NGC 6441 / C1746-370 (Updated January 2015) RA: 17:50:12.84 DEC: -37:03:03.9 (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 17:50:17.09 -37:03:49.7 R0 200.0 8.90 0.40 K M Note 2 17:50:16.16 -37:02:40.5 R0 145.0 9.23 0.52 K M Note 3 17:50:42.65 -37:04:29.0 R0 ---- -- -- L f? 4 17:50:17.91 -37:05:55.2 R0 ---- -- -- CST? Note 5 17:50:29.94 -36:59:15.1 R0 ---- -- -- L f? 6 17:50:15.65 -37:02:16.1 R0 21.365 14.885 1.274 V CW Note 7 17:50:09.13 -36:55:00.0 R0 261.8 14.506 -- V M f;Note 8 17:49:53.51 -37:10:36.1 R0 ---- -- -- ? f;Note 9 17:50:11.00 -37:03:52.8 R0 ---- -- -- L f? 10 17:50:19.51 -37:04:04.4 R0 102.36 13.001 0.162 I SR? Ogle 11 17:50:09.50 -37:01:27.9 R0 ---- -- -- CST 12 17:50:09.05 -37:02:11.5 R0 ---- -- -- CST 13 17:50:13.26 -37:04:19.1 R0 ---- -- -- L 14 17:50:32.38 -37:04:17.8 R0 94.83 13.112 0.258 I SR Ogle 15 17:50:08.27 -37:07:08.4 R0 ---- -- -- L 16 17:50:01.43 -37:04:04.1 R0 68.38 12.982 0.158 I SR Ogle 17 17:50:07.33 -37:02:40.4 R0 330.5 13.870 0.464 I SR? Ogle 18 17:49:57.92 -36:56:46.3 R0 ---- -- -- L 19 17:50:11.33 -37:07:56.5 R0 380.5 19.887 1.975 I M Ogle 20 17:50:30.92 -37:06:28.4 R0 307.0 13.308 0.245 I SR? Ogle 21 17:49:59.33 -37:05:45.8 R0 ---- -- -- L 22 17:50:04.49 -37:03:35.9 R0 ---- -- -- L 23 17:50:14.15 -37:03:56.9 R0 ---- -- -- L 24 17:50:30.73 -37:02:49.6 R0 46.392 13.271 0.074 I SR Ogle 25 17:49:59.09 -37:05:24.0 R0 200.0 14.718 0.244 I SR? Ogle 26 17:50:04.37 -37:01:24.6 R0 ---- -- -- L 27 17:50:19.27 -36:59:04.2 R0 ---- -- -- L 28 17:50:10.31 -36:57:42.0 R0 ---- -- -- L 29 17:49:57.20 -36:59:46.5 R0 ---- -- -- L 30 17:50:34.94 -37:00:48.3 R0 ---- -- -- L f? 31 17:50:20.00 -37:06:56.9 R0 ---- -- -- L f? 32 17:50:11.34 -37:03:24.4 R0 ---- -- -- L 33 17:50:15.55 -37:02:59.5 R0 46.367 13.167 0.102 I SR Ogle 34 17:50:26.78 -37:06:56.5 R0 42.06 13.261 0.104 I SR Ogle 35 17:50:17.54 -37:03:11.7 R0 48.927 13.558 0.136 I SR Ogle 36 17:49:50.01 -37:05:04.8 R0 0.5078 16.540 1.160 RR0 f 37 17:50:15.95 -37:01:07.6 R0 0.614 17.546 1.17 RR0 38 17:50:13.61 -37:00:27.3 R0 0.735 17.462 0.77 RR0 39 17:50:22.93 -37:02:03.4 R0 0.833 17.673 0.70 RR0 40 17:50:10.4 -37:04:05 R0 0.648 17.512 1.08 RR0 41 17:50:16.00 -37:03:57.7 R0 0.749 16.726 0.41 RR0 blend 42 17:50:13.12 -37:01:31.9 R0 0.813 17.475 0.58 RR0 43 17:50:16.86 -37:02:10.0 R0 0.773 17.529 0.60 RR0 44 17:50:14.2 -37:03:59 R0 0.609 16.673 0.60 RR0 blend 45 17:50:07.51 -37:05:19.9 R0 0.503 17.375 0.87 RR0 46 17:50:00.90 -37:04:24.3 R0 0.900 17.453 0.40 RR0 47 17:50:18.98 -37:08:10.3 R0 0.703 16.489 1.20 EA f?;Note 48 17:50:41.53 -37:04:12.5 R0 0.668 15.501 0.31 EW f;Note 49 17:50:34.58 -37:01:31.6 R0 0.335 16.814 -- RR1? 