Qudratillo Yuldoshev
@astrin.uz
Laboratory of Galatical astronomy
Ulugh Beg Astronomical Institute of the Uzbekistan Academy of Sciences
RESEARCH, TEACHING, or OTHER INTERESTS
Astronomy and Astrophysics
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
C. M. Raiteri, M. Villata, M. I. Carnerero, S. O. Kurtanidze, D. O. Mirzaqulov, E. Benítez, G. Bonnoli, D. Carosati, J. A. Acosta-Pulido, I. Agudo,et al.
EDP Sciences
Context. Blazars are beamed active galactic nuclei (AGNs) known for their strong multi-wavelength variability on timescales ranging from years down to minutes. Many different models have been proposed to explain this variability. Aims. We aim to investigate the suitability of the twisting jet model presented in previous works to explain the multi-wavelength behaviour of BL Lacertae, the prototype of one of the blazar classes. According to this model, the jet is inhomogeneous, curved, and twisting, and the long-term variability is due to changes in the Doppler factor due to variations in the orientation of the jet-emitting regions. Methods. We analysed optical data of the source obtained during monitoring campaigns organised by the Whole Earth Blazar Telescope (WEBT) in 2019–2022, together with radio data from the WEBT and other teams, and γ-ray data from the Fermi satellite. In this period, BL Lacertae underwent an extraordinary activity phase, reaching its historical optical and γ-ray brightness maxima. Results. The application of the twisting jet model to the source light curves allows us to infer the wiggling motion of the optical, radio, and γ-ray jet-emitting regions. The optical-radio correlation shows that the changes in the radio viewing angle follow those in the optical viewing angle by about 120 days, and it suggests that the jet is composed of plasma filaments, which is in agreement with some radio high-resolution observations of other sources. The γ-ray emitting region is found to be co-spatial with the optical one, and the analysis of the γ-optical correlation is consistent with both the geometric interpretation and a synchrotron self-Compton (SSC) origin of the high-energy photons. Conclusions. We propose a geometric scenario where the jet is made up of a pair of emitting plasma filaments in a sort of double-helix curved rotating structure, whose wiggling motion produces changes in the Doppler beaming and can thus explain the observed multi-wavelength long-term variability.
Ehgamberdiev Shuhrat Abdumannapovich, Yuldoshev Qudratillo Khabibullaevich, Turaev Sobir Jurakobilovich, Jianhai Zhao, Meiting Yang, Zhenghong Tang, and Yong Yu
SAGE Publications
This paper discusses a photographic plate archive of the Ulugh Beg Astronomical Institute (UBAI) of the Uzbek Academy of Sciences, the history of photometric observations, the current state of photometric plates, and the process of their digitization. We will talk about telescopes used for observations, their characteristics and observations. In addition, we will also talk about the preparation of photographic plates for scanning. Also, the work carried out in the “UBAI-SHAO scientific and technical project” on digitization of photographic plates in the UBAI archive at the Shanghai Astronomical Observatory (SHAO) of the Chinese Academy of Sciences and future work will be reviewed and discussed.
Zhou Fan, Gang Zhao, Wei Wang, Jie Zheng, Jingkun Zhao, Chun Li, Yuqin Chen, Haibo Yuan, Haining Li, Kefeng Tan,et al.
American Astronomical Society
Abstract The Stellar Abundances and Galactic Evolution Survey (SAGES) of the northern sky is a specifically designed multiband photometric survey aiming to provide reliable stellar parameters with accuracy comparable to those from low-resolution optical spectra. It was carried out with the 2.3 m Bok telescope of Steward Observatory and three other telescopes. The observations in the u s and v s passband produced over 36,092 frames of images in total, covering a sky area of ∼9960 deg2. The median survey completenesses of all observing fields for the two bands are u s = 20.4 mag and v s = 20.3 mag, respectively, while the limiting magnitudes with signal-to-noise ratio of 100 are u s ∼ 17 mag and v s ∼ 18 mag, correspondingly. We combined our catalog with the data release 1 (DR1) of the first Panoramic Survey Telescope And Rapid Response System (Pan-STARRS, PS1) catalog, and obtained a total of 48,553,987 sources that have at least one photometric measurement in each of the SAGES u s and v s and PS1 grizy passbands. This is the DR1 of SAGES, released in this paper. We compared our gri point-source photometry with those of PS1 and found an rms scatter of ∼2% difference between PS1 and SAGES for the same band. We estimated an internal photometric precision of SAGES to be of the order of ∼1%. Astrometric precision is better than 0.″2 based on comparison with DR1 of the Gaia mission. In this paper, we also describe the final end-user database, and provide some science applications.
