PoS(EVN2018)150 http://pos.sissa.it/ , e , a xico, ´ e , E.E. Lekht , I.E. Val’tts d noma de M a ´ o , S.E. Kurtz c , b , M.A. Shurov f , a O maser bursts G25.65+1.05 have been intensively stud- 2 h , g , R.A. Burns a O maser source G25.65+1.05: 2 , A.V. Alakoz , N. N. Shakhvorostova a e ∗ and A.E. Volvach h , g xico ´ e [email protected] ied with a wide range of baselinesKaVA) – to from space compact VLBI array (JVLA) (RadioAstron and mission ground supportedport VLBI by (EVN, gives VLBA VLBA, a and brief EVN summary telescopes) of – these the observations. re- Speaker. In 2017-18 the source of outstanding H ∗ Copyright owned by the author(s) under the terms of the Creative Commons c 14th European VLBI Network Symposium &8-11 Users October Meeting 2018 (EVN 2018) Granada, Spain ⃝ Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). on behalf of the Maser Monitoring Organization (M2O) from single-dish to space VLBI O.S. Bayandina Bursting H Instituto de Radioastronomía y Astrofísica, Universidad Nacional Aut G.M. Rudnitskii L.N. Volvach Astro Space Center, Lebedev Physical Institute, RussianMizusawa Academy VLBI of Observatory, National Sciences, Astronomical Moscow, Observatory Russia Joint of Institute Japan, for Tokyo, Japan VLBI ERIC, Dwingeloo, The Netherlands Morelia, M Sternberg Astronomical Institute, Moscow, Russia Astronomical Observatory, Institute for Natural SciencesUniversity, and Ekaterinburg, Mathematics, Russia Ural Federal Radio Astronomy and Geodinamics Department ofKatsively, Crimean Crimea Astrophysical Observatory, Institute of Applied Astronomy, Russian AcademyE-mail: of Sciences, St. Petersburg, Russia f c e a b g h d PoS(EVN2018)150 ] 5 3 , 2 3 Earth ∼ O.S. Bayandina O maser bursts detected in the 2 O maser emission. Long-term monitoring 2 ]. The most recent burst was short-lived: the 4 , 2 1 ] 6 [ O maser in G25.65+1.05 was carried out on August 10th, 2 20 to 76 KJy within half a day on November 20; the source faded to ]. ∼ 5 ]. The next powerful burst of 65 000 Jy was detected in September 2017 [ O maser bursts with flux densities of 60-70 kJy triggered intensive study of 1 2 K). But in contrast to them, the source is less known and did not attract as much at- Timeline of G25.65+1.05 observations. Red points indicate H 17 RadioAstron: 10-m SRT + VLBA 10 O maser with the RT-22 of the Pushchino Radio Astronomy Observatory (Moscow region) 2 1. Detected H The source G25.65+1.05 (RAFGL7009S, IRAS 18316-0602) is one of only three Galactic ∼ b 20 KJy on November 22 [ 2017 in simultaneous observation of theBaseline Array source (VLBA) with in 10-m the Space frames Radiostate of Telescope VLBI space and observation VLBI Very of project Long the RadioAstron. sourcebursts This at is of the the December only moment, 2016 stable- it and took September place on 2017. non-bursting epoch Achieved between projected baseline length of single-dish monitoring with RT-22 Pushchinoobservations and of RT-22 the Simeiz; source black (see references points in – the VLBI text). and compact array The very first VLBI study of 22 GHz H Figure 1: G25.65+1.05 with a wideon range the source of lately baselines is presented – on context Fig. for 1. the various observations carried out ∼ 2. Observations peak flux density rose from 1. Introduction water masers together with W49N and Oriontention KL before – that there are are known only to single-dish data flare on to H the level of 10 G25.65+1.05: from single-dish to space VLBI (T of H showed three flares in 2002,Jy, 2010, respectively [ and 2016 with the flux density of 3 400, 19 000, and 46 000 with RT-22 of the Crimean Astrophysical Observatory.source In showed new October increase 2017 of shortly flux after density this – burst see the [ PoS(EVN2018)150 ]. 11 O maser 2 OH maser 3 K. O.S. Bayandina 16 OH masers are 3 OH masers) and 10 3 O maser emission 2 × O bursting feature is 3 2 ∼ b OH masers are distributed 3 ] 7 [ as. In the experiment the signal was de- µ 80 ∼ O maser feature in the source showed that the O maser emission in the field. Only two anten- 0.5 mas. For more details see the article of R.A. 2 2 as were achieved. But very limited ground-based ∼ O masers. The first map of 44 GHz CH 2 µ 2 24 ∼ as with a brightness temperature T µ ] 25 ] ∼ 10 9 [ [ OH masers). For the first time ever four continuum sources are resolved 3 O maser spots were obtained for the first time, despite the fact that it was the final 2 VLA B-configuration RadioAstron:10-m SRT + 32-m Torun + 26-m HartRAO EVN / VLBA / KaVA 4. 