This file contains both GRBs 080413A and 080413B //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7593 SUBJECT: GRB 080413: ROTSE-III Detection of Optical Counterpart DATE: 08/04/13 03:03:03 GMT FROM: Wiphu Rujopakarn at U AZ/Steward GRB 080413: ROTSE-III Detection of Optical Counterpart E.S. Rykoff (UCSB), W. Rujopakarn (Steward), report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 080413A (Swift trigger 309096). The first image was at 02:54:39.7 UT, 20.4 s after the burst (6.7 s after the GCN notice time). The unfiltered images are calibrated relative to USNO A2.0. We detect a 12.8 magnitude, fading source with coordinates: 19:09:11.8 -27:40:41.6 (J2000), with positional uncertainty of 1' or better start UT mag mlim(of image) ---------------------------------- 02:54:39.7 12.8 15.3 This source is not visible in DSS (second epoch), 2MASS or the MPChecker database. A jpeg image is available at http://www.rotse.net/images/gsb309096_3c00_img.jpg Note that the object marked 7 is the candidate in question. Continuing observations are in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7594 SUBJECT: GRB 080413: Swift detection of a burst with an optical afterglow DATE: 08/04/13 03:06:53 GMT FROM: David Palmer at LANL A. P. Beardmore (U Leicester), D. N. Burrows (PSU), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), S. D. Hunsberger (PSU), J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD), K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sakamoto (NASA/UMBC), M. Stamatikos (NASA/ORAU) and E. Troja (U Leicester/INAF-IASFPA) report on behalf of the Swift Team: At 02:54:19 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080413 (trigger=309096). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 287.290, -27.679 which is RA(J2000) = 19h 09m 10s Dec(J2000) = -27d 40' 44" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a triple-peaked structure with a duration of about 55 sec. The peak count rate was ~10000 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 02:55:20.0 UT, 60.7 seconds after the BAT trigger. XRT found a bright, fading uncatalogued X-ray source located at RA, Dec 287.2978, -27.6779 which is equivalent to: RA(J2000) = 19h 09m 11.4s Dec(J2000) = -27d 40' 40.4" with an uncertainty of 4.7 arcseconds (radius, 90% containment). This location is 25 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to assess possible redshift constraints using X-ray spectroscopy and the nH-z relation from Grupe et al. (2007). UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 76 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 19:09:11.76 = 287.2990 DEC(J2000) = -27:40:40.1 = -27.6778 with a 1-sigma error radius of about 0.6 arc sec. This position is 3.9 arc sec. from the center of the XRT error circle. The estimated magnitude is 15.2 with a 1-sigma error of about 0.5 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.16. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7595 SUBJECT: GRB 080413: TAROT Calern observatory optical observations DATE: 08/04/13 03:54:16 GMT FROM: Alain Klotz at CESR-CNRS Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report: We imaged the field of GRB 080413 detected by SWIFT (trigger 309096) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. The observations started 21.8s after the GRB trigger (8.3s after the notice). The elevation of the field increased from from 11 degrees above horizon and weather conditions were poor at the beginning of observations. The first image showing stars started 480s after the trigger. We detected the candidate couterpart mentioned by Rykoff et al. (GCNC 7593) at the following position (+/- 2 arcsec): RA(J2000.0) = 19h 09m 11.85s DEC(J2000.0) -27d 40' 43.0" Unfiltered magnitudes are: t0+480s to t0+570s : R > 12.5 t0+1174s to t0+1263s : R = 15.0 +/- 0.2 t0+1470s to t0+1650s : R = 15.3 +/- 0.2 t0+2035s to t0+2215s : R = 15.5 +/- 0.2 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon= 9.5236 lat=-15.8249 and the galactic extinction in R band is 2.4 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7596 SUBJECT: GRB 080413: Enhanced Swift-XRT position DATE: 08/04/13 06:42:02 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 176 s of overlapping XRT Photon Counting mode and UVOT data for GRB 080413, 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 = 287.29829, -27.67807 which is equivalent to: RA (J2000): 19h 09m 11.59s Dec (J2000): -27d 40' 41.1" with an uncertainty of 2.3 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 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method. This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7597 SUBJECT: GRB 080413A: REM detection of the