//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18249 SUBJECT: GRB 150907B: Swift detection of a burst DATE: 15/09/07 23:37:45 GMT FROM: David Palmer at LANL T. G. R. Roegiers (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and T. N. Ukwatta (LANL) report on behalf of the Swift Team: At 23:26:27 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150907B (trigger=654803). Swift could not slew immediately to the burst due to an observing constraint. The BAT on-board calculated location is RA, Dec 255.219, -63.819 which is RA(J2000) = 17h 00m 53s Dec(J2000) = -63d 49' 07" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). Only partial BAT lightcurve data is available, but the light curve shows a complex structure at least 10 seconds long. The peak count rate was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+49.0 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is T. G. R. Roegiers (troegiers 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: 18251 SUBJECT: GRB 150907B: Swift-XRT observations DATE: 15/09/08 00:54:41 GMT FROM: Phil Evans at U of Leicester J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU), G. Cusumano (INAF-IASF PA), M. Perri (ASDC) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: The XRT began observing the field of GRB 150907B at 00:16:37.8 UT, 3010.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 255.30809, -63.78591 which is equivalent to: RA(J2000) = 17h 01m 13.94s Dec(J2000) = -63d 47' 09.3" with an uncertainty of 4.0 arcseconds (radius, 90% containment). This location is 185 arcseconds from the BAT onboard position, outside 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. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.52 x 10^21 cm^-2 (Willingale et al. 2013). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18252 SUBJECT: GRB 150907B: GROND Upper Limits DATE: 15/09/08 05:47:06 GMT FROM: Philip Wiseman at MPE/Swift P. Wiseman, C. Delvaux and J. Greiner (all MPE Garching) report on behalf of the GROND team: We observed the field of GRB 150907B (Swift trigger 654803; Roegiers et al., GCN #18249) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile). Observations started at 02:03 UT on 08/09/2015, 2.63 hours after the GRB trigger. They were performed at an average seeing of 2.5" and an average airmass of 2.0. We do not detect a source within the Swift-XRT error circle reported by Osborne et al. (GCN #18251) down to limits of: g' > 24.5 mag, r' > 23.9 mag, i' > 23.3 mag, z' > 23.2 mag, J > 21.1 mag, H > 20.6 mag, and K > 19.2 mag. We note a source at the eastern edge of the Swift-XRT error circle, at a position: RA = 255.3110 Dec = -63.7860, or 17h 01m 14.64s -64d 47' 09.6". This source does not seem to be fading, and with a non GRB-like SED, and matches to the known source S7FP064671 from The Guide Star Catalogue, Version 2.3.2 (Lasker B., Lattanzi M.G., McLean B.J., et al. Astron. J. 136, 735 (2008)). The given limits are derived based on calibrating the images against GROND zeropoints and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.1432 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18253 SUBJECT: GRB 150907B: Enhanced Swift-XRT position DATE: 15/09/08 06:27:12 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 3059 s of XRT Photon Counting mode data and 4 UVOT images for GRB 150907B, 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 = 255.30407, -63.78510 which is equivalent to: RA (J2000): 17h 01m 12.98s Dec (J2000): -63d 47' 06.4" with an uncertainty of 1.9 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: 18254 SUBJECT: GRB 150907B: MASTER-SAAO early optical observations DATE: 15/09/08 08:22:48 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs D.Buckley, S. Potter, M.Kotze South African Astronomical Observatory V. Lipunov, E.Gorbovskoy, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov, I.Gorbunov Lomonosov Moscow State University, Sternberg Astronomical Institute R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias A. Tlatov, D. Dormidontov, V.Senik 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 Ural Federal University, Kourovka Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Carlos Lopez, Claudio Mallamaci and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in SAAO was pointed to the Swift Alert (Roegiers