GRB130408A

This page lists all entries on GRB130408A in GRBweb

Summary IPN Swift GCN 14361 GCN 14362 GCN 14363 GCN 14364 GCN 14365 GCN 14366 GCN 14367 GCN 14368 GCN 14369 GCN 14370 GCN 14372 GCN 14373 GCN 14374 GCN 14375 GCN 14376

Summary table
Variable Value Source
T0 21:51:38 UTC GCN_circulars,Swift Det
ra 134.4054° Swift
decl -32.3608° Swift
pos_error 6.47e-05° Swift
T90 28.0 s Swift
T90_start 21:51:38 UTC Swift
fluence 2.30e-06 erg/cm² Swift
redshift 3.7580 GCN_circulars,Swift-BAT Det
T100 28.0 s
GBM_located False
mjd 56390.91085648148 GCN_circulars,Swift Det
IPN table
GRB_name GRB130408A
ra 134.4000°
decl -32.3667°
pos_error 5.00e-02°
redshift 3.7570
Swift table
GRB_name GRB130408A
t_trigger 21:51:38 UTC
ra 134.4054°
decl -32.3608°
pos_error 6.47e-05°
T90 28.0 s
fluence 2.30e-06 erg/cm²
redshift 3.7580
GCN 14361 table
GRB_name GRB130408A
GCN_number 14361
Detection_method Swift Det
t_trigger 21:51:38 UTC
ra 134.4010°
decl -32.3610°
Circular_text TITLE: GCN CIRCULAR NUMBER: 14361 SUBJECT: GRB 130408A: Swift detection of a burst DATE: 13/04/08 22:11:30 GMT FROM: David Palmer at LANL A. Y. Lien (NASA/GSFC/ORAU), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), D. Malesani (DARK/NBI), V. Mangano (INAF-IASFPA), C. Pagani (U Leicester), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Swift Team: At 21:51:38 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130408A (trigger=553132). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 134.401, -32.361 which is RA(J2000) = 08h 57m 36s Dec(J2000) = -32d 21' 37" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 12 sec. The peak count rate was ~3914 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 21:54:08.6 UT, 149.9 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 134.40809, -32.36136 which is equivalent to: RA(J2000) = 08h 57m 37.94s Dec(J2000) = -32d 21' 40.9" with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 21 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. 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 1.98 x 10^21 cm^-2 (Kalberla et al. 2005). UVOT data analysis is not available at this time. Burst Advocate for this burst is A. Y. Lien (yarleen AT gmail.com). 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.)
GCN 14362 table
GRB_name GRB130408A
GCN_number 14362
Detection_method Optical
ra 134.4054°
decl -32.3608°
Circular_text TITLE: GCN CIRCULAR NUMBER: 14362 SUBJECT: GRB 130408A: Liverpool Telescope Optical candidate detection DATE: 13/04/08 22:57:31 GMT FROM: Andrea Melandri at INAF-OAB A. Melandri (INAF-OAB), J. Japelj (U. Ljubljana), F.J. Virgili(LJMU), C.G. Mundell (LJMU) report: The 2-m Liverpool Telescope robotically followed up GRB130408A (Swift trigger 553132, Lien et al., GCN 14361) 19.42 min after the GRB trigger time observing with SLOAN-gri filters. The automatic LT-TRAP procedure detected an uncatalogued fading source candidate at: RA=08:57:37.30 Dec=-32:21:38.90 (J2000) with magnitude R~16.5 mag (vs USNOB1) ~20 min after the burst trigger. The object is clearly fading in all filters and we suggest this is the optical afterglow of GRB130408A. Observations and analysis are ongoing.
GCN 14363 table
GRB_name GRB130408A
GCN_number 14363
Detection_method Swift-UVOT Det
ra 134.4054°
decl -32.3608°
Circular_text TITLE: GCN CIRCULAR NUMBER: 14363 SUBJECT: GRB 130408A: Swift/UVOT Detection of the Optical Afterglow DATE: 13/04/09 00:21:52 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and A. Y. Lien (NASA/GSFC/ORAU) report on behalf of the UVOT team: UVOT took a finding chart exposure of 150 seconds with the White filter starting 155 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 08:57:37.30 = 134.40540 DEC(J2000) = -32:21:38.9 = -32.36081 with a 90%-confidence error radius of about 0.5 arc sec. This position is 8.4 arc sec. from the center of the XRT error circle. The estimated magnitude is 16.82 with a 1-sigma error of about 0.04. No correction has been made for the expected extinction corresponding to E(B-V) of 0.26.
