NGC 6304 / C1711-294 RA: 17:14:32.25 DEC: -29:27:43.3 (J2000) (Most recent updates: Membership probability flag - 2024; Remaining data - April 2013) ============================================================ Bytes Format Explanation 1-8 A8 Star ID 10-32 A11,1x,A11 Position 34-35 A2 Membership probability flag based on data published by Prudil & Arellano Ferro (2024) m1: prob >=0.85; m2: prob >=0.7 and <0.85; m3: prob >= 0.5 and <0.7; f: prob <0.5 u: no data available 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 Mem Period ampl C Type Notes/ RA Dec Flag Remarks ========================================================================= 1 17:14:40.47 -29:29:34.3 f 0.4723 17.000 0.81 V RR0 f;Og 2 17:14:18.69 -29:24:58.6 f 0.3989 16.586 1.21 V RR0 f;Og 3 17:14:47.57 -29:26:33.5 f 0.8555 16.731 0.65 V RR0 mem?;Og 4 17:14:11.58 -29:30:32.1 u 0.8122 15.968 0.58 V AC mem?;Note 5 17:14:49.51 -29:27:40.9 f 0.2145 -- -- RR? 6 17:14:56.40 -29:30:38.8 u ---- -- -- CST 7 17:14:33.35 -29:32:28.0 f 0.5758 17.237 0.63 V RR0 f;Og 8 17:15:09.74 -29:26:30.5 u 0.6079 -- -- RR0 9 17:15:16.91 -29:23:23.7 u 0.3489 -- -- RR1 10 17:13:47.25 -29:32:18.9 u 0.6283 16.729 0.78 V RR0 Og 11 17:14:14.97 -29:36:53.9 u ---- -- -- L f 12 17:14:19.26 -29:19:42.2 u ---- -- -- L f 13 17:14:20.61 -29:23:41.3 m1 ---- -- -- CST 14 17:14:23.14 -29:36:41.7 u ---- -- -- L Note 15 17:14:33.23 -29:25:48.4 m1 ---- -- -- CST? 16 17:14:41.79 -29:25:37.4 f ---- -- -- L f 17 17:14:58.27 -29:30:42.7 u ---- -- -- CST? 18 17:15:09.51 -29:27:36.1 u ---- -- -- L f 19 17:14:44.62 -29:35:45.4 u ---- -- -- CST? 20 17:14:46.71 -29:36:45.5 u ---- -- -- CST? 21 17:15:10.19 -29:26:18.0 u ---- -- -- CST? 22 17:14:37.67 -29:27:31.1 f 0.3380 16.289 0.39 V RR1 mem;Og 23 17:14:27.33 -29:27:40.2 f 0.3939 16.816 0.34 V RR1 mem?;Og 24 17:14:48.89 -29:32:00.7 u 0.3698 16.656 0.45 V RR1 mem?;Og ================================================================== Supplementary Notes The cluster NGC 6304 is a metal rich cluster located in a rich field in the galactic bulge. The first investigations of variable stars were by Rosino (1962) and Terzan (1966, 1968). Although both authors announced the discovery of variables, neither of them derived any periods. A later study of the variables in NGC 6304 and the surrounding field was by Hartwick et al. (1981). They derived periods for the 40 RR Lyrae stars in their field and identified a number of other suspected variables, many of which they classified as long period variables. It is generally assumed that most of the variables belong to the field around NGC 6304 and not to the cluster itself. For V1-21, most of the data are from their study unless indicated Og in the Notes/Remarks column in which case, the periods, magnitudes and amplitudes are from the OGLE III catalogue (Sosyzynski et al. 2011). The RA ad dec for these variabes are from Samus et al. (2009). For V22-24, all the data are from the OGLE III catalogue (Sosyzynski et al. 2011). De Lee et al. (2006) carried out a new study of the RR Lyrae variables to investigate the possibility that some of them might be cluster members in light of the discovery of long period RR Lyrae variables in the metal rich clusters NGC 6388 and NGC 6441. They estimated the membership status based on distance from the cluster, mean magnitude and reddening. The membership status listed for the RR Lyrae variables in