Variable Stars Discovered at the Maidanak Observatory: Field Center α=21h50m δ=+59°00′(2000.0)

F. Khamrakulov^#1,2, E. G. Lapukhin^#3, O. Burkhonov^#1,2, B. Satovskiy^#4, A. M. Zubareva^#5,6, R. Karimov^#1, B. Khafizov^#1

#1.Astronomical Institute of the Uzbekistan Academy of Sciences, Tashkent, Uzbekistan; #2.Samarkand State University, Samarkand, Uzbekistan; #3.Reshetnev Siberian State University of Science and Technology, Krasnoyarsk, Russia; #4.State Space Corporation "Roscosmos", Moscow, Russia; #5.Institute of Astronomy, Russian Academy of Sciences, Moscow, Russia; #6.Sternberg Astronomical Institute, Lomonosov Moscow State University, Moscow, Russia.

Received:   4.03.2023;   accepted:   28.04.2023
(E-mail for contact: slovoktk@mail.ru)

Comments:


1. Min_II = 17^m.28.

2. It was not possible to determine the period because only one minimum was observed. JDmin = 2459446.227.

3. It was not possible to determine the period because only one minimum was observed. JDmin = 2459447.390.

4. It was not possible to determine the period because only one minimum was observed. JDmin = 2459450.191.

5. Twice longer period is possible.

6. It was not possible to determine the period because only one minimum was observed.

7. It was not possible to determine the period because only one minimum was partially covered with observations. JDmin = 2459446.175.

8. Min_II = 17^m.3.

9. Min_II = 16^m.68.

11. Min_II = 15^m.22. The orbit of the star is possibly slightly eccentric.

12. It was not possible to determine the period because only one minimum was observed. JDmin = 2459451.287.

Remarks:
We present the results of searching for variable stars in a field in Cepheus with the center α=21h50m, δ=+59°00′ (2000.0). 11 stars from our sample are not mentioned as variables in the available star databases: GCVS (Samus et al. 2017), VSX, ZTF (Chen et al. 2020), and ASAS-SN Variable Stars Database. V1059 Cep was discovered by Lapukhin, Veselkov, and Zubareva (2015). We have monitoreded the star in order to improve the light curve. The coordinates were extracted from Gaia DR3 (Gaia Collaboration 2022).

Observations were carried out at the Maidanak Astronomical Observatory of the Ulugh Beg Astronomical Institute (UBAI) of the Academy of Sciences of the Republic of Uzbekistan (Ehgamberdiev 2018) using the 0.5-m AMT-1 telescope with Mathis Instruments MI-750/1000 equatorial fork mount equipped with an Apogee Alta U16M (4K×4K) CCD camera. The physical size of a CCD pixel is 9 microns. We used 2×2 binning, which corresponds to 0.907′′/pixel, and the field of view of 30.9′×30.9′. The exposure times were 120 seconds in the Bessel R filter. The temperature of the camera was set to –20°C. Calibration images: bias, dark and flat field were also obtained for each observational date. Observations were obtained during the period from August 15 to 26, 2021 (JD 2459442.3 – 2459452.2).

The VaST (Variability Search Toolkit) software package (Sokolovsky & Lebedev 2018) was used to reveal the brightness variability. The periods of brightness changes were determined by the Lafler-Kinman method in the LK program written by E. G. Lapukhin & A.V. Konovalchikov (private communication).

References:
Chen, X., Wang, S., et al., 2020, Astron. J. Suppl. Ser., 249, 18
Ehgamberdiev, Sh., 2018, Nature Astronomy, 2, 349
Gaia Collaboration, 2022, arXiv:2208.00211
Lapukhin, E. G., Veselkov, S. A., Zubareva, A. M., 2015, Perem. Zvezdy Prilozh., 15, 8
Samus, N. N., Kazarovets, E. V., Durlevich, O. V., Kireeva, N. N., Pastukhova, E. N., 2017, Astron. Rep., 61, No. 1, 80
Sokolovsky, K. V., Lebedev, A. A., 2018, Astron. and Computing, 22, 28