Gamma-ray Burst 120913B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  
  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Thu 13 Sep 12 23:56:15 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     533613,   Seg_Num: 0
  GRB_RA:          213.644d {+14h 14m 35s} (J2000),
                   213.817d {+14h 15m 16s} (current),
                   212.965d {+14h 11m 51s} (1950)
  GRB_DEC:         -14.535d {-14d 32' 04"} (J2000),
                   -14.594d {-14d 35' 36"} (current),
                   -14.302d {-14d 18' 06"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       5287 [cnts]    Image_Peak=197 [image_cnts]
  TRIGGER_DUR:     1.024 [sec] 
  TRIGGER_INDEX:   148     E_range: 25-100 keV
  BKG_INTEN:       34575 [cnts]
  BKG_TIME:        86142.35 SOD {23:55:42.35} UT
  BKG_DUR:         8 [sec]
  GRB_DATE:        16183 TJD;   257 DOY;   12/09/13
  GRB_TIME:        86158.09 SOD {23:55:58.09} UT
  GRB_PHI:         -60.03 [deg]
  GRB_THETA:        26.89 [deg]
  SOLN_STATUS:     0x20000003
  RATE_SIGNIF:     13.78 [sigma]
  IMAGE_SIGNIF:    7.76 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +0  +2  -2 -100  +0 -71  +0 
  SUN_POSTN:       172.26d {+11h 29m 03s}   +3.34d {+03d 20' 21"}
  SUN_DIST:         44.90 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
  MOON_POSTN:      145.08d {+09h 40m 19s}   +8.63d {+08d 37' 32"}
  MOON_DIST:        71.99 [deg]
  MOON_ILLUM:      6 [%]
  GAL_COORDS:      331.30, 43.71 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      216.30, -0.97 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Coordinates.  
  COMMENTS:        This is a rate trigger.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        This trigger occurred at longitude,latitude = 261.58,-20.04 [deg].  
  COMMENTS:           
  COMMENTS:        NOTE: This BAT event is temporally(0.0<100sec) coincident with the FERMI_GBM event (trignum=369273361).  
  

• red DSS finding chart ps-file
  
  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 14 Sep 12 00:00:23 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     533613,   Seg_Num: 0
  GRB_RA:          213.644d {+14h 14m 35s} (J2000),
                   213.817d {+14h 15m 16s} (current),
                   212.965d {+14h 11m 51s} (1950)
  GRB_DEC:         -14.535d {-14d 32' 04"} (J2000),
                   -14.594d {-14d 35' 36"} (current),
                   -14.302d {-14d 18' 06"} (1950)
  GRB_DATE:        16183 TJD;   257 DOY;   12/09/13
  GRB_TIME:        86158.09 SOD {23:55:58.09} UT
  TRIGGER_INDEX:   148
  GRB_PHI:         -60.03 [deg]
  GRB_THETA:        26.89 [deg]
  DELTA_TIME:      26.00 [sec]
  TRIGGER_DUR:     1.024 [sec] 
  SOLN_STATUS:     0x3
  RATE_SIGNIF:     13.78 [sigma]
  IMAGE_SIGNIF:    7.76 [sigma]
  LC_URL:          sw00533613000msb.lc
  SUN_POSTN:       172.27d {+11h 29m 04s}   +3.34d {+03d 20' 17"}
  SUN_DIST:         44.90 [deg]   Sun_angle= -2.8 [hr] (East of Sun)
  MOON_POSTN:      145.12d {+09h 40m 28s}   +8.61d {+08d 36' 46"}
  MOON_DIST:        71.95 [deg]
  MOON_ILLUM:      5 [%]
  GAL_COORDS:      331.30, 43.71 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      216.30, -0.97 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Lightcurve.  
  COMMENTS:           
  COMMENTS:        The next comments were copied from the BAT_POS Notice:  
  COMMENTS:        This is a rate trigger.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        This trigger occurred at longitude,latitude = 261.58,-20.04 [deg].  
  

