//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18374 SUBJECT: GRB 151001B: Swift detection of a burst DATE: 15/10/01 18:44:33 GMT FROM: Scott Barthelmy at NASA/GSFC H. A. Krimm (CRESST/GSFC/USRA), S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), C. Pagani (U Leicester), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 18:29:36 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 151001B (trigger=657321). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 336.845, +64.661, which is RA(J2000) = 22h 27m 23s Dec(J2000) = +64d 39' 39" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is typical for image triggers, there is nothing significant in the real-time TDRSS light curve. The XRT began observing the field at 18:31:55.6 UT, 138.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 336.8384, 64.6937 which is equivalent to: RA(J2000) = 22h 27m 21.22s Dec(J2000) = +64d 41' 37.4" with an uncertainty of 2.4 arcseconds (radius, 90% containment). This location is 118 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 (6.51 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 6.8 (+6.23/-4.70) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 1.89e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 148 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 1.71. Burst Advocate for this burst is H. A. Krimm (hans.krimm AT nasa.gov). 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: 18377 SUBJECT: GRB 151001B: Enhanced Swift-XRT position DATE: 15/10/02 04:03:19 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 1574 s of XRT Photon Counting mode data and 2 UVOT images for GRB 151001B, 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 = 336.83909, +64.69375 which is equivalent to: RA (J2000): 22h 27m 21.38s Dec (J2000): +64d 41' 37.5" with an uncertainty of 1.6 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: 18380 SUBJECT: GRB 151001B: MASTER-NET early optical observations. DATE: 15/10/02 09:22:48 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk E. Gorbovskoy, V. Lipunov, M.Pruzhinskaya, V.Kornilov, D.Kuvshinov, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, D.Denisenko, A.Sankovich Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory 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) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB151001B 20 sec after notice time and 96 sec after trigger time at 2015-10-01 18:31:13 UT. On our first (20s exposure) set we haven`t found optical transient within SWIFT error-box (Krimm et. al GCN 18374). The 5-sigma upper limit has been about 18.0 mag The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18382 SUBJECT: GRB 151001B: Swift-BAT refined analysis DATE: 15/10/02 13:09:51 GMT FROM: Scott Barthelmy at NASA/GSFC T. N. Ukwatta (LANL), 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), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlinks, we report further analysis of BAT GRB 151001B (trigger #657321) (Krimm, et al., GCN Circ. 18374). The BAT ground-calculated position is RA, Dec = 336.974, 64.637 deg, which is RA(J2000) = 22h 27m 53.7s Dec(J2000) = +64d 38' 13.5" with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 28%. The mask-weighted light curves shows several overlapping peaks starting at ~T-40 sec, peaking at ~T+50 sec, and ending at ~T+150 sec. T90 (15-350 keV) is 109 +- 17 sec (estimated error including systematics). The time-averaged spectrum from T-23.3 to T+97 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.12 +- 0.27. The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+47.47 sec in the 15-150 keV band is 0.5 +- 0.3 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/657321/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18383 SUBJECT: GRB 151001B: Swift-XRT refined Analysis DATE: 15/10/02 13:44:02 GMT FROM: Phil Evans at U of Leicester T.G.R. Roegiers (PSU), L.M. McCauley (PSU), J.A. Kennea (PSU), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'ai (INAF-IASFPA) and H.A. Krimm report on behalf of the Swift-XRT team: We have analysed 6.4 ks of XRT data for GRB 151001B (Krimm et al. GCN Circ. 18374), from 129 s to 59.3 ks after the BAT trigger. The data comprise 132 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 18377). The light curve can be modelled with an initial power-law decay with an index of alpha=2.38 (+/-0.08), followed by a break at T+963 s to an alpha of 1.12 (+0.12, -0.13). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.78 (+0.17, -0.16). The best-fitting absorption column is 1.09 (+0.19, -0.18) x 10^22 cm^-2, in excess of the Galactic value of 6.5 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.20 (+0.31, -0.30) and a best-fitting absorption column of 1.9 (+0.5, -0.4) x 10^22 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 5.4 x 10^-11 (1.4 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.9 (+0.5, -0.4) x 10^22 cm^-2 Galactic foreground: 6.5 x 10^21 cm^-2 Excess significance: 5.2 sigma Photon index: 2.20 (+0.31, -0.30) If the light curve continues to decay with a power-law decay index of 1.12, the count rate at T+24 hours will be 2.0 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-13 (2.8 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00657321. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18384 SUBJECT: GRB 151001B: Swift/UVOT Upper Limits DATE: 15/10/02 18:50:46 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (UCL-MSSL) and H. A. Krimm (CRESST/GSFC/USRA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 151001B 148 s after the BAT trigger (Krimm et al., GCN Circ. 18374). No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 18377) 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 148 298 147 >20.6 white 148 6765 805 >21.8 u_FC 307 557 246 >19.9 v 636 7175 529 >20.2 b 563 6561 333 >20.9 u 307 11107 685 >20.7 w1 686 7585 510 >20.2 m2 661 7380 529 >20.2 w2 613 6970 529 >20.6 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.71 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18401 SUBJECT: Konus-Wind observation of GRB 151001B DATE: 15/10/06 11:18:10 GMT FROM: Anna Kozlova at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report: At ~16 minutes before the Swift-BAT trigger on GRB 151001B (Krimm, et al., GCN Circ. 18374; T0(BAT)=18:29:36 UT) Konus-Wind detected, in the waiting mode, a burst of high X-ray/soft gamma-ray emission which had a duration of ~191 s. Taking into account the proximity of this burst to the Swift-BAT trigger and consistency of the KW ecliptic latitude response with the position of GRB 151001B we suggest this burst is the main part of GRB 151001B. The K-W light curve of this burst is available at http://www.ioffe.ru/LEA/GRBs/GRB151001B/ The count rate increase in the soft KW energy band, which follows the burst from T0(BAT)-838 s to T0(BAT)+2488 s, can not be unambiguously attributed to GRB 151001B. As observed by Konus-Wind, the burst had a fluence of 8.5(-2.3,+0.6)x10^-6 erg/cm2 and a 2.944-s peak flux, measured from ~T0(BAT)-1007.1 s, of 1.8(-0.6,+0.4)x10^-7 erg/cm2/s (both in the 20 - 1000 keV energy range). Modeling the K-W 3-channel time-integrated spectrum (from T0(BAT)-1018.9 s to T0(BAT)-827.5 s) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -0.9(-0.3,+0.5) and Ep = 179 (-52,+75) keV. All the quoted errors are at 1 sigma confidence level. All the quoted values are preliminary.