Peremennye Zvezdy

"Peremennye Zvezdy",
vol. 12, N 12 (2012)

New UV-type Variable Star USNO-A2.0 0900-17250765

T. Kryachko#1, A. Samokhvalov#2, B. Satovskiy#1
#1. Astrotel Observatory, Karachay-Cherkessia, Russia;
#2. Surgut, Russia

Received:   23.07.2012;   accepted:   7.11.2012
(E-mail for contact:,,

Star Name: USNO-A2.0 0900-17250765
Coordinates (J2000): 19 58 09.80, +05 19 25.1
Variability type: UV;   Limits, System: 15.85 - 18.4 (unfiltered) ;    
Period: Epoch(max): JD 

During observations of a field in Aquila, we discovered a new UV-type variable star. Our observations were carried out at the Astrotel-Caucasus observatory, located at the Astronomical station of the Kazan Federal university, using the 300-mm Ritchey-Chretien telescope, equipped with an unfiltered Apogee Alta U9000 CCD camera. A total of 203 images with 5-minute exposures were obtained on JD 2455676 – 2455832. For basic reductions for dark current, flat fields, and bias we used IRAF routines. For photometry of the new variable star, we applied VaST software by Sokolovsky and Lebedev (2005). The comparison star was USNO-A2.0 0900-17301510 = USNO-B1.0 0948-0507157 (α=19h59m01s.81, δ=+04°48′ 20″.5 (J2000, 2MASS)), R1=14m.30, R2=14m.60 (USNO-B1.0). Unfiltered magnitudes were calibrated using the comparison star, assuming Rcomp=14m.45.

A single flare was detected at 2455733.45 (see the light curve). The infrared colors J–H=0.630, H–K=0.302, J–K=0.932 (2MASS) are consistent with the M spectral type (Bessell and Brett 1988), typical of UV-type stars. Coordinates of the variable star were drawn from the 2MASS catalogue (Skrutskie et al. 2006).

Bessell, M.S., Brett, J.M., 1988, Publ. of Astron. Society of Pacific, 100, 1134
Skrutskie, M.F., Cutri, R.M., Stiening, R., et al., 2006, Astron. J, 131, 1163
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

Light Curve
New UV-type Variable Star USNO-A2.0 0900-17250765
Flare of USNO-A2.0 0900-17250765
Finding Chart
New UV-type Variable Star USNO-A2.0 0900-17250765
Data Source
  1. usno-a2.0-0900-17250765_data.txt

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