New Variable Stars in the Field of the Globular Cluster NGC5466

T. Kryachko^#1, A. Samokhvalov^#2, B. Satovskiy^#1

#1. Astrotel Observatory, Karachay-Cherkessia, Russia; #2. Surgut, Russia

Received:   8.03.2011;   accepted:   11.05.2011
(E-mail for contact: bredfild@mail.ru, sav@surgut.ru, bs25@mail.ru)

Comments:


1. Maximum: HJD(TT) 2455309.349 ± 0.001.

2. Min_II = 13^m.98:.

3. Primary minimum: HJD(TT) 2455301.3754 ± 0.0006. Min_II = 12^m.87.

4. Primary minimum: HJD(TT) 2455309.358 ± 0.001. Min_II = 15^m.80.

5. Maximum: HJD(TT) 2455257.4136 ± 0.0007.

Remarks:
During observations of the field of the globular cluster NGC 5466, we discovered five new variable stars. Our observations were carried out at the Astrotel-Caucasus observatory using the 300-mm Ritchey-Chretien telescope, equipped with an unfiltered Apogee Alta U9000 CCD camera. A total of 442 images with 5-minute exposures were obtained on JD 2455229–2455349. For basic reductions for dark current, flat fields, bias, and for removing cosmic rays hits we used IRAF routines. For search and photometry of new variable stars, we applied VaST software by Sokolovsky and Lebedev (2005). The comparison star was USNO-A2.0 1125-06876791 = USNO-B1.0 1183-0234090 (α=14^h05^m40^s.57, δ=+28°23′ 40″.3, J2000; 2MASS), R₁ = 14^m.27, R₂ = 14^m.07 (USNO-B1.0). Unfiltered magnitudes were calibrated using the comparison star, assuming R_comp = 14^m.17. All times in the Table and comments are expressed in the Terrestrial Time in accordance with IAU recommendations (resolution B1 XXIII IAU GA). The coordinates of the variable stars in the table were drawn from the 2MASS catalogue (Skrutskie et al. 2006). For search for periods and epochs of extrema, we use Peranso software.

References:
Skrutskie, M.F., Cutri, R.M., Stiening, R., et al., 2006, AJ, 131, 1163
Sokolovsky, K., Lebedev, A., 2005, in 12th Young Scientists' Conference on Astronomy and Space Physics, Kyiv, Ukraine, April 1923, 2005, eds.: Simon, A.; Golovin, A., p.79