  
• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Thu 13 Sep 12 23:56:37 UT
  NOTICE_TYPE:     Fermi-GBM Flight Position
  RECORD_NUM:      57
  TRIGGER_NUM:     369273361
  GRB_RA:          218.883d {+14h 35m 32s} (J2000),
                   219.066d {+14h 36m 16s} (current),
                   218.164d {+14h 32m 39s} (1950)
  GRB_DEC:         -24.567d {-24d 34' 00"} (J2000),
                   -24.622d {-24d 37' 17"} (current),
                   -24.349d {-24d 20' 55"} (1950)
  GRB_ERROR:       13.50 [deg radius, statistical plus systematic]
  GRB_INTEN:       152 [cnts/sec]
  DATA_SIGNIF:     13.00 [sigma]
  INTEG_TIME:      4.096 [sec]
  GRB_DATE:        16183 TJD;   257 DOY;   12/09/13
  GRB_TIME:        86158.77 SOD {23:55:58.77} UT
  GRB_PHI:         341.00 [deg]
  GRB_THETA:        55.00 [deg]
  DATA_TIME_SCALE: 4.0960 [sec]
  HARD_RATIO:      0.57
  LOC_ALGORITHM:   3 (version number of)
  MOST_LIKELY:      95%  GRB
  2nd_MOST_LIKELY:   4%  Generic Transient
  DETECTORS:       0,0,0, 1,1,0, 0,0,0, 0,0,0, 0,0,
  SUN_POSTN:       172.26d {+11h 29m 03s}   +3.34d {+03d 20' 21"}
  SUN_DIST:         53.35 [deg]   Sun_angle= -3.1 [hr] (East of Sun)
  MOON_POSTN:      145.08d {+09h 40m 20s}   +8.62d {+08d 37' 28"}
  MOON_DIST:        79.31 [deg]
  MOON_ILLUM:      6 [%]
  GAL_COORDS:      331.18, 32.53 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      224.23, -8.88 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
  COMMENTS:        This trigger occurred at longitude,latitude = 259.13,-9.45 [deg].  
  COMMENTS:           
  COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=533613).  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Thu 13 Sep 12 23:56:27 UT
  NOTICE_TYPE:     Fermi-GBM Flight Position
  RECORD_NUM:      48
  TRIGGER_NUM:     369273361
  GRB_RA:          234.667d {+15h 38m 40s} (J2000),
                   234.837d {+15h 39m 21s} (current),
                   233.999d {+15h 36m 00s} (1950)
  GRB_DEC:          -6.983d {-06d 58' 59"} (J2000),
                    -7.024d {-07d 01' 26"} (current),
                    -6.821d {-06d 49' 14"} (1950)
  GRB_ERROR:       19.83 [deg radius, statistical plus systematic]
  GRB_INTEN:       105 [cnts/sec]
  DATA_SIGNIF:     6.10 [sigma]
  INTEG_TIME:      2.048 [sec]
  GRB_DATE:        16183 TJD;   257 DOY;   12/09/13
  GRB_TIME:        86158.77 SOD {23:55:58.77} UT
  GRB_PHI:         314.00 [deg]
  GRB_THETA:        60.00 [deg]
  DATA_TIME_SCALE: 2.0480 [sec]
  HARD_RATIO:      0.50
  LOC_ALGORITHM:   3 (version number of)
  MOST_LIKELY:      94%  GRB
  2nd_MOST_LIKELY:   4%  Generic Transient
  DETECTORS:       0,0,0, 1,1,0, 0,0,0, 0,0,0, 0,0,
  SUN_POSTN:       172.26d {+11h 29m 03s}   +3.34d {+03d 20' 21"}
  SUN_DIST:         63.30 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
  MOON_POSTN:      145.08d {+09h 40m 19s}   +8.63d {+08d 37' 30"}
  MOON_DIST:        90.81 [deg]
  MOON_ILLUM:      6 [%]
  GAL_COORDS:      358.98, 37.09 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      234.04, 12.15 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
  COMMENTS:        This trigger occurred at longitude,latitude = 259.13,-9.45 [deg].  
  COMMENTS:           
  COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=533613).  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Thu 13 Sep 12 23:57:18 UT
  NOTICE_TYPE:     Fermi-GBM Ground Position
  RECORD_NUM:      56
  TRIGGER_NUM:     369273361
  GRB_RA:          216.740d {+14h 26m 58s} (J2000),
                   216.920d {+14h 27m 41s} (current),
                   216.032d {+14h 24m 08s} (1950)
  GRB_DEC:         -22.330d {-22d 19' 47"} (J2000),
                   -22.387d {-22d 23' 11"} (current),
                   -22.106d {-22d 06' 20"} (1950)
