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101 results on '"Ehgamberdiev, S. A."'

1. Extragalactic fast X-ray transient from a weak relativistic jet associated with a Type Ic-BL supernova

Author: Sun, H., Li, W. -X., Liu, L. -D., Gao, H., Wang, X. -F., Yuan, W., Zhang, B., Filippenko, A. V., Xu, D., An, T., Ai, S., Brink, T. G., Liu, Y., Liu, Y. -Q., Wang, C. -Y., Wu, Q. -Y., Wu, X. -F., Yang, Y., Zhang, B. -B., Zheng, W. -K., Ahumada, T., Dai, Z. -G., Delaunay, J., Elias-Rosa, N., Benetti, S., Fu, S. -Y., Howell, D. A., Huang, Y. -F., Kasliwal, M. M., Karambelkar, V., Stein, R., Lei, W. -H., Lian, T. -Y., Peng, Z. -K., Ridnaia, A. V., Svinkin, D. S., Wang, X. -Y., Wang, A. -L., Wei, D. -M., An, J., Andrews, M., Bai, J. -M, Dai, C. -Y., Ehgamberdiev, S. A., Fan, Z., Farah, J., Feng, H. -C., Fynbo, J. P. U., Guo, W. -J., Guo, Z., Hu, M. -K., Hu, J. -W., Jiang, S. -Q., Jin, J. -J., Li, A., Li, J. -D., Li, R. -Z., Liang, Y. -F., Ling, Z. -X., Liu, X., Mao, J. -R., McCully, C., Mirzaqulov, D., Newsome, M., Gonzalez, E. Padilla, Pan, X., Terreran, G., Tinyanont, S., Wang, B. -T., Wang, L. -Z., Wen, X. -D., Xiang, D. -F., Xue, S. -J., Yang, J., Zhu, Z. -P., Cai, Z. -M., Castro-Tirado, A. J., Chen, F. -S., Chen, H. -L., Chen, T. -X., Chen, W., Chen, Y. -H., Chen, Y. -F., Chen, Y., Cheng, H. -Q., Cordier, B., Cui, C. -Z., Cui, W. -W., Dai, Y. -F., Fan, D. -W., Feng, H., Guan, J., Han, D. -W., Hou, D. -J., Hu, H. -B., Huang, M. -H., Huo, J., Jia, S. -M., Jia, Z. -Q., Jiang, B. -W., Jin, C. -C., Jin, G., Kuulkers, E., Li, C. -K., Li, D. -Y., Li, J. -F., Li, L. -H., Li, M. -S., Li, W., Li, Z. -D., Liu, C. -Z, Liu, H. -Y., Liu, H. -Q., Liu, M. -J., Lu, F. -J., Luo, L. -D., Ma, J., Mao, X., Nandra, K., O'Brien, P., Pan, H. -W., Rau, A., Rea, N., Sanders, J., Song, L. -M., Sun, S. -L., Sun, X. -J., Tan, Y. -Y., Tang, Q. -J., Tao, Y. -H., Wang, H., Wang, J., Wang, L., Wang, W. -X., Wang, Y. -L., Wang, Y. -S., Xiong, D. -R., Xu, H. -T., Xu, J. -J., Xu, X. -P., Xu, Y. -F., Xu, Z., Xue, C. -B., Xue, Y. -L., Yan, A. -L., Yang, H. -N., Yang, X. -T., Yang, Y. -J., Zhang, C., Zhang, J., Zhang, M., Zhang, S. -N., Zhang, W. -D., Zhang, W. -J., Zhang, Y. -H., Zhang, Z., Zhang, Z. -L., Zhao, D. -H., Zhao, H. -S., Zhao, X. -F., Zhao, Z. -J., Zhou, Y. -L., Zhu, Y. -X., and Zhu, Z. -C.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Massive stars end their life as core-collapse supernovae, amongst which some extremes are Type Ic broad-lined supernovae associated with long-duration gamma-ray bursts (LGRBs) having powerful relativistic jets. Their less-extreme brethren make unsuccessful jets that are choked inside the stars, appearing as X-ray flashes or low-luminosity GRBs. On the other hand, there exists a population of extragalactic fast X-ray transients (EFXTs) with timescales ranging from seconds to thousands of seconds, whose origins remain obscure. Known sources that contribute to the observed EFXT population include the softer analogs of LGRBs, shock breakouts of supernovae, or unsuccessful jets. Here, we report the discovery of the bright X-ray transient EP240414a detected by the Einstein Probe (EP), which is associated with the Type Ic supernova SN 2024gsa at a redshift of 0.401. The X-ray emission evolution is characterised by a very soft energy spectrum peaking at < 1.3 keV, which makes it distinct from known LGRBs, X-ray flashes, or low-luminosity GRBs. Follow-up observations at optical and radio bands revealed the existence of a weak relativistic jet that interacts with an extended shell surrounding the progenitor star. Located on the outskirts of a massive galaxy, this event reveals a new population of explosions of Wolf-Rayet stars characterised by a less powerful engine that drives a successful but weak jet, possibly owing to a progenitor star with a smaller core angular momentum than in traditional LGRB progenitors., Comment: 43 pages, 9 figures, 4 tables, submitted. Comments are welcome
Published: 2024

2. The variability patterns of the TeV blazar PG 1553+113 from a decade of MAGIC and multi-band observations

Author: MAGIC Collaboration, Abe, H., Abe, S., Abhir, J., Acciari, V. A., Agudo, I., Aniello, T., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Arcaro, C., Artero, M., Asano, K., Baack, D., Babić, A., Baquero, A., de Almeida, U. Barres, Batković, I., Baxter, J., González, J. Becerra, Bernardini, E., Bernete, J., Berti, A., Besenrieder, J., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Bošnjak, Ž., Burelli, I., Busetto, G., Campoy-Ordaz, A., Carosi, A., Carosi, R., Carretero-Castrillo, M., Castro-Tirado, A. J., Chai, Y., Cifuentes, A., Cikota, S., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Del Popolo, A., Delfino, M., Delgado, J., Mendez, C. Delgado, Depaoli, D., Di Pierro, F., Di Venere, L., Prester, D. Dominis, Donini, A., Dorner, D., Doro, M., Elsaesser, D., Emery, G., Escudero, J., Fariña, L., Fattorini, A., Foffano, L., Font, L., Fukami, S., Fukazawa, Y., López, R. J. García, Gasparyan, S., Gaug, M., Paiva, J. G. Giesbrecht, Giglietto, N., Giordano, F., Gliwny, P., Grau, R., Green, J. G., Hadasch, D., Hahn, A., Heckmann, L., Herrera, J., Hovatta, T., Hrupec, D., Hütten, M., Imazawa, R., Inada, T., Iotov, R., Ishio, K., Martínez, I. Jiménez, Jormanainen, J., Kerszberg, D., Kluge, G. W., Kobayashi, Y., Kouch, P. M., Kubo, H., Kushida, J., Lezáun, M. Láinez, Lamastra, A., Leone, F., Lindfors, E., Liodakis, I., Lombardi, S., Longo, F., López-Moya, M., López-Oramas, A., Loporchio, S., Lorini, A., Fraga, B. Machado de Oliveira, Majumdar, P., Makariev, M., Maneva, G., Mang, N., Manganaro, M., Mannheim, K., Mariotti, M., Martínez, M., Martínez-Chicharro, M., Mas-Aguilar, A., Mazin, D., Menchiari, S., Mender, S., Miceli, D., Miener, T., Miranda, J. M., Mirzoyan, R., González, M. Molero, Molina, E., Mondal, H. A., Moralejo, A., Morcuende, D., Nakamori, T., Nanci, C., Neustroev, V., Nigro, C., Nikolić, L., Nilsson, K., Nishijima, K., Ekoume, T. Njoh, Noda, K., Nozaki, S., Ohtani, Y., Okumura, A., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavlović, D., Persic, M., Pihet, M., Pirola, G., Podobnik, F., Moroni, P. G. Prada, Prandini, E., Principe, G., Priyadarshi, C., Rhode, W., Ribó, M., Rico, J., Righi, C., Sahakyan, N., Saito, T., Satalecka, K., Saturni, F. G., Schleicher, B., Schmidt, K., Schmuckermaier, F., Schubert, J. L., Schweizer, T., Sciaccaluga, A., Sitarek, J., Spolon, A., Stamerra, A., Strišković, J., Strom, D., Suda, Y., Suutarinen, S., Tajima, H., Takeishi, R., Tavecchio, F., Temnikov, P., Terauchi, K., Terzić, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., van Scherpenberg, J., Ventura, S., Verguilov, V., Viale, I., Vigorito, C. F., Vitale, V., Walter, R., Wunderlich, C., Yamamoto, T., collaborators, MWL, Jermak, H., Steele, I. A., Smith, P. S., Blinov, D., Raiteri, C. M., Villata, M., Mirzaqulov, D. O., Kurtanidze, S. O., Carosati, D., Savchenko, S. S., Acosta-Pulido, J. A., Borman, G. A., Bozhilov, V., Carnerero, M. I., Chigladze, R. A., Damljanovic, G., Ehgamberdiev, S. A., Feige, M., Grishina, T. S., Gupta, A. C., Hagen-Thorn, V. A., Ibryamov, S., Ivanidze, R. Z., Jorstad, S. G., Kania, J., Kimeridze, G. N., Kopatskaya, E. N., Kopp, M., Kunkel, L., Kurtanidze, O. M., Larionov, V. M., Larionova, E. G., Larionova, L. V., Lorey, C., Marchini, A., Marscher, A. P., Minev, M., Morozova, D. A., Nikolashvili, M. G., Ovcharov, E., Reinhart, D., Sadun, A. C., Scherbantin, A., Schneider, L., Semkov, E., Sigua, L. A., Steineke, R., Troitskaya, Yu. V., Troitskiy, I. S., Valcheva, A., Vasilyev, A. A., Vince, O., Zaharieva, E., Zottmann, N., Kiehlmann, S., Readhead, A., Max-Moerbeck, W., Reeves, R. A., Sandrinelli, A., Ramazani, V. Fallah, Giroletti, M., Righini, S., Marchili, N., Patricelli, B., Ghirlanda, G., and Lico, R.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: PG 1553+113 is one of the few blazars with a convincing quasi-periodic emission in the gamma-ray band. The source is also a very high-energy (VHE; >100 GeV) gamma-ray emitter. To better understand its properties and identify the underlying physical processes driving its variability, the MAGIC Collaboration initiated a multiyear, multiwavelength monitoring campaign in 2015 involving the OVRO 40-m and Medicina radio telescopes, REM, KVA, and the MAGIC telescopes, Swift and Fermi satellites, and the WEBT network. The analysis presented in this paper uses data until 2017 and focuses on the characterization of the variability. The gamma-ray data show a (hint of a) periodic signal compatible with literature, but the X-ray and VHE gamma-ray data do not show statistical evidence for a periodic signal. In other bands, the data are compatible with the gamma-ray period, but with a relatively high p-value. The complex connection between the low and high-energy emission and the non-monochromatic modulation and changes in flux suggests that a simple one-zone model is unable to explain all the variability. Instead, a model including a periodic component along with multiple emission zones is required., Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Society. 19 pages, 9 figures. Corresponding authors: Elisa Prandini, Antonio Stamerra, Talvikki Hovatta
Published: 2024
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3. Ready for O4 II: GRANDMA Observations of Swift GRBs during eight-weeks of Spring 2022

