|#1. Astrotel Observatory, Karachay-Cherkessia, Russia
#2. Surgut, Russia
#3. Space Research Institute (IKI), Moscow, Russia
Received: 20.11.2008; accepted: 24.11.2008
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1. Five observed maxima: HJD 2454608.4576, 2454609.3469, 2454609.4646, 2454610.3674, 2454631.4796. A 1-day alias, P = 0.10096, is also possible.
2. We observed one primary minimum, HJD 2454609.3814. Min II = 16.16.
3. Min II = 14.02.
5. Min II = 17.16.
6. Min II = 15.5. O'Connell effect.
7. Min II = 16.58.
8. One observed maximum, HJD 2454610.3279.
9. We observed one primary minimum, HJD 2454609.3880. Min II = 17.2. The coordinates are from the USNO-A2.0 catalogue.
10. We observed one primary minimum, HJD 2454635.4642. Min II = 13.92. The light curve shape varies from one maximum to another.
11. Two observed maxima: HJD 2454609.4208, 2454610.4710.
12. We observed one primary minimum, HJD 2454609.3275. Min II = 16.49.
13. We observed one primary minimum, HJD 2454609.4690. Min II = 15.97.
14. One observed maximum, HJD 2454635.4458.
16. Min II = 15.6. O'Connell effect.
17. We observed one primary minimum, HJD 2454610.3426. Min II = 16.14.
18. The coordinates are from the USNO-B1.0 catalogue.
During observations of the field of the cataclysmic variable star 1RXS J180834.7+101041 (Denisenko et al. 2008) we discovered 18 new variable stars. Our observations were carried out at Astrotel-Caucasus observatory using a 300-mm Ritchey-Chretien telescope, equipped with an unfiltered SBIG STL-11000 CCD camera. In total, 248 images with 5-minute exposures were obtained on JD 2454608-2454648. For basic reduction for dark current, flat fields, and bias, we used MaxIm DL software. For search and photometry of new variable stars, we applied VaST software by Sokolovsky and Lebedev (2005). The comparison star is USNO-B1.0 1001-0318048 (18:09:22.82, +10:06:29.2, (J2000), R1 = 14.62, R2 = 14.97). Unfiltered magnitudes were calibrated using the comparison star, assuming Rcomp = 14.795. The coordinates were drawn from the 2MASS catalogue if a different source is not specified in the Comments.
Acknowledgements: We would like to thank S. V. Antipin for helpful discussion.
Denisenko, D.V., Kryachko, T.V., Satovskiy, B.L., 2008, The Astronomer's Telegram, #1640
Sokolovsky, K., Lebedev, A., 2005, in 12th Young Scientists' Conference on Astronomy and Space Physics, Kyiv, Ukraine, April 19-23, 2005, eds.: Simon, A.; Golovin, A., p.79