  GRB_ERROR:       4.33 [deg radius, statistical only]
  DATA_SIGNIF:     13.60 [sigma]
  DATA_INTERVAL:   4.096 [sec]
  GRB_DATE:        16183 TJD;   257 DOY;   12/09/13
  GRB_TIME:        86158.77 SOD {23:55:58.77} UT
  GRB_PHI:         341.00 [deg]
  GRB_THETA:        58.00 [deg]
  E_RANGE:         44.032 - 279.965 [keV]
  LOC_ALGORITHM:   4143 (Gnd S/W Version number)
  SUN_POSTN:       172.26d {+11h 29m 04s}   +3.34d {+03d 20' 20"}
  SUN_DIST:         50.62 [deg]   Sun_angle= -3.0 [hr] (East of Sun)
  MOON_POSTN:      145.09d {+09h 40m 21s}   +8.62d {+08d 37' 21"}
  MOON_DIST:        76.82 [deg]
  MOON_ILLUM:      6 [%]
  GAL_COORDS:      330.29, 35.42 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      221.63, -7.38 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
  COMMENTS:        In the LAT Field-of-view.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:           
  COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=533613).  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Thu 13 Sep 12 23:57:59 UT
  NOTICE_TYPE:     Fermi-GBM Ground Position
  RECORD_NUM:      84
  TRIGGER_NUM:     369273361
  GRB_RA:          215.320d {+14h 21m 17s} (J2000),
                   215.493d {+14h 21m 58s} (current),
                   214.639d {+14h 18m 33s} (1950)
  GRB_DEC:         -14.270d {-14d 16' 11"} (J2000),
                   -14.328d {-14d 19' 39"} (current),
                   -14.042d {-14d 02' 30"} (1950)
  GRB_ERROR:       4.30 [deg radius, statistical only]
  DATA_SIGNIF:     18.50 [sigma]
  DATA_INTERVAL:   4.096 [sec]
  GRB_DATE:        16183 TJD;   257 DOY;   12/09/13
  GRB_TIME:        86158.77 SOD {23:55:58.77} UT
  GRB_PHI:         337.00 [deg]
  GRB_THETA:        66.00 [deg]
  E_RANGE:         44.032 - 279.965 [keV]
  LOC_ALGORITHM:   4143 (Gnd S/W Version number)
  SUN_POSTN:       172.27d {+11h 29m 04s}   +3.34d {+03d 20' 19"}
  SUN_DIST:         46.34 [deg]   Sun_angle= -2.9 [hr] (East of Sun)
  MOON_POSTN:      145.09d {+09h 40m 23s}   +8.62d {+08d 37' 13"}
  MOON_DIST:        73.48 [deg]
  MOON_ILLUM:      6 [%]
  GAL_COORDS:      333.46, 43.21 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      217.74, -0.19 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:           
  COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=533613).  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Thu 13 Sep 12 23:58:45 UT
  NOTICE_TYPE:     Fermi-GBM Ground Position
  RECORD_NUM:      66
  TRIGGER_NUM:     369273361
  GRB_RA:          218.300d {+14h 33m 12s} (J2000),
                   218.478d {+14h 33m 55s} (current),
                   217.602d {+14h 30m 25s} (1950)
  GRB_DEC:         -18.620d {-18d 37' 11"} (J2000),
                   -18.675d {-18d 40' 31"} (current),
                   -18.400d {-18d 24' 01"} (1950)
  GRB_ERROR:       4.42 [deg radius, statistical only]
  DATA_SIGNIF:     17.00 [sigma]
  DATA_INTERVAL:   4.096 [sec]
  GRB_DATE:        16183 TJD;   257 DOY;   12/09/13
  GRB_TIME:        86158.77 SOD {23:55:58.77} UT
  GRB_PHI:         337.00 [deg]
  GRB_THETA:        60.00 [deg]
  E_RANGE:         44.032 - 279.965 [keV]
  LOC_ALGORITHM:   4143 (Gnd S/W Version number)
  SUN_POSTN:       172.27d {+11h 29m 04s}   +3.34d {+03d 20' 19"}
  SUN_DIST:         50.52 [deg]   Sun_angle= -3.1 [hr] (East of Sun)
  MOON_POSTN:      145.10d {+09h 40m 24s}   +8.62d {+08d 37' 04"}
  MOON_DIST:        77.29 [deg]
  MOON_ILLUM:      6 [%]
  GAL_COORDS:      334.05, 38.03 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      221.84, -3.40 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
  COMMENTS:        In the LAT Field-of-view.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:           
  COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=533613).  
  

