NGC 5946 / C1531-504 RA: 15:35:28.52 DEC: -50:39:34.8 (J2000) (Most recent updates: Membership probability flag - 2024; Remaining data - January 2025) ============================================================ Bytes Format Explanation 1-8 A8 Star ID 10-32 A11,1x,A11 Position 34-35 A2 Membership probability flag based on data published by Prudil & Arellano Ferro (2024) m1: prob >=0.85; m2: prob >=0.7 and <0.85; m3: prob >= 0.5 and <0.7; f: prob <0.5 u: no data available 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 Mem Period ampl C Type Notes/ RA Dec Flag Remarks ========================================================================= 1 15:35:48.09 -50:41:24.0 f ---- -- -- L 2 15:35:23.13 -50:39:50.8 m1 ---- -- -- CST? 3 15:35:37.86 -50:40:08.2 m1 0.70 17.9 1.3 B RR0 4 15:35:05.83 -50:40:29.7 f ---- -- -- L 5 15:35:26.00 -50:38:51.1 f ---- -- -- E? 6 15:35:29.37 -50:41:07.6 f 0.602 18.1 1.3 B RR0 7 15:35:30.91 -50:39:44.7 m1 ---- -- -- RR? blend ======================================================================== Supplementary Notes The RA and dec for the variables are from Samus et al. (2009). The remaining data are from Liller (1983) who also presented data for 12 field variables in the cluster vicinity. NGC 5946 has not been well studied. It is a difficult cluster to observe because it lies near the galactic plane and is heavily reddened. In the 2010 update to his catalogue of GC parameters, Harris (1996) lists [Fe/H] =-1.29 based on observations by Armandroff & Zinn (1988) and a CMD published by Alcaino et al. (1991) shows a predominantly blue HB. On the basis of the giant branch slope, both Alcaino et al. (1991) and Davidge (1985) have concluded that the metallicity of this cluster is lower than generally assumed. ======================================================================= Discovery of the variable stars in NGC 5946: V1-3 = Fourcade #1, 2 and 4 Fourcade et al. (1966) announced 8 variables in the field of NGC 5946 and published x,y coordinates and an ID chart. Sawyer Hogg (1973) designated Fourcade's V1, 2 and 4 as V1, 2 and 3 in her 3rd catalogue and considered the other 5 to be field variables. Since the Fourcade catalogue is not available in many libraries and has not been digitized, many of the stars listed in their catalogue will soon become lost to the literature on globular cluster variable stars. For this reason, Layden et al. (2025) published the RA and dec (J2000) for the other 5 variables, #3, #5, #6, #7 and #8. They derived these coordinates by matching the stars in Fourcade's charts with modern digital images. In their paper, Layden et al. also listed a Gaia Source ID for each star. V4-7 Liller (1983) with x,y coordinates and an ID chart Liller also announced an additional 7 field variables. ======================================================================== References Alcaino, G., Liller, W., Alvarado, F., Wenderoth, E. 1991, AJ, 102, 1371 Armandroff, T. E. & Zinn, R. 1988, AJ, 96,92 Davidge, T. J. 1995, AJ, 110, 1177 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 Layden, A. C., Revangelista, J., Gupta, S., Mittameda, M., Mulloy, E., Muslim, S. I., Olushola-Alao, T., Rishi, A. 2025, Astron. Nachr., 346, (in press) Liller, M. 1983, AJ, 88, 404 Prudil Z., Arellano Ferro, A. 2024, MNRAS, 534, 3654 Sawyer Hogg, H. 1973, Publ. DDO, 3, No. 6 ========================================================================