Author: Melo, I. Tosta e, Ducoin, J. -G., Vidadi, Z., Andrade, C., Rupchandani, V., Agayeva, S., Abdelhadi, J., Abe, L., Aguerre-Chariol, O., Aivazyan, V., Alishov, S., Antier, S., Bai, J. -M., Baransky, A., Bednarz, S., Bendjoya, Ph., Benkhaldoun, Z., Beradze, S., Bizouard, M. A., Bhardwaj, U., Blazek, M., Boër, M., Broens, E., Burkhonov, O., Christensen, N., Cooke, J., Corradi, W., Coughlin, M. W., Culino, T., Daigne, F., Dornic, D., Duverne, P. -A., Ehgamberdiev, S., Eymar, L., Fouad, A., Freeberg, M., Gendre, B., Guo, F., Gokuldass, P., Guessoum, N., Gurbanov, E., Hainich, R., Hasanov, E., Hello, P., Inasaridze, R., Iskandar, A., Ismailov, N., Janati, A., Laz, T. Jegou du, Kann, D. A., Karpov, S., Kiendrebeogo, R. W., Klotz, A., Kneip, R., Kochiashvili, N., Kaeouach, A., Kruiswijk, K., Lamoureux, M., Leroy, N., Lin, W. L., Mao, J., Marchais, D., Mašek, M., Midavaine, T., Moller, A., Morris, D., Natsvlishvili, R., Navarete, F., Guelbenzu, A Nicuesa, Noonan, K., Noysena, K., Oksanen, A., Orange, N. B., Pellouin, C., Peloton, J., Peng, H. W., Pilloix, M., Popowicz, A., Pradier, T., Pyshna, O., Raaijmakers, G., Rajabov, Y., Rau, A., Rinner, C., Rivet, J. -P., Ryh, A. S., Sabil, M., Sadibekova, T., Sasaki, N., Serrau, M., Simon, A., Shokry, A., Smith, K., Sokoliuk, O., Song, X., Takey, A., Thierry, P., Tillayev, Y., Turpin, D., Postigo, A. de Ugarte, Vasylenko, V., Vernet, D., Wang, L., Vachier, F., Vignes, J. P., Wang, X. F., Zeng, X., Zhang, J., and Zhu, Y.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: We present a campaign designed to train the GRANDMA network and its infrastructure to follow up on transient alerts and detect their early afterglows. In preparation for O4 II campaign, we focused on GRB alerts as they are expected to be an electromagnetic counterpart of gravitational-wave events. Our goal was to improve our response to the alerts and start prompt observations as soon as possible to better prepare the GRANDMA network for the fourth observational run of LIGO-Virgo-Kagra (which started at the end of May 2023), and future missions such as SM. To receive, manage and send out observational plans to our partner telescopes we set up dedicated infrastructure and a rota of follow-up adcates were organized to guarantee round-the-clock assistance to our telescope teams. To ensure a great number of observations, we focused on Swift GRBs whose localization errors were generally smaller than the GRANDMA telescopes' field of view. This allowed us to bypass the transient identification process and focus on the reaction time and efficiency of the network. During 'Ready for O4 II', 11 Swift/INTEGRAL GRB triggers were selected, nine fields had been observed, and three afterglows were detected (GRB 220403B, GRB 220427A, GRB 220514A), with 17 GRANDMA telescopes and 17 amateur astronomers from the citizen science project Kilonova-Catcher. Here we highlight the GRB 220427A analysis where our long-term follow-up of the host galaxy allowed us to obtain a photometric redshift of $z=0.82\pm0.09$, its lightcurve elution, fit the decay slope of the afterglows, and study the properties of the host galaxy.
Published: 2023

4. Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and $\gamma$-ray brightness levels

Author: Raiteri, C. M., Villata, M., Carnerero, M. I., Savchenko, S. S., Kurtanidze, S. O., Vlasyuk, V. V., Marchini, A., Matsumoto, K., Lorey, C., Joner, M. D., Gazeas, K., Carosati, D., Mirzaqulov, D. O., Pulido, J. A. Acosta, Agudo, I., Bachev, R., Benítez, E., Borman, G. A., Calcidese, P., Chen, W. P., Damljanovic, G., Ehgamberdiev, S. A., Elsässer, D., Feige, M., Frasca, A., Gaur, H., Grishina, T. S., Gupta, A. C., Hiriart, D., Holland, M., Horst, B., Ibryamov, S., Ivanidze, R. Z., Jensen, J., Jithesh, V., Jovanovic, M. D., Kiehlmann, S., Kimeridze, G. N., Kishore, S., Kopatskaya, E. N., Kurtanidze, O. M., Larionova, E. G., Lin, H. C., Mannheim, K., Marinelli, C., Reyes, J. Moreira, Morozova, D. A., Nikolashvili, M. G., Reinhart, D., Romanov, F. D., Semkov, E., Seufert, J., Shishkina, E. V., Sigua, L. A., Skalidis, R., Spiridonova, O. I., Stojanovic, M., Strigachev, A., Troitskaya, Y. V., Troitskiy, I. S., Tsai, A., Vasilyev, A. A., Vince, O., Vrontaki, K., Wani, K., Watts, D., and Zhovtan, A. V.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: In 2022 the BL Lac object S4 0954+65 underwent a major variability phase, reaching its historical maximum brightness in the optical and $\gamma$-ray bands. We present optical photometric and polarimetric data acquired by the Whole Earth Blazar Telescope (WEBT) Collaboration from 2022 April 6 to July 6. Many episodes of unprecedented fast variability were detected, implying an upper limit to the size of the emitting region as low as $10^{-4}$ parsec. The WEBT data show rapid variability in both the degree and angle of polarization. We analyse different models to explain the polarization behaviour in the framework of a twisting jet model, which assumes that the long-term trend of the flux is produced by variations in the emitting region viewing angle. All the models can reproduce the average trend of the polarization degree, and can account for its general anticorrelation with the flux, but the dispersion of the data requires the presence of intrinsic mechanisms, such as turbulence, shocks, or magnetic reconnection. The WEBT optical data are compared to $\gamma$-ray data from the Fermi satellite. These are analysed with both fixed and adaptive binning procedures. We show that the strong correlation between optical and $\gamma$-ray data without measurable delay assumes different slopes in faint and high brightness states, and this is compatible with a scenario where in faint states we mainly see the imprint of the geometrical effects, while in bright states the synchrotron self-Compton process dominates., Comment: 12 pages, 13 figures, in press for MNRAS
Published: 2023

5. International ISON project & databases on space debris and asteroids

Author: Molotov, I. E., Zhao, H., Li, B., Zhang, C., Elenin, L. V., Streltsov, A. I., Abdelaziz, A. M., Stepanyants, V. A., Ehgamberdiev, S. A., Schildknecht, T., Tungalag, N., Buyankhishig, R., Graziani, F., Zalles, R., Tijerina, E. G. P., and Tealib, S. K.
Published: 2024
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6. GRANDMA and HXMT Observations of GRB 221009A -- the Standard-Luminosity Afterglow of a Hyper-Luminous Gamma-Ray Burst

Author: Kann, D. A., Agayeva, S., Aivazyan, V., Alishov, S., Andrade, C. M., Antier, S., Baransky, A., Bendjoya, P., Benkhaldoun, Z., Beradze, S., Berezin, D., Boër, M., Broens, E., Brunier, S., Bulla, M., Burkhonov, O., Burns, E., Chen, Y., Chen, Y. P., Conti, M., Coughlin, M. W., Cui, W. W., Daigne, F., Delaveau, B., Devillepoix, H. A. R., Dietrich, T., Dornic, D., Dubois, F., Ducoin, J. -G., Durand, E., Duverne, P. -A., Eggenstein, H. -B., Ehgamberdiev, S., Fouad, A., Freeberg, M., Froebrich, D., Ge, M. Y., Gervasoni, S., Godunova, V., Gokuldass, P., Gurbanov, E., Han, D. W., Hasanov, E., Hello, P., Hussenot-Desenonges, T., Inasaridze, R., Iskandar, A., Ismailov, N., Janati, A., Laz, T. Jegou du, Jia, S. M., Karpov, S., Kaeouach, A., Kiendrebeogo, R. W., Klotz, A., Kneip, R., Kochiashvili, N., Kunert, N., Lekic, A., Leonini, S., Li, C. K., Li, W., Li, X. B., Liao, J. Y., Logie, L., Lu, F. J., Mao, J., Marchais, D., Ménard, R., Morris, D., Natsvlishvili, R., Nedora, V., Noonan, K., Noysena, K., Orange, N. B., Pang, P. T. H., Peng, H. W., Pellouin, C., Peloton, J., Pradier, T., Pyshna, O., Rajabo, Y., Rau, S., Rinner, C., Rivet, J. -P., Romanov, F. D., Rosi, P., Rupchandani, V. A., Serrau, M., Shokry, A., Simon, A., Smith, K., Sokoliuk, O., Soliman, M., Song, L. M., Takey, A., Tillayev, Y., Ramirez, L. M. Tinjaca, Melo, I. Tosta e, Turpin, D., Postigo, A. de Ugarte, Vanaverbeke, S., Vasylenko, V., Vernet, D., Vidadi, Z., Wang, C., Wang, J., Wang, L. T., Wang, X. F., Xiong, Shaolin L., Xu, Y. P., Xue, W. C., Zeng, X., Zhang, S. N., Zhao, H. S., and Zhao, X. F.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: GRB 221009A is the brightest Gamma-Ray Burst (GRB) detected in more than 50 years of study. In this paper, we present observations in the X-ray and optical domains after the GRB obtained by the GRANDMA Collaboration (which includes observations from more than 30 professional and amateur telescopes) and the Insight-HXMT Collaboration. We study the optical afterglow with empirical fitting from GRANDMA+HXMT data, augmented with data from the literature up to 60 days. We then model numerically, using a Bayesian approach, the GRANDMA and HXMT-LE afterglow observations, that we augment with Swift-XRT and additional optical/NIR observations reported in the literature. We find that the GRB afterglow, extinguished by a large dust column, is most likely behind a combination of a large Milky-Way dust column combined with moderate low-metallicity dust in the host galaxy. Using the GRANDMA+HXMT-LE+XRT dataset, we find that the simplest model, where the observed afterglow is produced by synchrotron radiation at the forward external shock during the deceleration of a top-hat relativistic jet by a uniform medium, fits the multi-wavelength observations only moderately well, with a tension between the observed temporal and spectral evolution. This tension is confirmed when using the extended dataset. We find that the consideration of a jet structure (Gaussian or power-law), the inclusion of synchrotron self-Compton emission, or the presence of an underlying supernova do not improve the predictions, showing that the modelling of GRB22109A will require going beyond the most standard GRB afterglow model. Placed in the global context of GRB optical afterglows, we find the afterglow of GRB 221009A is luminous but not extraordinarily so, highlighting that some aspects of this GRB do not deviate from the global known sample despite its extreme energetics and the peculiar afterglow evolution., Comment: Accepted to ApJL for the special issue, 37 pages, 23 pages main text, 6 tables, 13 figures
Published: 2023
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7. Rotation acceleration of asteroids (10115) 1992 SK, (1685) Toro, and (1620) Geographos due to the YORP effect

