Gamma-ray Burst 120913A

(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 20:18:47 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     533568,   Seg_Num: 0
  GRB_RA:          146.437d {+09h 45m 45s} (J2000),
                   146.619d {+09h 46m 29s} (current),
                   145.717d {+09h 42m 52s} (1950)
  GRB_DEC:         +26.977d {+26d 58' 36"} (J2000),
                   +26.918d {+26d 55' 04"} (current),
                   +27.208d {+27d 12' 28"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       4428 [cnts]    Image_Peak=185 [image_cnts]
  TRIGGER_DUR:     1.024 [sec] 
  TRIGGER_INDEX:   146     E_range: 25-100 keV
  BKG_INTEN:       28726 [cnts]
  BKG_TIME:        73086.35 SOD {20:18:06.35} UT
  BKG_DUR:         8 [sec]
  GRB_DATE:        16183 TJD;   257 DOY;   12/09/13
  GRB_TIME:        73101.90 SOD {20:18:21.90} UT
  GRB_PHI:         -91.67 [deg]
  GRB_THETA:        20.58 [deg]
  SOLN_STATUS:     0x20000003
  RATE_SIGNIF:     11.61 [sigma]
  IMAGE_SIGNIF:    7.27 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +0  +2  -3 -105  +0 -82  +0 
  SUN_POSTN:       172.13d {+11h 28m 31s}   +3.40d {+03d 23' 50"}
  SUN_DIST:         33.89 [deg]   Sun_angle= 1.7 [hr] (West of Sun)
  MOON_POSTN:      143.14d {+09h 32m 34s}   +9.30d {+09d 17' 49"}
  MOON_DIST:        17.92 [deg]
  MOON_ILLUM:      6 [%]
  GAL_COORDS:      202.09, 48.90 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      139.58, 12.72 [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 = 221.38,-2.63 [deg].  
  COMMENTS:           
  COMMENTS:        NOTE: This BAT event is temporally(1.0<100sec) coincident with the FERMI_GBM event (trignum=369260305).  
  

