//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6224 SUBJECT: GRB 070328: Swift detection of a burst DATE: 07/03/28 04:14:41 GMT FROM: David Palmer at LANL C. B. Markwardt (GSFC/UMD), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), H. A. Krimm (GSFC/USRA), F. E. Marshall (NASA/GSFC), C. Pagani (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), M. Stamatikos (NASA/ORAU) and E. Troja (INAF-IASFPA) report on behalf of the Swift Team: At 03:53:53 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070328 (trigger=272773). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 65.117, -34.069 which is RA(J2000) = 04h 20m 28s Dec(J2000) = -34d 04' 07" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 70 sec. The peak count rate was ~8000 counts/sec (15-350 keV), at ~3 sec after the trigger. The XRT began observing the field at 03:55:21 UT, 88 seconds after the BAT trigger. XRT found a bright, fading X-ray source located at RA, Dec 65.1160, -34.0646 which is RA(J2000) = 04h 20m 27.8s Dec(J2000) = -34d 03' 52.5" with an uncertainty of 4.7 arcseconds (radius, 90% containment). This location is 16 arcseconds from the BAT on-board position, within the BAT error circle. The initial flux in the 2.5s image was 2.6e-09 erg/cm2/s (0.2-10 keV). UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 98 seconds after the BAT trigger. No 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 18.5 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 0.04. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6225 SUBJECT: GRB 070328, Swift-BAT refined analysis DATE: 07/03/28 07:49:48 GMT FROM: Craig Markwardt at NASA/GSFC/UMD M. Stamatikos (GSFC/ORAU), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), J. Tueller (GSFC) on behalf of the Swift-BAT team: Using the data set from T-120 to T+183 sec from the recent telemetry downlink, we report further analysis of BAT GRB 070328 (trigger #272773) (Markwardt et al., GCN Circ. 6224). The BAT ground-calculated position is RA, Dec = 65.110, -34.077 deg which is RA(J2000) = 4h 20m 26.4s Dec(J2000) = -34d 4' 38.9" with an uncertainty of 0.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 60%. The mask weighted light curve shows a burst profile which consists of a rise starting at T-10, multiple spikes peaking between T+0 and T+22, and a gradual decay detected out to T+140. T90 (15-350 keV) is 69 +- 5 sec (estimated error including systematics). The time-averaged spectrum from T-8.5 to T+133 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.26 +- 0.04. The fluence in the 15-150 keV band is 8.9 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.78 sec in the 15-150 keV band is 4.2 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6226 SUBJECT: GRB 070328 : Suzaku ToO follow up starts DATE: 07/03/28 08:02:14 GMT FROM: Kazuhiro Nakazawa at ISAS/JAXA K. Nakazawa (ISAS/JAXA), T. Murakami (Kanazawa U.), M. Tashiro (Saitama U.), D. Yonetoku (Kanazawa U.), Y. Nakagawa (Aoyama Gakuin U.), S. Yokota (Kanazawa U.), Y. Kodama (Kanazawa U.), Y. Maeda (ISAS/JAXA), H. Murakami (ISAS/JAXA), S. Maeno (Miyazaki U.), N. Yamasaki (ISAS/JAXA) M. Namiki (Osaka U.), E. Sonoda (Miyazaki U.) and K. Mitsuda (ISAS/JAXA) on behald of the Suzaku team We will start the follow-up observation of GRB 070328 (Markwardt et al., GCN 6224) immediately (from around 07:20 on 28 March 2007 UT), with the Suzaku narrow field instruments (XIS and HXD). The observation will continue for about 28 hours. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6227 SUBJECT: GRB 070328: Swift/XRT Refined Analysis DATE: 07/03/28 11:32:45 GMT FROM: Phil Evans at U of Leicester P.A. Evans, A.P. Beardmore, M.R. Goad, K.L. Page, R.L.C. Starling, L.G. Tyler (U. Leicester) and C.B. Markwardt (GSFC/UMD) report on behalf of the Swift/XRT team: We have analysed the first two orbits of Swift-XRT data obtained for GRB 070328 (Markwardt et al., GCN Circ 6224) which includes 1.3 ks of Windowed Timing (WT) mode data and 2.2 ks of Photon Counting (PC) mode data. Using the PC mode data we find the following astrometrically corrected XRT refined position (by matching the UVOT images with the USNO-B1 catalogue): RA, Dec = 65.1150, -34.0668 deg, which is equivalent to: RA(J2000) = 04 20 27.60 Dec(J2000) = -34 04 00.4 with an estimated error radius of 2.31 arcsec (90% confidence). This lies 39.7 and 8.4 arcsec from the refined BAT and onboard XRT positions given in GCN Circs. 6225 and 6224 respectively. The XRT light curve begins 95 s after the trigger, and decays as a power-law with alpha1=1.33 +0.25/-0.12 until 184 +10/-20 s after the trigger. At this point the decay shallows to alpha2=0.28 +/-0.06. This shallow decay continues until 629 +33/-27 s after the trigger, when the lightcurve breaks again to alpha3=1.34 +/-0.03. All errors are quoted at the 90% confidence level. The WT spectrum can be modelled with a power-law of Gamma=2.22 +/-0.03 with a total absorbing column of 2.6 +/-0.4x10^21 cm-2, compared to the Galactic value of 2.1x10^20 cm^-2. The PC mode data give almost identical values, however with larger errors as there are less counts in the spectrum. If the decay continues with a slope of alpha=1.34 the count-rate at 24 hours post-trigger is predicted to be 0.029 counts s^-1. This corresponds to an observed (unabsorbed) 0.3-10 keV flux of 2.74e-12 (4.96e-12) erg cm^-2 s^-1 . This circular is an official product of the Swift/XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6229 SUBJECT: GRB 070328: Swift/UVOT Upper Limits DATE: 07/03/28 20:18:13 GMT FROM: Frank Marshall at GSFC F.E. Marshall (NASA/GSFC) and C.B. Markwardt (GSFC/UMD) report on behalf of the Swift UVOT team: Swift/UVOT began its initial finding chart exposure of the field of GRB 070328 (Markwardt et al. 2007, GCN Circ. 6224) 98 s after the Swift/BAT trigger. No afterglow candidate is seen in the refined XRT error region (Evans et al. 2007, GCN Circ. 6227) in any of the early UVOT exposures. Three-sigma upper limits for the initial finding chart exposure and for the total exposure for each of the UVOT filters are provided below. The times in the table are from the Swift/BAT trigger. Filter t_start(s) t_stop(s) Exp(s) Mag 3-sig UL WHITE 98 198 98 19.6 WHITE 98 6984 567 21.1 V 79 11988 1721 20.7 B 682 6823 397 20.8 U 657 6619 429 20.4 UVW1 634 6414 432 20.7 UVM2 609 12770 1197 21.6 UVW2 711 11076 1101 21.5 These upper limits are not corrected for extinction. The Galactic reddening in the direction of the burst is E_{B-V} = 0.04 mag (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6230 SUBJECT: Konus-Wind observation of GRB 070328 DATE: 07/03/29 14:06:43 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team report: The long GRB 070328 (Swift-BAT trigger #272773: Markwardt et al., GCN 6224; Stamatikos et al., GCN 6225), triggered Konus-Wind at T0=14029.993 s UT (03:53:49.993). The Konus-Wind light curve shows multipeaked structure with a duration of ~45 s, followed by a weak tail marginally seen up to T-T0~130 s in the 70-300 keV band. As observed by Konus-Wind