Author: Durech, J., Vokrouhlicky, D., Pravec, P., Krugly, Yu. N., Kim, M. J., Polishook, D., Ayvazian, V. V., Bonev, T., Choi, Y. J., Datashvili, D. G., Donchev, Z., Ehgamberdiev, S. A., Hornoch, K., Inasaridze, R. Ya., Kapanadze, G. V., Kim, D. H., Kucakova, H., Kusakin, A. V., Kusnirak, P., Lee, H. J., Molotov, I. E., Moon, H. K., Mykhailova, S. S., Nikolenko, I. V., Novichonok, A., Oey, J., Omarov, Ch. T., Pollock, J. T., Reva, I. V., Rumyantsev, V. V., and Zhornichenko, A. A.
Subjects: Astrophysics - Earth and Planetary Astrophysics
Abstract: The rotation state of small asteroids is affected by the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, which is a net torque caused by solar radiation directly reflected and thermally reemitted from the surface. Due to this effect, the rotation period slowly changes, which can be most easily measured in light curves because the shift in the rotation phase accumulates over time quadratically. We collected archived light curves and carried out new photometric observations for asteroids (10115) 1992 SK, (1620) Geographos, and (1685) Toro. We applied the method of light curve inversion to fit observations with a convex shape model. The YORP effect was modeled as a linear change of the rotation frequency $\upsilon \equiv \mathrm{d}\omega / \mathrm{d}t$ and optimized together with other spin and shape parameters. We detected the acceleration $\upsilon = (8.3 \pm 0.6) \times 10^{-8}\,\mathrm{rad}\,\mathrm{d}^{-2}$ of the rotation for asteroid (10115) 1992 SK. This observed value agrees well with the theoretical value of YORP-induced spin-up computed for our shape and spin model. For (1685) Toro, we obtained $\upsilon = (3.3 \pm 0.3) \times 10^{-9}\,\mathrm{rad}\,\mathrm{d}^{-2}$, which confirms an earlier tentative YORP detection. For (1620) Geographos, we confirmed the previously detected YORP acceleration and derived an updated value of $\upsilon$ with a smaller uncertainty. We also included the effect of solar precession into our inversion algorithm, and we show that there are hints of this effect in Geographos' data. The detected change of the spin rate of (10115) 1992 SK has increased the total number of asteroids with YORP detection to ten. In all ten cases, the $\mathrm{d}\omega / \mathrm{d}t$ value is positive, so the rotation of these asteroids is accelerated. It is unlikely to be just a statistical fluke, but it is probably a real feature that needs to be explained.
Published: 2021
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8. The dual nature of blazar fast variability. Space and ground observations of S5 0716+714

Author: Raiteri, C. M., Villata, M., Carosati, D., Benítez, E., Kurtanidze, S. O., Gupta, A. C., Mirzaqulov, D. O., D'Ammando, F., Larionov, V. M., Pursimo, T., Acosta-Pulido, J. A., Baida, G. V., Balmaverde, B., Bonnoli, G., Borman, G. A., Carnerero, M. I., Chen, W. -P., Dhiman, V., Di Maggio, A., Ehgamberdiev, S. A., Hiriart, D., Kimeridze, G. N., Kurtanidze, O. M., Lin, C. S., Lopez, J. M., Marchini, A., Matsumoto, K., Mujica, R., Nakamura, M., Nikiforova, A. A., Nikolashvili, M. G., Okhmat, D. N., Otero-Santos, J., Rizzi, N., Sakamoto, T., Semkov, E., Sigua, L. A., Stiaccini, L., Troitsky, I. S., Tsai, A. L., Vasilyev, A. A., and Zhovtan, A. V.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Blazar S5 0716+714 is well-known for its short-term variability, down to intra-day time-scales. We here present the 2-min cadence optical light curve obtained by the TESS space telescope in 2019 December - 2020 January and analyse the object fast variability with unprecedented sampling. Supporting observations by the Whole Earth Blazar Telescope Collaboration in B, V , R, and I bands allow us to investigate the spectral variability during the TESS pointing. The spectral analysis is further extended in frequency to the UV and X-ray bands with data from the Neil Gehrels Swift Observatory. We develop a new method to unveil the shortest optical variability time-scales. This is based on progressive de-trending of the TESS light curve by means of cubic spline interpolations through the binned fluxes, with decreasing time bins. The de-trended light curves are then analysed with classical tools for time-series analysis (periodogram, auto-correlation and structure functions). The results show that below 3 d there are significant characteristic variability time-scales of about 1.7, 0.5, and 0.2 d. Variability on time-scales < 0.2 d is strongly chromatic and must be ascribed to intrinsic energetic processes involving emitting regions, likely jet sub-structures, with dimension less than about milliparsec. In contrast, flux changes on time-scales > 0.5 d are quasi-achromatic and are probably due to Doppler factor changes of geometric origin., Comment: 17 pages, 18 figures, accepted by MNRAS
Published: 2020
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9. Multi-Wavelength Variability of BL Lacertae Measured with High Time Resolution

Author: Weaver, Zachary R., Williamson, K. E., Jorstad, S. G., Marscher, A. P., Larionov, V. M., Raiteri, C. M., Villata, M., Acosta-Pulido, J. A., Bachev, R., Baida, G. V., Balonek, T. J., Benitez, E., Borman, G. A., Bozhilov, V., Carnerero, M. I., Carosati, D., Chen, W. P., Damljanovic, G., Dhiman, V., Dougherty, D. J., Ehgamberdiev, S. A., Grishina, T. S., Gupta, A. C., Hart, M., Hiriart, D., Hsiao, H. Y., Ibryamov, S., Joner, M., Kimeridze, G. N., Kopatskaya, E. N., Kurtanidze, O. M., Kurtanidze, S. O., Larionova, E. G., Matsumoto, K., Matsumura, R., Minev, M., Mirzaqulov, D. O., Morozova, D. A., Nikiforova, A. A., Nikolashvili, M. G., Ovcharov, E., Rizzi, N., Sadun, A., Savchenko, S. S., Semkov, E., Slater, J. J., Smith, K. L., Stojanovic, M., Strigachev, A., Troitskaya, Yu. V., Troitsky, I. S., Tsai, A. L., Vince, O., Valcheva, A., Vasilyev, A. A., Zaharieva, E., and Zhovtan, A. V.
Subjects: Astrophysics - Astrophysics of Galaxies, Astrophysics - High Energy Astrophysical Phenomena
Abstract: In an effort to locate the sites of emission at different frequencies and physical processes causing variability in blazar jets, we have obtained high time-resolution observations of BL Lacertae over a wide wavelength range: with the \emph{Transiting Exoplanet Survey Satellite} (TESS) at 6,000-10,000 \AA\ with 2-minute cadence; with the Neil Gehrels \emph{Swift} satellite at optical, UV, and X-ray bands; with the Nuclear Spectroscopic Telescope Array at hard X-ray bands; with the \emph{Fermi} Large Area Telescope at $\gamma$-ray energies; and with the Whole Earth Blazar Telescope for measurement of the optical flux density and polarization. All light curves are correlated, with similar structure on timescales from hours to days. The shortest timescale of variability at optical frequencies observed with TESS is $\sim 0.5$ hr. The most common timescale is $13\pm1$~hr, comparable with the minimum timescale of X-ray variability, 14.5 hr. The multi-wavelength variability properties cannot be explained by a change solely in the Doppler factor of the emitting plasma. The polarization behavior implies that there are both ordered and turbulent components to the magnetic field in the jet. Correlation analysis indicates that the X-ray variations lag behind the $\gamma$-ray and optical light curves by up to $\sim 0.4$ days. The timescales of variability, cross-frequency lags, and polarization properties can be explained by turbulent plasma that is energized by a shock in the jet and subsequently loses energy to synchrotron and inverse Compton radiation in a magnetic field of strength $\sim3$ G, Comment: 33 pages, 25 figures, 14 tables. Accepted to ApJ
Published: 2020

10. SN 2018hti: a nearby superluminous supernova discovered in a metal-poor galaxy

Author: Lin, W. L., Wang, X. F., Li, W. X., Zhang, J. J., Mo, J., Sai, H. N., Zhang, X. H., Filippenko, A. V., Zheng, W. K., Brink, T. G., Baron, E., DerKacy, J. M., Ehgamberdiev, S. A., Mirzaqulov, D., Li, X., Zhang, J. C., Yan, S. Y., Xi, G. B., Hsiao, Y., Zhang, T. M., Wang, L. J., Liu, L. D., Xiang, D. F., Wu, C. Y., Rui, L. M., and Chen, Z. H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: SN 2018hti is a Type I superluminous supernova (SLSN~I) with an absolute $g$-band magnitude of $-22.2$ at maximum brightness, discovered in a metal-poor galaxy at a redshift of 0.0612. We present extensive photometric and spectroscopic observations of this supernova, covering the phases from $\sim -35$ days to more than +340 days from the $r$-band maximum. Combining our $BVgri$-band photometry with {\it Swift} UVOT optical/ultraviolet photometry, we calculated the peak luminosity as $\sim 3.5\times10^{44}$ erg s$^{-1}$. Modeling the observed light curve reveals that the luminosity evolution of SN 2018hti can be produced by an ejecta mass of 5.8 $M_\odot$ and a magnetar with a magnetic field of $B=1.8\times10^{13}$~G having an initial spin period of $P_0=1.8$ ms. Based on such a magnetar-powered scenario and a larger sample, a correlation between the spin of the magnetar and the kinetic energy of the ejecta can be inferred for most SLSNe~I, suggesting a self-consistent scenario. Like for other SLSNe~I, the host galaxy of SN 2018hti is found to be relatively faint ($M_{g} = -17.75$ mag) and of low metallicity ($Z=0.3~Z_\odot$), with a star-formation rate of 0.3 $M_\odot$ yr$^{-1}$. According to simulation results of single-star evolution, SN 2018hti could originate from a massive, metal-poor star with a zero-age main sequence (ZAMS) mass of 25--40 $M_\odot$, or from a less massive rotating star with $M_\mathrm{ZAMS} \approx 16$--25 $M_\odot$. For the case of a binary system, its progenitor could also be a star with $M_\mathrm{ZAMS} \gtrsim 25$ $M_\odot$., Comment: 26 pages, 12 figures, 7 tables, published in MNRAS
Published: 2020
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11. Liverpool-Maidanak monitoring of the Einstein Cross in 2006$-$2019. I. Light curves in the $gVrRI$ optical bands and microlensing signatures

Author: Goicoechea, L. J., Artamonov, B. P., Shalyapin, V. N., Sergeyev, A. V., Burkhonov, O. A., Akhunov, T. A., Asfandiyarov, I. M., Bruevich, V. V., Ehgamberdiev, S. A., Shimanovskaya, E. V., and Zheleznyak, A. P.
Subjects: Astrophysics - Astrophysics of Galaxies
Abstract: Quasar microlensing offers a unique opportunity to resolve tiny sources in distant active galactic nuclei and study compact object populations in lensing galaxies. We therefore searched for microlensing-induced variability of the gravitationally lensed quasar QSO 2237+0305 (Einstein Cross) using 4374 optical frames taken with the 2.0 m Liverpool Telescope and the 1.5 m Maidanak Telescope. These $gVrRI$ frames over the 2006$-$2019 period were homogeneously processed to generate accurate long-term multi-band light curves of the four quasar images A-D. Through difference light curves, we found strong microlensing signatures. We then focused on the analytical modelling of two putative caustic-crossing events in image C, finding compelling evidence that this image experienced a double caustic crossing. Additionally, our overall results indicate that a standard accretion disc accounts reasonably well for the brightness profile of UV continuum emission sources and for the growth in source radius when the emission wavelength increases: $R_{\lambda} \propto \lambda^{\alpha}$, $\alpha$ = 1.33 $\pm$ 0.09. However, we caution that numerical microlensing simulations are required before firm conclusions can be reached on the UV emission scenario because the $VRI$-band monitoring during the first caustic crossing and one of our two $\alpha$ indicators lead to a few good solutions with $\alpha \approx$ 1., Comment: Accepted to A&A; 10 pages, 10 long tables (Tables 4-8 and 10-14) are available at the CDS; correction of affiliation
Published: 2020
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12. Diagnosing the Clumpy Protoplanetary Disk of the UXor Type Young Star GM Cephei

