NGC 6712 / C1850-087 (Updated August 2021) RA: 18:53:04.30 DEC: -08:42:22.0 (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 18:52:59.85 −08:42:31.3 R0 0.5120 16.31 1.11 V RR0 MPSct 2 18:53:08.79 −08:41:56.8 R0 109.0 12.55 -- V SR Note;APSct 3 18:53:02.29 −08:43:47.4 R0 0.6560 16.24 0.57 V RR0 4 18:53:16.29 −08:42:38.1 R0 0.6117 16.47 0.56 V RR0 5 18:53:08.68 −08:43:24.1 R0 0.5454 16.41 1.14 V RR0 6 18:53:05.35 −08:42:53.6 R0 0.5109 16.45 0.86 V RR0 Bl 7 18:52:55.39 −08:42:32.6 R0 193.0 16.98 -- V M Note;CHSct 8 18:53:05.66 −08:41:12.4 R0 116.29 13.17 -- V SR Note;MRSct 9 18:53:03.59 -08:37:23.7 R0 ---- 16.80 -- P UG? f;max;Note 10 18:52:57.35 −08:41:43.9 R0 ---- 13.94 -- V L Note 11 18:52:56.34 -08:47:53.5 R0 1.2176 15.8 0.6 V E? f;max;Note 12 18:53:06.02 −08:41:33.4 R0 0.5028 16.30 1.21 V RR0 13 18:52:57.77 −08:41:46.5 R0 0.5627 16.13 1.02 V RR0 14 18:52:34.34 -08:41:45.1 R0 200.323 15.336 -- V SR f;Note;LRSct 15 18:53:20.99 −08:42:48.2 R0 ---- 13.83 -- V L Note;MWSct 16 18:52:54.55 -08:39:17.0 R0 ---- 14.98 -- V E? f;Note;LZSct 17 18:53:05.86 -08:41:23.4 R0 ---- 14.89 -- V CST? f;Note 18 18:53:02.44 −08:42:14.0 R0 0.3535 16.15 0.47 V RR1 19 18:53:03.22 −08:41:39.2 R0 0.4122 16.00 0.40 V RR1 20 18:53:04.16 −08:42:03.7 R0 0.2505 16.20 0.34 V RR1 21 18:52:58.80 −08:42:06.2 R0 ---- 13.58 -- V L LEM;MNSct 22 18:52:59.08 −08:41:20.5 R0 0.6548 16.17 0.58 V RR0 23 18:53:03.83 −08:42:39.4 R0 0.6425 16.23 0.31 V RR0 24 18:53:04.37 −08:42:26.9 R0 0.5765 16.23 0.99 V RR0 25 18:53:04.83 -08:42:20.9 R0 0.0143 19.56 0.19 U LMXB Note 26 18:53:06.80 −08:41:31.2 R0 0.3343 16.16 0.12 V RR1 27 18:53:08.88 -08:42:30.7 R0 0.4257 16.51 0.12 V EW f;Note 28 18:53:08.09 −08:40:52.2 R0 0.4345 18.23 0.26 V EW f 29 18:53:04.17 −08:42:25.0 R0 0.4536 18.45 – V EW f 30 18:53:02.51 −08:43:11.9 R0 0.5047 18.68 0.61 V EW 31 18:53:03.49 −08:40:34.4 R0 0.4188 18.53 0.40 V EW 32 18:52:59.32 −08:41:34.7 R0 31.1 13.72 -- V SRs amp>0.14 33 18:53:06.20 −08:42:43.2 R0 ---- 13.68 -- V SR amp>0.24 34 18:53:01.99 −08:42:18.8 R0 ---- 13.54 -- V SR amp>0.25 35 18:53:09.02 −08:41:12.4 R0 ---- 13.93 -- V SR amp>0.17 36 18:53:09.39 −08:43:12.9 R0 17.8 13.66 -- V SRs amp>0.22 ======================================================================= Supplementary Notes NGC 6712 is a moderately metal rich ([Fe/H]=-1.02) cluster located in a rich star field in the Scutum cloud. A CM diagram by Paltrinieri et al. (2001) shows a well populated blue straggler sequence and an HB that is predominantly red. According to the 2010 update to the Harris (1996) catalogue, its tidal radius is 8.5 arcminutes, but the CM diagram shows that field stars dominate at distances greater than 2.5 arcminutes from the cluster centre. The most comprehensive study of the vartiables in NGC 6712 was by Deras et al. (2020, hereafter Deras20). Their investigation included all of the variables except V9, V11, V14 and V25. Therefore, in the above table, all the data are from the Deras20 investigation unless indicated otherwise in the notes on individual stars. Some of the variables are listed in the Moscow GCVS. For these stars, the GCVS designation listed by Samus et al. (2009) is indicated in the remarks column. ====================================================================== Notes on individual stars V2: The 109 day period was derived by Sloan et al. (2010). V7: The period and classification are from Sloan et al. (2010). V8: The period and classification are from Rosino (1966). He commented that there might be a slow periodic variation of the period. The RA, dec and V magnitude are from Deras20. They noted that the V amplitude is greater than 0.48 mag V9: This star was not measured by Deras et al. because it was outside their field of view. From GAIA data, they determined that it is not a cluster member. The RA and dec are from Samus et al. (2009). In her discovery paper, Sawyer (1953) indicated maximum and minimum photographic magnitudes of 16.4 and fainter than 17.4 Rosino (1966) carried out a more detailed analysis and concluded that V9 is probably a foreground UGem variable. His observations indicated m_pg = 16.8 at maximum light (which is the value listed in the above table) and approximately 19.0 mag at mminimum. He also noted that the star was at minimum more frequently than at maximum. Sandage et al. (1966) commented that the star was