GCN 14364 table
GRB_name GRB130408A
GCN_number 14364
Detection_method GROND
Circular_text TITLE: GCN CIRCULAR NUMBER: 14364 SUBJECT: GRB 130408A: GROND detection of the afterglow DATE: 13/04/09 00:38:53 GMT FROM: Alexander Kann at TLS Tautenburg V. Sudilovsky (MPE Garching), A. Nicuesa Guelbenzu (TLS Tautenburg) and J.Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 130408A (Swift trigger 553132; Lien et al., GCN 14361) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla Observatory (Chile). Observations started at 23:22 UT on April 8th, 1.5 hrs after the GRB trigger. They were performed at an average seeing of 1.0 and at an average airmass of 1.0. Based integrations of 260s in the optical and 240s in the NIR taken at a mid-time of UT 23:34, we detect the variable source reported by Melandri et al. (GCN 14362) and Siegel & Lien (GCN 14363), with preliminary magnitudes (all AB): g' = 21.0 +- 0.1, r' = 19.7 +- 0.1, i' = 19.1 +- 0.1, z' = 18.8 +- 0.1, J = 18.0 +- 0.1, H = 17.8 +- 0.1, and K > 17.0. The large r-g color implies a redshift of z>3. Observations are ongoing. Given magnitudes are calibrated against GROND zeropoints in g'r'i'z' and 2MASS field stars in JHK. They are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.26 mag in the direction of the burst (Schlegel et al. 1998).
GCN 14365 table
GRB_name GRB130408A
GCN_number 14365
Detection_method Swift-BAT Det
redshift 3.7580
Circular_text TITLE: GCN CIRCULAR NUMBER: 14365 SUBJECT: GRB 130408A - VLT/X-shooter redshift determination DATE: 13/04/09 01:47:22 GMT FROM: Jens Hjorth at U.Copenhagen J. Hjorth (DARK), A. Melandri (INAF-OAB), D. Malesani (DARK), T. Kruehler (DARK), and D. Xu (DARK) report on behalf of a larger collaboration: We observed the afterglow of GRB 130408A (Lien et al. GCN 14361; Melandri et al. GCN 14362; Siegel et al. GCN 14363) with the X-shooter spectrograph on the ESO VLT, beginning approximately 1 h 55 min after the BAT trigger. We detect damped Ly-alpha absorption, Ly-alpha forest, the Lyman break, and numerous metal lines consistent with a redshift of 3.758. We thank Maria Teresa Ruiz, Avril Day-Jones, Cedric Ledoux, Leo Rivas, Alex Correa, and Lorenzo Monaco for conducting the observations.
GCN 14366 table
GRB_name GRB130408A
GCN_number 14366
Detection_method Swift-BAT Det
redshift 3.7570
Circular_text TITLE: GCN CIRCULAR NUMBER: 14366 SUBJECT: GRB 130408A - Gemini-S/GMOS redshift determination DATE: 13/04/09 01:47:25 GMT FROM: Nial Tanvir at U.Leicester N. R. Tanvir (U. Leicester), A. Cucchiara (UCSC/UCO Lick Observatory) and S. B. Cenko (UC Berkeley) report on behalf of a larger collaboration: We observed the afterglow of GRB 130408A (Lien et al. GCN 14361, Melandri et al. GCN 14362, Siegel et al. GCN 14363) with the GMOS-S spectrograph on Gemini-S, beginning approximately 1 hr 56 mins after the BAT trigger. The integration was 4x600s and the wavelength covered approximately 3950-6700A. We detect numerous lines, including Lyman alpha, beta, gamma, SII1250, SII1253, CII/CII*1260, SiII*1264, OI1302, SiII/OI*1304, SiII*1309, CII/CII* 1334/1335, SiIV1394/1402 at a common redshift of z=3.757. We thank D. Krogsrud for performing the observation.
