Palomar 2 / C0443+313 (Updated September 2023) RA: 04:46:05.91 DEC: +31:22:53.4 (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) - only 4 decimal places listed 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 04:46:03.57 +31:22:45.8 R0 0.5428 20.534 0.805 V RR0 2 04:46:04.60 +31:23:41.5 R0 0.5514 21.342 1.056 V RR0 3 04:46:05.53 +31:23:29.0 R0 0.5544 21.792 0.951 V RR0 4 04:46:05.61 +31:23:43.2 R0 0.6519 21.413 0.814 V RR0 5 04:46:07.02 +31:23:13.5 R0 0.5116 21.382 0.997 V RR0 6 04:46:07.82 +31:23:07.7 R0 0.5533 21.461 1.168 V RR0 7 04:46:08.11 +31:23:37.1 R0 0.6558 20.925 0.914 V RR0 8 04:46:08.06 +31:22:21.7 R0 0.3734 20.757 0.548 V RR1 9 04:46:08.24 +31:23:09.3 R0 0.6296 21.521 0.787 V RR0 10 04:46:09.11 +31:22:38.0 R0 0.6859 20.700 0.512 V RR0 11 04:46:10.58 +31:22:35.0 R0 0.5753 20.673 0.842 V RR0 12 04:46:12.82 +31:22:26.3 R0 0.5836 20.894 0.603 V RR0 13 04:46:07.17 +31:23:15.5 R0 0.5470 21.327 0.887 V RR0 14 04:46:07.21 +31:22:47.2 R0 0.5747 21.842 1.610 V RR0 15 04:46:05.00 +31:22:52.9 R0 0.5085 20.918 0.323 V RR0 16 04:46:04.64 +31:22:42.0 R0 0.4902 19.179 0.330 V RR? 17 04:46:02.96 +31:23:09.2 R0 ---- 19.0 0.9 V SR? 18 04:46:05.85 +31:23:03.3 R0 0.5102 18.876 0.768 V RR? ========================================================================== Supplementary Notes Palomar 2 is a distant, heavily obscured globular cluster, close to the Galactic plane, in the direction of the Galactc anticentre. Because of its location, the cluster is challenging to observe and early searches for variable stars were unsuccessful. The first published search was by Rosino & Pinto (1973) who concluded that the cluster does not contain any red variables. However, the possibility that any RR Lyrae may be present could not be ruled out. Later, Harris et al. (1997) published a CM diagram that showed a well populated red horizontal branch with a sparser extension to the blue. Based on this, they concluded that it is likely that Pal 2 contains RR Lyrae variables, but their observational data were not suitable for performing a search. Subsequently, a CM diagram published by Sarajedini et al. (2007) confirmed that the HB is bimodal in color. Eventually, some of the cluster's elusive RR Lyrae variable stars were discovered by Arellano Ferro et al. (2022, hereafter AF22). For their search, they employed difference imaging software. The RR Lyrae variables were among the faintest objects they could detect in their images so their discovery was a major achievement. All of the data in the above table are from the AF22 paper, with a minor exception. They listed 6 decimal places for the RR Lyrae periods they derived, but only 4 decimal places are listed in the above table. ===================================================================== Discovery of the variable stars in Palomar 2: V1-18 AF22 with RA, dec (J2000) and an identifcation chart These are all considered to be cluster members. They also discovered 7 variables which were not confirmed cluster members. They numbered these variables SV1-SV7. In addition, they identified a few more variables in the Gaia-DR3 data base. None of these were considered to be cluster members. ====================================================================== References Arellano Ferro, A., Bustos Ferro, I., Muneer, S., Giridhar, S. 2022, Rev. Mex A&A, 59, 3 (= arXiv:2208.07849v2), AF22 Harris, W. E., Durrell, P. R., Petitpas, G. R., Webb, T. M., Woodworth, S. C. 1997, AJ, 114, 1043 Rosino, L. & Pinto, G. 1973, IAU Colloq. No. 21, Variable Stars in Globular Clusters and in Related Systems, 21 Sarajedini, A., Bedin, L. R., Chaboyer, B., Dotter, A., Siegel, M., Anderson, J., Aparicio, A., KIng, I., Majewski, S., Marin-Franch, A., Piotto, G., Reid, I. N., Rosenberg, A. 2007, AJ, 133, 1658 ======================================================================