50 17:50:18.79 -37:05:49.4 R0 0.433 18.183 0.52 EW f;Note 51 17:50:25.29 -37:00:10.9 R0 0.713 17.711 1.00 RR0 52 17:50:10.19 -37:01:37.6 R0 0.858 17.461 0.23 RR0 53 17:50:12.45 -37:01:46.9 R0 0.853 17.442 0.36 RR0 54 17:50:58.56 -37:02:18.6 R0 0.620 16.535 0.51 RR0 f? 55 17:50:12.44 -37:02:28.0 R0 0.698 17.523 0.97 RR0 56 17:50:11.10 -37:02:39.9 R0 0.905 16.497 -- RR0 57 17:50:10.41 -37:02:55.9 R0 0.696 17.313 0.95 RR0 58 17:50:14.71 -37:03:07.2 R0 0.685 16.868 -- RR0 59 17:50:09.04 -37:03:32.2 R0 0.703 17.508 0.92 RR0 60 17:50:13.31 -37:03:51.6 R0 0.857 16.823 -- RR0 61 17:50:14.69 -37:04:02.6 R0 0.750 17.623 0.77 RR0 62 17:50:13.18 -37:04:06.3 R0 0.680 16.887 0.51 RR0 blend 63 17:50:11.31 -37:02:47.4 R0 0.700 17.064 -- RR0 64 17:50:09.67 -37:03:07.4 R0 0.718 16.986 -- RR0 65 17:50:13.16 -37:02:29.9 R0 0.757 16.911 0.40 RR0 blend 66 17:50:11.46 -37:02:07.0 R0 0.860 17.057 -- RR0 67 17:50:44.02 -37:03:50.8 R0 0.654 16.889 0.87 RR0 f 68 17:50:01.32 -37:06:25.5 R0 0.324 16.129 -- RR1? f? 69 17:50:28.90 -37:03:27.6 R0 0.561 17.453 0.40 RR1 70 17:50:04.52 -37:03:56.7 R0 0.317 17.513 0.50 RR1 71 17:50:16.38 -37:01:43.5 R0 0.362 17.471 0.48 RR1 72 17:50:14.86 -36:59:31.9 R0 0.312 17.348 0.480 RR1 73 17:50:58.44 -37:00:22.7 R0 0.320 16.968 0.380 RR1? f? 74 17:50:18.62 -37:02:56.1 R0 0.317 17.578 0.500 RR1 75 17:50:12.47 -37:03:40.5 R0 0.405 17.349 -- RR1? 76 17:50:22.60 -37:03:45.8 R0 0.473 17.912 0.390 RR1 77 17:50:29.95 -37:04:31.4 R0 0.376 17.494 0.470 RR1 78 17:50:27.29 -37:06:58.6 R0 0.351 17.843 0.510 RR1 79 17:50:13.96 -37:03:40.7 R0 0.417 17.228 RR1 80 17:50:27.43 -37:04:41.7 R0 0.900 17.409 0.380 EW 81 17:50:17.47 -36:58:37.1 R0 0.428 17.878 0.370 E? 82 17:50:07.62 -37:00:11.6 R0 0.747 16.505 0.240 EW 83 17:50:38.91 -37:01:04.2 R0 0.622 17.625 0.280 EW 84 17:50:09.12 -37:02:46.9 R0 0.316 17.377 RR1? 85 17:50:06.18 -37:04:10.0 R0 0.283 17.636 0.360 EW 86 17:50:04.77 -37:05:03.6 R0 0.325 17.949 0.480 EW 87 17:50:58.20 -37:05:44.6 R0 0.369 17.140 0.240 EW 88 17:50:47.86 -37:07:22.3 R0 0.452 17.698 0.440 EW 89 17:50:15.93 -36:58:50.1 R0 0.456 18.486 0.340 EW 90 17:50:51.67 -37:02:25.6 R0 0.726 18.523 0.300 EW 91 17:50:13.20 -37:07:48.4 R0 0.457 19.518 0.700 EW 92 17:50:31.30 -37:02:23.4 R0 0.577 18.581 0.340 EW 93 17:50:06.31 -37:02:44.2 R0 0.339 17.332 0.540 RR1? 94 17:50:11.84 -37:02:28.0 R0 0.386 17.368 0.360 RR1? 95 17:50:08.49 -37:04:13.6 R0 0.090 17.611 0.550 SXPHE f;DSCT? 96 17:50:01.47 -37:05:19.0 R0 0.856 17.664 -- RR0? 97 17:50:06.77 -37:03:23.7 R0 0.844 17.446 -- RR0? 98 17:50:22.86 -36:59:48.0 R0 ---- -- -- ? 99 17:51:01.62 -37:03:59.4 R0 ---- -- -- ? 100 17:50:23.66 -36:58:33.0 R0 1.660 16.966 1.050 EA 101 17:50:34.39 -36:56:56.2 R0 3.500 18.319 1.750 EA 102 17:50:09.64 -37:04:10.5 R0 0.308 15.834 RR1? 