GCN 14367 table
GRB_name GRB130408A
GCN_number 14367
Detection_method Swift-XRT Det
ra 134.4054°
decl -32.3609°
Circular_text TITLE: GCN CIRCULAR NUMBER: 14367 SUBJECT: GRB 130408A: Enhanced Swift-XRT position DATE: 13/04/09 07:40:32 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 573 s of XRT Photon Counting mode data and 3 UVOT images for GRB 130408A, 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 = 134.40543, -32.36089 which is equivalent to: RA (J2000): 08h 57m 37.30s Dec (J2000): -32d 21' 39.2" with an uncertainty of 1.7 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.
GCN 14368 table
GRB_name GRB130408A
GCN_number 14368
Detection_method Konus-Wind Det
t_trigger 21:51:41.184 UTC
redshift 3.7580
Circular_text TITLE: GCN CIRCULAR NUMBER: 14368 SUBJECT: Konus-Wind observation of GRB 130408A DATE: 13/04/09 09:49:43 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 130408A (Swift/BAT trigger=553132: Lien et al., GCN 14361) triggered Konus-Wind at T0=78701.184s UT (21:51:41.194) The light curve shows a bright pulse from ~T0-0.5 to ~T0+5 s followed by a much weaker emission pulse peaked around ~T0+12; a total duration of the burst is ~15 s. The emission is seen up to several MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB130408_T78701/ As observed by Konus-Wind, the burst had a fluence of (1.2 0.2)x10-5 erg/cm2, and a 64-ms peak flux, measured from T0+3.328s, of (5.2 0.5)x10-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum (measured from T0 to T0+16.640 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.4 0.2, the high energy photon index beta = -2.3 0.2, the peak energy Ep = 211 29 keV, chi2 = 99.4/97 dof. The spectrum at the maximum count rate (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.70 0.15, the high energy photon index beta = -2.3 0.3, the peak energy Ep = 272 40 keV, chi2 = 87.7/99 dof. Assuming redshift z=3.758 (Hjorth et al., GCN 14365; Tanvir et al., GCN 14366), and a standard cosmology (H_0=70 km/s/Mpc, Omega_M=0.3, Omega_\Lambda=0.7), we estimate the following cosmological rest-frame parameters of the prompt gamma-ray emission: - the isotropic equivalent energy release E_iso = (3.3 0.6)x10^53 erg; - the peak luminosity L_iso = (5.5 0.5)x10^53 erg/s; - the peak energy of the time-integrated spectrum Ep_rest = 1.00 0.14 MeV. All the quoted results are preliminary.
GCN 14369 table
GRB_name GRB130408A
GCN_number 14369
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14369 SUBJECT: GRB 130408A: Swift-XRT refined Analysis DATE: 13/04/09 10:11:03 GMT FROM: Phil Evans at U of Leicester V. D'Elia (ASDC), A. Maselli (INAF-IASFPA), V. Mangano (INAF-IASFPA), J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), B.P. Gompertz (U. Leicester) and A.Y. Lien report on behalf of the Swift-XRT team: We have analysed 6.2 ks of XRT data for GRB 130408A (Lien et al. GCN Circ. 14361), from 134 s to 28.6 ks after the BAT trigger. The data comprise 28 s in Windowed Timing (WT) mode (the first 9 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 Beardmore et al. (GCN. Circ 14367). The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=0.39 (+0.06, -0.07). At T+3999 s the decay steepens to an alpha of 8.0 (+0.0, -3.0) before breaking again at T+4518 s to a final decay with index alpha=0.97 (+0.14, -0.15). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.00 (+0.08, -0.07). The best-fitting absorption column is consistent with the Galactic value of 2.0 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (5.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Galactic foreground: 2.0 x 10^21 cm^-2 Intrinsic column: 0 (+4.9, -0) x 10^21 cm^-2 at z=3.758 Photon index: 2.00 (+0.08, -0.07) If the light curve continues to decay with a power-law decay index of 0.97, the count rate at T+24 hours will be 0.020 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.8 x 10^-13 (1.1 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00553132. This circular is an official product of the Swift-XRT team.
