//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21821 SUBJECT: GRB 170906A: Swift detection of a burst with an optical afterglow DATE: 17/09/06 00:55:00 GMT FROM: David Burrows at PSU/Swift M. H. Siegel (PSU), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), C. Gronwall (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), B. Sbarufatti (PSU) and A. Tohuvavohu (PSU) report on behalf of the Swift Team: At 00:43:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170906A (trigger=770957). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 203.992, -47.125 which is RA(J2000) = 13h 35m 58s Dec(J2000) = -47d 07' 28" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multiply-peaked structure with a duration of about 120 sec. The peak count rate was ~16000 counts/sec (15-350 keV), at ~30 sec after the trigger. The XRT began observing the field at 00:44:18.9 UT, 67.3 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 203.9546, -47.1007 which is equivalent to: RA(J2000) = +13h 35m 49.10s Dec(J2000) = -47d 06' 02.5" with an uncertainty of 5.2 arcseconds (radius, 90% containment). This location is 126 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 0.1 s image was 4.12e-08 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 77 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 13:35:49.19 = 203.95497 DEC(J2000) = -47:06:01.9 = -47.10054 with a 90%-confidence error radius of about 0.61 arc sec. This position is 1.1 arc sec. from the center of the XRT error circle. The estimated magnitude is 16.59 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.14. Burst Advocate for this burst is M. H. Siegel (siegel 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: 21824 SUBJECT: GRB 170906A: Enhanced Swift-XRT position DATE: 17/09/06 06:43:24 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 1313 s of XRT Photon Counting mode data and 2 UVOT images for GRB 170906A, 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 = 203.95523, -47.10089 which is equivalent to: RA (J2000): 13h 35m 49.26s Dec (J2000): -47d 06' 03.2" 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: 21825 SUBJECT: GRB 170906A: REM optical/NIR observations DATE: 17/09/06 07:08:29 GMT FROM: Stefano Covino at Brera Astronomical Observatory S. Covino, D. Fugazza (INAF / OAB) report on behalf of the REM team: We observed the field of the GRB 170906A (Siegel et al., GCN 21821) with the 60-cm robotic telescope REM located at the La Silla Observatory (Chile). The observations started at 00:44:23 UT, about 72 s after the burst, and were carried out simultaneously in the g, r, i, z and H bands. A preliminary analysis shows that the optical counterpart reported by UVOT (Siegel et al., GCN 21821) is well detected in all bands and between 2 and 3min after the burst it was: r = 13.10 +- 0.10 (AB) H = 12.00 +/- 0.05 (Vega) Magnitudes are calibrated against the 2MASS catalog in the NIR and the APASS catalogue for the optical. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21827 SUBJECT: GRB 170906A: Fermi-LAT detection DATE: 17/09/06 08:12:32 GMT FROM: Elisabetta Bissaldi at U.Innsbruk/IAPP E. Bissaldi (Politecnico & INFN Bari), D. Kocevski (NASA/GSFC), G. Vianello (Stanford University), M. Arimoto (Waseda University) and J. Racusin (NASA/GSFC) report on behalf of the Fermi-LAT team: At 00:43:11.66 UT on September, 06, 2017 Fermi-LAT detected high-energy emission from GRB 170906A, which was also detected by Fermi-GBM (trigger 526351393 / 170906030) and Swift (Siegel et al., GCN #21821). The best LAT on-ground location is found to be RA, Dec = 203.94, -47.12 (J2000) with an error radius of 0.10 deg (90 % containment, statistical error only). This is consistent with the enhanced Swift-XRT position (Beardmore et al., GCN #21824). This was 75 deg from the LAT boresight at the time of the trigger. The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the trigger with high significance. The highest-energy photon is a 3.6 GeV event, which is observed 200 seconds after the GBM trigger. The Fermi-LAT point of contact for this burst is Judith Racusin (judith.racusin@nasa.gov). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21830 SUBJECT: GRB 170906A: MASTER-OAFA (Argentina) early automatic OT detection DATE: 17/09/06 09:01:51 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, D.Kuvshinov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko, I.Gorbunov, A.V.Krylov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University R. Podesta, Carlos Lopez and F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk Irkutsk State University A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory V. Yurkov, A. Gabovich, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk D. Buckley, S. Potter, A. Kniazev, M. Kotze South African Astronomical Observatory MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Argentina was pointed to the Swift GRB170906A (Siegel rt al. GCN21821) 44 sec after trigger time at 2017-09-06 00:43:56 UT with 10 sec exposition. Robot found 1 optical transient within SWIFT error-box (ra=13:35:49.19 dec=-47:06:01.9 r=0.61(90%)) at RA, DEC = 13h 35m 49.3s , -47d 6m 02.7s We see OT brightenning from unfiltered mag 15.6 up to 14.4 at 2017-09-06 00:50:54 UT (midle time). The 5-sigma upper limit on the single images has been about 16.8mag This OT was also detected by UVOT (Siegel et al GCN 21821) and REM (Covino et al. GCN 21825). The observations made on zenit distance = 64 degrees, galaxy latitude b = 15 degree. The moon (100 % bright part) is 35 degrees above the horizon. The distance between moon and object is 113 The sun altitude is -31.7 degree. The object can be observed till 2017-09-06 04:04:24. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21836 SUBJECT: GRB 170906A: Swift-XRT refined Analysis DATE: 17/09/06 19:39:09 GMT FROM: Phil Evans at U of Leicester A. D'Ai (INAF-IASFPA), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB) and M.H. Siegel report on behalf of the Swift-XRT team: We have analysed 6.4 ks of XRT data for GRB 170906A (Siegel et al. GCN Circ. 21821), from 71 s to 62.4 ks after the BAT trigger. The data comprise 683 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 21824). The late-time light curve (from T0+10.2 ks) can be modelled with a power-law decay with a decay index of alpha=2.08 (+0.27, -0.25). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.64 (+/-0.03). The best-fitting absorption column is 2.60 (+0.16, -0.15) x 10^21 cm^-2, in excess of the Galactic value of 1.4 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.23 (+0.24, -0.23) and a best-fitting absorption column of 4.7 (+1.3, -1.1) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (6.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 4.7 (+1.3, -1.1) x 10^21 cm^-2 Galactic foreground: 1.4 x 10^21 cm^-2 Excess significance: 4.9 sigma Photon index: 2.23 (+0.24, -0.23) If the light curve continues to decay with a power-law decay index of 2.08, the count rate at T+24 hours will be 2.8 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x 10^-13 (1.9 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/00770957. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21838 SUBJECT: GRB 170906A: Swift-BAT refined analysis DATE: 17/09/06 20:53:57 GMT FROM: Scott Barthelmy at NASA/GSFC J. R. Cummings (CPI), S. D. Barthelmy (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. H. Siegel (PSU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-239 to T+603 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170906A (trigger #770957) (Siegel, et al., GCN Circ. 21821). The BAT ground-calculated position is RA, Dec = 203.949, -47.088 deg, which is RA(J2000) = 13h 35m 47.7s Dec(J2000) = -47d 05' 18.3" with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 67%. The mask-weighted light curve shows multiple peaks starting at ~T-40 sec, with a max peak at ~T+30, and returning to baseline at ~T+170 sec. T90 (15-350 keV) is 88.1 +- 1.5 sec (estimated error including systematics). The time-averaged spectrum from T-44.9 to T+121.5 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.21 +- 0.10, and Epeak of 205.4 +- 71.9 keV (chi squared 36.4 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.2 +- 0.0 x 10^-5 erg/cm2 and the 1-sec peak flux measured from T+29.82 sec in the 15-150 keV band is 10.9 +- 0.4 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.45 +- 0.02 (chi squared 52.7 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/770957/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21839 SUBJECT: GRB 170906A: Fermi GBM detection DATE: 17/09/06 21:32:38 GMT FROM: Rachel Hamburg at UAH R. Hamburg (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 00:43:08.15 UT on 06 September 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170906A (trigger 526351393 / 170906030), which was also detected by Swift (Siegel et al. 2017, GCN 21821). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 75 degrees. The GBM light curve shows a multi-peaked structure with a duration (T90) of about 79 s (50-300 keV). The time-averaged spectrum from T0-2.6 s to T0+107.0 is best fit by a Band function with Epeak = 288 +/- 12 keV, alpha = -1.02 +/- 0.02, and beta = -2.09 +/- 0.04. The event fluence (10-1000 keV) in this time interval is (1.17 +/- 0.01)E-04 erg/cm^2. The 1-sec peak photon flux measured starting from T0+33.4 s in the 10-1000 keV band is 21.7 +/- 0.5 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21847 SUBJECT: GRB 170906A: Swift/UVOT Detection DATE: 17/09/07 18:30:36 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 170906A 77 s after the BAT trigger (Siegel et al., GCN Circ. 21821). A source consistent with the XRT position (Siegel et al. GCN Circ. 21821) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 13:35:49.20 = 203.95501 (deg.) Dec (J2000) = -47:06:02.1 = -47.10057 (deg.) with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are listed below. The afterglow appears to have brightened during the early observations and faded by later orbits, confirming the analysis of Lipunov et al. (GCN Circ. 21830). Filter T_start(s) T_stop(s) Exp(s) Mag white (fc) 77 227 147 16.41 +/- 0.03 white 570 590 19 15.47 +/- 0.04 white 744 764 19 15.65 +/- 0.05 v 620 639 19 14.65 +/- 0.07 v 11125 23192 901 >19.82 b 545 565 20 15.59 +/- 0.06 b 12629 12744 112 >19.63 u 290 539 246 15.47 +/- 0.03 u 694 714 19 15.47 +/- 0.08 u 17786 18086 295 >19.82 