103 17:50:39.48 -37:01:09.8 R0 0.673 18.411 0.230 EW 104 17:50:02.99 -37:08:45.6 R0 0.735 19.407 1.050 EW 105 17:50:12.32 -37:02:52.6 R0 113.6 16.151 1.487 V SR Note 106 17:50:10.61 -37:03:26.0 R0 0.3609 17.650 0.426 V RR1 107 17:50:15.24 -37:03:07.1 R0 0.7389 17.650 0.853 V RR0 108 17:50:14.45 -37:02:42.9 R0 0.3442 17.531 0.426 V RR1 109 17:50:14.72 -37:02:50.0 R0 0.3646 17.611 0.470 V RR1 110 17:50:14.07 -37:03:00.8 R0 0.7687 17.399 0.878 V RR0 111 17:50:13.69 -37:02:57.8 R0 0.7446 17.552 0.781 V RR0 112 17:50:13.61 -37:02:54.3 R0 0.6142 17.363 1.067 V RR0 113 17:50:13.56 -37:02:56.6 R0 0.5885 17.605 1.136 V RR0 114 17:50:13.46 -37:02:53.3 R0 0.6739 17.610 1.015 V RR0 115 17:50:13.27 -37:02:46.4 R0 0.8631 17.552 0.536 V RR0 116 17:50:13.12 -37:03:22.7 R0 0.5823 17.612 1.257 V RR0 117 17:50:13.10 -37:03:12.2 R0 0.7453 17.557 0.908 V RR0 118 17:50:12.50 -37:03:20.8 R0 0.9792 17.201 0.846 V RR0 Note 119 17:50:12.45 -37:03:01.3 R0 0.6863 17.511 1.014 V RR0 120 17:50:12.19 -37:02:53.5 R0 0.3640 17.558 0.430 V RR1 121 17:50:12.18 -37:02:59.5 R0 0.8375 17.522 0.637 V RR0 122 17:50:11.78 -37:03:04.8 R0 0.7427 17.531 0.838 V RR0 123 17:50:11.44 -37:03:06.9 R0 0.3357 17.532 0.507 V RR1 124 17:50:09.73 -37:02:46.9 R0 0.3159 17.631 0.459 V RR1 125 17:50:14.36 -37:02:44.7 R0 0.3368 17.569 0.502 V RR1 126 17:50:12.54 -37:03:12.0 R0 20.625 14.997 1.110 V CW 127 17:50:12.08 -37:03:12.3 R0 19.773 15.048 1.057 V CW 128 17:50:11.80 -37:02:59.1 R0 13.519 15.257 0.500 V CW 129 17:50:12.87 -37:03:18.1 R0 17.832 15.128 0.918 V CW 130 17:50:14.43 -37:03:04.8 R0 58.00 15.500 0.628 V L? Note 131 17:50:15.52 -37:03:07.4 R0 122.8 15.914 1.667 V L 132 17:50:12.87 -37:03:08.6 R0 2.5474 16.478 0.900 V CW 133 17:50:13.98 -37:02:57.0 R0 ---- 16.371 0.520 V L Note 134 17:50:15.37 -37:03:19.5 R0 128.9 16.731 1.088 V L 135 17:50:12.61 -37:02:38.0 R0 162.6 16.574 3.919 V L 136 17:50:12.69 -37:03:16.2 R0 0.8057 17.360 0.580 V RR0 137 17:50:11.85 -37:03:03.0 R0 ---- 16.792 0.593 V L Note 138 17:50:14.00 -37:03:07.7 R0 0.8020 17.707 0.424 V RR0 139 17:50:13.58 -37:03:16.2 R0 249.1 16.009 5.819 V L 140 17:50:10.80 -37:03:05.9 R0 0.616 17.539 0.372 V RR1? Note 141 17:50:13.98 -37:03:16.2 R0 0.8448 17.536 0.404 V RR0 142 17:50:13.83 -37:02:49.7 R0 0.8840 17.523 0.349 V RR0 143 17:50:13.75 -37:02:47.8 R0 0.8628 17.532 0.487 V RR0 144 17:50:11.34 -37:02:59.6 R0 70.6 16.103 0.377 V L 145 17:50:12.72 -37:03:09.6 R0 0.5558 17.372 0.355 V RR01 Note 146 17:50:13.15 -37:03:00.4 R0 0.402 -- -- RR1 147 17:50:13.26 -37:02:52.3 R0 0.355 -- -- RR1 148 17:50:12.79 -37:02:50.9 R0 0.390 -- -- RR1 149 17:50:10.06 -37:02:26.5 R0 0.557 -- -- RR Note 150 17:50:07.07 -37:03:16.1 R0 0.529 -- -- RR Note 151 17:50:11.98 -37:03:11.6 R0 0.4872 16.46 0.80 I RR0 152 17:50:12.84 -37:03:03.5 R0 0.9432 - - I RR0? 153 17:50:12.77 -37:03:16.6 R0 9.89 13.72 0.15 I CWA 154 17:50:13.34 -37:03:01.1 R0 10.83 13.57 0.15 I CWA 155 17:50:13.23 -37:03:10.9 R0 11.45 13.03 0.04 I ? 