Author: Huang, P. C., Chen, W. P., Mugrauer, M., Bischoff, R., Budaj, J., Burkhonov, O., Ehgamberdiev, S., Errmann, R., Garai, Z., Hsiao, H. Y., Janulis, R., Jensen, E. L. N., Kiyota, S., Kuramoto, K., Lin, C. S., Lin, H. C., Liu, J. Z, Lux, O., Naito, H., Neuhäuser, R., Ohlert, J., Pakštienė, E., Pribulla, T., Qvam, J. K. T., Raetz, St., Sato, S., Schwartz, M., Semkov, E., Takagi, S., Wagner, D., Watanabe, M., and Zhang, Y.
Subjects: Astrophysics - Solar and Stellar Astrophysics
Abstract: UX Orionis stars (UXors) are Herbig Ae/Be or T Tauri stars exhibiting sporadic occultation of stellar light by circumstellar dust. GM\,Cephei is such a UXor in the young ($\sim4$~Myr) open cluster Trumpler\,37, showing prominent infrared excess, emission-line spectra, and flare activity. Our photometric monitoring (2008--2018) detects (1)~an $\sim$3.43~day period, likely arising from rotational modulation by surface starspots, (2)~sporadic brightening on time scales of days due to accretion, (3)~irregular minor flux drops due to circumstellar dust extinction, and (4)~major flux drops, each lasting for a couple of months with a recurrence time, though not exactly periodic, of about two years. The star experiences normal reddening by large grains, i.e., redder when dimmer, but exhibits an unusual "blueing" phenomenon in that the star turns blue near brightness minima. The maximum extinction during relatively short (lasting $\leq 50$~days) events, is proportional to the duration, a consequence of varying clump sizes. For longer events, the extinction is independent of duration, suggestive of a transverse string distribution of clumps. Polarization monitoring indicates an optical polarization varying $\sim3\%$--8$\%$, with the level anticorrelated with the slow brightness change. Temporal variation of the unpolarized and polarized light sets constraints on the size and orbital distance of the circumstellar clumps in the interplay with the young star and scattering envelope. These transiting clumps are edge-on manifestations of the ring- or spiral-like structures found recently in young stars with imaging in infrared of scattered light, or in submillimeter of thermalized dust emission., Comment: 20 pages, 9 figures
Published: 2019
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13. Rapid quasi-periodic oscillations in the relativistic jet of BL Lacertae

Author: Jorstad, S. G., Marscher, A. P., Raiteri, C. M., Villata, M., Weaver, Z. R., Zhang, H., Dong, L., Gómez, J. L., Perel, M. V., Savchenko, S. S., Larionov, V. M., Carosati, D., Chen, W. P., Kurtanidze, O. M., Marchini, A., Matsumoto, K., Mortari, F., Aceti, P., Acosta-Pulido, J. A., Andreeva, T., Apolonio, G., Arena, C., Arkharov, A., Bachev, R., Banfi, M., Bonnoli, G., Borman, G. A., Bozhilov, V., Carnerero, M. I., Damljanovic, G., Ehgamberdiev, S. A., Elsässer, D., Frasca, A., Gabellini, D., Grishina, T. S., Gupta, A. C., Hagen-Thorn, V. A., Hallum, M. K., Hart, M., Hasuda, K., Hemrich, F., Hsiao, H. Y., Ibryamov, S., Irsmambetova, T. R., Ivanov, D. V., Joner, M. D., Kimeridze, G. N., Klimanov, S. A., Knött, J., Kopatskaya, E. N., Kurtanidze, S. O., Kurtenkov, A., Kuutma, T., Larionova, E. G., Leonini, S., Lin, H. C., Lorey, C., Mannheim, K., Marino, G., Minev, M., Mirzaqulov, D. O., Morozova, D. A., Nikiforova, A. A., Nikolashvili, M. G., Ovcharov, E., Papini, R., Pursimo, T., Rahimov, I., Reinhart, D., Sakamoto, T., Salvaggio, F., Semkov, E., Shakhovskoy, D. N., Sigua, L. A., Steineke, R., Stojanovic, M., Strigachev, A., Troitskaya, Y. V., Troitskiy, I. S., Tsai, A., Valcheva, A., Vasilyev, A. A., Vince, O., Waller, L., Zaharieva, E., and Chatterjee, R.
Published: 2022
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14. Accretion Disk Size and Updated Time-delay Measurements in the Gravitationally Lensed Quasar SDSS J165043.44+425149.3

Author: Rivera, A. B., primary, Morgan, C. W., additional, Florence, S. M., additional, Kniezewski, K., additional, Millon, M., additional, Courbin, F., additional, Dahm, S. E., additional, Vrba, F. J., additional, Tilleman, T. M., additional, Cornachione, M. A., additional, Asfandiyarov, I. M., additional, Ehgamberdiev, S. A., additional, and Burkhonov, O. A., additional
Published: 2024
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15. Ready for O4 II: GRANDMA observations of Swift GRBs over eight weeks in spring 2022

Author: Tosta e Melo, I., primary, Ducoin, J.-G., additional, Vidadi, Z., additional, Andrade, C., additional, Rupchandani, V., additional, Agayeva, S., additional, Abdelhadi, J., additional, Abe, L., additional, Aguerre-Chariol, O., additional, Aivazyan, V., additional, Alishov, S., additional, Antier, S., additional, Bai, J.-M., additional, Baransky, A., additional, Bednarz, S., additional, Bendjoya, Ph., additional, Benkhaldoun, Z., additional, Beradze, S., additional, Bizouard, M. A., additional, Bhardwaj, U., additional, Blazek, M., additional, Boër, M., additional, Broens, E., additional, Burkhonov, O., additional, Christensen, N., additional, Cooke, J., additional, Corradi, W., additional, Coughlin, M. W., additional, Culino, T., additional, Daigne, F., additional, Dornic, D., additional, Duverne, P.-A., additional, Ehgamberdiev, S., additional, Eymar, L., additional, Fouad, A., additional, Freeberg, M., additional, Gendre, B., additional, Guo, F., additional, Gokuldass, P., additional, Guessoum, N., additional, Gurbanov, E., additional, Hainich, R., additional, Hasanov, E., additional, Hello, P., additional, Inasaridze, R., additional, Iskandar, A., additional, Ismailov, N., additional, Janati, A., additional, Jegou du Laz, T., additional, Kann, D. A., additional, Karpov, S., additional, Kiendrebeogo, R. W., additional, Klotz, A., additional, Kneip, R., additional, Kochiashvili, N., additional, Kaeouach, A., additional, Kruiswijk, K., additional, Lamoureux, M., additional, Leroy, N., additional, Lin, W. L., additional, Mao, J., additional, Marchais, D., additional, Mašek, M., additional, Midavaine, T., additional, Moller, A., additional, Morris, D., additional, Natsvlishvili, R., additional, Navarete, F., additional, Nicuesa Guelbenzu, A., additional, Noonan, K., additional, Noysena, K., additional, Oksanen, A., additional, Orange, N. B., additional, Pellouin, C., additional, Peloton, J., additional, Peng, H. W., additional, Pilloix, M., additional, Popowicz, A., additional, Pradier, T., additional, Pyshna, O., additional, Raaijmakers, G., additional, Rajabov, Y., additional, Rau, A., additional, Rinner, C., additional, Rivet, J.-P., additional, Ryh, A. S., additional, Sabil, M., additional, Sadibekova, T., additional, Sasaki, N., additional, Serrau, M., additional, Simon, A., additional, Shokry, A., additional, Smith, K., additional, Sokoliuk, O., additional, Song, X., additional, Takey, A., additional, Thierry, P., additional, Tillayev, Y., additional, Turpin, D., additional, de Ugarte Postigo, A., additional, Vasylenko, V., additional, Vernet, D., additional, Wang, L., additional, Vachier, F., additional, Vignes, J. P., additional, Wang, X. F., additional, Zeng, X., additional, Zhang, J., additional, and Zhu, Y., additional
Published: 2024
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16. Measurement of optical turbulence in free atmosphere above Mt.Maidanak in 2005-2007

Author: Kornilov, V., Ilyasov, S., Voziakova, O., Tillaev, Yu., Safonov, B., Ibragimov, M., Shatsky, N., and Ehgamberdiev, S.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: Results of 2005-2007 campaign of measurement of the optical turbulence vertical distribution above Mt. Maidanak are presented. Measurements are performed with the MASS (Multi-Aperture Scintillation Sensor) device which is widely used in similar studies during last years at several observatories across the world. The data analysis shows that median seeing in free atmosphere (at altitudes above 0.5km) is 0.46 arcsec and median isoplanatic angle is 2.47 arcsec. Given a rather long atmospheric coherence time (about 7 ms when the seeing is good) such conditions are favorable for adaptive optics and interferometry in the visible and near-IR., Comment: Accepted for publication in Astronomy Letters, V.35 (2009); 14 pages, 8 figures
Published: 2009
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17. Extreme photometric and polarimetric variability of blazar S4 0954+65 at its maximum optical and γ-ray brightness levels

Author: Raiteri, C M, primary, Villata, M, additional, Carnerero, M I, additional, Savchenko, S S, additional, Kurtanidze, S O, additional, Vlasyuk, V V, additional, Marchini, A, additional, Matsumoto, K, additional, Lorey, C, additional, Joner, M D, additional, Gazeas, K, additional, Carosati, D, additional, Mirzaqulov, D O, additional, Acosta Pulido, J A, additional, Agudo, I, additional, Bachev, R, additional, Benítez, E, additional, Borman, G A, additional, Calcidese, P, additional, Chen, W P, additional, Damljanovic, G, additional, Ehgamberdiev, S A, additional, Elsässer, D, additional, Feige, M, additional, Frasca, A, additional, Gaur, H, additional, Grishina, T S, additional, Gupta, A C, additional, Hiriart, D, additional, Holland, M, additional, Horst, B, additional, Ibryamov, S, additional, Ivanidze, R Z, additional, Jensen, J, additional, Jithesh, V, additional, Jovanovic, M D, additional, Kiehlmann, S, additional, Kimeridze, G N, additional, Kishore, S, additional, Kopatskaya, E N, additional, Kurtanidze, O M, additional, Larionova, E G, additional, Lin, H C, additional, Mannheim, K, additional, Marinelli, C, additional, Moreira Reyes, J, additional, Morozova, D A, additional, Nikolashvili, M G, additional, Reinhart, D, additional, Romanov, F D, additional, Semkov, E, additional, Seufert, J, additional, Shishkina, E V, additional, Sigua, L A, additional, Skalidis, R, additional, Spiridonova, O I, additional, Stojanovic, M, additional, Strigachev, A, additional, Troitskaya, Y V, additional, Troitskiy, I S, additional, Tsai, A, additional, Vasilyev, A A, additional, Vince, O, additional, Vrontaki, K, additional, Wani, K, additional, Watts, D, additional, and Zhovtan, A V, additional
Published: 2023
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18. GRANDMA and HXMT Observations of GRB 221009A: The Standard Luminosity Afterglow of a Hyperluminous Gamma-Ray Burst—In Gedenken an David Alexander Kann