the Notes/Remarks column is based on their study. ===================================================================== Notes on individual stars V4: De Lee et al. (2006) pointed out that this star might be an anomalous Cepheid because its light curve does not have the characteristic shape expected for an RR Lyrae with a such a long period. V14: This star might be a cluster member. It was Terzan's (1966) #30 and Hartwick's (1981) #62. The magnitudes published by Hartwick et al. (1981) are in the appropriate range for cluster membership. ================================================================== Discovery of the variable stars in NGC 6304: V1-11 Rosino (1962) with x,y coordinates and an ID chart Some of these variables are also in the OGLE III catalogue (Sosyzynski et al. 2011). V1, 2, 3, 4, 7, 10 are OGLE-BLG-RRLYR 00247, 00232, 00253, 00225, 00242, 00201 respectively. V12-18 = #28, 29, 30, 32, 33, 40, 43 Terzan (1966) with an ID chart The numbers V12-18 were assigned by Sawyer Hogg (1973) in her 3rd catalogue. Terzan announced 58 (V1-58) variables in his paper, but Sawyer Hogg assigned numbers only to the ones that were located within approximately 15 arcminutes of the cluster centre. The 2010 revision of the Harris (1996) catalogue inicates a tidal radius of 13.25 arcminutes for NGC 6304. V19-21 = #68, 69, 72 Terzan (1968) with an ID chart The numbers V19-21 were assigned by Sawyer Hogg (1973) in her 3rd catalogue. Terzan announced 25 new variables (V59-83) in his paper, but Sawyer Hogg assigned numbers only to the ones within 15 arcminutes of the cluster centre. V22-23 = #1247 & #4209, suspected variables Hesser & Hartwick (1976) with ID chart Their variability was later confirmed by De Lee et al. (2006). Both stars are included in the OGLE III catalogue of RR Lyrae variables as OGLE-BLG-RRLYR 00246 and 00237 respectively (Sosyzynski et al. 2011). The numbers V22 and V23 were assigned in this on-line catalogue. V24 = NV1 De Lee et al. (2006) with no ID or coordinates However, based on the period they derived, this star appears to be OGLE-BLG-RRLYR-00255 (Sosyzynski et al. 2011). The number V24 was assigned in this on-line catalogue. De Lee et al. included a few other 'new' RR Lyrae variables in their investigation, but they did not consider any of them to be possible cluster members. Therefore they are not listed in the above table. These stars were listed as HBH67, Va46, NV2 which are the same stars as OGLE-BLG-RRLYR-00256,-00251 and -00238 respectively (Sosyzynski et al. 2011). =================================================================== References de Lee, N., Catelan, M., Layden, A., Pritzl, B., Smith, H., Sweigart, A., Welch, D. 2006, Mem SAI, 77, 117 Harris, W. E. 1996, AJ, 112, 1487 Hesser, J. E. & Hartwick, F. D. A. 1976, ApJ, 203, 113 Prudil Z., Arellano Ferro, A. 2024, MNRAS, 534, 3654 Rosino, L. 1962, Mem SAI, 33, 351 = Asiago-Padova Cont. 132 Samus, N. N., Kazarovets, E. V., Pastukhova, E. N., Tsvetkova, T. M., Durlevich, O. V. 2009, PASP, 121, 1378 Sawyer Hogg, H. 1973, Publ. DDO, 3, No. 6 Sosyzynski, I., Dziembowski, W. A., Udalski, A., Poleski, R., Szymanski, M. K., Kubiak, M., Pietrzynski, G., Wyrzkowski, L., Ulaczyk, K., Kozlowski, S., Pietrukowicz, P. 2011, AcA, 61, 1 Terzan, A. 1966, POHP, 9, 1 Terzan, A. 1968, POHP, 9, 24 ========================================================================