extremely blue and might be a field UGem variable. They did not have enough good images to publish reliable magnitudes. However, Sesar et al. (2017) classified the star as an RR Lyrae with a period of 0.70 days from the PSI survey. This classification was made by machine and the period was derived by fitting to a template. Since Rosino (1966) was a skilled observer who carefully examined his observations, V9 is tentatively classified as UGem. Stetson et al. (2019) published B=18.545, V=18.040, I=17.452, and a large variability index of 27.5, thus confirming that the star is variable. Their mean B magnitude is consistent with the m_pg values derived by Rosino (1966). V10: Sandage et al. (1966) derived a period of 174 days and Russev (1975) found that P=71.2 days gave a better fit. However, Rosino (1966) found that the star showed irregular fluctuations and was unable to derive a period. The classification in the above table is from Rosino. Whitelock (1986) commented that V10 is probably a mode switching star. Deras20 showed that the V ampltude is greater than 0.21 mag. V11: This star was not measured by Deras20 because it was near the lower boundary of their reference image. From GAIA data, they found that it is not a cluster member. The RA and dec are from Samus et al. (2009). Sandage et al. (1966) commented that V11 might be an eclipsing binary, but its great distance form the cluster centre precluded membership. The binary classification was confirmed by Heinze et al. (2018). They detected V11 in their ATLAS survey and classified it as a detached binary. Their published period (0.608791 days) is the half period. The V mag and amplitude listed are from Sandage et al. (1966) and the period is from Heinze et al. (2018) V14: This star was not measured by Deras20 because it was outside their field of view. From GAIA data, they determined that it is not a cluster member. The RA and dec are from Samus et al. (2009). Rosino (1966) commented that V14 showed a semiregular fluctuation with a mean period of 202.2 days, mean photographic magnitude and amplitude of 16.6 and 2.6 mag respectively and that it was probably a field star. V14 was also classified as an SR variable, with a period of 200.3233 days, in the ASAS-SN survey (Jayasinghe et al. 2018) and according to the UBVRI photometry of Stetson et al. (2019), the star is highly variable. In the above table, the V magnitude is the value listed by Stetson et al. (2019) and the period is the one derived by Jayasinghe et al. (2018). V15: The classification for V15 is form Rosino (1966). The remaining data are from Deras20 who found that its V amplitude was greater than 1.5 mag. V16: In the discovery paper, Harwood (1962) classified this star (#411) as an eclipsing binary. Rosino (1966) concurred and concluded that it undoubtedly belongs to the field. He observed 3 times of minimum. The field status was confirmed by Deras20 based on data from Gaia DR2. The V magnitude listed above is from their study. They found that the V amplitude was greater than 0.06 mag. However, they did not classify the star or derive a period. V17: Harwood (1962) classified this star as a possible variable. It is listed as NSV 11462 in the Moscow GCVS who cited Harwood's (1962) data. They did not list a variability type. However, neither Sandage et al. (1966) nor Rosino (1966) detected any variability. We therefore conclude it is probably not variable. The proper motion study of Cudworth (1988) indicates that it is a field star. Deras20 reached the same conclusion from their analysis of GAIA data. The V magnitude listed above is from their study. Their data indicated a V amplitude that was greater than 0.24 mag. V25: This variable was not included in the investigation of Deras20 because it was below the limit of their photometry. All of the data are from the paper by Pietrukowicz & Kaluzny (2004), V27: In their discovery paper, Pietrukowicz & Kaluzny (2004), classified this star as an RR1 variable with an unstable light curve. However, Deras20 found that the star was an eclipsing (EW) variable and that it is not a cluster member. ======================================================================= Discovery of the variable stars in NGC 6712: V1 Davis (1917) with x,y coordinates V2 = AP Sct Oosterhoff (1943) with 1900 RA & dec and a finder chart The number V2 was