2. 3. determined in the experiment (available phasewith reference VLBI sources resolution). are weak Class anddisk II tend rotating methanol to around maser one be of emission resolved the atspatially detected associated 6.7 continuum with sources. GHz not-bursting 22 Detected seems GHz 6.7 H to GHzemission trace in CH the an source edge-on was obtained. Fourperpendicular spatial to clusters large-scale of 44 outflow GHz revealed CH in molecular line observations of the source [ in the field.22 Thanks GHz to H fast dataobservation in reduction the with presented VLA series. CASA The Calibration absolute position Pipeline of the the maps 22 GHz of H The first multi-frequency compact array overviewwas on carried continuum and out maser with emission B-configuration22 in VLA the GHz source on and December at 9th, three44 2017. methanol GHz frequencies: (class Observations 6.7 were I GHz made CH and at 12 GHz (class II CH telescope support prevented us from imaging of H estimated size of the features is In the period between bursts ofservations September of and G25.65+1.05. November Observations 2017 were there carried were- out the three with: European ground VLBI VLBI Network ob- (EVN)- on the October Korean 2nd, very-long-baseline 2017; interferometryRadio (VLBI) Astrometry network (VERA) (KVN) Array and (KaVA) on VLBI October- Exploration 11th, the of 2017; Very Long Baseline ArrayIn (VLBA) on the October listed 28th, VLBI 2017. experimentsfeature was the conducted study with angular of resolution the of Burns fine et al. spatial “Multi-epoch structure VLBI of of the a double bursting maser H super-burst” in these conference proceedings. nas of intermediate size participated –Nicolaus 32-m Copernicus radio University telescope (Torun, of Poland) theRadio and Torun Centre 26-m Astronomy for radio Observatory Astronomy telescope of (Johannesburg, offunction South the of Africa). Hartebeesthoek the baseline Analysis length of for the the flux bursting H density as a Diameters provided an angular resolution of about G25.65+1.05: from single-dish to space VLBI tected on all space-ground baselines and ain detailed the high-resolution field map was of obtained. the H The second RadioAstron session was conductedto on the September burst 29th, observation of 2017 the andEarth source. become Diameters the and In angular closest the resolution experiment of the unique projected baseline length of 9 PoS(EVN2018)150 n, M. T., ´ a O.S. Bayandina 3 pez-Sepulcre, A., Cesaroni, R., Walmsley, C. M., Codella, C., Beltr ´ o nchez-Monge, A., L ´ a Bayandina et al. 2018, in preparation Bayandina et al. 2018, ASR, submitted Lobanov, A., 2015, A&A, 574, A84 Burns et al. 2018, in preparation Bayandina et al. 2018, ApJ, arXiv:1812.11353 S Pestalozzi, M., Molinari, S. 2013, A&A, 557, A94 Ashimbaeva, N. T., Platonov, M. A., Rudnitskij, G. M., Tolmachev, A. M. 2017, ATel #11042 Lekht, E. E., Pashchenko, M. I.,213 Rudnitskij, G. M., Tolmachev, A. M. 2018, AstronomyVolvach, Reports, L. 62, N., Volvach, A. E., Larionov,Olech, M. M. G., 2019, MacLeod, MNRAS G. 482, C., L90 van den Heever,Volvach, S. A. P., E., Wolak, P., Volvach, L. & N., MacLeod, G., Lekht,Volvach, E. A. E. E., et Volvach, L. al. N., 2017a, MacLeod, ATel2017b, #10728 G., Atel Bayandina, #10853 O. S., Shakhvorostova, N. N., Val’tts, I. E. The high intensity of the burst provides a large dynamic range for the analysis of the parameters [8] [9] [4] [5] [6] [7] [2] [3] [1] [10] [11] 3. Summary of compact structures that are detected inVLBI the observations source on of ground-ground the and space-ground sourceincreasing baselines. baseline show length that – correlated this flux indicates that density the remains detected almost feature is constant veryReferences with compact. G25.65+1.05: from single-dish to space VLBI