et al., GCN 18249) GRB150907B 25 sec after notice time and 40 sec after trigger time at 2015-09-07 23:27:10 UT. On our first (10s exposure) set we haven`t found optical transient within SWIFT error-box (ra=17 00 51 dec=-63 49 07 r=0.050000). The next images limit without OT: Id Coord Pro.type Time,UT Exp.time Lim Filt. Tube 110113 16h 59m 04.1s -63d 41m 01s Alert 23:27:10 10 15.5 P EAST 110114 17h 00m 00.1s -63d 42m 55s Alert 23:27:10 10 15.7 P WEST 110115 16h 59m 47.7s -63d 42m 57s Alert 23:27:34 10 15.4 P WEST 110116 16h 59m 22.0s -63d 41m 10s Alert 23:27:34 10 15.2 P EAST 110117 16h 59m 47.5s -63d 42m 57s Alert 23:27:56 20 15.9 P WEST 110118 16h 59m 21.8s -63d 41m 10s Alert 23:27:56 20 15.7 P EAST 110119 16h 59m 21.6s -63d 41m 09s Alert 23:28:27 20 15.9 P EAST 110120 16h 59m 47.4s -63d 42m 56s Alert 23:28:27 20 16.1 P WEST 110121 16h 59m 21.6s -63d 41m 09s Alert 23:28:58 30 13.2 P EAST 110122 16h 59m 47.4s -63d 42m 56s Alert 23:28:58 30 13.5 P WEST 110123 17h 00m 00.1s -63d 42m 55s SumAlert23:27:10 40 16.3 P WEST 110124 16h 59m 21.4s -63d 41m 08s Alert 23:29:39 40 15.1 P EAST 110125 16h 59m 47.1s -63d 42m 55s Alert 23:29:39 40 15.5 P WEST 110126 16h 59m 04.1s -63d 41m 01s SumAlert23:27:10 40 16.1 P EAST 110127 16h 59m 47.1s -63d 42m 55s Alert 23:30:30 50 15.9 P WEST 110128 16h 59m 21.3s -63d 41m 08s Alert 23:30:30 50 15.5 P EAST 110129 16h 59m 47.4s -63d 42m 56s SumAlert23:28:27 90 15.9 P WEST 110130 16h 59m 21.2s -63d 41m 08s Alert 23:31:31 60 14.8 P EAST 110131 16h 59m 47.1s -63d 42m 56s Alert 23:31:31 60 15.4 P WEST 110132 16h 59m 21.6s -63d 41m 09s SumAlert23:28:27 110 16.1 P EAST There was a short time between rain and clouds. Then the clouds returned. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18256 SUBJECT: GRB 150907B: Swift-BAT refined analysis DATE: 15/09/08 12:27:43 GMT FROM: Scott Barthelmy at NASA/GSFC H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. G. R. Roegiers (PSU), 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+962 sec from the recent telemetry downlinks, we report further analysis of BAT GRB 150907B (trigger #654803) (Roegiers, et al., GCN Circ. 18249). The BAT ground-calculated position is RA, Dec = 255.265, -63.798 deg, which is RA(J2000) = 17h 01m 03.5s Dec(J2000) = -63d 47' 51.6" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 50%. The mask-weighted light curve shows a Fred-like starting at ~T-1 sec, peaking at ~T+1 sec, and ending around T+100 sec. T90 (15-350 keV) is 62.0 +- 11.1 sec (estimated error including systematics). The time-averaged spectrum from T-1.48 to T+64.53 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.17 +- 1.03, and Epeak of 67.4 +- 29.7 keV (chi squared 53.2 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.1 +- 0.2 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+0.59 sec in the 15-150 keV band is 1.0 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.47 +- 0.18 (chi squared 59.8 for 57 d.o.f.). 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/654803/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18260 SUBJECT: GRB 150907B: Swift-XRT refined Analysis DATE: 15/09/08 18:29:56 GMT FROM: Tineke Roegiers at PSU B. Sbarufatti (INAF-OAB/PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU) and T. G. R. Roegiers (PSU) report on behalf of the Swift-XRT team: We have analysed 7.9 ks of XRT data for GRB 150907B (Roegiers et al. GCN Circ. 18249), from 3.0 ks to 32.2 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 18253). The light curve can be modelled with a power-law decay with a decay index of alpha=1.61 (+0.37, -0.28). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.02 (+0.28, -0.35). The best-fitting absorption column is 4.4 (+7.7, -1.8) x 10^21 cm^-2, in excess of the Galactic value of 1.5 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10^-11 (6.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 4.4 (+7.7, -1.8) x 10^21 cm^-2 Galactic foreground: 1.5 x 10^21 cm^-2 Excess significance: 2.6 sigma Photon index: 2.02 (+0.28, -0.35) If the light curve continues to decay with a power-law decay index of 1.61, the count rate at T+24 hours will be 3.4 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.4 x 10^-14 (2.3 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00654803. This circular is an official product of the Swift-XRT team.