NGC 6553 / C1806-259 (Updated March 2015) RA: 18:09:15.68 DEC: -25:54:27.9 (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 18:09:31.17 -25:54:15.1 R0 0.5642 16.817 -- V RR0 f?;Note 2 18:09:23.11 -25:57:04.8 R0 0.5818 17.877 -- V RR0 f;Note 3 18:09:15.8 -25:55:13 R0 0.4886 17.474 -- V RR0 f;Note 4 18:09:18.84 -25:54:35.8 R0 267.0 6.66 1.06 K M Sloan 5 18:09:12.23 -25:54:46.1 R0 ---- -- -- L? 6 18:09:11.64 -25:54:55.0 R0 ---- -- -- L? 7 18:09:14.78 -25:54:35.0 R0 ---- -- -- L? 8 18:09:07.74 -25:54:44.5 R0 ---- -- -- L? 9 18:09:18.59 -25:55:34.6 R0 ---- -- -- L? 10 18:09:16.93 -25:55:48.1 R0 ---- -- -- L? 11 18:09:21.58 -25:54:32.8 R0 ---- -- -- L? 12 18:09:20.38 -25:53:57.2 R0 ---- -- -- L? 13 18:09:17.58 -25:53:20.5 R0 ---- -- -- L? 14 18:09:17.51 -25:54:53.7 R0 ---- -- -- L? Nova 18:09:05.82 -25:59:07.6 R0 ---- 8.0 8.0 P N max;Note =========================================================================== Supplementary Notes NGC 6553 is a metal rich cluster located in a heavily reddened field near the galactic centre. According to the 2010 version of the Harris (1996) catalogue, [Fe/H] = -0.18. A CM dagram by Zoccali et al. (2001) shows a stubby red HB and a blue straggler star sequence. In the above table, the RA and dec are from Samus et al. (2009). For V1-3, the periods and magnitudes and classifications are from Soszynski et al. (2011). The period, magnitude, amplitude and classification for V4 is from Sloan et al. (2010). The classifications for V5-14 are from Lloyd Evans & Menzies who plotted their positions on a CM diagram. All of these variables (with the exception of V11 and V12) have been detected in the VVV survey (Minniti et al. 2010) but no periods have been published. ======================================================================= Notes on individual stars V1-3: These stars are Ogle III #35097, #202433 and #27160 respectively. Their membership status is based on the fact that the cluster is located in a crowded field in the Galactic bulge and their V magnitudes are all fainter than the level of the horizontal branch (V=16.6) established by Zoccali et al. (2001). Nova = V1148 Sgr = Nova Sgr 1943: The magnitudes listed in the above table are from the Moscow GCVS where the nova is listed as V1148 Sgr. ======================================================================== Discovery of the variable stars in NGC 6553: V1-5 Thackeray who provided his unpublished x,y coordinates to Sawyer (1955) V6-14 = A1, A2, 3, 6, 7, 13, 14, 24, 33 of Lloyd Evans & Menzies (1973) who labelled them on an ID chart The numbers V6-14 were assigned by Sawyer Hogg (1973). Nova = Nova Sgr 1943 = V1148 Sgr Mayall (1949) with 1950 RA and dec Sawyer (1955) listed the x,y coordinates based on information provided in a letter from A. D. Thackeray and Samus et al. (2009) later derived the RA and dec (J2000). --------------------------------------------------------------------- A search for long period variable stars in NGC 6553 was undertaken with the PROMPT4 telescope at Cerro Tololo with preliminary results reported by Kager (2010). Layden and his collaborators have obtained additional observations and are currently analysing their data. ======================================================================= References Andrews, P. J., Feast, M. W., Lloyd Evans, T., Thackeray, A. D., Menzies, J. W. 1974, Obs., 94, 133 Harris, W. E. 1996, AJ, 112, 1487 Kager, E. 2010, APS, Ohio Section, 55, No. 4 Lloyd Evans, T. & Menzies, J. W. 1973, IAU Colloq. No. 21, Variable Stars in Globular Clusters and in Related Systems, 151 Mayall, M. W. 1949, AJ, 54, 191 Minniti, D., Lucas, P. W., Emerson, J. P., Saito, R. K., Hempel, M., Pietrukowicz, P., Ahumada, A. V. and 59 coauthors, 2010, New Astron., 15, 433 Samus, N. N., Kazarovets, E. V., Pastukhova, E. N., Tsvetkova, T. M., Durlevich, O. V. 2009, PASP, 121, 1378 Sawyer, H. B. 1955, Publ. DDO, 2, No. 2 Sawyer Hogg, H. 1973, Publ. DDO, 3, No. 6 Sloan, G. C., Matsunaga, N., Matsuura, M., Zijlstra, A. A., Kraemer, K. E., Wood, P. R., Nieusma, J., Bernard-Salas, J., Devost, D., Houck, J. R. 2010, ApJ, 719, 1274 Soszynski, I., Dziembowski, W. A., Udalski, A., Poleski, R., Szymanski, M. K., Kubiak, M., Pietrzynski, G. and 4 coauthors, 2011a, Ac. A., 61, 1 Zoccali, M., Renzini, A., Ortolani, S., Bica, E., Barbuy, B. 2001, AJ, 121, 2638 =======================================================================