NGC 7006 / C2059+160 (Updated October 2024) 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 21:01:16.81 +16:13:07.1 R0 0.4927 18.901 1.121 V RR0 2 21:01:26.73 +16:10:34.9 R0 0.5870 18.916 0.961 V RR0 3 21:01:27.48 +16:11:46.2 R0 0.5596 18.943 0.806 V RR0 4 21:01:27.7 +16:10:30 R0 ---- -- -- CST Note 5 21:01:27.74 +16:11:50.4 R0 0.5351 18.839 0.832 V RR0 6 21:01:28.23 +16:10:27.6 R0 0.4981 19.005 1.109 V RR0 7 21:01:29.43 +16:10:34.4 R0 ---- -- -- CST Note 8 21:01:31.58 +16:11:25.6 R0 0.5643 19.097 0.913 V RR0 9 21:01:32.06 +16:11:29.1 R0 ---- -- -- CST Note 10 21:01:32.15 +16:11:00.3 R0 0.5420 18.492 0.920 V RR0 11 21:01:39.53 +16:12:02.4 R0 0.5760 18.958 0.864 V RR0 12 21:01:37.64 +16:10:08.0 R0 0.5741 18.902 0.755 V RR0 13 21:01:36.31 +16:11:51.7 R0 0.5516 18.953 0.990 V RR0 14 21:01:31.65 +16:13:20.1 R0 0.5604 18.958 0.917 V RR0 15 21:01:28.41 +16:13:06.5 R0 0.5881 18.883 0.852 V RR0 16 21:01:26.47 +16:13:27.2 R0 0.5376 18.858 1.170 V RR0 17 21:01:22.28 +16:12:31.9 R0 0.5115 18.934 1.104 V RR0 18 21:01:27.13 +16:09:42.6 R0 0.6037 18.955 0.764 V RR0 19 21:01:29.18 +16:10:46.7 R0 41.0 15.601 -- V SR 20 21:01:27.73 +16:10:47.7 R0 0.5775 18.961 0.861 V RR0 21 21:01:27.72 +16:10:53.8 R0 0.6125 18.910 0.786 V RR0 22 21:01:28.31 +16:10:56.4 R0 0.5269 18.935 1.048 V RR0 23 21:01:27.29 +16:11:04.4 R0 0.6069 18.797 0.876 V RR0 24 21:01:27.40 +16:11:09.1 R0 0.6094 18.356 0.396 V RR0 f?;Note 25 21:01:27.83 +16:11:17.1 R0 0.5432 18.844 0.913 V RR0 26 21:01:28.44 +16:11:08.6 R0 0.5407 18.628 0.9 V RR0 Note;W99 27 21:01:28.38 +16:11:12.3 R0 0.5647 18.257 0.582 V RR0 f 28 21:01:28.13 +16:11:17.9 R0 0.4991 19.012 1.191 V RR0 Note 29 21:01:31.6 +16:11:43.4 R0 0.5592 18.975 0.976 V RR0 30 21:01:29.56 +16:11:28.8 R0 0.5690 18.634 0.661 V RR0 f?;Note 31 21:01:29.88 +16:11:23.3 R0 0.5626 18.901 0.966 V RR0 32 21:01:30.65 +16:11:26.0 R0 0.5627 18.756 0.733 V RR0 33 21:01:31.39 +16:11:34.5 R0 0.5568 19.032 0.997 V RR0 34 21:01:30.89 +16:11:15.5 R0 0.9088 17.884 -- V EW? Note 35 21:01:31.70 +16:11:09.7 R0 0.5963 18.983 0.727 V RR0 36 21:01:30.94 +16:11:07.6 R0 0.2770 19.05 0.5 B RR1 Note;W92 37 21:01:30.50 +16:11:08.1 R0 ---- -- -- RR? Note 38 21:01:30.68 +16:10:53.6 R0 0.6223 18.837 0.830 V RR0 39 21:01:29.99 +16:10:46.4 R0 0.5785 18.824 0.7 V RR0 Note;W99 40 21:01:29.83 +16:10:57.1 R0 ---- -- -- CST Note 41 21:01:29.30 +16:11:00.8 R0 0.5663 18.635 0.762 V RR0 f;Note 42 21:01:29.86 +16:11:04.4 R0 0.7466 18.458 -- V RR0 f 43 21:01:28.93 +16:10:43.4 R0 0.5966 18.944 0.622 V RR0 44 21:01:38.90 +16:08:18.1 R0 0.5878 18.910 0.727 V RR0 45 21:01:15.95 +16:09:55.7 R0 0.5838 18.903 0.752 V RR0 46 21:01:20.51 +16:10:16.3 R0 0.6689 18.872 0.318 V RR0 47 21:01:16.41 +16:10:48.3 R0 0.5675 18.949 0.653 V RR0 48 21:01:22.33 +16:12:43.7 R0 0.6120 18.967 0.718 V RR0 49 21:01:29.78 +16:11:53.8 R0 0.5819 18.984 0.859 V RR0 50 21:01:26.37 +16:11:04.9 R0 0.5903 18.919 0.835 V RR0 51 21:01:33.26 +16:11:59.1 R0 0.6438 18.977 0.439 V RR0 52 21:01:29.36 +16:12:38.7 R0 0.6217 18.938 0.550 V RR0 53 21:01:32.56 +16:11:03.2 R0 0.2602 18.837 0.248 V RR1 54 21:01:29.46 +16:10:42.4 R0 30.7 16.081 -- V L 55 21:01:12.40 +16:16:13.9 R0 0.5377 19.22 1.25 B RR0 Note;W92 56 21:01:28.45 +16:10:59.9 R0 0.5474 19.086 1.097 V RR0 57 21:01:28.76 +16:10:59.9 R0 0.3519 18.956 0.630 V RR0 58 21:01:30.27 +16:11:28.2 R0 0.7437 18.851 0.256 V RR0 59 21:01:31.01 +16:11:21.0 R0 0.4810 18.975 1.093 V RR0 Note 60 21:01:28.46 +16:11:19.7 R0 0.6266 18.913 0.611 V RR0 61 21:01:26.66 +16:11:32.1 R0 0.5891 18.816 1.025 V RR0 62 21:01:27.70 +16:11:15.5 R0 0.3469 18.873 0.439 V RR0 63 21:01:30.22 +16:11:33.8 R0 0.5472 18.800 0.957 V RR0 64 21:01:30.68 +16:11:17.5 R0 0.3064 18.877 0.386 V RR1 65 21:01:28.63 +16:11:22.2 R0 0.5588 