//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17966 SUBJECT: GRB 150626B: Swift detection of a burst DATE: 15/06/26 20:36:42 GMT FROM: Scott Barthelmy at NASA/GSFC L. M. McCauley (PSU), S. D. Barthelmy (GSFC), N. Gehrels (NASA/GSFC), H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team: At 20:22:52 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150626B (trigger=646786). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 187.672, +66.779, which is RA(J2000) = 12h 30m 41s Dec(J2000) = +66d 46' 45" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a FRED-like structure with a duration of about 30 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 20:24:58.9 UT, 126.1 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 187.6342, 66.7722 which is equivalent to: RA(J2000) = 12h 30m 32.22s Dec(J2000) = +66d 46' 19.8" with an uncertainty of 2.4 arcseconds (radius, 90% containment). This location is 58 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (1.69 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 1.1 (+0.98/-0.61) x 10^22 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 131 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.01. Burst Advocate for this burst is L. M. McCauley (marissamc AT swift.psu.edu). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17967 SUBJECT: GRB 150626B: MASTER observations DATE: 15/06/26 21:27:43 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov,D.Kuvshinov, Lomonosov Moscow State University, Sternberg Astronomical Institute Rafael Rebolo, Miquel Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory K.Ivanov, O.Gres, N.M.Budnev, S.Yazev, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Kislovodsk was pointed to the GRB150626B 216 sec after notice time and 260 sec after trigger time at 2015-06-26 20:27:12 UT in two polarizations, directly after automatic weather control system give permit for observations. On our first (50s exposure) set we not found optical transient within SWIFT error-box (McCauley et al. GCN 17966) brighter then 17.5. The 5-sigma upper limit has been about 17.5 mag MASTER-IAC pointed to the GRB150626B 46 sec after notice time and 90 sec after trigger time at 2015-06-26 2015-06-26 20:24:22 UT, but the images overexposed due to eveninig sky (Sun alt -4 deg.). The observations is continued. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17968 SUBJECT: GRB 150626B: Enhanced Swift-XRT position DATE: 15/06/27 00:32:38 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 591 s of XRT Photon Counting mode data and 1 UVOT images for GRB 150626B, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 187.63331, +66.77177 which is equivalent to: RA (J2000): 12h 30m 31.99s Dec (J2000): +66d 46' 18.4" with an uncertainty of 1.8 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17969 SUBJECT: GRB 150626B: NOT optical upper limits DATE: 15/06/27 00:42:55 GMT FROM: Dong Xu at NAOC/CAS D. Xu (NAOC/CAS), J. Telting (NOT), J. P. U. Fynbo (DARK/NBI) report on behalf of a larger collaboration: We observed the field of GRB 150626B (McCauley et al., GCN 17966) using the 2.56m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. We obtained 2x150s SDSS r-band and 6x180s SDSS z-band frames, with their median time of 1.379 hr and 1.936 hr after the burst, respectively. No optical source is detected at the (enhanced) XRT position (McCauley et al., GCN 17966; Goad et al., GCN 17968) in our stacked r- and z-band images, down to the limiting magnitudes of r~22.3 mag and z~21.6 mag, respectively. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17970 SUBJECT: GRB 150626B: Swift/UVOT Upper Limits DATE: 15/06/27 13:38:34 GMT FROM: Massimiliano de Pasquale at IASF-Palermo M. De Pasquale (UCL-MSSL) and L. M. McCauley (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150626B 131 s after the BAT trigger (McCauley et al., GCN Circ. 17966). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 17968) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 131 281 147 >20.7 u_FC 289 539 246 >20.1 white 131 6476 628 >21.6 v 620 6887 529 >19.5 b 545 7647 469 >20.8 u 289 7502 756 >20.7 w1 669 7298 529 >20.4 m2 644 7092 510 >20.3 w2 595 6682 346 >20.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17974 SUBJECT: GRB 150626B: Swift-XRT refined Analysis DATE: 15/06/27 15:16:40 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), B.P. Gompertz (U. Leicester), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), T.G.R. Roegiers (PSU), J.P. Osborne (U. Leicester) and L.M. McCauley report on behalf of the Swift-XRT team: We have analysed 8.9 ks of XRT data for GRB 150626B (McCauley et al. GCN Circ. 17966), from 111 s to 23.5 ks after the BAT trigger. The data comprise 8 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 17968). The late-time light curve (from T0+5.3 ks) is consistent with a constant source of mean count rate 1.9e-01 ct/sec. A power-law fit gives an index of 0.2 (+0.6, -0.5). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.99 (+/-0.15). The best-fitting absorption column is 9.6 (+1.4, -1.3) x 10^21 cm^-2, in excess of the Galactic value of 1.7 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.8 x 10^-11 (8.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 9.6 (+1.4, -1.3) x 10^21 cm^-2 Galactic foreground: 1.7 x 10^20 cm^-2 Excess significance: 11.7 sigma Photon index: 1.99 (+/-0.15) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00646786. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17981 SUBJECT: GRB 150626B, Swift-BAT refined analysis DATE: 15/06/28 20:03:41 GMT FROM: Amy Lien at GSFC S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), L. M. McCauley (PSU), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-240 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 150626B (trigger #646786) (McCauley et al., GCN Circ. 17966). The BAT ground-calculated position is RA, Dec = 187.627, 66.794 deg which is RA(J2000) = 12h 30m 30.6s Dec(J2000) = +66d 47' 39.6" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 35%. The mask-weighted light curve shows a single-peaked structure that starts at ~T-15 s, peaks at ~T+1 s, and ends at ~T+30 s. T90 (15-350 keV) is 48.0 +- 22.6 sec (estimated error including systematics). The time-averaged spectrum from T-15.6 to T+32.4 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.36 +- 0.21. The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+7.94 sec in the 15-150 keV band is 0.6 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/646786/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17997 SUBJECT: GRB 150626B: AMI 16 GHz detection of the radio counterpart DATE: 15/07/07 14:12:27 GMT FROM: Kunal Mooley at Oxford U K. P. Mooley, G. E. Anderson, R. P. Fender, T. D. Staley (University of Oxford), A. J. van der Horst (George Washington University), A. Rowlinson (CASS) We observed the position of GRB 150626B (McCauley et al., GCN 17966, Goad et al., GCN 17968) at 16 GHz with the Arcminute Microkelvin Imager (AMI-LA) at 2015 June 26.85, June 27.58, and July 03.56 UT, corresponding to 0.01 days, 0.73 days and 6.71 days post-burst respectively. The GRB flux densities at these three epochs were <0.19 mJy (3 sigma upper limit), 0.17+/-0.05 mJy (marginal detection), and 0.29+/-0.06 mJy (confirmed detection) respectively. Further AMI monitoring is ongoing. We thank the AMI scheduling team for carrying out these observations.