Author: Kann, D. A., primary, Agayeva, S., additional, Aivazyan, V., additional, Alishov, S., additional, Andrade, C. M., additional, Antier, S., additional, Baransky, A., additional, Bendjoya, P., additional, Benkhaldoun, Z., additional, Beradze, S., additional, Berezin, D., additional, Boër, M., additional, Broens, E., additional, Brunier, S., additional, Bulla, M., additional, Burkhonov, O., additional, Burns, E., additional, Chen, Y., additional, Chen, Y. P., additional, Conti, M., additional, Coughlin, M. W., additional, Cui, W. W., additional, Daigne, F., additional, Delaveau, B., additional, Devillepoix, H. A. R., additional, Dietrich, T., additional, Dornic, D., additional, Dubois, F., additional, Ducoin, J.-G., additional, Durand, E., additional, Duverne, P.-A., additional, Eggenstein, H.-B., additional, Ehgamberdiev, S., additional, Fouad, A., additional, Freeberg, M., additional, Froebrich, D., additional, Ge, M. Y., additional, Gervasoni, S., additional, Godunova, V., additional, Gokuldass, P., additional, Gurbanov, E., additional, Han, D. W., additional, Hasanov, E., additional, Hello, P., additional, Hussenot-Desenonges, T., additional, Inasaridze, R., additional, Iskandar, A., additional, Ismailov, N., additional, Janati, A., additional, du Laz, T. Jegou, additional, Jia, S. M., additional, Karpov, S., additional, Kaeouach, A., additional, Kiendrebeogo, R. W., additional, Klotz, A., additional, Kneip, R., additional, Kochiashvili, N., additional, Kunert, N., additional, Lekic, A., additional, Leonini, S., additional, Li, C. K., additional, Li, W., additional, Li, X. B., additional, Liao, J. Y., additional, Logie, L., additional, Lu, F. J., additional, Mao, J., additional, Marchais, D., additional, Ménard, R., additional, Morris, D., additional, Natsvlishvili, R., additional, Nedora, V., additional, Noonan, K., additional, Noysena, K., additional, Orange, N. B., additional, Pang, P. T. H., additional, Peng, H. W., additional, Pellouin, C., additional, Peloton, J., additional, Pradier, T., additional, Pyshna, O., additional, Rajabov, Y., additional, Rau, S., additional, Rinner, C., additional, Rivet, J.-P., additional, Romanov, F. D., additional, Rosi, P., additional, Rupchandani, V. A., additional, Serrau, M., additional, Shokry, A., additional, Simon, A., additional, Smith, K., additional, Sokoliuk, O., additional, Soliman, M., additional, Song, L. M., additional, Takey, A., additional, Tillayev, Y., additional, Ramirez, L. M. Tinjaca, additional, e Melo, I. Tosta, additional, Turpin, D., additional, de Ugarte Postigo, A., additional, Vanaverbeke, S., additional, Vasylenko, V., additional, Vernet, D., additional, Vidadi, Z., additional, Wang, C., additional, Wang, J., additional, Wang, L. T., additional, Wang, X. F., additional, Xiong, S. L., additional, Xu, Y. P., additional, Xue, W. C., additional, Zeng, X., additional, Zhang, S. N., additional, Zhao, H. S., additional, and Zhao, X. F., additional
Published: 2023
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19. The optical behaviour of BL Lacertae at its maximum brightness levels: a blend of geometry and energetics

Author: Raiteri, C M, primary, Villata, M, additional, Jorstad, S G, additional, Marscher, A P, additional, Acosta Pulido, J A, additional, Carosati, D, additional, Chen, W P, additional, Joner, M D, additional, Kurtanidze, S O, additional, Lorey, C, additional, Marchini, A, additional, Matsumoto, K, additional, Mirzaqulov, D O, additional, Savchenko, S S, additional, Strigachev, A, additional, Vince, O, additional, Aceti, P, additional, Apolonio, G, additional, Arena, C, additional, Arkharov, A, additional, Bachev, R, additional, Bader, N, additional, Banfi, M, additional, Bonnoli, G, additional, Borman, G A, additional, Bozhilov, V, additional, Brown, L F, additional, Carbonell, W, additional, Carnerero, M I, additional, Damljanovic, G, additional, Dhiman, V, additional, Ehgamberdiev, S A, additional, Elsaesser, D, additional, Feige, M, additional, Gabellini, D, additional, Galán, D, additional, Galli, G, additional, Gaur, H, additional, Gazeas, K, additional, Grishina, T S, additional, Gupta, A C, additional, Hagen-Thorn, V A, additional, Hallum, M K, additional, Hart, M, additional, Hasuda, K, additional, Heidemann, K, additional, Horst, B, additional, Hou, W-J, additional, Ibryamov, S, additional, Ivanidze, R Z, additional, Jovanovic, M D, additional, Kimeridze, G N, additional, Kishore, S, additional, Klimanov, S, additional, Kopatskaya, E N, additional, Kurtanidze, O M, additional, Kushwaha, P, additional, Lane, D J, additional, Larionova, E G, additional, Leonini, S, additional, Lin, H C, additional, Mannheim, K, additional, Marino, G, additional, Minev, M, additional, Modaressi, A, additional, Morozova, D A, additional, Mortari, F, additional, Nazarov, S V, additional, Nikolashvili, M G, additional, Otero Santos, J, additional, Ovcharov, E, additional, Papini, R, additional, Pinter, V, additional, Privitera, C A, additional, Pursimo, T, additional, Reinhart, D, additional, Roberts, J, additional, Romanov, F D, additional, Rosenlehner, K, additional, Sakamoto, T, additional, Salvaggio, F, additional, Schoch, K, additional, Semkov, E, additional, Seufert, J, additional, Shakhovskoy, D, additional, Sigua, L A, additional, Singh, C, additional, Steineke, R, additional, Stojanovic, M, additional, Tripathi, T, additional, Troitskaya, Y V, additional, Troitskiy, I S, additional, Tsai, A, additional, Valcheva, A, additional, Vasilyev, A A, additional, Vrontaki, K, additional, Weaver, Z R, additional, Wooley, J H F, additional, Zaharieva, E, additional, and Zhovtan, A V, additional
Published: 2023
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20. GRANDMA and HXMT Observations of GRB 221009A: The Standard Luminosity Afterglow of a Hyperluminous Gamma-Ray Burst—In Gedenken an David Alexander Kann

Author: Kann, D. A., Agayeva, S., Aivazyan, V., Alishov, S., Andrade, C. M., Antier, S., Baransky, A., Bendjoya, P., Benkhaldoun, Z., Beradze, S., Berezin, D., Boër, M., Broens, E., Brunier, S., Bulla, M., Burkhonov, O., Burns, E., Chen, Y., Chen, Y. P., Conti, M., Coughlin, M. W., Cui, W. W., Daigne, F., Delaveau, B., Devillepoix, H. A. R., Dietrich, T., Dornic, D., Dubois, F., Ducoin, J.-G., Durand, E., Duverne, P.-A., Eggenstein, H.-B., Ehgamberdiev, S., Fouad, A., Freeberg, M., Froebrich, Dirk, Ge, M. Y., Gervasoni, S., Godunova, V., Gokuldass, P., Gurbanov, E., Han, D. W., Hasanov, E., Hello, P., Hussenot-Desenonges, T., Inasaridze, R., Iskandar, A., Ismailov, N., Janati, A., du Laz, T. Jegou, Jia, S. M., Karpov, S., Kaeouach, A., Kiendrebeogo, R. W., Klotz, A., Kneip, R., Kochiashvili, N., Kunert, N., Lekic, A., Leonini, S., Li, C. K., Li, W., Li, X. B., Liao, J. Y., Logie, L., Lu, F. J., Mao, J., Marchais, D., Ménard, R., Morris, D., Natsvlishvili, R., Nedora, V., Noonan, K., Noysena, K., Orange, N. B., Pang, P. T. H., Peng, H. W., Pellouin, C., Peloton, J., Pradier, T., Pyshna, O., Rajabov, Y., Rau, S., Rinner, C., Rivet, J.-P., Romanov, F. D., Rosi, P., Rupchandani, V. A., Serrau, M., Shokry, A., Simon, A., Smith, K., Sokoliuk, O., Soliman, M., Song, L. M., Takey, A., Tillayev, Y., Ramirez, L. M. Tinjaca, e Melo, I. Tosta, Turpin, D., de Ugarte Postigo, A., Vanaverbeke, S., Vasylenko, V., Vernet, D., Vidadi, Z., Wang, C., Wang, J., Wang, L. T., Wang, X. F., Xiong, S. L., Xu, Y. P., Xue, W. C., Zeng, X., Zhang, S. N., Zhao, H. S., Zhao, X. F., Kann, D. A., Agayeva, S., Aivazyan, V., Alishov, S., Andrade, C. M., Antier, S., Baransky, A., Bendjoya, P., Benkhaldoun, Z., Beradze, S., Berezin, D., Boër, M., Broens, E., Brunier, S., Bulla, M., Burkhonov, O., Burns, E., Chen, Y., Chen, Y. P., Conti, M., Coughlin, M. W., Cui, W. W., Daigne, F., Delaveau, B., Devillepoix, H. A. R., Dietrich, T., Dornic, D., Dubois, F., Ducoin, J.-G., Durand, E., Duverne, P.-A., Eggenstein, H.-B., Ehgamberdiev, S., Fouad, A., Freeberg, M., Froebrich, Dirk, Ge, M. Y., Gervasoni, S., Godunova, V., Gokuldass, P., Gurbanov, E., Han, D. W., Hasanov, E., Hello, P., Hussenot-Desenonges, T., Inasaridze, R., Iskandar, A., Ismailov, N., Janati, A., du Laz, T. Jegou, Jia, S. M., Karpov, S., Kaeouach, A., Kiendrebeogo, R. W., Klotz, A., Kneip, R., Kochiashvili, N., Kunert, N., Lekic, A., Leonini, S., Li, C. K., Li, W., Li, X. B., Liao, J. Y., Logie, L., Lu, F. J., Mao, J., Marchais, D., Ménard, R., Morris, D., Natsvlishvili, R., Nedora, V., Noonan, K., Noysena, K., Orange, N. B., Pang, P. T. H., Peng, H. W., Pellouin, C., Peloton, J., Pradier, T., Pyshna, O., Rajabov, Y., Rau, S., Rinner, C., Rivet, J.-P., Romanov, F. D., Rosi, P., Rupchandani, V. A., Serrau, M., Shokry, A., Simon, A., Smith, K., Sokoliuk, O., Soliman, M., Song, L. M., Takey, A., Tillayev, Y., Ramirez, L. M. Tinjaca, e Melo, I. Tosta, Turpin, D., de Ugarte Postigo, A., Vanaverbeke, S., Vasylenko, V., Vernet, D., Vidadi, Z., Wang, C., Wang, J., Wang, L. T., Wang, X. F., Xiong, S. L., Xu, Y. P., Xue, W. C., Zeng, X., Zhang, S. N., Zhao, H. S., and Zhao, X. F.
Abstract: Object GRB 221009A is the brightest gamma-ray burst (GRB) detected in more than 50 yr of study. In this paper, we present observations in the X-ray and optical domains obtained by the GRANDMA Collaboration and the Insight Collaboration. We study the optical afterglow with empirical fitting using the GRANDMA+HXMT-LE data sets augmented with data from the literature up to 60 days. We then model numerically using a Bayesian approach, and we find that the GRB afterglow, extinguished by a large dust column, is most likely behind a combination of a large Milky Way dust column and moderate low-metallicity dust in the host galaxy. Using the GRANDMA+HXMT-LE+XRT data set, we find that the simplest model, where the observed afterglow is produced by synchrotron radiation at the forward external shock during the deceleration of a top-hat relativistic jet by a uniform medium, fits the multiwavelength observations only moderately well, with a tension between the observed temporal and spectral evolution. This tension is confirmed when using the augmented data set. We find that the consideration of a jet structure (Gaussian or power law), the inclusion of synchrotron self-Compton emission, or the presence of an underlying supernova do not improve the predictions. Placed in the global context of GRB optical afterglows, we find that the afterglow of GRB 221009A is luminous but not extraordinarily so, highlighting that some aspects of this GRB do not deviate from the global known sample despite its extreme energetics and the peculiar afterglow evolution.
Published: 2023

21. Light equation in eclipsing binary CV Boo: third body candidate in elliptical orbit

Author: Bogomazov, A. I., Kozyreva, V. S., Satovskii, B. L., Krushevska, V. N., Kuznyetsova, Y. G., Ehgamberdiev, S. A., Karimov, R. G., Khalikova, A. V., Ibrahimov, M. A., Irsmambetova, T. R., and Tutukov, A. V.
Published: 2016
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22. Timing of eclipsing binary V0873 Per: a third body candidate

