NGC 7006 / C2059+160 (Updated October 2015) RA: 21:01:29.38 DEC: +16:11:14.4 (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 21:01:16.84 +16:13:06.7 R0 0.4927 18.848 1.1 V RR0 2 21:01:26.70 +16:10:34.1 R0 0.5870 18.838 0.8 V RR0 3 21:01:27.51 +16:11:46.0 R0 0.5606 18.977 0.9 V RR0 4 21:01:27.7 +16:10:30 R0 ---- -- -- CST 5 21:01:27.72 +16:11:50.0 R0 0.5333 18.696 0.6 V RR0 6 21:01:28.24 +16:10:27.1 R0 0.4980 18.957 1.2 V RR0 7 21:01:29.43 +16:10:34.4 R0 ---- -- -- CST 8 21:01:31.59 +16:11:24.7 R0 0.5643 18.898 0.7 V RR0 9 21:01:32.06 +16:11:29.1 R0 ---- -- -- CST 10 21:01:32.12 +16:10:59.6 R0 0.5429 18.875 0.9 V RR0 11 21:01:39.50 +16:12:01.9 R0 0.5760 18.816 1.0 V RR0 12 21:01:37.63 +16:10:07.6 R0 0.5740 18.833 0.6 V RR0 13 21:01:36.31 +16:11:51.1 R0 0.5516 18.866 0.8 V RR0 14 21:01:31.65 +16:13:19.8 R0 0.5604 18.868 0.9 V RR0 15 21:01:28.42 +16:13:06.2 R0 0.5881 18.820 0.8 V RR0 16 21:01:26.48 +16:13:26.7 R0 0.5376 18.883 0.9 V RR0 17 21:01:22.30 +16:12:31.5 R0 0.5115 18.768 1.0 V RR0 18 21:01:27.15 +16:09:42.1 R0 0.6037 18.865 0.6 V RR0 19 21:01:29.17 +16:10:46.3 R0 92.17 15.65 0.5 V SR RC 20 21:01:27.74 +16:10:47.5 R0 0.5775 18.801 0.7 V RR0 21 21:01:27.72 +16:10:53.7 R0 0.6126 18.913 0.5 V RR0 22 21:01:28.31 +16:10:56.2 R0 0.5269 18.900 1.0 V RR0 23 21:01:27.32 +16:11:04.5 R0 0.6079 18.639 0.8 V RR0 24 21:01:27.43 +16:11:08.7 R0 0.6272 18.195 0.4 V RR0 Blend 25 21:01:27.83 +16:11:16.7 R0 0.5432 18.560 0.9 V RR0 26 21:01:28.44 +16:11:08.6 R0 0.5407 18.628 0.9 V RR0 27 21:01:28.38 +16:11:11.9 R0 0.5641 18.238 0.7 V RR0 28 21:01:28.12 +16:11:17.6 R0 0.4970 18.867 1.4 V RR0 29 21:01:31.65 +16:11:43.1 R0 0.5592 18.827 1.0 V RR0 30 21:01:29.47 +16:11:28.6 R0 ---- -- -- CST? Note 31 21:01:29.85 +16:11:22.2 R0 0.5631 18.431 1.0 V RR0 32 21:01:30.62 +16:11:25.3 R0 0.5627 18.650 0.7 V RR0 33 21:01:31.32 +16:11:33.5 R0 0.5568 18.526 0.7 V RR0 34 21:01:30.84 +16:11:15.0 R0 19.030 0.55 V CST Note 35 21:01:31.66 +16:11:08.9 R0 0.5963 18.849 0.7 V RR0 36 21:01:30.94 +16:11:07.6 R0 0.2770 19.05 0.5 B RR1 W92 37 21:01:30.50 +16:11:08.1 R0 0.5679 18.93 1.05 P RR0 PR 38 21:01:30.65 +16:10:52.9 R0 0.6244 18.383 1.0 V RR0 39 21:01:29.99 +16:10:46.4 R0 0.5785 18.824 0.7 V RR0 40 21:01:29.83 +16:10:57.1 R0 ---- -- -- ? Note 41 21:01:29.28 +16:11:00.4 R0 0.5669 19.16 1.0 B RR0 W92 42 21:01:29.83 +16:11:04.0 R0 ---- -- -- ? Note 43 21:01:28.92 +16:10:42.8 R0 0.5966 18.865 0.7 V RR0 44 21:01:38.89 +16:08:17.7 R0 0.5878 18.831 0.6 V RR0 45 21:01:15.96 +16:09:54.8 R0 0.5839 18.851 0.85 V RR0 46 21:01:20.52 +16:10:15.8 R0 0.6676 18.957 0.5 V RR0 47 21:01:16.44 +16:10:47.9 R0 0.5683 19.147 0.9 B RR0 48 21:01:22.35 +16:12:43.1 R0 0.6120 18.813 0.6 V RR0 49 21:01:29.81 +16:11:53.3 R0 0.5819 18.876 0.9 V RR0 50 21:01:26.36 +16:11:04.7 R0 0.5904 18.807 1.0 V RR0 51 21:01:33.29 +16:11:59.2 R0 0.6438 18.792 0.5 V RR0 52 21:01:29.36 +16:12:38.3 R0 0.6217 18.823 0.65 V RR0 53 21:01:32.57 +16:11:02.7 R0 0.3577 18.662 0.45 V RR1 54 21:01:29.46 +16:10:42.0 R0 ---- 15.85 0.5 V L SW;Note 55 21:01:12.40 +16:16:13.9 R0 0.5377 19.22 1.25 B RR0 W92 56 21:01:28.42 +16:10:59.6 R0 0.5497 19.21 0.8 B RR0 W92 57 21:01:28.75 +16:10:59.3 R0 0.3519 18.956 0.5 V RR0 58 21:01:30.23 +16:11:27.5 R0 0.5150 19.15 0.6 P RR0 PR 59 21:01:30.98 +16:11:20.3 R0 0.4810 18.919 0.9 V RR0 60 21:01:28.46 +16:11:19.4 R0 0.3858 18.787 0.6 V RR1 61 21:01:26.87 +16:11:31.7 R0 0.5891 18.861 1.0 V RR0 62 