156 17:50:11.36 -37:03:13.6 R0 11.76 13.97 0.03 I SR? 157 17:50:11.67 -37:03:14.7 R0 15.10 13.71 0.04 I SR? 158 17:50:13.64 -37:02:48.9 R0 17.50 13.89 0.05 I SR? 159 17:50:13.15 -37:03:06.6 R0 18.5 13.03 0.06 I SR? 160 17:50:13.54 -37:03:20.4 R0 20.3 13.31 0.11 I SR 161 17:50:12.65 -37:03:12.6 R0 24.6 12.95 0.09 I SR 162 17:50:14.22 -37:02:51.0 R0 29.3 13.68 0.06 I SR 163 17:50:13.74 -37:03:03.3 R0 41.03 12.59 0.11 I SR? 164 17:50:11.92 -37:03:11.1 R0 41.14 14.37 0.27 I ? 165 17:50:12.03 -37:03:10.8 R0 51.6 12.86 0.21 I SR 166 17:50:13.43 -37:02:54.7 R0 52. 12.83 0.17 I SR 167 17:50:14.04 -37:03:02.9 R0 86. 12.78 0.13 I SR 168 17:50:13.98 -37:03:12.9 R0 128. 13.13 0.11 I SR 169 17:50:13.92 -37:03:25.1 R0 138.23 13.061 0.624 I SR Ogle 170 17:50:13.63 -37:03:08.1 R0 ---- 12.89 0.48 I L 171 17:50:13.07 -37:02:58.8 R0 ---- 12.71 0.29 I L 172 17:50:14.56 -37:03:14.8 R0 ---- 13.06 0.21 I L 173 17:50:14.25 -37:03:04.7 R0 ---- 13.10 0.16 I L 174 17:50:12.06 -37:02:51.5 R0 ---- 13.06 0.14 I L 175 17:50:11.37 -37:03:23.2 R0 ---- 13.27 0.14 I L 176 17:50:12.22 -37:03:04.9 R0 ---- 12.65 0.11 I L 177 17:50:14.38 -37:03:19.1 R0 ---- 13.35 0.09 I L 178 17:50:12.93 -37:02:56.3 R0 ---- 12.91 0.08 I L 179 17:50:12.82 -37:03:04.4 R0 ---- 12.72 0.07 I L 180 17:50:12.43 -37:03:12.2 R0 ---- 13.72 0.07 I L 181 17:50:14.29 -37:03:15.4 R0 ---- 13.73 0.07 I L 182 17:50:13.17 -37:03:08.8 R0 ---- 12.62 0.06 I L 183 17:50:11.94 -37:02:52.4 R0 ---- 12.72 0.06 I L 184 17:50:12.91 -37:03:19.3 R0 ---- 12.84 0.06 I L 185 17:50:11.85 -37:03:00.6 R0 ---- 13.07 0.06 I L 186 17:50:13.91 -37:03:15.8 R0 ---- 13.17 0.06 I L 187 17:50:12.58 -37:02:49.1 R0 75.75 13.228 0.023 I SR? Ogle 188 17:50:12.36 -37:03:24.9 R0 ---- 13.70 0.06 I L 189 17:50:14.45 -37:03:08.2 R0 ---- 13.81 0.06 I L 190 17:50:13.03 -37:03:00.0 R0 ---- 13.04 0.05 I L 191 17:50:13.31 -37:03:04.1 R0 ---- 12.46 0.04 I L 192 17:50:13.41 -37:03:06.8 R0 ---- 12.80 0.04 I L 193 17:50:12.27 -37:03:10.1 R0 ---- 13.19 0.04 I L 194 17:50:13.90 -37:03:05.7 R0 ---- 13.19 0.04 I L 195 17:50:13.65 -37:02:53.9 R0 ---- 13.41 0.04 I L 196 17:50:11.54 -37:02:56.8 R0 ---- 13.81 0.04 I L 197 17:50:11.86 -37:02:49.2 R0 ---- 14.07 0.04 I L 198 17:50:13.17 -37:02:56.0 R0 ---- 13.13 0.03 I L 199 17:50:12.35 -37:02:57.3 R0 ---- 13.46 0.03 I L PSR:A-D -- -- ---- -- -- PSR U1 17:50:12.73 -37:03:06.5 R0 ---- -- -- LMXB? ================================================================ Supplementary Notes NGC 6441 is a massive metal rich cluster that is located in a rich field in the Galactic bulge. Its [Fe/H]= -0.46 according to the 2010 version of the Harris (1996) catalogue. Layden et al. (1999) and Pritzl et al. (2001) discovered that it had a significant number of RR Lyrae variables with relatively long periods, an