Author: Bogomazov, A. I., Ibrahimov, M. A., Satovskii, B. L., Kozyreva, V. S., Irsmambetova, T. R., Krushevska, V. N., Kuznyetsova, Y. G., Gaynullina, E. R., Karimov, R. G., Ehgamberdiev, S. A., and Tutukov, A. V.
Published: 2016
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23. Rotation acceleration of asteroids (10115) 1992 SK, (1685) Toro, and (1620) Geographos due to the YORP effect

Author: Ďurech, J., primary, Vokrouhlický, D., additional, Pravec, P., additional, Krugly, Yu. N., additional, Kim, M.-J., additional, Polishook, D., additional, Ayvazian, V. V., additional, Bonev, T., additional, Choi, Y.-J., additional, Datashvili, D. G., additional, Donchev, Z., additional, Ehgamberdiev, S. A., additional, Hornoch, K., additional, Inasaridze, R. Ya., additional, Kapanadze, G. V., additional, Kim, D.-H., additional, Kučáková, H., additional, Kusakin, A. V., additional, Kušnirák, P., additional, Lee, H.-J., additional, Molotov, I. E., additional, Moon, H.-K., additional, Mykhailova, S. S., additional, Nikolenko, I. V., additional, Novichonok, A., additional, Oey, J., additional, Omarov, Ch. T., additional, Pollock, J. T., additional, Reva, I. V., additional, Rumyantsev, V. V., additional, and Zhornichenko, A. A., additional
Published: 2021
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24. Multi-Wavelength Variability of BL Lacertae Measured with High Time Resolution

Author: Nikiforova, A. A., Vasilyev, A. A., Gupta, A. C., Tsai, A. L., Marscher, A. P., Sadun, A., Strigachev, A., Zhovtan, A. V., Valcheva, A., Raiteri, C. M., Morozova, D. A., Carosati, D., Hiriart, D., Dougherty, D. J., Mirzaqulov, D. O., Benitez, E., Larionova, E. G., Kopatskaya, E. N., Evgeni Ovcharov, Semkov, E., Zaharieva, E., Borman, G. A., Damljanovic, G., Kimeridze, G. N., Baida, G. V., Hsiao, H. Y., Troitsky, I. S., Acosta-Pulido, J. A., Slater, J. J., Williamson, K. E., Smith, K. L., Matsumoto, K., Nikolashvili, M. G., Hart, M., Carnerero, M. I., Joner, M., Minev, M., Stojanovic, M., Villata, M., Rizzi, N., Kurtanidze, O. M., Vince, O., Bachev, R., Matsumura, R., Ehgamberdiev, S. A., Jorstad, S. G., Ibryamov, S., Kurtanidze, S. O., Savchenko, S. S., Balonek, T. J., Grishina, T. S., Bozhilov, V., Dhiman, V., Larionov, V. M., Chen, W. P., Troitskaya, Yu V., and Weaver, Zachary R.
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics::High Energy Astrophysical Phenomena, Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: In an effort to locate the sites of emission at different frequencies and physical processes causing variability in blazar jets, we have obtained high time-resolution observations of BL Lacertae over a wide wavelength range: with the \emph{Transiting Exoplanet Survey Satellite} (TESS) at 6,000-10,000 \AA\ with 2-minute cadence; with the Neil Gehrels \emph{Swift} satellite at optical, UV, and X-ray bands; with the Nuclear Spectroscopic Telescope Array at hard X-ray bands; with the \emph{Fermi} Large Area Telescope at $\gamma$-ray energies; and with the Whole Earth Blazar Telescope for measurement of the optical flux density and polarization. All light curves are correlated, with similar structure on timescales from hours to days. The shortest timescale of variability at optical frequencies observed with TESS is $\sim 0.5$ hr. The most common timescale is $13\pm1$~hr, comparable with the minimum timescale of X-ray variability, 14.5 hr. The multi-wavelength variability properties cannot be explained by a change solely in the Doppler factor of the emitting plasma. The polarization behavior implies that there are both ordered and turbulent components to the magnetic field in the jet. Correlation analysis indicates that the X-ray variations lag behind the $\gamma$-ray and optical light curves by up to $\sim 0.4$ days. The timescales of variability, cross-frequency lags, and polarization properties can be explained by turbulent plasma that is energized by a shock in the jet and subsequently loses energy to synchrotron and inverse Compton radiation in a magnetic field of strength $\sim3$ G, Comment: 33 pages, 25 figures, 14 tables. Accepted to ApJ
Published: 2020
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25. The dual nature of blazar fast variability: Space and ground observations of S5 0716+714

Author: Raiteri, C M, primary, Villata, M, additional, Carosati, D, additional, Benítez, E, additional, Kurtanidze, S O, additional, Gupta, A C, additional, Mirzaqulov, D O, additional, D’Ammando, F, additional, Larionov, V M, additional, Pursimo, T, additional, Acosta-Pulido, J A, additional, Baida, G V, additional, Balmaverde, B, additional, Bonnoli, G, additional, Borman, G A, additional, Carnerero, M I, additional, Chen, W-P, additional, Dhiman, V, additional, Di Maggio, A, additional, Ehgamberdiev, S A, additional, Hiriart, D, additional, Kimeridze, G N, additional, Kurtanidze, O M, additional, Lin, C S, additional, Lopez, J M, additional, Marchini, A, additional, Matsumoto, K, additional, Mujica, R, additional, Nakamura, M, additional, Nikiforova, A A, additional, Nikolashvili, M G, additional, Okhmat, D N, additional, Otero-Santos, J, additional, Rizzi, N, additional, Sakamoto, T, additional, Semkov, E, additional, Sigua, L A, additional, Stiaccini, L, additional, Troitsky, I S, additional, Tsai, A L, additional, Vasilyev, A A, additional, and Zhovtan, A V, additional
Published: 2020
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26. Differential photometry of δ Scuti stars at Maidanak observatory

Author: Ayukov, S., primary, Artamonov, B., additional, Ezhkova, O., additional, Magnitskiy, A., additional, Ehgamberdiev, S., additional, and Serebryanskiy, A., additional
Published: 2010
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27. Multiwavelength Variability of BL Lacertae Measured with High Time Resolution

Author: Weaver, Z. R., primary, Williamson, K. E., additional, Jorstad, S. G., additional, Marscher, A. P., additional, Larionov, V. M., additional, Raiteri, C. M., additional, Villata, M., additional, Acosta-Pulido, J. A., additional, Bachev, R., additional, Baida, G. V, additional, Balonek, T. J., additional, Benítez, E., additional, Borman, G. A., additional, Bozhilov, V., additional, Carnerero, M. I., additional, Carosati, D., additional, Chen, W. P., additional, Damljanovic, G., additional, Dhiman, V., additional, Dougherty, D. J., additional, Ehgamberdiev, S. A., additional, Grishina, T. S., additional, Gupta, A. C., additional, Hart, M., additional, Hiriart, D., additional, Hsiao, H. Y., additional, Ibryamov, S., additional, Joner, M., additional, Kimeridze, G. N., additional, Kopatskaya, E. N., additional, Kurtanidze, O. M., additional, Kurtanidze, S. O., additional, Larionova, E. G., additional, Matsumoto, K., additional, Matsumura, R., additional, Minev, M., additional, Mirzaqulov, D. O., additional, Morozova, D. A., additional, Nikiforova, A. A., additional, Nikolashvili, M. G., additional, Ovcharov, E., additional, Rizzi, N., additional, Sadun, A., additional, Savchenko, S. S., additional, Semkov, E., additional, Slater, J. J., additional, Smith, K. L., additional, Stojanovic, M., additional, Strigachev, A., additional, Troitskaya, Yu. V., additional, Troitsky, I. S., additional, Tsai, A. L., additional, Vince, O., additional, Valcheva, A., additional, Vasilyev, A. A., additional, Zaharieva, E., additional, and Zhovtan, A. V., additional
Published: 2020
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28. SN 2018hti: a nearby superluminous supernova discovered in a metal-poor galaxy

Author: Lin, W L, primary, Wang, X F, additional, Li, W X, additional, Zhang, J J, additional, Mo, J, additional, Sai, H N, additional, Zhang, X H, additional, Filippenko, A V, additional, Zheng, W K, additional, Brink, T G, additional, Baron, E, additional, DerKacy, J M, additional, Ehgamberdiev, S A, additional, Mirzaqulov, D, additional, Li, X, additional, Zhang, J C, additional, Yan, S Y, additional, Xi, G B, additional, Hsiao, Y, additional, Zhang, T M, additional, Wang, L J, additional, Liu, L D, additional, Xiang, D F, additional, Wu, C Y, additional, Rui, L M, additional, and Chen, Z H, additional
Published: 2020
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29. Liverpool-Maidanak monitoring of the Einstein Cross in 2006–2019

Author: Goicoechea, L. J., primary, Artamonov, B. P., additional, Shalyapin, V. N., additional, Sergeyev, A. V., additional, Burkhonov, O. A., additional, Akhunov, T. A., additional, Asfandiyarov, I. M., additional, Bruevich, V. V., additional, Ehgamberdiev, S. A., additional, Shimanovskaya, E. V., additional, and Zheleznyak, A. P., additional
Published: 2020
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30. Is the solar core rotating faster or slower than the envelope?

Author: Lazrek, M., Pantel, A., Fossat, E., Gelly, B., Schmider, F. X., Fierry-Fraillon, D., Grec, G., Loudagh, S., Ehgamberdiev, S., Khamitov, I., Hoeksema, J. T., Pallé, P. L., and Régulo, C.
Published: 1996
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31. General presentation of a single IRIS site raw data analysis problem

Author: Ehgamberdiev, S., Khalikov, S., and Fossat, E.
Published: 1991
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32. Catalog of equatorial coordinates and B‐magnitudes of the Kitab's part of the FON project

Author: Yuldoshev, Q., primary, Protsyuk, Y., additional, Relke, H., additional, Ehgamberdiev, S., additional, Muminov, M., additional, and Andruk, V., additional
Published: 2019
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33. ISON NETWORK TRACKING OF SPACE DEBRIS: CURRENT STATUS AND ACHIEVEMENTS

Author: Molotov, I., primary, Zakhvatkin, M., additional, Elenin, L., additional, Canals Ros, L., additional, Graziani, F., additional, Teofilatto, P., additional, Schildknecht, T., additional, Ehgamberdiev, S., additional, Aliev, A., additional, Ivashchenko, Y., additional, Zalles, R., additional, Streltsov, A., additional, Krylov, A., additional, Erofeeva, A., additional, Chornaya, E., additional, Rusakov, O., additional, Stepanyants, V., additional, Agletdinov, V., additional, Borovin, G., additional, and Pavlova, E., additional
Published: 2019
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34. Diagnosing the Clumpy Protoplanetary Disk of the UXor Type Young Star GM Cephei

Author: Huang, P. C., primary, Chen, W. P., additional, Mugrauer, M., additional, Bischoff, R., additional, Budaj, J., additional, Burkhonov, O., additional, Ehgamberdiev, S., additional, Errmann, R., additional, Garai, Z., additional, Hsiao, H. Y., additional, Hu, C. L., additional, Janulis, R., additional, Jensen, E. L. N., additional, Kiyota, S., additional, Kuramoto, K., additional, Lin, C. S., additional, Lin, H. C., additional, Liu, J. Z., additional, Lux, O., additional, Naito, H., additional, Neuhäuser, R., additional, Ohlert, J., additional, Pakštienė, E., additional, Pribulla, T., additional, Qvam, J. K. T., additional, Raetz, St., additional, Sato, S., additional, Schwartz, M., additional, Semkov, E., additional, Takagi, S., additional, Wagner, D., additional, Watanabe, M., additional, and Zhang, Yu, additional
Published: 2019
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35. Optical observations of NEA 3200 Phaethon (1983 TB) during the 2017 apparition

Author: Kim, M.-J., primary, Lee, H.-J., additional, Lee, S.-M., additional, Kim, D.-H., additional, Yoshida, F., additional, Bartczak, P., additional, Dudziński, G., additional, Park, J., additional, Choi, Y.-J., additional, Moon, H.-K., additional, Yim, H.-S., additional, Choi, J., additional, Choi, E.-J., additional, Yoon, J.-N., additional, Serebryanskiy, A., additional, Krugov, M., additional, Reva, I., additional, Ergashev, K. E., additional, Burkhonov, O., additional, Ehgamberdiev, S. A., additional, Turayev, Y., additional, Lin, Z.-Y., additional, Arai, T., additional, Ohtsuka, K., additional, Ito, T., additional, Urakawa, S., additional, and Ishiguro, M., additional
Published: 2018
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36. The dual nature of blazar fast variability: Space and ground observations of S5 0716+714.

