NGC 6681 / C1840-323 / Messier 70 (Updated June 2016) RA: 18:43:12.76 DEC: -32:17:31.6 (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 18:43:16.70 -32:19:18.9 R0 0.402 15.85 0.7 B RR1 2 18:43:05.68 -32:27:16.7 R0 0.318 15.35 0.5 B RR1 f?;V4082 Sgr 3 18:43:11.71 -32:18:23.5 R0 0.564 15.55 1.7 B RR0 4 18:43:23.30 -32:23:01.2 R0 0.3 15.75 0.5 B RR? 5 18:43:02.60 -32:25:32.1 R0 0.492 17.80 1.0 B RR0 f?;V4081 Sgr 6 18:43:12.02 -32:17:29.7 R0 0.3416 15.09 0.23 I RR1 =========================================================================== Supplementary Notes NGC 6681 is located in the same region of the sky as the main body of the Sagittarius dwarf galaxy. CM diagrams by Brocato et al. (1996) and Massari et al. (2013) show an extended blue HB. The RA and dec for V1-5 are from Samus et al. (2009). The remaining data are from Liller (1983). The data for V6 are from the discovery paper by Figuera Jaimes et al. (2016). ====================================================================== Discovery of the variable stars in NGC 6681: V1-2 = V1 and V3 of Rosino (1962) who published x,y coordinates and an ID chart for five variables, V1-5 Sawyer Hogg (1973) assigned the number V2 to Rosino's V3 because Rosino's V2 was considered to be a field star. V3-5 Liller (1983) with x,y coordinates and an ID chart Kadla et al. (1996) pointed out that the x coordinates Liller published for V3 and V4 had an error in sign. The corrected coordinates are x=-8 (V3) and x=+142 (V4). Liller also published identifications for 13 field variables including Rosino's V2, V4 and V5. V6 Figuera Jaimes et al. (2016) with RA, dec and a finding chart. ----------------------------------------------------------------------- Kadla et al. (1996) announced an additional 7 RR Lyrae variables, based on B and V photometry they obtained for stars in the instability strip of the CM diagram. They published x,y ccoordinates, but did not carry out any further analysis. Of Kadla's seven new variables, six should have been in the 41 by 41 arcsecond field observed by Figuera Jaimes et al. (2016). However, Figuera Jaimes et al. did not detect variability in any of them, with the possible exception of one star. The Kadla et al. chart is difficult to decipher, but it appears that their N7 might be V6. ======================================================================== References Brocato, E., Buonanno, R., Malakhova, Y., Piersimoni, A. M. 1996, A&A, 311, 778 Figuera Jaimes, R., Bramich, D. M., Skottfelt, J., Kains, N., Jorgensen, U. G., Horne, K., Dominik, M. and 26 coauthors, 2016, A&A, 588, A128 Kadla, Z. I., Gerashchenko, A. N., Malakhova, Yu. N. 1996, IBVS, 4414 Liller, M. 1983, AJ, 88, 1463 Massari, D., Bellini, A., Ferraro, F. R., van der Marel, R. P., Anderson, J., Dalessandro, E., Lanzoni, B. 2013, ApJ, 779, 81 Rosino, L. 1962, Mem. SAI, 33, 351 = Asiago Contr. 132 Samus, N. N., Kazarovets, E. V., Pastukhova, E. N., Tsvetkova, T. M., Durlevich, O. V. 2009, PASP, 121, 1378 Sawyer Hogg, H. 1973, Publ. DDO, 3, No. 6 =======================================================================