the burst had a fluence of 5.95(-0.76, +1.06)x10^-5 erg/cm2, and the 256-ms peak flux measured from T0+1.808 s 4.57(-0.91, +1.07)x10^-6 erg/cm2/s (both in the 20 keV - 6 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+41.216 s) is well fitted (in the 20 keV - 6 MeV range) by GRBM (Band) model for which: the low-energy photon index is alpha = -0.99(-0.11, +0.13), the high energy photon index beta = -1.99(-0.40, +0.18), the peak energy Ep = 496(-117, +172) keV (chi2 = 80/77 dof). Fitting by a power law with exponential cutoff model: dN/dE ~ E^(-alpha) * exp(-(2-alpha)*E/Ep) yields alpha = 1.09 +/- 0.08, and Ep = 688(-119, +173) keV (chi2 = 88/78 dof). All the quoted errors are at the 90% confidence level. The Konus-Wind light curve of this GRB is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB070328_T14029/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6231 SUBJECT: GRB 070328: pseudo-z~2.75 from spectral parameters of the prompt DATE: 07/03/30 16:46:17 GMT FROM: Alexandre Pelangeon at LATT,OMP,Toulouse A. Pelangeon & J-L. Atteia (LATT-OMP) report: We have used the spectral parameters obtained for the most intense part of GRB 070328 -- from T0 to T-T0 ~22 sec, Konus time (V. Pal'shin, Ioffe Inst., private communication) -- observed by Konus-Wind (Golenetskii et al., GCNC 6230) to compute the spectral pseudo-redshift** of this burst detected by SWIFT-BAT (Markwardt et al., GCNC 6224; Stamatikos et al., GCNC 6225). We find a pseudo-redshift pz= 2.75 +/- 0.95 We thank V. Pal'shin for having kindly performed the spectrum analysis of the most intense part and providing us the spectral parameters. ** cf. http://www.ast.obs-mip.fr/grb/pz //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6240 SUBJECT: GRB 070328: Suzaku WAM observation of the prompt emission DATE: 07/04/03 12:56:49 GMT FROM: Kazutaka Yamaoka at Aoyama Gakuin U S. Hong (Nihon U.), K. Yamaoka, Y.E. Nakagawa, S. Sugita (Aoyama Gakuin U.), M. Ohno, T. Takahashi, T. Asano, T. Uehara, Y. Fukazawa (Hiroshima U.), Y. Urata, M. Tashiro, K. Abe, K. Onda, Y. Sato, M. Suzuki (Saitama U.), T. Enoto, R. Miyawaki, K. Makishima (Univ. of Tokyo), M. Suzuki, T. Tamagawa, Y. Terada (RIKEN), K. Nakazawa, M. Kokubun, T. Takahashi (ISAS/JAXA), E. Sonoda, M. Yamauchi (Univ. of Miyazaki), on behalf of the Suzaku WAM team report: The bright, long GRB 070328 (Markwardt et al., GCN 6224; Stamatikos et al., GCN 6225) triggered the Suzaku Wide-band All-sky Monitor (WAM), which covers the energy range of 50 keV - 5 MeV, at 03:53:46 UT(=T0). The light curve shows multiple separate pulses with the T90 duration of about 38 seconds. The fluence in 100 keV - 3 MeV was 4.42 (-1.65, +0.54) x 10^-5 erg/cm^2, while the 1-s peak flux measured from T0+8 was 4.28 (-2.95, +0.18) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0+1 to T0+39 is described with a Band model as follows: the low-energy photon index alpha : -1.00 (-0.18, 0.21), the high-energy photon index beta : -1.89 (-0.43, 0.20), the Break energy E0 : 959 (-343, 664) keV, and the peak energy Epeak : 959 (-453, 1005) keV (chi^2/dof = 33.2/22). Fitting by a power law with exponential cutoff model: dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) alpha 1.17 (-0.15 +0.14), and Epeak 1126 (-426, +868) keV (chi^2/dof = 37.6/23). All the quoted errors are at statistical 90% confidence level, while systematic errors are not included. The WAM light curve of this event is available at http://www.astro.isas.ac.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html