18.776 0.563 V RR0 66 21:01:31.09 +16:11:08.5 R0 0.3611 18.452 0.339 V RR0 Note 67 21:01:28.21 +16:11:11.3 R0 0.5549 18.508 0.408 V RR0 f 68 21:01:30.18 +16:11:16.9 R0 0.5557 19.015 0.995 V RR0 69 21:01:29.89 +16:11:15.7 R0 0.6566 19.422 1.466 V RR0 f 70 21:01:29.81 +16:11:12.4 R0 11.7 16.680 -- V CW? 71 21:01:28.99 +16:10:58.3 R0 0.3352 18.703 0.494 V RR1 f 72 21:01:30.96 +16:11:09.8 R0 ---- -- -- RR? Note 73 21:01:28.18 +16:11:12.7 R0 0.5550 18.129 0.566 V RR0 f 74 =V41;Note 75 21:01:39.30 +16:08:29.9 R0 13.5071 18.628 0.121 V CW? f? 76 21:01:29.84 +16:11:24.8 R0 0.5663 19.118 1.240 V RR0 77 21:01:24.24 +16:11:52.7 R0 0.3172 19.044 0.086 V RR1 78 21:01:28.26 +16:11:18.0 R0 0.3322 18.805 0.261 V RR1 79 21:01:28.68 +16:11:03.0 R0 0.5989 19.055 0.804 V RR0 80 21:01:29.43 +16:10:56.9 R0 0.5418 19.181 0.119 V RR0 81 21:01:29.44 +16:11:15.6 R0 4.63 17.888 -- V CW 82 21:01:26.78 +16:11:30.6 R0 14.01 16.455 -- V SR 83 21:01:29.77 +16:11:15.1 R0 18.68 15.934 -- V SR 84 21:01:29.98 +16:11:02.9 R0 10.22 16.266 -- V SR 85 21:01:30.80 +16:11:23.9 R0 8.37 15.858 -- V SR 86 21:01:31.33 +16:11:13.9 R0 36.14 16.215 -- V SR ============================================================ 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 Arellano Ferro et al. (2023). The data in the above table are from their study except for a few cases where the stars' images were unresolved or outside of their field of view. For these stars, the RA and dec are from Samus et al. (2009) and the source for the remaining data is indicated in the remarks column: W92 refers to Wehlau et al. (1992) W99 refers to Wehlau et al. (1999). ================================================================= Notes on individual stars V4, V7, V9: Sandage (1954) reported that Hubble concluded that V4 and V7 were probably not variable and that the variabiity of V9 was questionable. Wehlau et al. (1999) later confirmed that V4, V7 and V9 were not significantly variable. The RA and dec listed for these stars are from Samus et al. (2009). V24: AF23 commented that this might be a foreground star. V26: AF23 did not measure this star because it was in a crowded region. W92 derived a period of 0.540695 days from photographic (B) observations and noted that it agreed with an alternate period derived by Pinto & Rosino (1973, hereafter PR73). W99 subsequently derived V magnitudes from CCD data and these are listed in the above table. The RA and dec are from Samus et al. (2009). V28: AF23 derived two periods for this star: 0.49914 and 0.33213 days respectively, which are aliases. Both are close to a fraction of a day (one half and one third respectively), and because of this, it was not possible to obtain adequate phase coverage to determine which was correct. However, the location of the star on the period-amplitude relation indicates that it is probably pulsating in the fundamental mode. Thus the 0.499 day period is the correct one. Furthermore W99 also concluded that V28 is a fundamental mode pulsator. The star exhibits the Blazhko effect. 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. However, AF23 were able to detect the variability with their images and showed that the star's RA is 1.3 arcseconds east of its previously published position. V34, V59: Gerashchenko (2006) noted that the x,y coordinates listed for these two stars in Sawyer Hogg's (1973) catalogue and also in an earlier version of this electronic 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 was traced to the paper that Sandage (1954) prepared, based on notes made by Hubble. The location of V34 on the chart Sandage published did 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. This is the star listed as V59 in the above table, and