Author: Raiteri, C M, Villata, M, Carosati, D, Benítez, E, Kurtanidze, S O, Gupta, A C, Mirzaqulov, D O, D'Ammando, F, Larionov, V M, Pursimo, T, Acosta-Pulido, J A, Baida, G V, Balmaverde, B, Bonnoli, G, Borman, G A, Carnerero, M I, Chen, W-P, Dhiman, V, Di Maggio, A, and Ehgamberdiev, S A
Subjects: BL Lacertae objects, TIME series analysis, SPACE telescopes, CUBIC curves
Abstract: Blazar S5 0716+714 is well-known for its short-term variability, down to intraday time-scales. We here present the 2-min cadence optical light curve obtained by the TESS space telescope in 2019 December–2020 January and analyse the object fast variability with unprecedented sampling. Supporting observations by the Whole Earth Blazar Telescope Collaboration in B, V, R , and I bands allow us to investigate the spectral variability during the TESS pointing. The spectral analysis is further extended in frequency to the UV and X-ray bands with data from the Neil Gehrels Swift Observatory. We develop a new method to unveil the shortest optical variability time-scales. This is based on progressive de-trending of the TESS light curve by means of cubic spline interpolations through the binned fluxes, with decreasing time bins. The de-trended light curves are then analysed with classical tools for time-series analysis (periodogram, autocorrelation, and structure functions). The results show that below 3 d there are significant characteristic variability time-scales of about 1.7, 0.5, and 0.2 d. Variability on time-scales |$\lesssim 0.2$| d is strongly chromatic and must be ascribed to intrinsic energetic processes involving emitting regions, likely jet substructures, with dimension less than about 10−3 pc. In contrast, flux changes on time-scales |$\gtrsim 0.5$| d are quasi-achromatic and are probably due to Doppler factor changes of geometric origin. [ABSTRACT FROM AUTHOR]
Published: 2021
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37. Blazar spectral variability as explained by a twisted inhomogeneous jet

Author: Raiteri C., Villata M., Acosta-Pulido J., Agudo I., Arkharov A., Bachev R., Baida G., Benítez E., Borman G., Boschin W., Bozhilov V., Butuzova M., Calcidese P., Carnerero M., Carosati D., Casadio C., Castro-Segura N., Chen W., Damljanovic G., D'Ammando F., Di Paola A., Echevarría J., Efimova N., Ehgamberdiev S., Espinosa C., Fuentes A., Giunta A., Gómez J., Grishina T., Gurwell M., Hiriart D., Jermak H., Jordan B., Jorstad S., Joshi M., Kopatskaya E., Kuratov K., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionov V., Larionova E., Larionova L., Lázaro C., Lin C., Malmrose M., Marscher A., Matsumoto K., McBreen B., Michel R., Mihov B., Minev M., Mirzaqulov D., Mokrushina A., Molina S., Moody J., Morozova D., Nazarov S., Nikolashvili M., Ohlert J., Okhmat D., Ovcharov E., Pinna F., Polakis T., Protasio C., Pursimo T., Redondo-Lorenzo F., Rizzi N., Rodriguez-Coira G., Sadakane K., Sadun A., Samal M., Savchenko S., Semkov E., Skiff B., Slavcheva-Mihova L., Smith P., and Steele I.
Subjects: Astrophysics::High Energy Astrophysical Phenomena
Abstract: © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. Blazars are active galactic nuclei, which are powerful sources of radiation whose central engine is located in the core of the host galaxy. Blazar emission is dominated by non-thermal radiation from a jet that moves relativistically towards us, and therefore undergoes Doppler beaming. This beaming causes flux enhancement and contraction of the variability timescales, so that most blazars appear as luminous sources characterized by noticeable and fast changes in brightness at all frequencies. The mechanism that produces this unpredictable variability is under debate, but proposed mechanisms include injection, acceleration and cooling of particles, with possible intervention of shock waves or turbulence. Changes in the viewing angle of the observed emitting knots or jet regions have also been suggested as an explanation of flaring events and can also explain specific properties of blazar emission, such as intra-day variability, quasi-periodicity and the delay of radio flux variations relative to optical changes. Such a geometric interpretation, however, is not universally accepted because alternative explanations based on changes in physical conditions - such as the size and speed of the emitting zone, the magnetic field, the number of emitting particles and their energy distribution - can explain snapshots of the spectral behaviour of blazars in many cases. Here we report the results of optical-to-radio-wavelength monitoring of the blazar CTA 102 and show that the observed long-term trends of the flux and spectral variability are best explained by an inhomogeneous, curved jet that undergoes changes in orientation over time. We propose that magnetohydrodynamic instabilities or rotation of the twisted jet cause different jet regions to change their orientation and hence their relative Doppler factors. In particular, the extreme optical outburst of 2016-2017 (brightness increase of six magnitudes) occurred when the corresponding emitting region had a small viewing angle. The agreement between observations and theoretical predictions can be seen as further validation of the relativistic beaming theory.
Published: 2017

38. Timing of eclipsing binary V0873 Per: a third body candidate

Author: Bogomazov, A. I., primary, Ibrahimov, M. A., additional, Satovskii, B. L., additional, Kozyreva, V. S., additional, Irsmambetova, T. R., additional, Krushevska, V. N., additional, Kuznyetsova, Y. G., additional, Gaynullina, E. R., additional, Karimov, R. G., additional, Ehgamberdiev, S. A., additional, and Tutukov, A. V., additional
Published: 2015
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39. IRIS++ database: Merging of IRIS + Mark-1 + LOWL

Author: Salabert, D., primary, Fossat, E., additional, Gelly, B., additional, Tomczyk, S., additional, Pallé, P., additional, Jiménez-Reyes, S. J., additional, Cacciani, A., additional, Corbard, T., additional, Ehgamberdiev, S., additional, Grec, G., additional, Hoeksema, J. T., additional, Kholikov, S., additional, Lazrek, M., additional, and Schmider, F. X., additional
Published: 2002
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40. IRIS++database: Merging of IRIS + Mark-1 + LOWL*

Author: Salabert, D., Fossat, E., Gelly, B., Tomczyk, S., Pallé, P., Jiménez-Reyes, S. J., Cacciani, A., Corbard, T., Ehgamberdiev, S., Grec, G., Hoeksema, J. T., Kholikov, S., Lazrek, M., Schmider, F. X., Salabert, D., Fossat, E., Gelly, B., Tomczyk, S., Pallé, P., Jiménez-Reyes, S. J., Cacciani, A., Corbard, T., Ehgamberdiev, S., Grec, G., Hoeksema, J. T., Kholikov, S., Lazrek, M., and Schmider, F. X.
Abstract: The IRIS network has been operated continuously since July 1st 1989. To date, it has acquired more than a complete solar cycle of full-disk helioseismic data which has been used to constrain the structure and rotation of the deep solar interior. However, the duty cycle of the network data has never reached initial expectations. To improve this situation, several cooperations have been developed with teams collecting observations with similar instruments. This paper demonstrates that we are able to merge data from these different instruments in a consistent manner resulting in a very significant improvement in network duty cycle over more than one solar cycle initiating what we call the IRIS++network.
Published: 2002
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41. The astroclimate of Maidanak Observatory in Uzbekistan

Author: Ehgamberdiev, S. A., primary, Baijumanov, A. K., additional, Ilyasov, S. P., additional, Sarazin, M., additional, Tillayev, Y. A., additional, Tokovinin, A. A., additional, and Ziad, A., additional
Published: 2000
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42. An estimation of global solar p-mode frequencies from IRIS network data: 1989-1996

Author: Serebryanskiy, A., Ehgamberdiev, S., Kholikov, S., Fossat, E., Gelly, B., Schmider, F. X., Grec, G., Cacciani, A., Palle, P. L., and Lazrek, M.
Published: 2001
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43. Analysis of variability of p-mode parameters in 11 years of IRIS data

Author: Salabert, D., Sebastián Jiménez Reyes, Fossat, E., Cacciani, A., Ehgamberdiev, S., Gelly, B., Grec, G., Hoeksema, J. T., Khalikov, S., Lazrek, M., Pallé, P., Schmider, F. X., and Tomczyk, S.

44. Acoustic imaging in helioseismology

Author: Chou, D. -Y, Hsiang-Kuang Chang, Sun, M. -T, Labonte, B., Chen, H. -R, Yeh, S. -J, Tang, H. -T, Shiu, W. -C, Chen, Y. -L, Jimenez, A., Rabello-Soares, M. C., Ai, G., Wang, G. -P, Goode, P., Marquette, W., Ehgamberdiev, S., and Khalikov, S.

45. Astrometry of the h and χ Persei clusters based on the processing of digitized photographic plates

Author: Muminov, M., Qudratillo Yuldoshev, Ehgamberdiev, S., Kahharov, B., Relke, H., Protsyuk, Y., Pakuliak, L., and Andruk, V.

46. LIGO/Virgo S190814bv: CFHTphotometryof AT2019npv

Author: Wang, X., Antier, S., Coughlin, M., Li, W., Zhang, X., Mo, J., Xi, G., Bai, J., Basa, S., Bertin, E., Blazek, M., Michel Boer, Coleiro, A., Christensen, N., Ehgamberdiev, S., Kann, D. A., Klotz, A., David Coward, Corre, D., Ducoin, J. G., Bruce Gendre, Hello, P., Hu, L., Lachaud, C., Jiang, X., Leroy, N., Li, B., Lin, W., Mirzaqulov, D., Sun, T., Thoene, C., Turpin, D., Wang, L., Ugarte Postigo, A., Wu, X., Zhao, H., Zeng, X., Zhang, J. J., Zhang, J. C., Aogot Collaboration, and Grandma Collaboration