NIR Afterglow DATE: 08/04/13 09:06:15 GMT FROM: Angelo Antonelli at Obs. Astro. di Roma L.A. Antonelli, P. D'Avanzo, D. Malesani, S. Covino, D. Fugazza, L. Calzoletti, S. Campana, G. Chincarini, M.L. Conciatore, S. Cutini, V. D'Elia, F. D'Alessio, F. Fiore, P. Goldoni, D. Guetta, C. Guidorzi, G.L. Israel, E. Maiorano, N. Masetti, A. Melandri, E.J.A. Meurs, L. Nicastro, E. Palazzi, E. Pian, F. Piranomonte, S. Piranomonte, L. Stella, G. Stratta, G. Tagliaferri, G. Tosti, V. Testa, S.D. Vergani, and F. Vitali, report on behalf of the REM team: The robotic 60-cm REM telescope located at La Silla (Chile) observed automatically the field of the GRB 080413A (Beardmore et al., GCN 7594) starting about 1.3 hours after the burst due to object visibility constraints. Observation started as soon as the object is risen so the Airmass was large. A preliminary investigation of our earliest images (R,z,J,H,K) showed that the candidate optical counterpart (Rykoff et al. GCN 7593, Beardmore et al., GCN 7594, Klotz et al., GCN 7595) is observed in all bands. At the beginning of REM observation, the object had a H mag of about H=15.2 calibrated against 2MASS and not corrected for galactic extinction. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7598 SUBJECT: GRB 080413B: Swift detection of a possibly short burst with optical counterpart DATE: 08/04/13 09:20:28 GMT FROM: David Palmer at LANL M. Stamatikos (NASA/ORAU), A. P. Beardmore (U Leicester), N. Gehrels (NASA/GSFC), S. D. Hunsberger (PSU), C. B. Markwardt (CRESST/GSFC/UMD), J. P. Osborne (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sakamoto (NASA/UMBC), R. L. C. Starling (U Leicester) and E. Troja (U Leicester/INAF-IASFPA) report on behalf of the Swift Team: At 08:51:12 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080413B (trigger=309111). Swift started slewing approximately 70 seconds after the burst. The BAT on-board calculated location is RA, Dec 326.134, -19.969 which is RA(J2000) = 21h 44m 32s Dec(J2000) = -19d 58' 08" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peaked structure with a duration of about 3 sec. The peak count rate was ~15,000 counts/sec (15-350 keV), at ~0.2 sec after the trigger. The XRT began observing the field at 08:53:23.8 UT, 131.2 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 326.14434, -19.98104 which is equivalent to: RA(J2000) = 21h 44m 34.64s Dec(J2000) = -19d 58' 51.7" with an uncertainty of 2.6 arcseconds (radius, 90% containment). This location is 55 arcseconds from the BAT onboard position, within the BAT error circle. A power-law fit to a spectrum formed from promptly downlinked event data does not constrain the column density, so we cannot provide limits on the redshift using spectroscopy and the relation from Grupe et al. (2007). A summary of the promptly downlinked data is given at http://www.swift.ac.uk/sper/309111/. UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 134 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 21:44:34.68 = 326.1445 DEC(J2000) = -19:58:52.0 = -19.9811 with a 1-sigma error radius of about 0.6 arc sec. This position is 0.6 arc sec. from the XRT position. The estimated magnitude is 16.5 with a 1-sigma error of about 0.5 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04. Burst Advocate for this burst is M. Stamatikos (michael AT milkyway.gsfc.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: 7599 SUBJECT: GRB 080413B: GROND detection of afterglow in all bands DATE: 08/04/13 09:32:15 GMT FROM: Jochen Greiner at MPI T. Kruehler, J. Greiner, A. Kupcu Yoldas, C. Clemens, A. Yoldas (all MPE Garching) and G. Szokoly (Eoetvoes Univ. Budapest and MPE Garching) report on behalf of the GROND team: We observed the field of GRB 080413B detected by Swift/BAT (trigger 309111, Stamatikos et al. 2008, GCN Circ. 7598) simultaneously in g'r'i'z'JHK with GROND mounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile). Observations started at 08:56 UT on April 13th, 2008, 5 min after the burst. We detect a new bright point source at RA (J2000.0) = 21:44:34.67 DEC (J2000.0) = -19:58:52.4 with an uncertainty of 0.5", which is consistent with the UVOT position. The object is detected in all seven bands, implying a redshift smaller than 3.5. Preliminary photometry of the first 4 min exposure yields an J band magnitude of 16.5 calibrated against 2MASS field stars. The given magnitude is not corrected for the Galactic foreground reddening of E(B-V)=0.04 mag (Schlegel et al., 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7600 SUBJECT: GRB080413B: REM NIR & Optical Observation DATE: 08/04/13 10:06:45 GMT FROM: Angelo Antonelli at Obs. Astro. di Roma