the data are from AF23. Meanwhile AF23 tentatively classified V34 as a possible binary (EW) and noted that it was located on the RGB in the CM diagram. V36: In their CCD observations, AF23 found that this star formed a close group with V66 and V72 and as a result, their images were badly blended. They were able to obtain a reasonable light curve for V66, but not the others. On the other hand, in independent studies based on photographic observations, W92 and PR73 both derived a period of 0.2770 and mean B magnitude of 19.05 for V36. Their result is listed in the above table. The RA and dec are from Samus et al. (2009). V37: AF23 did not measure this star because it was in a crowded region. No period is listed for this star in the above table. PR73 derived a period of 0.567923 days, but W92 could not confirm it with their data and could not derive any other period that fit all the data. The RA and dec are from Samus et al. (2009). V39: AF23 did not measure this star because it was in a crowded region. The period listed above (0.57845 days) was derived by W99 and is in good agreement (0.001 days) with the period derived earlier by PR73. The RA and dec are from Samus et al. (2009). V40: Wehlau et al. (1999) were unable to obtain many good measures for this star, but commented that it was too red to be an RR Lyrae variable. Rosino & Ciatti (1967) also noted that V40 is not an RR Lyrae. Arellano Ferro et al. (2023) did not detect any variability in their data so it is classified as CST in the above table. The RA and dec are from Samus et al. (2009). 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. V55: AF23 did not measure this star because it was outside of their field of view. The period, magnitudes and classification in the above table are from W92. The RA and dec are from Samus et al. (2009). V66: AF23 found that their images of this star were badly blended with V36 and V72. V66 was the only star of the group for which they could isolate a reasonable light curve. On the other hand, W99 were unable to obtain to obtain any CCD measurements for V66 and V72, but in their earlier photographic study (W92), they obtained photographic magnitudes and derived a period for V36. V72: Wehlau et al. (1999) could not obtain accurate magnitudes. AF23 found that its images were badly blended with V36 and V66. PR73 listed two possible periods: 0.2610439 and 0.318936 days. Thus it might be an RR1 variable, but its period is uncertain. The RA and dec are from Samus et al. (2009). ================================================================= 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 (1967) with an ID chart and x,y coordinates V76 Wehlau et al. (1992) with ID chart x,y coordinates were later published by Gerashchenko (2006). V77-86 Arellano Ferro et al. (2023) with RA, dec (J2000) and an ID chart. --------------------------------------------------------------------- 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. AF23 identified these two stars in their photometry and found them to be non-variable. ====================================================================== References Arellano Ferro, A., Rojas Galindo, F. C., Bustos Fierro, I. H., Muneer, S., Yepez, M. A., Giridhar, S. 2023, MNRAS, 519, 2451 (AF23) 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 (PR73) Rosino, L. & Ciatti, F. 1967, Asiago-Padova Cont., 199 Rosino, L. & Mannino, G. 1955, Asiago Contr. 59 = Mem. SAI, 26, 275 Samus, N. N., Kazarovets, E. V., Pastukhova, E. N., Tsvetkova, T. M., Durlevich, O. V. 2009, PASP, 121, 1378 Sandage, A. 1954, PASP, 66, 324 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 (W92) Wehlau, A., Slawson, R. W., Nemec, J. M. 1999, AJ, 117, 286 (W99)