L.L. Wang, Y. Yu, Q.X. Yuldoshev, Sh.A. Ehgamberdiev, Z.J. Shang, M.T. Yang, J. Yang, S. Dong, D.M. Da, Z.H. Tang,et al.
Elsevier BV
Q. Yuldoshev, Y. Protsyuk, H. Relke, S. Ehgamberdiev, M. Muminov, and V. Andruk
Wiley
AbstractWe present a catalog of stars with equatorial coordinates α and δ and B‐magnitudes of stars for the Kitab's section of the FON project (FON‐Kitab). The photographic plates of the FON project were exposed on the double telescope Double Zeiss Astrograph (DAZ, D/F = 40/300, 69″/mm) at the Kitab observatory of the Republic of Uzbekistan. A total of 1963 plates, with size of 5.5 × 5.5 degrees (30 × 30 cm or 13,000 × 13,000 pixels) were digitized by Epson Expression 10000XL scanner with 1,200 dpi resolution. The reduction of plates was processed in the four astronomical organizations: Ulugh Beg Astronomical Institute (UBAI) of the Uzbek Academy of Sciences; the Mykolaiv Astronomical Observatory of the Ministry of Education and Science of Ukraine; the Walter Hohmann Observatory of Essen, Germany; and the Main Astronomical Observatory of the National Academy of Sciences of Ukraine. The catalogue contains nearly 13.4 million stars and galaxies from 0° to −20° according to declination down to B = 17. m5 in the middle epoch of observation 1985.0. The coordinates of the stars and galaxies were obtained from the Tycho‐2 catalogue, while B‐magnitudes were determined in the system of photoelectric standards. The mean internal errors of the new catalogue for all objects were σαδ = 0. ′′23 and σB = 0. m15 (for the stars in the range of B = 5m − 14m, the errors are σαδ = 0. ′′085 and σB = 0. m054 for the equatorial coordinates and the B‐magnitudes, respectively). The convergence between the calculated and reference positions was σαδ = 0. ′′042. The convergence with the photoelectric B‐magnitudes is σB = 0. m16. External comparison with UCAC‐4 based on 9,892,697 or 73.8% cross‐identified objects yield σαδ = 0. ′′26.
Q. X. Yuldoshev, Sh. A. Ehgamberdiev, M. M. Muminov, Yu. I. Protsyuk, H. Relke, and V. M. Andruk
Allerton Press
Yu.I. Protsyuk, , O.E. Kovylianska, S.V. Protsyuk, O.M. Yizhakevych, V.M. Andruk, V.V. Golovnia, Q.K. Yuldoshev, , ,et al.
National Academy of Sciences of Ukraine (Co. LTD Ukrinformnauka) (Publications)
V.M. Andruk, , L.K. Pakuliak, V.V. Golovnia, S.V. Shatokhina, O.M. Yizhakevych, Yu.I. Protsyuk, I. Eglitis, M. Eglite, L.V. Kazantseva,et al.
National Academy of Sciences of Ukraine (Co. LTD Ukrinformnauka) (Publications)
This paper discusses the issues of characteristic curve restoration for astronegatives exposed in the wide range of expositions in U, B Johnson color bands using different telescopes. Photographic plates are digitized by Epson commercial scanners. Digitized images are processed in MIDAS/ROMAFOT software. The accuracy of characteristic curve restoration using photoelectric data is within the range 0,1—0,2 m .