We analyse the efficiency of observational campaigns which were carried out during seven years involving four astropoints in Ukraine, Russia, Greece, and Bulgaria. A possibility of the synchronous monitoring of stellar flares is discussed in this paper

Romanyuk, Ya.

Kinematika i fizika nebesnyh tel (Online)

Наукова електронна бібліотека періодичних видань НАН України (Vernadsky National Library of Ukraine)

SOME POINTS OF THE MONITORING OF FLARE STARSUSING THE SYNCHRONOUS NETWORK OF REMOTE TELESCOPESYa. RomanyukMain Astronomical Observatory, NAS of Ukraine27 Akademika Zabolotnoho Str., 03680 Kyiv, Ukrainee-mail: romanyuk@mao.kiev.uaWe analyse the eﬃciency of observational campaigns which were carried out during seven years in-volving four astropoints in Ukraine, Russia, Greece, and Bulgaria. A possibility of the synchronousmonitoring of stellar ﬂares is discussed in this paper.INTRODUCTIONThe Synchronous Network of Remote Telescopes (SNT) [3] started as a coordinated network of telescopes in1997, when the 50-inch telescope at the Crimean Astrophysical Observatory was equipped with the secondHigh Speed Two Channel Photometer [4]. The SNT activities are supporting by ﬁve groups of astronomerswhich are working at the Crimean Astrophysical Observatory (CrAO, Ukraine), in the International Center forAstronomical, Medical and Ecological Research (Ukraine–Russia), at the Aristoteleon University (Greece), inthe Institute of Astronomy of the Bulgarian Academy of Sciences and at the Main Astronomical Observatoryof the National Academy of Sciences of Ukraine. They use photometric complexes at the Terskol Observatory(the Northern Caucasus), CrAO, the Stephanion Observatory (Greece), the Belogradchik Observatory, and/orthe Rozhen Observatory (Bulgaria). Three sets of photometers are able to synchronize their time clocks tothe UTC with an accuracy up to 1 μs using GPS antennas Acutime 2000.The primary focus of the SNT is the synchronous monitoring of UV Ceti type stars [2] with high speed (about10–100 ms per count). Hereby, the data obtained synchronously at distant observatories promote the gettingnew results in the study of ﬂare-related phenomena in stars. In the previous years simultaneous observationsof stars EV Lac, AD Leo, BY Dra, YZ Cmi, KR Aur, etc. were performed.The greatest attention was paid to synchronous observations of the ﬂare star EV Lac with the use of two,three, four, and ﬁve photometers at four observatories. A short statistic analysis of the results obtained in1998–2003 is presented below.OBSERVATIONS AND RESULTSA complete and detailed review of the ﬁrst coordinated international observations with the SNT in September1998 was prepared by Alekseev et al. [1]. Five telescopes at four observatories registered 18 ﬂares. Ten of themwere observed simultaneously at two observatories, ﬁve – at three observatories, and one – at four observatories.Some observations in the IR region as well spectra were obtained too. The whole campaign was carried outduring seven nights with the observing time planned as six hours for each night.In August 1999 observations were carried out at the Terskol Observatory and the Stephanion Observatory.The observing time was planned as four hours for each night. Two telescopes registered 23 ﬂares during 12 nightsbut there was not ﬂare observed simultaneously at two astrosites because the bad weather conditions.The total coverage of EV Lac with observations achieved during the international campaigns in 2000–2003is showed in Tables 1–5. They present our observations for each night using three terms:• Synchronous time of monitoring at piece of astrosites (ST#S).• Number of ﬂares registered simultaneously at piece of astrosites (FR#S).