uvm2 15973 16873 885 >20.09 uvw1 669 689 19 17.00 +/- 0.24 uvw1 16880 17780 885 >20.23 uvw2 595 615 19 >17.0 uvw2 10219 22561 1771 >20.61 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.14 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21856 SUBJECT: GRB 170906A: AstroSat CZTI(Veto) detection DATE: 17/09/11 14:29:14 GMT FROM: Vidushi Sharma at IUCAA V. Sharma (IUCAA), V. Bhalerao (IIT-B), D. Bhattacharya (IUCAA), A. R. Rao (TIFR), S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration: The bright GRB 170906A was detected using the CsI veto detectors on Astrosat CZTI (Bhalerao et al., arXiv:1608.03408), which was also detected by Swift (Siegel M.H. et al., GCN Circ. 21821) and Fermi GBM (Hamburg R. et al, GCN Circ. 21839). The source was clearly detected in the 125-250 keV energy range. The light curve shows a multiple peak structure. The peak count rate in the CsI detectors was 2262 counts/sec above the background (four quadrants summed together), with a total of 49316 counts. The local mean background count rate was 1606.7 counts/sec. Using cumulative rates, we measure a T90 of 70.5 secs. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb . CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21859 SUBJECT: Konus-Wind observation of GRB 170906A DATE: 17/09/11 16:11:07 GMT FROM: Anastasia Tsvetkova at Ioffe Institute A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 170906A (Swift-BAT trigger #770957: Siegel et al., GCN 21821; Cummings et al., GCN 21838; Fermi-LAT detection: Bissaldi et al., GCN 21827; Fermi GBM detection: Hamburg & Meegan, GCN 21839; AstroSat CZTI(Veto) detection: Sharma et al., GCN 21856) triggered Konus-Wind at T0=2607.999 s UT (00:43:27.999). The burst light curve shows a double-peaked structure started at ~T0-23 s with a total duration of ~91 s, followed by a weaker emission seen up to ~T0+135 s. The KW data above 1.5 MeV are largely contaminated by high solar particle background. As observed by Konus-Wind, the burst had a fluence of 1.19(-0.21,+0.22)x10^-4 erg/cm2, and a 64-ms peak energy flux, measured from T0+11.184 s, of 9.25(-2.67,+2.97)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (measured from T0 to T0+68.608 s) is best fit in the 20 keV - 1.5 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.91(-0.10,+0.12), the high energy photon index beta = -2.41(-0.94,+0.28), the peak energy Ep = 274(-37,+43) keV, chi2 = 86/59 dof. The spectrum near the peak count rate (measured from T0+6.400 to T0+16.384 s) is best fit in the 20 keV - 1.5 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.60(-0.12,+0.15), the high energy photon index beta = -2.36(-0.75,+0.31), the peak energy Ep = 360(-54,+58) keV, chi2 = 64/59 dof. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB170906_T02607/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21884 SUBJECT: GRB 170906A CALET Gamma-Ray Burst Monitor detection DATE: 17/09/15 04:28:50 GMT FROM: Takanori Sakamoto at AGU A. V. Penacchioni, A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama, Y. Yamada, A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena) and the CALET collaboration: The long-duration GRB 170906A (Siegel et al., GCN Circ. 21821; Hamburg et al., GCN Circ. 21839; Tsvetkova et al., GCN Circ. 21859) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 00:43:05.59 on 6 September 2017. The burst signal was seen by the all CGBM instruments. The light curve of the SGM shows a complex structure. The emission starts at T0 sec and the brightest pulse peaks at T+35 sec. The entire emission ends at T+100 sec. The T90 duration measured by the SGM data is 78.4 +- 1.9 sec (40-1000 keV). The light curve is available at http://cgbm.calet.jp/cgbm_trigger/flight/1188693801/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21921 SUBJECT: GRB 170906A: Insight-HXMT detection DATE: 17/09/24 03:22:42 GMT FROM: Yifei Zhang at IHEP Y. F. Zhang, S. L. Xiong, J. Y. Liao, C. K. Li, X. F. Lu, X. B. Li, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, J. L. Zhao, A. M. Zhang, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team: During the commissioning phase, at 2017-09-06T00:43:06.00 (T0), Insight-HXMT/HE detected GRB 170906A (trigger ID: HEB170906029) in a routine search of the data,which is also detected by CALET (Penacchioni et al., GCN 21884), Fermi/GBM (Hamburg et al., GCN 21839) and Swift/BAT (Siegel et al., GCN 21821). The Insight-HXMT light curve mainly consists of multi-pulses with a duration (T90) of 64.6 s measured from T0+2.3 s. The 1-second peak rate, measured from T0+35.3 s, is 1870.6 cnts/sec. The total counts from this burst is 26305.3 counts. URL_LC: http://www.hxmt.org/images/GRB/HEB170906029_lc.jpg All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (record energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. The time-averaged spectrum from T0-5 s to T0+70 s is adequately fit by a Power Law model with spectral index = -2.70 +/- 0.06. The energy fluence is (5.94 +/- 0.20)E-04 erg/cm^2 in 200 - 5000 keV in this time interval. The analysis results presented above are preliminary; final results will be published elsewhere. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org/index.php/enhome .