137, 11142, 11249, 11252, 11372, 11376. Most of these additional variables have mean magnitudes that indicate they are probably in the cluster foreground or beyond the cluster. ================================================================ References Clement, C. M., Muzzin, A., Dufton, Q., Ponnampalam, T., Wang, J., Burford, J., Richardson, A., Rosebery, T. 2001, AJ, 122, 2587 Harris, W. E. 1996, AJ, 112, 1487 Soszynski, I., Dziembowski, W. A., Udalski, A., Poleski, R., Szymanski, M. K., Kubiak, M., Pietrzynski, G. and 4 coauthors, 2011a, Ac. A., 61, 1 Soszynski, I., Udalski, A., Szymanski, M. K., Pietrukowicz, P., Mroz, P., Skowron, J., Kozlowski, S. and 6 coauthors, 2014, Ac. A. 64, 177 Valenti, E., Ferraro, F. R., Origlia, L. 2010, MNRAS, 410, 1729 ====================================================================