GCN 14370 table
GRB_name GRB130408A
GCN_number 14370
Detection_method Swift-UVOT Other
ra 134.4054°
decl -32.3608°
Circular_text TITLE: GCN CIRCULAR NUMBER: 14370 SUBJECT: GRB130408A: Swift/UVOT followup observations DATE: 13/04/09 11:07:36 GMT FROM: Alice Breeveld at MSSL-UCL A. Breeveld (MSSL/UCL) and A. Y. Lien (NASA/GSFC/ORAU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130408A 134 s after the BAT trigger (Lien et al., GCN Circ. 14361). A bright but rapidly fading source is detected in the initial exposures (Siegel and Lien, GCN Circ. 14363) with a position consistent with detections by Melandri et al., (GCN Circ., 14362), Sudilovsky et al., (GCN Circ., 14364) and Beardmore et al., (GCN Circ. 14367). The preliminary UVOT position is: RA(J2000) = 08:57:37.30 = 134.40540 DEC(J2000) = -32:21:38.9 = -32.36081 with a 90%-confidence error radius of about 0.5 arc sec. Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early and summed exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 156 305 147.4 16.80 0.05 white 3708 3900 189.2 20.29 0.22 white 6083 10367 924.3 21.99 0.35 v 134 145 10.1 15.75 0.15 v 4201 4400 196.7 19.61 0.35 b 3503 6078 393.2 >20.84 u 313 5872 236.2 >20.55 uvw1 4611 4752 139.0 >19.82 uvm2 4405 4605 196.6 >19.75 uvw2 3996 21851 1748.0 >21.56 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.258 in the direction of the burst (Schlegel et al. 1998).
GCN 14372 table
GRB_name GRB130408A
GCN_number 14372
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14372 SUBJECT: GRB 130408A: Zadko observatory - Gingin optical observations DATE: 13/04/09 19:16:12 GMT FROM: Husne Dereli at ARTEMIS/OCA H. Dereli (UNS-CNRS-OCA), A. Klotz (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. Coward (UWA), B. Gendre (IRAP-CNRS-OMP), M. Boer, K. Siellez, O. Bardho (UNS-CNRS-OCA), A. Williams (PO-UWA), R. Martin (PO-UWA) We imaged the field of GRB 130408A detected by SWIFT (trigger 553132) with the Zadko robotic telescope (D=100cm) located at the observatory - Gingin, Australia. The observations started 13.99h after the GRB trigger. The elevation of the field increased from 87.5 degrees above horizon and weather conditions were good. The co addition of the six images filtered C, g, r gives one image with an equivalent exposure time of 540s. We did not detected the afteglow mentioned in Melandri et al. (GCNC 14362): t0+13.99h to t0+14.56h : Rlim = 20.5 The limiting magnitude of the zadko image is R~20.5. Magnitudes were estimated with the nearby NOMAD1 stars and are not corrected for galactic dust extinction. [GNC OPS NOTE(17apr13): Per athor's request, the GRB name was changed from "1130408A" to "130408A".]