unexpected result for such a metal rich cluster. NGC 6441 shares these properties with NGC 6388. Bellini et al. (2013) have examined the CM diagrams for both clusters and provided evidence that both clusters host at least two stellar populations. The RA and dec in the above table are from the following sources: V1-V104 from Samus et al. (2009), V105 to V145 from Pritzl et al. (2003), V146-V150 from Corwin et al. (2006) and V151-V199 from Skottfelt et al. (2015). The remaining data are from the following sources: V1-V36 from Layden et al. (1999), V37-V104 from Pritzl et al. (2001) V105-V148 from Pritzl et al. (2003) V151-V199 from Skottfelt et al. (2015) unless indicated otherwise in the Notes/Remarks column. "Ogle" in the Remarks column indicates that the period, magnitude, amplitude and classification are from the Ogle III Catalog of Long Period variables in the Galactic Bulge by Soszynski et al. (2013). The Ogle observations provided better coverage for long period variables than the other studies so they are included when available. Soszynski et al. (2011) also published a catalog of RR Lyrae variables in the Galactic Bulge which includes some of the RR Lyrae variables in NGC 6441, but their data have not been included here. V47, V48, V49, V50, V68 are listed in the Moscow GCVS as V1168, V1170, V1169, V1167 and V1166 Sco respectively. ================================================================ Notes on individual stars V1, V2: The periods, magnitudes, amplitudes and classifications for these stars are from Sloan et al. (2010). They published K-band light curves. V4: The variability status of V4 is uncertain. It showed no significant variations in the observations of Layden et al. (1999): mean V = 15.88, mean I =13.00 in May 1996 and mean V = 15.90, mean I = 13.00 in June 1996, while the other previously known variables showed variations of more than 0.5 mag in V. V4 was outside the field of view in subsequent studies. V6: The period, magnitude, amplitude and classification are from Pritzl et al. (2003). V7, V8: These two variables are considered to be field stars. Both lie outside the tidal radius which is 7.14 arcminutes according to the 2010 update to the Harris (1996) catalogue. V7 is Ogle #92539 and the period, magnitude and classification in the above table are from Soszynski et al. (2013). V47, V48, V50 Layden et al. (1999) concluded that these binary systems probably belonged to the foreground stellar populations. Rucinski (2000) deduced that the contact binaries V48 and V50 were not cluster members. V105: The period and classification are from Skottfelt et al. (2015). V118: The RR0 classification is from Skottfelt et al. (2015). In earlier studies, its classification was uncertain (either RR0 or CW). V130: The period is