• GCN Circular #13763
  E. A. Helder (PSU), S. D. Barthelmy (GSFC), N. Gehrels (NASA/GSFC), D. Grupe (PSU), S. T. Holland (STScI), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team:
  At 23:55:58 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120913B (trigger=533613). Swift did not slew because of the Sun observing constraint. The BAT on-board calculated location is RA, Dec 213.644, -14.535 which is

     RA(J2000)  =  14h 14m 35s
     Dec(J2000) = -14d 32' 04"
  

  with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows several peaks with a total duration of about 70 sec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~5 sec after the trigger.
  Due to a Sun observing constraint, Swift cannot slew to the BAT position until 20:57 UT on 2012 December 14. There will thus be no XRT or UVOT data for this trigger before this time.
  Burst Advocate for this burst is E. A. Helder (helder AT 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.)
• GCN Circular #13764
  A. LaCluyze, K. Ivarsen, J. Haislip, D. Reichart, J. Moore, H. T. Cromartie, R. Egger, A. Foster, N. Frank, M. Nysewander, A. Oza, E. Speckhard, A.Trotter, and J. A. Crain report:
  Skynet observed the field of GRB120913B (GCN 13763, Swift trigger #533613) with four of the PROMPT telescopes located at CTIO in Chile in BVRI beginning ~58 seconds after the burst. We detect a fading source at RA 14:14:38.46 DEC -14:30:57.2, within the BAT error circle.
  The object peaked at a magnitude of ~15.9 in R (calibrated to nearby SDSS catalog stars) at ~4.2 minutes after the burst before beginning to fade.
  Further observations are ongoing.
• GCN Circular #13765
  Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR), Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:
  We imaged the field of GRB 120913B detected by SWIFT (trigger 533613) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile.
  The observations started 30.6s after the GRB trigger (17.7s after the notice). The elevation of the field decreased from 26 degrees above horizon and weather conditions were good.
  We detect a new fading source in the error box given by SWIFT. We detected the candidate couterpart mentioned by LaCluyze et al. (GCNC 13764) at the following position (+/- 2 arcsec):

  RA(J2000.0) = 14h 14m 38.57s
  DEC(J2000.0) -14d 30' 55.8"
  

  OT raised until R=15.8 5 min after the GRB. Now the afterglow is fading.
  Magnitudes were estimated with the nearby NOMAD1 star 0754-0289300 (R.A.=213.6332611 Decl=-14.5238889 J2000) R=15.99. MAgnitutes are not corrected for galactic dust extinction.
  N.B. Galactic coordinates are lon=331.3041 lat=+43.7095 and the galactic extinction in R band is about 0.2 magnitude estimated from D. Schlegel et al. 1998ApJ...500..525S.
  This message may be cited.
• GCN Circular #13766
  Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR), Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:
  We continue to observe the afterglow of GRB 120913B (LaCluyze et al. GCNC 13764). A rapid photometric analysis gives the following magnitudes:

  t0+Mid(s)  Rmag
      159     16.5
      200     16.3
      281     15.8
      351     15.9
      451     16.2
      652     16.6
     1054     17.0
  

  We measure an optical decay alpha=-1 from observations after 300s, i.e. after the optical peak.
  Considering the optical decay, optical predicted magnitudes are:

  2012-09-14T00:56 UT R=18.4 (t0+1h)
  2012-09-14T01:56 UT R=19.1 (t0+2h)
  2012-09-14T02:56 UT R=19.6 (t0+3h)
  2012-09-14T03:56 UT R=20.0 (t0+4h)
  2012-09-15T00:56 UT R=21.0 (t0+1day)
  