21:01:27.70 +16:11:15.0 R0 0.3469 18.802 0.5 V RR0 63 21:01:30.20 +16:11:33.0 R0 0.5280 18.93 1.15 P RR0 PR 64 21:01:30.63 +16:11:16.7 R0 0.3131 18.705 0.5 V RR1 65 21:01:28.59 +16:11:21.8 R0 ---- 19.10 0.8 P RR0 PR;Note 66 21:01:31.09 +16:11:07.9 R0 0.6172 19.13 0.75 P RR0 PR 67 21:01:28.21 +16:11:11.0 R0 0.3175 19.15 0.6 P RR1 PR 68 21:01:30.14 +16:11:16.0 R0 ---- 19.05 0.9 P RR? PR 69 21:01:29.87 +16:11:14.8 R0 ---- 19.10 0.4 P RR? PR 70 21:01:29.80 +16:11:10.9 R0 ---- 18.630 0.45 P ? PR;Note 71 21:01:28.97 +16:10:57.9 R0 0.3483 18.558 0.6 V RR1 72 21:01:30.96 +16:11:09.8 R0 ---- 19.10 0.6 P RR1 PR;Note 73 21:01:28.17 +16:11:12.2 R0 0.5780 18.85 0.9 P RR0 PR 74 =V41;Note 75 21:01:39.29 +16:08:29.3 R0 ---- -- -- ? Note 76 21:01:29.80 +16:11:24.2 R0 0.5617 18.499 0.6 V RR0 ============================================================ Supplementary Notes The remote globular cluster NGC 7006 was one of the first clusters known to exhibit the "second parameter" effect. Although it is relatively metal poor, with [Fe/H] = -1.52 according to the 2010 update of the Harris (1996) catalogue, the predominance of red stars on its horizontal branch is characteristic of a more metal rich cluster. The most recent and comprehensive investigation of the variable stars in NGC 7006 was by Wehlau et al. (1999). In the above table, the RA and dec are from Samus et al. (2009). The remaining data are from Wehlau et al. (1999) unless indicated otherwise in the remarks column where SW refers to Sandage & Wildey (1967) RC refers to Rosino & Ciatti (1967) PR refers to Pinto & Rosino (1973) W92 refers to Wehlau et al. (1992) ================================================================= Notes on individual stars V30: Wehlau et al. (1999) questioned the variability of this star because it lies in a crowded region. They suggested that its image might be blended with that of a red giant. V34, V59: Gerashchenko (2006) noted that the x,y coordinates listed for these two stars in the electronic catalogue (Clement et al. 2001) and in Sawyer Hogg's (1973) catalogue were practically the same. He pointed out that the x,y coordinates for V34 were incorrect because they did not correspond to the chart position published by Wehlau et al. (1992). The source of this problem can be traced to the paper that Sandage (1954) prepared, based on notes made by Hubble. The location of V34 on the chart Sandage published does not agree with the x,y coordinates he published. In subsequent investigations, authors assumed that V34 was the star labelled on Sandage's (1954) chart and it was considered to be non-variable. Consequently, Rosino & Ciatti (1967) announced V59 as a new variable. In the above table, the numbering system of Rosino & Ciatti is used. V40: Wehlau et al. (1999) were unable to obtain many good measures for this star, but comment that it is too red to be an RR Lyrae star. Rosino & Ciatti (1967) also noted that V40 is not an RR Lyrae variable. V41, V74: V41 and V74 are the same star. This was recognized by Wehlau et al. (1992). They consulted Rosino (who discovered V74) and he confirmed this in a private communication in 1991. V42: According to Wehlau et al. (1999), no data have ever been published for this star which is situated in a very crowded region of the cluster. V49: Gerashchenko pointed out that x,y should be +8.62,+41.85. They were previously listed as +4.8,+40.5. V54: Rosino & Ciatti (1967) and Wehlau et al. (1999) confirmed the classification of Sandage & Wildey (1967) for this star. It lies near the RG tip in the CM diagram and its variations appear to be irregular. No one has been able to detrive a period. V65: Wehlau et al. (1999) could not obtain accurate magnitudes. Pinto & Rosino listed two possible periods: 0.544081 and 0.515043 days. V70: This star is very close to the cluster centre. According to Pinto & Rosino (1973), it is probably not an RR Lyrae variable. V72: Wehlau et al. (1999) could not obtain accurate magnitudes. Pinto & Rosino listed two possible periods: 0.2610439 and 0.318936 days. V75: Wehlau et al. (1999) did not detect any short term variations in this star, but found that it varied from year to year with B magnitudes ranging from 18.74 to 19.25. They noted that it is farther from the cluster centre than most of the other variables and might be a field star. Rosino & Ciatti (1967) also concluded that V75 is probably not an RR Lyrae variable. ================================================================= Discovery of the variable stars in NGC 7006: V1-11 Shapley & Mayberry (1921) with x,y coordinates They noted that V2 and V5 had been announced previously by Shapley (1920). In the earlier study, V5 was numbered V1. V12-43 Discovered by Hubble and reported by Sandage (1954) with x,y coordinates and an ID chart, based on Hubble's unpublished notes The origin of his x,y coordinate system differed from that of Shapley & Mayberry by a small amount. Sawyer (1955) published the conversion. Hubble also recovered 8 of Shapley's 11 variables. He concluded that V4 and V7 were not variable and that the variabiity of V9 was questionable. V44-52 Rosino & Mannino (1955) with x,y coordinates and an ID chart Mannino (1957) derived periods for many of the variables, but did not discover any new ones V53-54 Sandage & Wildey (1967) with ID chart Many of the other known variables were also labelled on their chart. Rosino & Ciatti (1967) published x,y coordinates for V53-54 V55-75 Rosino & Ciatti, Asiago Contr 199 (1967) V76 Wehlau et al. (1992) with ID chart x,y coordinates were later derived by Gerashchenko (1999). --------------------------------------------------------------------- Gerashchenko (2006) announced two additional RR Lyrae candidates based on their location in the BV and VR CM diagrams. He derived their x,y, coordinates and published an ID chart. He assigned the numbers V77 and V78 and listed V amplitudes of 0.2 and 0.25 mag respectively. No periods were determined. ====================================================================== References Clement, C. M., Muzzin, A., Dufton, Q., Ponnampalam, T., Wang, J., Burford, J., Richardson, A., Rosebery, T. 2001, AJ, 122, 2587 Gerashchenko, A. N. 2006, Per. Zvez., 26, No. 1 Harris, W. E. 1996, AJ, 112, 1487 Mannino, G. 1957, Asiago Contr. 84 = Mem. SAI, 28, 185 Pinto, G. & Rosino, L. 1973, Mem. SAI, 44, 255 Rosino, L. & Ciatti, F. 1967, Asiago-Padova Cont., 199 Rosino, L. & Mannino, G. 1955, Asiago Contr. 59 = Mem. SAI, 26, 275 Sandage, A. & Wildey, R. 1967, ApJ, 150, 469 Sawyer, H. B. 1955, Publ. DDO, 2, No. 2 Sawyer Hogg, H. 1973, Publ. DDO, 3, No. 6 Shapley, H. 1920, ApJ, 52, 73 Shapley, H. & Mayberry, B. 1921, Proc. Nat. Acad. Sci., 7, 152 Wehlau, A., Nemec, J. M., Hanlan, P., Rich, R. M. 1992, AJ, 103, 1583 Wehlau et al., 1999, AJ, 117, 286