• Rate of synchronous time at piece of astrosites (RST#S).The international campaign in October 2000 (Table 1) was not enough successful, because it was too cloudyat observational sites during the observational period. The high-speed two-channel photometer of the 50-inchtelescope of the Crimean Astrophysical Observatory was in non-operational state, therefore many sets of the datac© Ya. Romanyuk, 2004291were unassured. Five telescopes at four observatories have registered 21 ﬂares during 10 nights with the plannedobserving time of six hours per night, but there were only two ﬂares observed simultaneously with two telescopes.Table 1. Observations of EV Lacertae in October 2000Date ST2S ST3S ST4S FR1S FR2S FR3S FR4S RST2S RST3S RST4S21/22.10.2000 0 0 0 1 0 0 0 0 0 022/23.10.2000 4h37m 1h33m 0 2 0 0 0 77% 26% 023/24.10.2000 4h45m 0 0 0 0 0 0 79% 0 024/25.10.2000 5h45m 4h43m 2h44m 4 0 1 0 96% 77% 46%25/26.10.2000 3h55m 0h37m 0 1 0 0 0 65% 10% 026/27.10.2000 5h17m 0 0 6 0 1 0 88% 0 027/28.10.2000 3h00m 2h15m 0 5 0 0 0 50% 38% 029/30.10.2000 2h54m 1h19m 0 2 0 0 0 48% 22% 030/31.10.2000 3h28m 0 0 0 0 0 0 58% 0 0Two observational campaigns were organized in 2001: the ﬁrst one was carried out during 9 nights inSeptember and the second – during 11 nights in October. For the September campaign (Table 2) we hadpossibilities for the synchronous monitoring from two astrosites during ﬁve nights (ﬁve hours per night wereplanned), but only during 2.2 hours of one night it was possible to observe simultaneously from three sites.Three telescopes at three observatories have registered 19 ﬂares, but no ﬂare was observed at least with twotelescopes.Table 2. Observations of EV Lacertae in September 2001Date ST2S ST3S FR1S FR2S FR3S RST2S RST3S09/10.09.2001 0 0 0 0 0 0 010/11.09.2001 0 0 1 0 0 0 011/12.09.2001 0 0 6 0 0 0 012/13.09.2001 0h13m 0 3 0 0 5% 013/14.09.2001 1h30m 0 0 0 0 34% 014/15.09.2001 3h57m 2h10m 3 0 0 79% 44%15/16.09.2001 2h33m 0 0 0 0 58% 016/17.09.2001 0 0 2 0 0 0 017/18.10.2001 3h01m 0 4 0 0 64% 0The weather conditions during the campaign on October 8–18, 2001 (Table 3) were bad at two of threeobservatories. Only one of four ﬂares was synchronously registered at two astrosites.Table 3. Observations of EV Lacertae in October 2001Date ST2S ST3S FR1S FR2S FR3S RST2S RST3S08/09.10.2001 0 0 0 0 0 0 009/10.10.2001 0 0 0 0 0 0 010/11.10.2001 2h07m 0 0 0 0 0 011/12.10.2001 2h45m 0 0 0 0 0 012/13.10.2001 0 0 0 0 0 0 013/14.10.2001 1h23m 0 1 0 0 0 014/15.10.2001 2h15m 0 2 1 0 0 015/16.10.2001 20 0 0 0 0 0 016/17.10.2001 0 0 0 0 0 0 017/18.10.2001 0 0 1 0 0 0 018/19.10.2001 0 0 0 0 0 0 0292The 2002 international campaign for the monitoring the red dwarf EV Lac (Table 4) was carried out during11 nights (ﬁve hours per night were planned). Four telescopes at three observatories were involved. Theyregistered 13 ﬂares and three of them were simultaneously observed at two astrosites. The weather conditionswere bad in the Crimea and in the Northern Caucasus.Table 4. Observations of EV Lacertae in October 2002Date ST2S ST3S FR1S FR2S FR3S RST2S RST3S01/02.10.2002 0 0 1 0 0 0 003/04.10.2002 2h00m 0 1 0 0 45% 004/05.10.2002 1h49m 0 2 0 0 39% 005/06.10.2002 0 0 0 0 0 0 008/09.10.2002 2h16m 0 2 0 0 45% 009/10.10.2002 3h35m 1h05m 1 1 0 66% 20%10/11.10.2002 3h42m 0 3 2 0 100% 011/12.10.2002 0 0 3 0 0 0 0The last international campaign for the monitoring EV Lac was carried out from September 23 to Octo-ber 4, 2003 (Table 5). The planned time for monitoring was 4 hours per night. In spite of the inability ofthe 2-m telescope of the Terskol Observatory, it was the most successful period for the synchronous observa-tions the target star from two observatories. Four telescopes at three observatories registered 26 ﬂares. 