L.A. Antonelli, S. Covino, P. D'Avanzo, D. Fugazza, L. Calzoletti, S. Campana, G. Chincarini, M.L. Conciatore, S. Cutini, V. D'Elia, F. D'Alessio, F. Fiore, P. Goldoni, D. Guetta, C. Guidorzi, G.L. Israel, E. Maiorano, N. Masetti, A. Melandri, E. Meurs, L. Nicastro, E. Palazzi, E. Pian, S. Piranomonte, L. Stella, G. Stratta, G. Tagliaferri, G. Tosti, V.Testa, S.D. Vergani, F. Vitali report on behalf of the REM team: The robotic 60-cm REM telescope located at La Silla (Chile) observed automatically the field of the GRB 080413B on April 13 08:52:43 UT (about 91 seconds after the burst). The afterglow reported in GCN 7598, 7599 (Stamatikos et al., Kruehler et al.) is well detected in our early images at about H~14.3. Further analyses and observations are in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7601 SUBJECT: GRB 080413B: VLT redshift DATE: 08/04/13 10:58:47 GMT FROM: Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center Paul M. Vreeswijk, Christina C. Thoene, Daniele Malesani, Johan P. U. Fynbo, Jens Hjorth (DARK/NBI), Pall Jakobsson (Univ. Hertfordshire), Nial R. Tanvir (Univ. Leicester), and Andrew J. Levan (Univ. Warwick), report on behalf of a larger collaboration: We observed the afterglow of the possibly short GRB 080413B (Stamatikos et al., GCN 7598) with the ESO VLT equipped with FORS1. A 600 s spectrum centered on Apr 13.403 UT (49.5 min after the GRB) was acquired covering the range 3500-9000 AA. From detection of numerous absorption features, including Fe II, Mg II and Mg I lines, we infer a redshift z = 1.10. In particular, we detect the Fe II 2396 fine-structure line, which confirms this redshift is very likely that of the host of the GRB. We acknowledge excellent support from the VLT staff, particularly Thomas Szeifert, Jose Cortes, and Gianni Marconi. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7602 SUBJECT: GRB 080413A: VLT/UVES redshift DATE: 08/04/13 12:10:21 GMT FROM: Christina Thoene at Niels Bohr Institute,DARK Cosmo Ctr Christina C. Thoene, Daniele Malesani, Paul M. Vreeswijk, Johan P. U. Fynbo (DARK/NBI), Pall Jakobsson (Univ. of Hertfordshire), Cedric Ledoux and Alain Smette (ESO) report on behalf of a larger collaboration: We observed the afterglow of GRB 080413A (GCN 7593, Rykoff & Rujopakarn; GCN 7594, Stamatikos et al.) on Apr. 13 starting UT 06:36 with UVES at the VLT. Spectra of 2700 s with low S/N were acquired in the DIC 2R and 2B settings covering the wavelength range between 3250 and 9000 AA. We detect several narrow absorption features including SII, Si II, CII, Fe II, AlII, C IV, Si IV as well as broad Lyman alpha absorption at the highest redshift system which has z=2.433 and is very likely the redshift of GRB 080413A. We thank the Paranal staff for executing the observations, in particular Swetlana Hubrig and Jose Cortes. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7603 SUBJECT: GRB 080413A Bootes observation DATE: 08/04/13 12:50:49 GMT FROM: Petr Kubanek at AIO P. Kubanek, M. Jelinek, J. Gorosabel, A. J. Castro-Tirado (IAA-CSIC Granada), L. Sabau-Graziati (INTA Madrid), A. de Ugarte Postigo (ESO Santiago), R. Hudec (ASU-CAS Ondrejov), P. Perez-Gonzalez and J. Zamorano (UCM Madrid) report on behalf of a larger collaboration: The BOOTES-1 0.3m telescope in South Spain observed GRB 080413A, starting at 02:55:20 UT (46 sec after receiving trigger, 1 minute after GRB). A sequence of preprogrammed 6 sec, 20 and 60 sec exposures was obtained. The optical counterpart reported by Rykoff at al. (GCN 7593) is clearly detected on the initial exposures. Further data were obtained at the 2.5m NOTin La Palma under non-optimal conditions. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7604 SUBJECT: GRB 080413A, Swift-BAT refined analysis DATE: 08/04/13 15:58:16 GMT FROM: Scott Barthelmy at NASA/GSFC J. Tueller (GSFC), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+454 sec from recent telemetry downlinks, we report further analysis of BAT GRB 080413A (trigger #309096) (Beardmore, et al., GCN Circ. 7594). The BAT ground-calculated position is RA, Dec = 287.301, -27.677 deg, which is RA(J2000) = 19h 09m 12.1s Dec(J2000) = -27d 40' 36.8" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 81%. The mask-weighted light curve shows four peaks. The first starting at T-0.1 sec, peaking at T+2.0 sec. The second peak overlaps with the first and peaks at ~T+7 sec. The third and fourth peaks are well separated with peaks at T+16 and T+47 sec, repsectively. The lightcurve returns to baseline at ~T+80 sec. T90 (15-350 keV) is 46 +- 1 sec (estimated error including systematics). The time-averaged spectrum from T-0.1 to T+50.