from Skottfelt et al. (2015) because the 48.90 day period of Pritzl et al. (2003) did not fit their data. The classification is uncertain V130 might be L or Sr. V133, V137: Pritzl et al. (2003) derived periods of 122.9 and 51.2 days respectively for these two variables, but they did not fit the observations of Skottfelt et al. (2015). V140: The 0.616 day period was derived by Corwin et al. (2006). They found that the 0.3518 period derived in their earlier study (Pritzl et al. 2003) did not fit their observations. V145: The RR01 (double mode) classification is from Skottfelt et al. (2015). V149, V150: The periods for these two stars were derived by Corwin et al. (2006). They were unable to establish unequivocally the Bailey types for these stars. Based on a plot of skewness versus phi21, they concluded that V140 and V149 might be RR1 and V150 might be RR0. =============================================================== Discovery of the variable stars in NGC 6441: V1-10 Fourcade et al. (1966) with x,y coordinates and an ID chart V7 and V8 have not been studied in subsequent investigations of NGC 6441 because they were outside the field of view. Both are considered to be field stars because they are outside the tidal radius. V11-12 = star #4427 and 4323 (suspected RR Lyrae variables) Hesser & Hartwick (1976) with ID chart The numbers V11 and V12 were assigned by Clement (1997) in the first electronic update of the Sawyer Hogg (1973) catalogue. Layden et al. (1999) did not confirm their variability. V13-50 Layden et al. (1999) with X,Y pixel numbers and individual finder charts Their observations were made on 3 nights in May and 8 nights in June 1996. As a result, they were able to identify many long period variables in their field, but they could not derive their periods. Some of these long period variables were included in the Ogle III catalog of long period variables in the Galactic Bulge (Soszynski et al. 2013) and for those stars, the Ogle data are listed in the above table. Layden et al. also published finder charts for 9 suspected variables SV1-9. Pritzl et al. (2001) found that SV1-5 and SV8 were variable and numbered them V68, V69, V80, V70, V71 and V51 respectively. SV9 was outside their field of view and they did not detect any variation in SV6 or SV7. However, in a later paper (Pritzl et al. 2003), they discovered that SV7 was a long period variable and assigned the number V105. V51-104 Pritzl et al. (2001) with x,y coordinates and ID charts They concluded that most of the binaries they discovered were not likely to be members of the cluster. Pritzl et al. also derived properties of 6 suspected variables which they numbered SV10-15 and labelled on finding charts. In a later study, Pritzl et al. (2003) confirmed the variability