13 ofthem were synchronously observed at the Crimean Astrophysical Observatory and the Stephanion Observatoryand one was registered with all four telescopes.Table 5. Observations of EV Lacertae in October 2003Date ST2S ST3S FR1S FR2S FR3S RST2S RST3S23/24.09.2003 3h11m 2h49m 0 0 0 80% 70%24/25.09.2003 3h47m 0 4 3 0 86% 025/26.09.2003 4h10m 0 1 1 0 81% 026/27.09.2003 0h30m 0 3 0 0 12% 027/28.09.2003 2h32m 2h27m 2 1 1 70% 68%28/29.09.2003 1h48m 0 5 2 0 42% 029/30.09.2003 0 0 3 0 0 0 030/01.10.2003 4h15m 0 3 2 0 99% 001/02.10.2003 3h21m 0 2 0 0 80% 002/03.10.2003 3h52m 0 3 2 0 74% 003/04.10.2003 0 0 0 0 0 0 0CONCLUSIONSThe observations statistics of the ﬁve international campaigns carried out in 2000–2003 are presented inTables 1–5. At least three of four observatories from Russia (Terskol), Ukraine (CrAO), Greece (Stephanion),and Bulgaria (Rozhen or Belogradchik) were involved in each campaign. In the monitoring campaign 2000all four observatories with ﬁve telescopes have participated, in campaigns in 2001–2003 – three observato-ries. 241 hours during 53 nights were planned for synchronous observations during all campaigns. We ob-tained 97 (40%) hours of synchronous observations at two astrosites and about 19 hours – at three astrosites.20 ﬂares were synchronously registered with photometers at two sites and only one – with photometers at threesites. We have not any minute of synchronous observations at four sites during possible 60 hours (10 nights) in2000. The good common statistics for the data obtained simultaneously at two astropoints do not satisfy us.There are some reasons of the non-coincidence of observational tine intervals periods at the participatedobservatories. The main one is a weather factor, the next – operational integrity and possibility to get observa-tional time on ﬁxed dates on the telescopes. Sometime distant telescopes use diﬀerent time intervals to measurethe sky background or reference stars for the same observational set. This makes impossible to register someﬂares simultaneously at least with two photometers.293We hope this information will be useful for astronomers who plan synchronous observations of such rarephenomena as ﬂares on UV Ceti stars [2] or similar.Acknowledgements. I am grateful to B. Zhilyaev, I. Verlyuk, J. Seiradakis, S. Avgoloupis, M. Contadakis,R. Konstantinova-Antova, and A. Antov for the help in the collection of all obtained observational data, and toV. Godunova for her useful remarks.Observations of the Kyiv team at the Crimean Astrophysical Observatory and at the Terskol Observatoryduring 2000–2003 were mostly supported by grants of the Ministry of the Education and Science of Ukraine2M/146–2000 and 2M/86–2001.[1] Alekseev I. Yu., Antov A. P., Avgoloupis S. J., et al. Coordinated observations of the red dwarf ﬂare star EV Lacin 1998 // Kinematics and Physics of Celestial Bodies.–2001.–17, N 2.–P. 147–156.[2] Gershberg R. E. The solar-type activity amongst the main sequence stars.–Odessa: Astroprint, 2002.–688 p.[3] Romanyuk Ya., Zhilyaev B., Svyatogorov O., et al. The synchronous network of optical telescopes: a new in-strument for stellar photometry // Proc. of 5th Conf. of the Hellenic Astron. Soc. Crete, Sept. 20–22, 2001.[http://www.astro.auth.gr/∼helasmtg/2001].[4] Zhilyaev B. E., Romanyuk Ya. O., Svyatogorov O. A. The high-speed automatic two-channel photometer // Astron.Zh.–1992.–69, N 4.–P. 895–900.294

Some points of the monitoring of flare stars using the synchronous network of remote telescopes

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Some points of the monitoring of flare stars using the synchronous network of remote telescopes

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