  These predictions can help spectrometry observations.
• GCN Circular #13767
  A. LaCluyze, K. Ivarsen, J. Haislip, D. Reichart, J. Moore, H. T. Cromartie, R. Egger, A. Foster, N. Frank, M. Nysewander, A. Oza, E. Speckhard, A.Trotter, and J. A. Crain report:
  Skynet continued observing the field of GRB120913B (GCN 13763, Swift trigger #533613) in BVRI using four of the PROMPT telescopes located at CTIO in Chile until the object set.
  A preliminary light curve of the first night's data from PROMPT can be found at: http://skynet.unc.edu/grb/grb120913b.png
  
• GCN Circular #13768
  S. Covino, D. Fugazza, A. Melandri, on behalf of the REM team report:
  We imaged the field of GRB120913B (Helder et al., GCN 13763) with the NIR camera only with the H filter. The REM telescope is at present under substantial maintenance and the optical camera and some of the subsystems are still off-line.
  Observations started at UT 23:56:47, about 49 sec after the GRB, and frames were unfortunately not properly focussed. Yet the afterglow (LaClyyze et al., GCN 13764; Klotz et al., GCN 13765) is detectable and approximately 2 min after the GRB was at H = 13.72 +- 0.15, calibrated by means of isolated unsaturated 2MAS stars in the field.
• GCN Circular #13770
  Martin Jelinek (IAA Granada, Spain), Petr Kubanek, Martin Masek, Jakub Cerny, Jan Ebr and Michael Prouza (FZU Praha, Czech Rep.) on behalf of the FRAM team, coordinated by FZU Praha
  report:
  The 30cm FRAM telescope, located at Pierre Auger observatory in Malargue, Argentina, followed the GRB 120913B (Helder et al. GCNC13763, Swift trigger #533613). Observations started 24.4s after the GRB trigger.
  10s R-band (lambda_eff = 640nm) images with a limit of ~16.0 were obtained. We identify the optical transient reported by LaCluyze et al. (GCNC13764) and Klotz et al. (GCNC13765) with a magnitude R = 16.3 +/- 0.2 on a sum of 8x10s images obtained between 271 and 364s after the GRB.
  This message may be cited
• GCN Circular #13772
  S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), E. A. Helder (PSU), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):
  Using the data set from T-240 to T+882 sec from the recent telemetry downlink, we report further analysis of BAT GRB 120913B (trigger #533613) (Helder, et al., GCN Circ. 13763). The BAT ground-calculated position is RA, Dec = 213.660, -14.508 deg, which is

     RA(J2000)  =  14h 14m 38.3s 
     Dec(J2000) = -14d 30' 27.9" 
  

  with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 59%.
  The mask-weighted light curve shows two main pulses riding on top of a broad peak. The burst starts at ~T-50 sec, with peaks at ~T+5 and ~T+39 sec, and ending at ~T+140 sec. T90 (15-350 keV) is 126 +- 4 sec (estimated error including systematics).
  The time-averaged spectrum from T-51.70 to T+111.79 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.63 +- 0.04. The fluence in the 15-150 keV band is 1.11 +- 0.02 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+38.46 sec in the 15-150 keV band is 3.2 +- 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/533613/BA/
• GCN Circular #13773
  V. Pelassa (UAH) reports on behalf of the Fermi GBM Team:
  "At 23:55:58.77 UT on 13 september 2012, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 120913B (trigger 369273361 / 120913997), which was also detected by the Swift/BAT (E.A. Helder et al. 2008, GCN 13763) The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 66 degrees.
  The GBM light curve consists of 2 peaks at T0-10 and T0+30s on top of a longer plateau, with a duration (T90) of about 110 s (50-300 keV). The time-averaged spectrum from T0-40.961 s to T0+98.306 s is best fit by a Band function with Epeak = 163 +/- 23 keV, alpha = -1.19 +/- 0.06, and beta = -1.97 +/- 0.07 (Cstat 604 for 483 d.o.f.).
  The event fluence (10-1000 keV) in this time interval is (2.9 +/- 0.7)E-05 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+37.632 s in the 10-1000 keV band is 5.0 +/- 0.3 ph/s/cm^2.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
• GCN Report 394.1
  GCN_Report 394.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_394_1.pdf by E.A. Helder at PSU titled: "Swift Observations of GRB 120913B"