GCN 14373 table
GRB_name GRB130408A
GCN_number 14373
Detection_method Swift-BAT Det
ra 134.3980°
decl -32.3630°
Circular_text TITLE: GCN CIRCULAR NUMBER: 14373 SUBJECT: GRB 130408A, Swift-BAT refined analysis DATE: 13/04/09 23:45:37 GMT FROM: Craig Markwardt at NASA/GSFC W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+960 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130408A (trigger #553132) (Lien, et al., GCN Circ. 14361). The BAT ground-calculated position is RA, Dec = 134.398, -32.363 deg which is RA(J2000) = 08h 57m 35.5s Dec(J2000) = -32d 21' 45.9" with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 6%. T90 (15-350 keV) is 28 +- 13 sec (estimated error including systematics). The mask weighted light curve has a main FRED-like component with a rise time of about 2 sec and decline of 5 sec, peaking at time T+1 sec, followed by a smaller peak at T+12 sec. There is possible low-level emission out to about T+33 sec. The time-averaged spectrum from T-0.1 to T+33.5 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.28 +- 0.26. The fluence in the 15-150 keV band is 2.3 +- 0.4 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+1.12 sec in the 15-150 keV band is 4.9 +- 1.0 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/553132/BA/
GCN 14374 table
GRB_name GRB130408A
GCN_number 14374
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14374 SUBJECT: GRB 130408A: SMARTS optical/IR afterglow observations DATE: 13/04/12 20:46:37 GMT FROM: Bethany Cobb at GWU B. E. Cobb (GWU), reports: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 130408A (GCN 14361, Lien et al.) over several epochs (with mid-exposure times of 2013-04-09 00:30 UT, 02:15 UT, 03:41 UT and 2013-04-11 02:24 UT). For each epoch, several dithered images were obtained with total summed exposure times of 15 min in V and I and 12 min in J and K. For the final epoch, total exposure times were 36 min in I and 30 min in J. The fading afterglow of GRB 130408A (e.g. GCN 14362, Melandri et al.; GCN 14363, Siegel et al.; GCN 14364, Sudilovsky et al.) was detected with the following magnitudes (or 3-sigma limits): mid-exposure time (hours) I mag J mag K mag 2.64611 18.8 +/- 0.1 17.8 +/- 0.1 > 16.1 4.38444 19.6 +/- 0.1 18.6 +/- 0.2 16.8 +/- 0.2 5.82472 20.0 +/- 0.1 18.6 +/- 0.2 > 17.2 52.53694 > 21.5 > 19.6 ... (Optical photometry is calibrated against USNO-B1.0 stars and IR photometry is calibrated against 2MASS stars in the field.) Between about 2.6 hrs and 5.8 hrs post-burst, the GRB afterglow fades with a decay rate of approximately alpha = 1.4 (where afterglow flux is proportional to t^-alpha).
GCN 14375 table
GRB_name GRB130408A
GCN_number 14375
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14375 SUBJECT: GRB 130408a: Skynet Optical Observations DATE: 13/04/15 12:41:15 GMT FROM: Aaron LaCluyze at U.North Carolina A. Trotter, N. Frank, A. LaCluyze, D. Reichart, J. Haislip, K. Ivarsen, J. Moore, H. T. Cromartie, R. Egger, A. Foster, M. Nysewander, A. Oza, E. Speckhard, and J. A. Crain report: Skynet began observing the field of GRB130408A (Swift trigger 553132, GCN 14361) in BVRI beginning ~93 minutes after the burst using four of the PROMPT telescopes located at CTIO in Chile. A fading source is detected at the enhanced position reported by the Swift-XRT team (GCN 14367.) A preliminary light curve of the first two night's data from PROMPT can be found at: http://skynet.unc.edu/grb/grb130408a.png
GCN 14376 table
GRB_name GRB130408A
GCN_number 14376
Detection_method Suzaku WAM Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 14376 SUBJECT: GRB 130408A: Suzaku WAM observation of the prompt emission DATE: 13/04/15 20:47:15 GMT FROM: Masanori Ohno at Hiroshima U K. Takaki, M. Ohno, T. Kawano, R. Nakamura, S. Furui, Y. Fukazawa (Hiroshima U.), M. Tashiro, Y. Terada, T. Yasuda, Y. Ishida, H. Ueno, S. Sugimoto(Saitama U.), K. Yamaoka (Nagoya U.), M. Yamauchi, M. Akiyama, N. Ohmori (Univ. of Miyazaki), S. Sugita (Ehime U.), Y. E. Nakagawa, M. Kokubun, T. Takahashi (ISAS/JAXA), W. Iwakiri(RIKEN), Y. Hanabata (ICRR), Y. Urata (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo) on behalf of the Suzaku WAM team, report: The long GRB 130408A (Lien et al., GCN14361) triggered by the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 21:51:38 UT (=T0). The observed light curve shows a single peak starting at T0-2s, ending at T0+5s with a duration (T90) of about 7 seconds. The fluence in 100 - 1000 keV was 7.18(+0.06/-0.15) x 10^-6 erg/cm^2. The 1-s peak flux measured from T0s was 5.42(+1.37/-2.27) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-2s to T0+5s is well fitted by a single power-law with a photon index of 2.32 (+0.41/-0.34) (chi2/d.o.f = 12.19/13). All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included. The light curves for this burst will be available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html