Study of Variable Stars in the Field of Open Cluster Stock 1

M. Parmanova^#1, R. Gaysin^#1, R. Karimov^#1, O. Burkhanov^#1,2, B. Satovskiy^#4, B. Khafizov^#1, S. A. Ehgamberdiev^#1,3

#1. Astronomical Institute of the Uzbekistan Academy of Sciences, Tashkent, Uzbekistan; #2. Samarkand State University, Samarkand, Uzbekistan; #3. National University of Uzbekistan, Tashkent, Uzbekistan; #4. State Space Corporation "Roscosmos", Moscow, Russia.

Received:   4.12.2023;   accepted:   4.03.2024
(E-mail for contact: parmanovamehriniso@gmail.com)

Comments:


1. Known variable star of EW type in the VSX. According to our data, variability type of the star is different. MinII = 16^m.40.

2. MinII = 16^m.26. According to the Gaia DR3 Part 1 Main source catalog, the star is indicated as a possible variable star.

5. Known variable star of EW type in the VSX. According to our data, variability type of the star is different. MinII = 17^m.15.

6. Known variable star of EA type in the VSX. MinII = 16^m.33.

10. Our original observations were insufficient to determine periodicities. We used the available longer-term ZTF catalog data for this star via SNAD ZTF viewer (Malanchev et al., 2023).

11. Known variable star of EW type in the VSX. According to our data, variability type of the star is different. MinII = 16^m.74.

12. Known variable star of EW-type in the VSX. According to our data, variability type of the star is different. MinII = 15^m.25.

13. Twice longer period is also possible.

14. Unclassified variable star - insufficient data.

Remarks:
We present the results of searching for variable stars in the vicinity of the open cluster Stock 1 in Vulpecula with the center at α=19^h36^m, δ=+25°.2(J2000.0). For 9 stars we did not find any references in the available star databases: GCVS (Samus et al., 2017), VSX, and ASAS-SN Variable Stars Database. The coordinates were extracted from Gaia DR3 (Gaia Collaboration et al., 2023).

Our observations were carried out at the Maidanak Astronomical Observatory of the Astronomical Institute of the Academy of Sciences of the Republic of Uzbekistan (Ehgamberdiev, 2018) using the 0.5-meter AMT-1 telescope with Mathis Instruments MI-750/1000 equatorial fork mount equipped with an Apogee Alta U16M (2K×2K) 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 was 30.9′×30.9′. We used Bessel R filter with exposure time 210 seconds. The temperature of the camera was set to 15°C. Calibration images: bias, dark and flat were also obtained for each observational date. Observations were carried out during the time interval from July 20 to July 28, 2022 (JD 2459781.27 – 2459789.26). During 7 nights we obtained 466 images. All of them were processed with master bias, dark, and flat frames using standard IRAF packages. The VaST software package (Sokolovsky and Lebedev, 2018) was used to search for variable stars.

Acknowledgments: We are grateful to the staff of the Maidanak Astronomical Observatory for their efforts to support observations. We thank Dr. A. M. Zubareva for helpful discussion.

References:
Ehgamberdiev, Sh., 2018, Nature Astronomy, 2, 349
Gaia Collaboration, Vallenari, A., Brown, A. G. A., et al., 2023, Astron. Astrophys., 674, A1
Malanchev, K., Kornilov, M. V., Pruzhinskaya, M. V., et al., 2023, Publ. Astron. Soc. Pacific, 135, 1044
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. Computing, 22, 28