{
  "bibcode": "2015GCN.18240....1D",
  "body": "D. Dornic (CPPM), V.Lipunov (Lomonosov MSU),  S. Basa (LAM), P. A. Evans (U. \nLeicester), J. A. Kennea (PSU), E.Gorbovskoy and N. Tyurina (Lomonosov MSU), D. \nBuckley (SAAO), R. Rebolo (IAC)\n\nMASTER-SAAO robotic telescope (MASTER��Net: http://observ.pereplet.ru) located \nin Sutherland received Antares neutrino alert at 2015-09-01 07:38:24.99UT \n(sunrise) in 16s after trigger time. So and we start observations at nearest \navailable time.\n\nMASTER-SAAO automatically started Inspect ��survey on the Antares neutrino \nAlert150901.32 error��box (ra=16 25 42 dec=��27 23 24 r=1.726600) 35107 sec after \nnotice time and 35123 sec after trigger time (2015-09-01 07:38:24.99, sunrise) \nat 2015��09��01 17:23:48 UT. Observations were up to 2015-09-01 20:25:18 (very \ncloudy) . MASTER auto-detection system didn���t find any real transient inside \nthe neutrino error box, the unfiltered optical limit on single images is \n18.5-19.8 (180s), the sum limit is 20.6 (540s).\n\nObservations were continuing on 2015-09-03 17:13:59 (sunset) up to 2015-09-03 \n21:21:59 (the weather disappeared). We observed in parallel MASTER twin tubes \nin different filters BV, RI. ��The optical limit in B filter on single images \nwas m_B_lim=19.1 (180s), 19.6 on sum (540s) in V filter: m_V_lim=19.3(180s), \n19.9 on the sum(540s). The optical limit n R is m_R_lim=18.4-19.0 on single \nimages(60-180s), m_R_lim=19.7-20.3 on sum (540s-1800s). The limit in I was \nm_I_lim=17.5-18.0 on single images(180s), 18.5 on sum (540s).\n\nMASTER-IAC robotic telescope automatically started Inspect observations on \n2015-09-01 21:02:44, observed up to 2015-09-01 21:17:34, unfiltered \n��(W=0.2B+0.8R, USNOB1 calibrated) limit m_lim=18.7-19.2 (180s exposition), \n19.8(540s). Observations were continuing in B and V on 2015-09-03 20:08:40 up \nto 2015-09-03 22:09:12 with limit up to 19.8 in B(180s) and 18.6 in V (180s). \nNo optical transient inside the neutrino error box.\n\nThe Swift location 16h 26m 02.1s -27d 18m 14s ��is difficult for observations \nfrom Nothern hemisphere (MASTER-Kislovodsk, -Tunka, -Ural, -Amur). It can be \nobserved at sunset near the horizon.\n\nMASTER-Kislovodsk: 02 of Sept there was rain at this observatory at sunset. \nMASTER-Kislovodsk robotic telescope automatically started Inspect survey on \nAntares Alert Alert150901.32 on 2015-09-03 16:39:11 UT, at sunset (Object: \nAltitude: 14.85, Sun: Altitude: -10.65), and were continuing up to 2015-09-03 \n18:04:47 when the objects��� set. The first hour we have 7 ��of 30-s expositions \n��with bad weather condition, the optical�� limit in V is 12.0-14.1. Unfiltered \nobservations ��starts from 2015-09-03 17:21:39 (Object���s Altitude: 11.01)with \noptical limit 17.8 on single images (60s expositions), 18.4 on sum (180s). No \noptical transients detected by MASTER auto-detection system inside ANTARES \nerror-box.\n\nMASTER-Tunka robotic telescope started observations of this alert at sunset at \n2015-09-03 12:40:59. The Object���s Altitude was 6.86 , the Sun: Altitude: -8.12. \nVery close to horizon, the object goes under it, 16 expositions of 60s in V,R , \nno OT inside ANTARES error-box..\n\nMASTER-SAAO optical light curve of bright star USNO-B1.0 0626-0501169 inside \nSwift XRT error box �� in B,V,R and I bands (top diagram) and color diagram \n(bottom)�� represented here:\n\nhttp://master.sai.msu.ru/static/master_antares_alert_150901.png\nThe source is stable in all four band as well as its color. The average color \nis:\n\nB-V = 0.93 +- 0.06\n\nR-I�� = 1.07 +- 0.03\n\n\n  A few words about  association USNO-B1.0 0626-0501169  and X-ray Swift source \n(Dornic et al. GCN 18231, ATel #7987 ).  Following Swift XRT observation the \nX-ray flux is changing from 5e-13 to  4e-12 erg/cm2/s (in 0.3-10keV). Full \noptical flux in MASTER system calibrates as:  15 mag correspond 6.4 \n10<sub>-12</sub> erg/sm<sub>2</sub>/s .  MASTER-SAAO observations of USNO-B1.0 \n0626-0501169 in January, May and September 2015 show that unfiltered magnitude \nis m (unfiltered) = 12.36 +-0.03 (Jan); 12.32+- 0.03(May) and 12.32+-0.04 \n(Sep). Thus it can be argued that the brightness of the star has not changed by \nmore than 3%. Since the X-ray emission occurs near the stellar photosphere, so \ndue to the heating effect of its brightness should slightly increase. The \nobserved brightness of the star persistence restricts the change in X-ray flux \nin September compared with a May and January: F_x/ F_opt  < 3 %. Consequently, \nF_x < 7 e-11 erg/s.  This means that the X-ray heating can  not cause optical \nvariability more than  0.003 magnitude.\n  It seems the X-ray is result of the X-ray flare activity of the star (de \nUgarte Postigo et al. GCN 18236, ATel #7994; Smartt et al. ATel 7992; Dichiara \net al. ATel#7993 ).\n\nThere is Globular Cluster M4 (NGC621) with millisecond pulsar (Lyne et al., \n1988, Nature, V.332, 45-47) and possible massive (~10e3  Solar Mass) black hole \ninside ANTARES alert 3-sigma error box (the MASTER images of the Antares  error \nbox is available at http://master.sai.msu.ru/static/Antares_alert_Image.jpeg\n\nBy the way there is star Antares (1.3 degrees from center ANTARES error box, \nbut outside! ).\n\nSo, we propose M4 (with relativistic objects inside) is the possible source of \nthe neutrino, which created after cosmic partical acceleration. The follow up \nmillisecond pulsars observations request.\n\n  The message may be cited.",
  "circularId": 18240,
  "createdOn": 1441396460000,
  "email": "lipunov@xray.sai.msu.ru",
  "subject": "ANTARES neutrino Alert150901.32 alert and Swift XRT counterpart: MASTER optical observations and new possible candidate",
  "submitter": "Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>"
}