of SV14 and SV15 and assigned the numbers V106 and V140 respectively. V105-145 Pritzl et al. (2003) with RA, dec and individual finder charts V146-150 Corwin et al. (2006) with RA, dec V151-199 Skottfelt et al. (2015) with RA, dec and a finding chart ------------------------------------------------------------------- PSR: According to Paulo Freire's website, there are 4 pulsars in NGC 6441. (www.naic.edu/~pfreire/GCpsr.html) -------------------------------------------------------------------- U1 - the probable optical counterpart to the X-ray burster X1746-370 (4U 1746-37) according to Homer et al. (2002) who published its RA and dec. They concluded that it is probably an LMXB with a period of 5.73 hours. -------------------------------------------------------------------- Alonso-Garcia et al. (2013) announced that the VVV is surveying the central regions of the Milky Way at near-infrared wavelengths to look for variable stars, especially RR Lyrae, in globular clusters. NGC 6441 is one of the clusters in their study. ============================================================== References Alonso-Garcia, J., Dekany, I., Catelan, M., Contreras Ramos, R., Minniti, D. 2013, arXiv:1307.0419v1 Bellini, A., Piotto, G., Milone, A. P., King, I. R., Renzini, A., Cassisi, S., Anderson, J. and 3 coauthors, 2013, ApJ, 765, 32 Clement, C. M. 1997, AAS Newsletter, 84, 15 Corwin, T. M., Sumerel, A. N., Pritzl, B. J., Smith, H. A., Catelan, M., Sweigart, A. V., Stetson, P. B. 2006, AJ, 132, 1014 Fourcade, C. R., Laborde, J. R., Albarracin, J. 1966, Atlas y Catalogue de Estrellas Variables en Cumulos Globulares al sur de -29 degrees, Cordoba Harris, W. E. 1996, AJ, 112, 1487 Hesser, J. E. & Hartwick, F. D. A. 1976, ApJ, 203, 97 Homer, L., Anderson, S. F., Margon, B., Downes, R. A., Deutsch, E. W. 2002, AJ, 123, 3255 Layden, A. C., Ritter, L. A., Welch, D. L., Webb, T. M. A. 1999, AJ, 117, 1313 Pritzl, B., Smith, H. A., Catelan, M., Sweigert, A. V. 2001, AJ, 122, 2600 Pritzl, B., Smith, H. A., Stetson, P. B., Catelan, M., Sweigert, A. V., Layden, A. C., Rich, R. M. 2003, AJ, 126, 1381 Rucinski, S. M. 2000, AJ, 120, 319 Samus, N. N., Kazarovets, E. V., Pastukhova, E. N., Tsvetkova, T. M., Durlevich, O. V. 2009, PASP, 121, 1378 Skottfelt, J., Bramich, D. M., Figuera Jaimes, R., Jorgensen, U. G., Kains, N., Arellano Ferro, A., Alsubai, K. A. and 27 coauthors, 2015, A&A, 573, A103 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., Udalksi, A., Poleski, R., Szymanski, M. K., Kubiak, M., Pietrzynski, G. and 4 coauthors, 2011, Acta A., 61, 1 Soszynski, I., Udalksi, A., Szymanski, M. K., Kubiak, M., Pietrzynski, G., Wyrzykowski, L., Ulaczyk, K. and 3 coauthors, 2013, Acta A., 63, 21 ====================================================================