CURiuos Variables Experiment (CURVE): Variable Stars in the metal-poor   Globular Cluster M56
  We have surveyed a 6.5' x 6.5' field centered on the globular cluster M56 (NGC 6779) in search for variable stars. We have detected seven variables, among which two objects are new identifications. One of the new variables is an RR Lyrae star, the third such star in M56. Comparison of the new observations and old photometric data for an RV Tauri variable V6 indicates a likely period change in the star. Its slow and negative rate of -0.005+/-0.003 d/yr would disagree with post-AGB evolution, however this could be a result of blue-loop evolution and/or random fluctuations of the period. 
P. Pietrukowicz, A. Olech, P. Kedzierski, K. Zloczewski, M.   Wisniewski, K. Mularczyk