47. The beamed jet and quasar core of the distant blazar 4C 71.07

Author: Raiteri C., Villata M., Carnerero M., Acosta-Pulido J., Mirzaqulov D., Larionov V., Romano P., Vercellone S., Agudo I., Arkharov A., Bach U., Bachev R., Baitieri S., Borman G., Boschin W., Bozhilov V., Butuzova M., Calcidese P., Carosati D., Casadio C., Chen W., Damljanovic G., Di Paola A., Doroshenko V., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., Grishina T., Ibryamov S., Jermak H., Jorstad S., Kimeridze G., Klimanov S., Kopatskaya E., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionova E., Marscher A., Mihov B., Minev M., Molina S., Moody J., Morozova D., Nazarov S., Nikiforova A., Nikolashvili M., Ovcharov E., Peneva S., Righini S., Rizzi N., Sadun A., Samal M., Savchenko S., Semkov E., Sigua L., Slavcheva-Mihova L., Steele I., Strigachev A., Tornikoski M., Troitskaya Y., Troitsky I., Vince O., Raiteri C., Villata M., Carnerero M., Acosta-Pulido J., Mirzaqulov D., Larionov V., Romano P., Vercellone S., Agudo I., Arkharov A., Bach U., Bachev R., Baitieri S., Borman G., Boschin W., Bozhilov V., Butuzova M., Calcidese P., Carosati D., Casadio C., Chen W., Damljanovic G., Di Paola A., Doroshenko V., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., Grishina T., Ibryamov S., Jermak H., Jorstad S., Kimeridze G., Klimanov S., Kopatskaya E., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionova E., Marscher A., Mihov B., Minev M., Molina S., Moody J., Morozova D., Nazarov S., Nikiforova A., Nikolashvili M., Ovcharov E., Peneva S., Righini S., Rizzi N., Sadun A., Samal M., Savchenko S., Semkov E., Sigua L., Slavcheva-Mihova L., Steele I., Strigachev A., Tornikoski M., Troitskaya Y., Troitsky I., and Vince O.
Abstract: © 2019 The Author(s). The object 4C 71.07 is a high-redshift blazar whose spectral energy distribution shows a prominent big blue bump and a strong Compton dominance. We present the results of a 2- yr multiwavelength campaign led by the Whole Earth Blazar Telescope (WEBT) to study both the quasar core and the beamed jet of this source. The WEBT data are complemented by ultraviolet and X-ray data from Swift, and by γ-ray data by Fermi. The big blue bump is modelled by using optical and near-infrared mean spectra obtained during the campaign, together with optical and ultraviolet quasar templates. We give prescriptions to correct the source photometry in the various bands for the thermal contribution, in order to derive the non-thermal jet flux. The role of the intergalactic medium absorption is analysed in both the ultraviolet and X-ray bands.We provide opacity values to deabsorb ultraviolet data, and derive a best-guess value for the hydrogen column density of Nbest H = 6.3 × 1020 cm-2through the analysis of X-ray spectra.We estimate the disc and jet bolometric luminosities, accretion rate, and black hole mass. Light curves do not show persistent correlations among flux changes at different frequencies. We study the polarimetric behaviour and find no correlation between polarization degree and flux, even when correcting for the dilution effect of the big blue bump. Similarly, wide rotations of the electric vector polarization angle do not seem to be connected with the source activity.

48. AGILE, Fermi, Swift, and GASP/WEBT multi-wavelength observations of the high-redshift blazar 4C +71.07 in outburst

Author: Vercellone S., Romano P., Piano G., Vittorini V., Donnarumma I., Munar-Adrover P., Raiteri C., Villata M., Verrecchia F., Lucarelli F., Pittori C., Bulgarelli A., Fioretti V., Tavani M., Acosta-Pulido J., Agudo I., Arkharov A., Bach U., Bachev R., Borman G., Butuzova M., Carnerero M., Casadio C., Damljanovic G., D'Ammando F., Di Paola A., Doroshenko V., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., Grishina T., Järvelä E., Klimanov S., Kopatskaya E., Kurtanidze O., Lähteenmäki A., Larionov V., Larionova L., Mihov B., Mirzaqulov D., Molina S., Morozova D., Nazarov S., Orienti M., Righini S., Savchenko S., Semkov E., Slavcheva-Mihova L., Strigachev A., Tornikoski M., Troitskaya Y., Vince O., Cattaneo P., Colafrancesco S., Longo F., Morselli A., Paoletti F., Parmiggiani N., Vercellone S., Romano P., Piano G., Vittorini V., Donnarumma I., Munar-Adrover P., Raiteri C., Villata M., Verrecchia F., Lucarelli F., Pittori C., Bulgarelli A., Fioretti V., Tavani M., Acosta-Pulido J., Agudo I., Arkharov A., Bach U., Bachev R., Borman G., Butuzova M., Carnerero M., Casadio C., Damljanovic G., D'Ammando F., Di Paola A., Doroshenko V., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., Grishina T., Järvelä E., Klimanov S., Kopatskaya E., Kurtanidze O., Lähteenmäki A., Larionov V., Larionova L., Mihov B., Mirzaqulov D., Molina S., Morozova D., Nazarov S., Orienti M., Righini S., Savchenko S., Semkov E., Slavcheva-Mihova L., Strigachev A., Tornikoski M., Troitskaya Y., Vince O., Cattaneo P., Colafrancesco S., Longo F., Morselli A., Paoletti F., and Parmiggiani N.
Abstract: © ESO 2019. Context. The flat-spectrum radio quasar 4C +71.07 is a high-redshift (z = 2.172), γ-loud blazar whose optical emission is dominated by thermal radiation from the accretion disc. Aims. 4C +71.07 has been detected in outburst twice by the AGILE γ-ray satellite during the period from the end of October to mid-November 2015, when it reached a γ-ray flux of the order of F(E > 100 MeV)=(1.2 ± 0.3)×10 -6 photons cm -2 s -1 and F(E > 100 MeV)=(3.1 ± 0.6)×10 -6 photons cm -2 s -1 , respectively, allowing us to investigate the properties of the jet and the emission region. Methods. We investigated its spectral energy distribution by means of almost-simultaneous observations covering the cm, mm, near-infrared, optical, ultraviolet, X-ray, and γ-ray energy bands obtained by the GASP-WEBT Consortium and the Swift, AGILE, and Fermi satellites. Results. The spectral energy distribution of the second γ-ray flare (whose energy coverage is more dense) can be modelled by means of a one-zone leptonic model, yielding a total jet power of about 4 × 10 47 erg s -1 . Conclusions. During the most prominent γ-ray flaring period our model is consistent with a dissipation region within the broad-line region. Moreover, this class of high-redshift, flat-spectrum radio quasars with high-mass black holes might be good targets for future γ-ray satellites such as e-ASTROGAM.

49. The Bright γ-ray Flare of 3C 279 in 2015 June: AGILE Detection and Multifrequency Follow-up Observations

Author: Chen W., Ehgamberdiev S., Goded A., Grishina T., Hiriart D., Hsiao H., Jorstad S., Kimeridze G., Kopatskaya E., Kurtanidze O., Kurtanidze S., Larionov V., Larionova L., Marscher A., Mirzaqulov D., Morozova D., Nilsson K., Samal M., Sigua L., Spassov B., Strigachev A., Takalo L., Antonelli L., Bulgarelli A., Cattaneo P., Colafrancesco S., Giommi P., Longo F., Morselli A., Paoletti F., Chen W., Ehgamberdiev S., Goded A., Grishina T., Hiriart D., Hsiao H., Jorstad S., Kimeridze G., Kopatskaya E., Kurtanidze O., Kurtanidze S., Larionov V., Larionova L., Marscher A., Mirzaqulov D., Morozova D., Nilsson K., Samal M., Sigua L., Spassov B., Strigachev A., Takalo L., Antonelli L., Bulgarelli A., Cattaneo P., Colafrancesco S., Giommi P., Longo F., Morselli A., and Paoletti F.
Abstract: © 2018. The American Astronomical Society. All rights reserved.. We report the AGILE detection and the results of the multifrequency follow-up observations of a bright γ-ray flare of the blazar 3C 279 in 2015 June. We use AGILE and Fermi gamma-ray data, together with Swift X-ray andoptical-ultraviolet data, and ground-based GASP-WEBT optical observations, including polarization information, to study the source variability and the overall spectral energy distribution during the γ-ray flare. The γ-ray flaring data, compared with as yet unpublished simultaneous optical data that will allow constraints on the big blue bump disk luminosity, show very high Compton dominance values of ∼100, with the ratio of γ-ray to optical emission rising by a factor of three in a few hours. The multiwavelength behavior of the source during the flare challenges one-zone leptonic theoretical models. The new observations during the 2015 June flare are also compared with already published data and nonsimultaneous historical 3C 279 archival data.

50. Multiwavelength behaviour of the blazar OJ 248 from radio to γ -rays

Author: Carnerero M., Raiteri C., Villata M., Acosta-Pulido J., D'Ammando F., Smith P., Larionov V., Agudo I., Arévalo M., Arkharov A., Bach U., Bachev R., Benítez E., Blinov D., Bozhilov V., Buemi C., Bueno Bueno A., Carosati D., Casadio C., Chen W., Damljanovic G., Di Paola A., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., González-Morales P., Grinon-Marin A., Grishina T., Gurwell M., Hiriart D., Hsiao H., Ibryamov S., Jorstad S., Joshi M., Kopatskaya E., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionova E., Larionova L., Lázaro C., Leto P., Lin C., Lin H., Manilla-Robles A., Marscher A., McHardy I., Metodieva Y., Mirzaqulov D., Mokrushina A., Molina S., Morozova D., Nikolashvili M., Orienti M., Ovcharov E., Panwar N., Pastor Yabar A., Puerto Giménez I., Ramakrishnan V., Richter G., Rossini M., Sigua L., Strigachev A., Taylor B., Tornikoski M., Trigilio C., Troitskaya Y., Troitsky I., Umana G., Valcheva A., Velasco S., Vince O., Wehrle A., Wiesemeyer H., Carnerero M., Raiteri C., Villata M., Acosta-Pulido J., D'Ammando F., Smith P., Larionov V., Agudo I., Arévalo M., Arkharov A., Bach U., Bachev R., Benítez E., Blinov D., Bozhilov V., Buemi C., Bueno Bueno A., Carosati D., Casadio C., Chen W., Damljanovic G., Di Paola A., Efimova N., Ehgamberdiev S., Giroletti M., Gómez J., González-Morales P., Grinon-Marin A., Grishina T., Gurwell M., Hiriart D., Hsiao H., Ibryamov S., Jorstad S., Joshi M., Kopatskaya E., Kurtanidze O., Kurtanidze S., Lähteenmäki A., Larionova E., Larionova L., Lázaro C., Leto P., Lin C., Lin H., Manilla-Robles A., Marscher A., McHardy I., Metodieva Y., Mirzaqulov D., Mokrushina A., Molina S., Morozova D., Nikolashvili M., Orienti M., Ovcharov E., Panwar N., Pastor Yabar A., Puerto Giménez I., Ramakrishnan V., Richter G., Rossini M., Sigua L., Strigachev A., Taylor B., Tornikoski M., Trigilio C., Troitskaya Y., Troitsky I., Umana G., Valcheva A., Velasco S., Vince O., Wehrle A., and Wiesemeyer H.
Abstract: © 2015 The Authors. We present an analysis of the multiwavelength behaviour of the blazar OJ 248 at z = 0.939 in the period 2006-2013. We use low-energy data (optical, near-infrared, and radio) obtained by 21 observatories participating in the Gamma-Ray Large Area Space Telescope (GLAST)-AGILE Support Program of the Whole Earth Blazar Telescope, as well as data from the Swift (optical-UV and X-rays) and Fermi (γ -rays) satellites, to study flux and spectral variability and correlations among emissions in different bands. We take into account the effect of absorption by the Damped Lyman α intervening system at z = 0.525. Two major outbursts were observed in 2006-2007 and in 2012-2013 at optical and near-IR wavelengths, while in the high-frequency radio light curves prominent radio outbursts are visible peaking at the end of 2010 and beginning of 2013, revealing a complex radio-optical correlation. Crosscorrelation analysis suggests a delay of the optical variations after the γ -ray ones of about a month, which is a peculiar behaviour in blazars. We also analyse optical polarimetric and spectroscopic data. The average polarization percentage P is less than 3 per cent, but it reaches~19 per cent during the early stage of the 2012-2013 outburst.Avague correlation of P with brightness is observed. There is no preferred electric vector polarization angle and during the outburst the linear polarization vector shows wide rotations in both directions, suggesting a complex behaviour/structure of the jet and possible turbulence. The analysis of 140 optical spectra acquired at the Steward Observatory reveals a strong Mg II broad emission line with an essentially stable flux of 6.2 × 10-15 erg cm-2 s-1 and a full width at half-maximum of 2053 km s-1.

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