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.57 +- 0.06. The fluence in the 15-150 keV band is 3.5 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+1.64 sec in the 15-150 keV band is 5.6 +- 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/309096/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7605 SUBJECT: GRB 080413A: Swift-XRT refined analysis DATE: 08/04/13 16:39:02 GMT FROM: Phil Evans at U of Leicester P.A. Evans, K.L. Page, A.P. Beardmore, R.L.C. Starling (U. Leicester) and F.E. Marshall (NASA/GSFC) report on behalf of the Swift-XRT team: We have analysed 5.2 ks of Swift XRT data for GRB 080413A (Beardmore et al. GCN Circ. 7594), from T0+67 s to T0+21000 s. The first 186 s of data were obtained in Windowed Timing (WT mode); the remainder in Photon Counting mode. The best XRT position for this object is the UVOT-enhanced position given in Osborne et al. (GCN Circ. 7596). The X-ray light curve is well fitted by a power-law decay, with an initial decay slope of 2.87 (+/- 0.19) up to T0+175 (+23/-16) s, at which point the decay shallows to a slope of 1.10 (+0.06/-0.07). A spectrum obtained from all of the WT mode data can be modelled with an absorbed power-law with a photon index gamma=3.12 (+0.16/-0.15). A redshifted absorbing column of 1.53 (+0.43/-0.38) x 10^22 cm^-2, at a redshift of z=2.433 (Thoene et al. GCN Circ 7602) is necessary in addition to the Galactic column of 8.71 x 10^20 cm^-2 (Kalberla et al. 2005). The observed (unabsorbed) 0.3-10 keV flux in this spectrum is 4.1 x 10^-10 (1.71 x 10^-9) erg cm^-2 s^-1. If the source continues to decay at the present rate, we predict a count rate of 3.51 x 10^-3 count/sec at T0+24 hours, which correponds to a 0.3-10 keV observed (unabsorbed) flux of 9.54 x 10^-14 (2.72 x 10^-13) erg cms^-2 s^-1. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7606 SUBJECT: GRB 080413B, Swift-BAT refined analysis DATE: 08/04/13 17:27:57 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-119 to T+148 sec from recent telemetry downlinks, we report further analysis of BAT GRB 080413B (trigger #309111) (Stamatikos, et al., GCN Circ. 7598). The BAT ground-calculated position is RA, Dec = 326.138, -19.981 deg, which is RA(J2000) = 21h 44m 33.1s Dec(J2000) = -19d 58' 49.8" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 20%. The mask-weighted light curve shows a single FRED-like peak starting at T-1.1 sec, peaking at T+0.2 sec, and returning to baseline at ~T+30 sec. T90 (15-350 keV) is 8.0 +- 1.0 sec (estimated error including systematics). The time-averaged spectrum from T-1.3 to T+10.7 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.26 +- 0.27, and Epeak of 73.3 +- 15.8 keV (chi squared 32.60 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.2 +- 0.1 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T-0.26 sec in the 15-150 keV band is 18.7 +- 0.8 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.80 +- 0.06 (chi squared 45.07 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/309111/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7607 SUBJECT: GRB080413A: Swift/UVOT observations DATE: 08/04/13 17:49:17 GMT FROM: Samantha Oates at MSSL S. R. Oates and F. E. Marshall report on behalf of the Swift/UVOT team. The Swift/UVOT observed the field of GRB 080413A starting at 77s after the BAT trigger (Beardmore et al., GCN 7594). We detect the afterglow in white,v,b and u filters at the position: RA(J2000.0) = 19:09:11.76 DEC(J2000.0) = -27:40:40.27 with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence). This position is consistent with the enhanced XRT position and the position reported by ROSTE-III (Rykoff et al., GCN 7593). The magnitudes and 3 sigma upper limits are reported below: Filter T_Mid(s) Expo(s) Magnitude/3sigUL ----------------------------------------------------- White 126 98 15.37 +/- 0.01 White 5478 197 19.74 +/- 0.17 v 268 169 15.08 +/- 0.03 v 5888 197 19.16 +/- 0.51 b 5273 197 19.33 +/- 0.21 u 5068 197 19.05 +/- 0.22 w1 4863 197 >19.55 m2 4658 197 >19.48 w2 5684 197 >19.57 ----------------------------------------------------- The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.16 mag (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT flight system described in Poole et al. (2008,MNRAS,383,627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7608 SUBJECT: GRB 080413B: Swift XRT refined analysis DATE: 08/04/13 18:55:01 GMT FROM: Eleonora Troja at INAF-IASFPA E. Troja (U. Leicester/INAF-IASFPa) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift-XRT team: We have analysed 9.9 ks of Swift XRT data for GRB 080413B (Stamatikos et al. GCN Circ. 7598), from T0+134 s to T0+20.1 ks. The data set consists of 376 s exposure in Windowed Timing (WT) mode