assigned by Sawyer (1953). V3-12 Sawyer (1953) with x,y coordinates and an ID chart for V1-12 She also announced a field variable which she called F1. F1 was later designated as V14 by Sandage et al. (1966). V13 = #144 of Harwood (1962) who derived RA & dec (1900) The number V13 was assigned by Sandage et al. (1966) who published x,y coordinates and an ID chart V14-15 = #131, #160 of Harwood (1962) who derived RA & dec (1900) The numbers V14 and V15 were assigned by Sandage et al. (1966) who published x,y coordinates. They also pointed out that V14 is star F1 of Sawyer (1953). V14 and V15 were labelled on the finding chart published by Sandage & Smith (1966). V16-17 = #141, #151 of Harwood (1962) who derived RA & dec (1900) The numbers V16 and V17 were assigned by Sandage et al. (1966) who published x,y coordinates and an ID chart. However, neither Sandage et al. (1966) nor Rosino (1966) detected variability in V17. V18-20 Sandage et al. (1966) with x,y coordinates and an ID chart V21 = L18 of Lloyd Evans & Menzies (1973) The number V21 was assigned by Sawyer Hogg (1973) in her 3rd catalogue. Lloyd Evans & Menzies (1977) published an ID chart and Samus et al. (2009) derived the RA and dec based on the ID chart. V22 = KC460 of Cudworth (1988) who published x,y coordinates and stated that the star exhibited low amplitude variability (see page 113). The number V22 has been assigned in this catalogue. V23-24 = P1 & P2 of Tuairisg et al. (2003) who published RA, dec (see page 965) and an ID chart (page 964). The numbers V23 and V24 have been assigned in this catalogue. V25 = NGC6712_01 of Pietrukowicz & Kaluzny (2004) who published RA and dec. This star is the optical counterpart of the X-ray source X1850-087 and its optical variability was originally detected by Homer et al. (1996) from HST U filter observations. The number V25 has been assigned in this catalogue. V26-29 = NGC6712_06, _07, _08, _09) of Pietrukowicz & Kaluzny (2004) who published RA and dec. Pietrukowicz & Kaluzny (2004) recovered 4 additional variables that were previously known: NGC6712_02=V20, NGC6712_03=V12, NGC6712_04=V19, and NGC6712_05=V24. The numbers V26 to V29 have been assigned in this catalogue. V30-36 Deras20 with RA, dec and ID charts They also announced a candidate SR variable with position: RA = 18:53:02.30 and dec = −08:42:38.4 and 12 variables in the field. Three of the field variables were the previously known variables, V16, V17 and V27 and nine were new ones which they numbered FV1 to FV9. ==================================================================== References Cudworth, K. M. 1988, AJ, 96, 105 Davis, H. 1917, PASP, 29, 260 Deras, D., Arellano Ferro, A., Lazaro, C., Bustos Fierro, I. H., Calderon, J. H., Muneer, S., Giridhar, S. 2020, MNRAS, 493, 1996 Harwood, M. 1962, Leiden Ann., 21, p.387 Heinze, A. N., Tonry, J. L., Denneau, L., Flewelling, H., Stalder, B., Rest, A., Smith, K. W. and 2 coauthors, 2018, AJ, 156, Homer, L., Charles, P. A., Naylor, T., van Paradijs, J., Auriere, M., Koch-Miramond, L. 1996, MNRAS, 282, L37 Jayasinghe, T., Kochanek, C. S., Stanek, K. Z., Shappee, B. J., Hololen, T. W.-S., Thompson, T. A., Prieto, J.L. and 7 coauthors, 2018, MNRAS, 477, 3145 Lloyd Evans, T. & Menzies, J. W. 1973, in IAU Colloq. No. 21, Variable Stars in Globular Clusters and in Related Systems, 151 Lloyd Evans, T. & Menzies, J. W. 1977, MNRAS, 178, 163 Oosterhoff, P. Th. 1943, BAN, 9, 399 (see pp 411-412) Paltrinieri, B., Ferraro, F. R., Paresce, F., De Marchi, G. 2001, AJ, 121, 3114 Pietrukowicz, P. & Kaluzny, J. 2004, AcA, 54, 19 Rosino, L. 1966, ApJ, 144, 903 Russev, R. M. 1975, in IAU Symp. No. 67, Variable Stars and Stellar Evolution, 563 Sandage, A. & Smith, L. L. 1966, ApJ, 144, 886 Sandage, A., Smith, L. L., Norton, R. H. 1966, ApJ, 144, 894 Sawyer, H. B. 1953, JRASC, 47, 229 Sawyer Hogg, H. 1973, Publ. DDO, 3, No. 6 Sesar, B., Hernitschek, N., Mitrovic, S., Ivezic, Z., Rix, H.-W., Cohen, J., Bernard, E. J. and 12 coauthors, 2017, AJ, 153, 204 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 Stetson, P. B., Pancino, E., Zocchi, A., Sanna, N., Monelli, M. 2019, MNRAS, 485, 3042 Tuairisg, S. O., Butler, R. F., Shearer, A., Redfern, R. M., Butler, D., Penny, A. 2003, MNRAS 345, 960 Whitelock, P. A. 1986, MNRAS, 219, 525 ==================================================================