followed by 9.5 ks exposure in Photon Counting (PC) mode. By using orbits 2-4 of PC data [from T0+6.0 ks to T0+20.1 ks] in order to avoid pile-up effects, we derive an XRT refined position RA (2000) = 21h 44m 34.43s = 326.1435 d Dec (2000) = -19d 58' 52.9" = -19.9814 d with an uncertainty of 3.7 arcsec (90% containment). This position is 3.6 arcsec from the UVOT candidate afterglow (GCN Circ. 7598), and 3.4 arcsec from the source reported in Kruehler et al. (GCN Circ. 7599). The X-ray light curve is well fitted by a simple power-law, with a decay slope of 0.88 +/- 0.06. A spectrum obtained from the WT mode data, from T0+135 s to T0+511 s, can be modelled with an absorbed power-law with a photon index of 2.05 +/- 0.10 , and a redshifted absorbing column of (0.32 +/- 0.13) x 10^22 cm^-2 at a redshift of z=1.1 (Vreeswijk et al. GCN Circ 7601) in addition to the Galactic column of 3.06 x 10^20 cm^-2 (Kalberla et al. 2005). The observed (unabsorbed) 0.3-10 keV flux in this spectrum is 1.79 x 10^-10 (2.13 x 10^-10) erg/cm^2/s. The PC spectrum of the first four orbits, from T0+512 s to T0+20.1 ks, can be fit by an absorbed power-law model with photon index 1.93 +/- 0.08 and a column density consistent with the WT spectrum. All the reported errors are at the 90% confidence level. If the source continues to decay at the present rate, we predict a count rate of 0.035 count/sec at T0+24 hours, which corresponds to a 0.3-10 keV observed (unabsorbed) flux of 1.6 x 10^-12 (1.8 x 10^-12) erg/cm^2/s. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7609 SUBJECT: GRB 080413a, SMARTS optical/IR afterglow observations DATE: 08/04/13 19:22:38 GMT FROM: Bethany Cobb at Yale U B. E. Cobb (Yale), part of the larger SMARTS consortium, reports: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 080413a (GCN 7594, Beardmore et al.), starting at 2008-04-13 05:48 UT, which is ~2.9 hours post-burst. Several dithered images were obtained in each filter, with total summed exposure times of 180s in each of BRIYJK and 120s in each of H and V. The GRB afterglow (GCN 7593 Rykoff & Rujopakarn; GCN 7594, Beardmore et al.) is detected in all our images. At a mid-exposure time of 2008-04-13 06:02 (~3.1 hours post-burst) the afterglow has the following magnitudes (which have not been corrected for Galactic reddening): B= 20.88 +/- 0.10 V= 20.25 +/- 0.11 R= 19.25 +/- 0.05 I= 18.84 +/- 0.06 J= 18.23 +/- 0.23 H= 17.05 +/- 0.15 K= 16.19 +/- 0.12 Optical photometry is calibrated against Landolt standard stars and IR photometry is calibrated against 2MASS stars in the field. Between 3.1 and 5.1 hours post burst, the afterglow decays by ~0.75 magnitudes, indicating an approximate decay rate of alpha = -1.4 (where afterglow flux is proportional to t^alpha). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7610 SUBJECT: Swift-BAT spectral lag analysis of GRB 080413B DATE: 08/04/13 19:59:34 GMT FROM: Michael Stamatikos at GSFC T. Sakamoto (GSFC/UMBC), T. Ukwatta (GWU), M. Stamatikos (GSFC/ORAU), S. D. Barthelmy (GSFC), N. Gehrels (GSFC), We further report on additional spectral lag analysis regarding the possible short duration burst classification of GRB 080413B (Stamatikos et al. GCN Circ. 7598). We now believe GRB 080413B to be a long GRB based upon the following BAT prompt emission properties: 1) The spectral lag in 25-50 to 100-350 keV bands and 15-25 to 50-100 keV bands are 0.238 +- 0.016 sec and 0.136 +- 0.008 sec for 4 ms binning. Therefore, GRB 080413B shows a significant lag. 2) The T90 of the spike is 8.0 +- 1.0 sec based on the mask-weighted light curve (Barthelmy et al., GCN 7606), which is well within the long duration GRB population (Sakamoto et al. ApJS, 175, 179). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7611 SUBJECT: GRB080413B DATE: 08/04/13 20:38:00 GMT FROM: Samantha Oates at MSSL S. R. Oates and M. Stamatikos report on behalf of the Swift/UVOT team. The Swift/UVOT began settled observations of the field of GRB 080413B 135s after the BAT trigger (Stamatikos et al., GCN 7598). We detect the afterglow in the 7 UVOT filters at the position: RA(J2000.0) = 21:44:34.65 DEC(J2000.0) = -19:58:52.40 with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence). This position is consistent with the refined XRT position and the GROND optical position (Kruehler et al., GCN 7599). The magnitudes are reported below: Filter T_Mid(s) Expo(s) Magnitude ------------------------------------------------------- White 184 98 16.67 ± 0.02 White 740 10 17.67 ± 0.15 v 440 393 17.64 ± 0.10 v 1183 393 18.64 ± 0.22 b 727 10 18.82 ± 0.71 u 796 19 17.67 ± 0.27 w1 682 19 17.42 ± 0.27 m2 810 19 18.07 ± 0.47 w2 762 19 17.92 ± 0.36 ------------------------------------------------------- The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.04 mag (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT flight system described in Poole et al. (2008,MNRAS,383,627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7612 SUBJECT: GRB 080413B: Ep,i-Eiso correlation DATE: 08/04/13 22:47:19 GMT FROM: Lorenzo Amati at INAF-IASF/Bologna L. Amati (INAF - IASF Bologna), By assuming the VLT redshift of 1.10 (Vreeswijk et al., GCN 7601), the values of spectral parameters alpha and Ep, and the fluence, provided by Swift/BAT (Barthelmy et al., GCN 7606), a value of spectral parameter beta of -2.3 and a Lambda-CDM cosmology with H0=70 km/s/Mpc, Omega_M=0.27 and Omega_Lambda=0.73, the values of Ep,i and Eiso (1-10000 keV cosmological rest-frame) of GRB 080413B are approximately 150+/30 keV and (2.4+/-0.2)x10^52 erg, fully consistent with the Ep,i-Eiso correlation. Given that this correlation holds for long GRBs only (see, e.g., Amati, MNRAS, 2006; Amati, astroph/0611189), this is a further evidence that GRB 080412B is not a short GRB. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7614 SUBJECT: VLA radio observations of GRB 080413A DATE: 08/04/14 14:33:02 GMT FROM: Poonam Chandra at U Virginia/NRAO Poonam Chandra (NRAO/UVA) and Dale A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration: "We used the Very Large Array to observe the field of view toward GRB 080413A (GCN 7594) at a frequency of 8.46 GHz at 2008 April 14.53 UT. We do not detect the GRB afterglow at the ROTSE optical position (GCN 7593). The flux density at the GRB afterglow position is -61 +/- 49 uJy. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7615 SUBJECT: GRB 080413B: Gemini-South Spectroscopy DATE: 08/04/14 16:42:35 GMT FROM: Antonino Cucchiara at PSU A. Cucchiara and D. B. Fox (Penn State) with S. B. Cenko (Caltech), report on behalf of a larger collaboration: "Starting on 2008 April 13.41 UT we observed GRB 080413B (Stamatikos et al. GCN 7598) with the GMOS spectrograph on the Gemini South telescope. We obtained a single 900-sec spectrum in the wavelength range 3900-6700A. The resolution of our spectrum is 5 Ang/pixel (R ~ 1100 at 5900A). We clearly observe several metal absorption features corresponding to the MgII doublet (2796,2803 A), MgI (2853A), FeII (2586A and 2600A), and FeI (3021A). These identifications are consistent with a host galaxy redshift of z = 1.10, confirming the result reported from VLT observations by Vreeswijk et al.(GCN 7601)." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7616 SUBJECT: GRB 080413A: Gemini-South Spectroscopy DATE: 08/04/14 17:27:38 GMT FROM: Antonino Cucchiara at PSU A. Cucchiara and D. B. Fox (Penn State) with S. B. Cenko (Caltech), report on behalf of a larger collaboration: "Starting on 2008 April 13.27 UT we observed GRB 080413A (GCN 7593 and 7594) with the GMOS spectrograph on the Gemini South telescope. We obtained 2x1200-sec spectra in the wavelength range 3900-8000A. The resolution of our spectrum is 5.2 Ang/pixel (R ~1200 at 6000A). We clearly observe several metal absorption features corresponding to the SiIV (1393,1402 A), CIV (1548, 1550A), SiII (1526A), and AlII (1670A) transitions. A Lyman break is also present at the blue edge of our spectra (~ 4170A). These identifications are consistent with a host galaxy redshift of z = 2.43, confirming the result reported from VLT observations by Thoene et al.(GCN 7602)." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7617 SUBJECT: VLA radio observations of GRB 080413B DATE: 08/04/14 17:34:10 GMT FROM: Poonam Chandra at U Virginia/NRAO Poonam Chandra (NRAO/UVA) and Dale A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration: "We used the Very Large Array to observe the field of view toward GRB 080413B (GCN 7598) at a frequency of 8.46 GHz at 2008 April 14.59 UT. We do not detect the GRB afterglow at the GROUND optical position (GCN 7599). The flux density at the GRB afterglow position is 86 ± 36 uJy. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7622 SUBJECT: GRB 080413A: MOA-II optical afterglow observations DATE: 08/04/15 23:48:14 GMT FROM: Nobuyuki Kawai at Tokyo Tech A. Fukui, Y. Itow, T. Sumi (STE Lab, Nagoya Univ.), and P. Tristram (Canterbury Univ.) on behalf of the MOA Collabration (Bond et al. 2001, Sumi et al. 2003) report: We observed the optical afterglow of GRB080413A (GCN 7593, Rykoff & Rujopakarn; GCN 7594, Beardmore et al.) on Apr. 13 between 12:29:16.4 UTC and 14:13:06.6 UTC, corresponding to about 9.5-11 h after the burst, with the 1.8m MOA-II telescope at Mt. John observatory in New Zealand. Total 5 images were obtained with a wide- band Red filter (center wavelength ~ 750nm and FWHM ~ 250nm) and we could identify the faint afterglow within the error circle (<0.5"). The identified R.A. Dec. are 19:09:11.752 -27:40:39.99 with an uncertainty of 0.14" (radius, 1sigma) and following are the photometric results: I magnitude = 20.24 +/- 0.32 at the mid-exposure time of 2008-04-13 12:29:16.4 UTC, 20.09 +/- 0.19 at 12:51:10.7 UTC, 21.40 +/- 0.61 at 13:03:0.1 UTC, 20.05 +/- 0.17 at 13:42:47.0 UTC, and 20.75 +/- 0.25 at 14:13:06.6 UTC. These photometry were done by using the IRAF and calibrated against the USNO-B1.0 catalog stars, and not corrected for the Galactic extinction. [GCN OPS NOTE(18apr08): By the moderator's choice, the "GCN 7594, Stamatikos et al" wash changed to "GCN 7594, Beardmore et al". Ack to F. Marshall.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7623 SUBJECT: GRB 080413B: Suzaku WAM observation of the prompt emission DATE: 08/04/16 15:33:02 GMT FROM: Kazutaka Yamaoka at Aoyama Gakuin U T. Enoto (Univ. of Tokyo), Y.E. Nakagawa, T. Tamagawa (RIKEN), T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima U.), K. Yamaoka, S. Sugita (Aoyama Gakuin U.), M. Tashiro, Y. Terada, Y. Urata, A. Endo, K. Onda, N. Kodaka, K. Morigami (Saitama U.), K. Nakazawa, K. Makishima (Univ. of Tokyo), E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara (Univ. of Miyazaki), M. Ohno, M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report: The Swift GRB 080413B (Swift/BAT trigger #309111 ; Stamatikos et al., GCN 7598) was detected by the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 8:51:11.645 UT (=T0). The observed light curve shows a single peak starting at T0-0s, with a duration (T90) of about 2 seconds. The fluence in 150 - 1000 keV was (1.4 +/- 0.3) x 10^-6 erg/cm^2. The 1-s peak flux measured from T0+1s was 3.4 +/- 0.2 photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-1s to T0+8s is fitted by a single power-law with a photon index of 3.02 (+0.36, -0.32) (chi^2/d.o.f = 16.7/16) in 150 - 1000 keV. All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included. The light curves with 1-sec time resolution for this burst are now available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7624 SUBJECT: GRB 080413A: Suzaku WAM observation of the prompt emission DATE: 08/04/16 16:11:23 GMT FROM: Kazutaka Yamaoka at Aoyama Gakuin U T. Enoto (Univ. of Tokyo), Y.E. Nakagawa, T. Tamagawa (RIKEN), T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima U.), K. Yamaoka, S. Sugita (Aoyama Gakuin U.), M. Tashiro, Y. Terada, Y. Urata, A. Endo, K. Onda, N. Kodaka, K. Morigami (Saitama U.), K. Nakazawa, K. Makishima (Univ. of Tokyo), E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara (Univ. of Miyazaki), M. Ohno, M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report: The long GRB 080413A (Swift/BAT trigger #309096 ; Beardmore et al., GCN 7594) was detected by the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 02:54:18.648 UT (=T0). The observed light curve shows a clear double-peaked structure at T0+2s and T0+16s, and possible weak peak at T0+45s, with a total duration (T90) of about 19 seconds. The fluence in 150 - 1000 keV was (2.2 +/- 0.5) x 10^-6 erg/cm^2. The 1-s peak flux measured from T0+2s was 0.77 +/- 0.19 photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0+0s to T0+20s is fitted by a single power-law with a photon index of 2.4 +/- 0.4 (chi^2/d.o.f = 15.1/10) in 150 - 1000 keV. All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included. The light curves with 1-sec time resolution for this burst are now available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7625 SUBJECT: GRB 080413A: Liverpool Telescope and Faulkes Telescope South optical observations DATE: 08/04/16 17:23:09 GMT FROM: Andreja Gomboc at LT,ARI,Liverpool JMU A. Gomboc (Ljubljana), C. Guidorzi (U. Bicocca/INAF-OAB), A. Melandri, I.A. Steele, C.G. Mundell, D.F. Bersier, M.F. Bode, M.J. Burgdorf, S.N. Fraser, S. Kobayashi, C.J. Mottram, R.J. Smith (Liverpool JMU), P. O'Brien, N. Bannister, N. Tanvir (U. Leicester) report on behalf of larger GRB collaboration: The Liverpool Telescope observed the field of GRB 080413A (trigger=309096, Beardmore et al. GCN 7594) under poor weather conditions starting 2-hr after the trigger. Observations continued with the Faulkes Telescope South. In our coadded frames we do not detect any source at the position of the optical afterglow (Beardmore et al. GCN 7594, Rykoff & Rujopakarn GCN 7593) down to the limiting magnitudes reported below. Telescope Filter Tstart(hr) Tstop(hr) Exposure(s) M_lim ---------------------------------------------------------------------- Liverpool R 2.0 2.5 760 15.7 Faulkes South R 12.2 12.2 30 19.2 I 12.2 13.1 2080 21.7 ---------------------------------------------------------------------- Magnitudes were calibrated with respect to USNOB1 R2 and I. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7626 SUBJECT: GRB 080413B: Faulkes Telescope South optical afterglow observations DATE: 08/04/16 17:48:34 GMT FROM: Andreja Gomboc at LT,ARI,Liverpool JMU A. Gomboc (Ljubljana), C. Guidorzi (U. Bicocca/INAF-OAB), A. Melandri, I.A. Steele, C.G. Mundell, D.F. Bersier, M.F. Bode, M.J. Burgdorf, S.N. Fraser, S. Kobayashi, C.J. Mottram, R.J. Smith (Liverpool JMU), P. O'Brien, N. Bannister, N. Tanvir (U. Leicester) report on behalf of larger GRB collaboration: The 2-m Faulkes Telescope South observed the field of GRB 080413B (trigger=309111, Stamatikos et al. GCN 7598) starting 8.7-hr after the trigger time. We detect the optical afterglow (Stamatikos et al. GCN 7598, Kruehler et al. GCN 7599, Antonelli et al. GCN 7600) and measure the following magnitudes: Filter T_mid(hr) Exposure(s) Mag ---------------------------------------------------------------------- R 8.74 30 19.00 +/- 0.15 I 8.90 640 18.91 +/- 0.05 I 9.20 1080 19.15 +/- 0.05 I 9.54 1080 19.22 +/- 0.06 ---------------------------------------------------------------------- Magnitudes were calibrated with respect to USNOB1 R2 and I. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7629 SUBJECT: GRB 080413B: Rapid PROMPT Observations DATE: 08/04/17 17:02:01 GMT FROM: Thomas Summers Brennan at UNC/GRB Group T. Brennan, D. Reichart, M. Nysewander, A. LaCluyze, K. Ivarsen, J. A. Crain, M. Schubel, A. Foster, J. Haislip, J. Styblova, and A. Trotter report: Skynet observed the localization of GRB 080413B (Stamatikos et al., GCN 7598) with four of the 16" PROMPT telescopes at CTIO beginning 27 seconds after the trigger (10 seconds after notification) in UBVRz' We detect the afterglow (Stamatikos et al., GCN 7598) in BVRz'. At 42 seconds after the burst we measure B ~ 15.7 mag (calibrated to 2 USNO B1 stars), at 55 seconds we measure V ~ 15.4 mag (calibrated to 2 USNO B1 stars), and at 87 seconds we measure R ~ 15.4 mag (calibrated to 2 NOMAD stars). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7630 SUBJECT: GRB 080413A: Suzaku/WAM and Swift/BAT joint spectral analysis DATE: 08/04/18 21:50:05 GMT FROM: Takanori Sakamoto at NASA/GSFC M. Ohno, M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA) K. Yamaoka, S. Sugita (Aoyama Gakuin U.), T. Enoto (Univ. of Tokyo), Y.E. Nakagawa, T. Tamagawa (RIKEN), T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima U.), M. Tashiro, Y. Terada, Y. Urata, A. Endo, K. Onda, N. Kodaka, K. Morigami (Saitama U.), K. Nakazawa, K. Makishima (Univ. of Tokyo), E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara (Univ. of Miyazaki), , S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report: J. Tueller (GSFC), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), T. Ukwatta (GWU) (i.e. the Swift-BAT team): report: We performed the Suzaku/WAM and Swift/BAT joint fit spectral analysis of GRB 080413A (Swift/BAT trigger #309096; Beardmore et al., GCN 7594). The time interval of the spectral data for each instrument is chosen from T0(WAM)-1 to T0(WAM)+22 sec where T0(WAM) is the trigger time of WAM at 02:54:18.648 UTC. This time interval includes the initial two peaks, but not the relatively soft third peak around T0(WAM)+45 sec which is clearly visible in the BAT data (Tueller et al., GCN 7604). The energy ranges which we used in the joint spectral analysis are 13-150 keV and 150-1000 keV for Swift/BAT and Suzaku/WAM respectively. The spectral data of two instruments are fit with the spectral model multiplied by the constant factor to take into account the systematic uncertainties in the response matrices of each instrument. The spectrum is well fit with a power-law with exponential cutoff model (dN/dE ~ E^{alpha} * exp(-(2+alpha)*E/Epeak)). The constant factors of each instrument agree within 20%. No systematic residual from the best fit model is seen in the spectral data of each instrument. The best fit spectral parameters are: alpha = -1.2 +- 0.1 and Epeak = 170 (-40/+80) keV (chi2/dof = 75/73). The energy fluence in the 15-1000 keV band calculated by a power-law with exponential cutoff model for this 23 sec interval is 4.8 (-1.2/+0.4) x 10^-6 erg/cm2 (assuming the constant factor of the BAT is fixed to 1). Assuming z = 2.433 (Thoene et al., GCN 7602) and a standard cosmology model with H_0 = 71 km/s/Mpc, Omega_M = 0.27, Omega_\Lambda = 0.73, the isotropic energy release is E_iso ~8x10^52 erg in 1 keV to 10 MeV at the GRB rest frame. All the quoted errors are at the 90% confidence level.