• red DSS finding chart ps-file
  
  
• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Thu 13 Sep 12 20:18:52 UT
  NOTICE_TYPE:     Fermi-GBM Flight Position
  RECORD_NUM:      44
  TRIGGER_NUM:     369260305
  GRB_RA:          139.850d {+09h 19m 24s} (J2000),
                   140.030d {+09h 20m 07s} (current),
                   139.140d {+09h 16m 34s} (1950)
  GRB_DEC:         +20.967d {+20d 58' 00"} (J2000),
                   +20.913d {+20d 54' 45"} (current),
                   +21.178d {+21d 10' 42"} (1950)
  GRB_ERROR:       33.58 [deg radius, statistical plus systematic]
  GRB_INTEN:       82 [cnts/sec]
  DATA_SIGNIF:     4.70 [sigma]
  INTEG_TIME:      2.048 [sec]
  GRB_DATE:        16183 TJD;   257 DOY;   12/09/13
  GRB_TIME:        73102.89 SOD {20:18:22.89} UT
  GRB_PHI:          35.00 [deg]
  GRB_THETA:        90.00 [deg]
  DATA_TIME_SCALE: 2.0480 [sec]
  HARD_RATIO:      0.61
  LOC_ALGORITHM:   3 (version number of)
  MOST_LIKELY:      95%  GRB
  2nd_MOST_LIKELY:   3%  Generic Transient
  DETECTORS:       0,0,1, 0,0,1, 0,0,0, 0,0,0, 0,0,
  SUN_POSTN:       172.13d {+11h 28m 31s}   +3.40d {+03d 23' 50"}
  SUN_DIST:         35.80 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
  MOON_POSTN:      143.14d {+09h 32m 34s}   +9.30d {+09d 17' 48"}
  MOON_DIST:        12.00 [deg]
  MOON_ILLUM:      6 [%]
  GAL_COORDS:      208.16, 41.54 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      135.77,  5.09 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
  COMMENTS:        This trigger occurred at longitude,latitude = 208.92,-21.03 [deg].  
  COMMENTS:           
  COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=533568).  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Thu 13 Sep 12 20:19:01 UT
  NOTICE_TYPE:     Fermi-GBM Ground Position
  RECORD_NUM:      56
  TRIGGER_NUM:     369260305
  GRB_RA:          141.950d {+09h 27m 48s} (J2000),
                   142.129d {+09h 28m 31s} (current),
                   141.244d {+09h 24m 59s} (1950)
  GRB_DEC:         +20.640d {+20d 38' 24"} (J2000),
                   +20.584d {+20d 35' 03"} (current),
                   +20.858d {+20d 51' 29"} (1950)
  GRB_ERROR:       12.19 [deg radius, statistical only]
  DATA_SIGNIF:     6.20 [sigma]
  DATA_INTERVAL:   4.096 [sec]
  GRB_DATE:        16183 TJD;   257 DOY;   12/09/13
  GRB_TIME:        73102.89 SOD {20:18:22.89} UT
  GRB_PHI:          33.00 [deg]
  GRB_THETA:        90.00 [deg]
  E_RANGE:         44.032 - 279.965 [keV]
  LOC_ALGORITHM:   4143 (Gnd S/W Version number)
  SUN_POSTN:       172.13d {+11h 28m 31s}   +3.40d {+03d 23' 49"}
  SUN_DIST:         33.89 [deg]   Sun_angle= 2.0 [hr] (West of Sun)
  MOON_POSTN:      143.14d {+09h 32m 35s}   +9.30d {+09d 17' 47"}
  MOON_DIST:        11.33 [deg]
  MOON_ILLUM:      6 [%]
  GAL_COORDS:      209.41, 43.31 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      137.75,  5.39 [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(1.0<100sec) coincident with the SWIFT_BAT event (trignum=533568).  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Thu 13 Sep 12 20:22:35 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     533568,   Seg_Num: 0
  GRB_RA:          146.437d {+09h 45m 45s} (J2000),
                   146.619d {+09h 46m 29s} (current),
                   145.717d {+09h 42m 52s} (1950)
  GRB_DEC:         +26.977d {+26d 58' 36"} (J2000),
                   +26.918d {+26d 55' 04"} (current),
                   +27.208d {+27d 12' 28"} (1950)
  GRB_DATE:        16183 TJD;   257 DOY;   12/09/13
  GRB_TIME:        73101.90 SOD {20:18:21.90} UT
  TRIGGER_INDEX:   146
  GRB_PHI:         -91.67 [deg]
  GRB_THETA:        20.58 [deg]
  DELTA_TIME:      45.00 [sec]
  TRIGGER_DUR:     1.024 [sec] 
  SOLN_STATUS:     0x3
  RATE_SIGNIF:     11.61 [sigma]
  IMAGE_SIGNIF:    7.27 [sigma]
  LC_URL:          sw00533568000msb.lc
  SUN_POSTN:       172.13d {+11h 28m 31s}   +3.40d {+03d 23' 46"}
  SUN_DIST:         33.89 [deg]   Sun_angle= 1.7 [hr] (West of Sun)
  MOON_POSTN:      143.18d {+09h 32m 42s}   +9.29d {+09d 17' 07"}
  MOON_DIST:        17.93 [deg]
  MOON_ILLUM:      6 [%]
  GAL_COORDS:      202.09, 48.90 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      139.58, 12.72 [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 = 221.38,-2.63 [deg].  
  

  
• GCN Circular #13762
  E. A. Helder (PSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), N. Gehrels (NASA/GSFC), C. Gronwall (PSU), D. Grupe (PSU), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), C. B. Markwardt (NASA/GSFC), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and B.-B. Zhang (PSU) report on behalf of the Swift Team:
  At 20:18:21 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120913A (trigger=533568). Swift did not slew because of the Sun observing constraint. The BAT on-board calculated location is RA, Dec 146.437, +26.977 which is

     RA(J2000)  =  09h 45m 45s
     Dec(J2000) = +26d 58' 36"
  

  with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows several peaks with a total duration of at least 40 sec. (At T+30s, Swift executed a pre-planned slew that moved the GRB outside of the BAT FOV) The peak count rate was ~2600 counts/sec (15-350 keV), at ~23 sec after the trigger.
  Due to a Sun observing constraint, Swift cannot slew to the BAT position until 22:34 UT on 2012 September 27. 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 #13769
  W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), 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+962 sec from recent telemetry downlinks, we report further analysis of BAT GRB 120913A (trigger #533568) (Helder, et al., GCN Circ. 13762). The BAT ground-calculated position is RA, Dec = 146.400, 26.959 deg, which is

     RA(J2000)  =  09h 45m 36.1s 
     Dec(J2000) = +26d 57' 32.4" 
  

  with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 71%.
  The mask-weighted light curve shows three slightly overlapping FRED peaks starting at ~T-5 sec, peaking at ~T+1, ~T+23, & ~T+40 sec, and ending at ~T+42 sec. Due to a slew, the burst location left the BAT FoV at ~T+115 sec. T90 (15-350 keV) is 30.1 +- 4.8 sec (estimated error including systematics).
  The time-averaged spectrum from T-0.72 to T+39.80 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.18 +- 0.15. The fluence in the 15-150 keV band is 8.7 +- 0.8 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+22.45 sec in the 15-150 keV band is 2.3 +- 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/533568/BA/
• GCN Circular #13771
  V. Pelassa and V. Connaughton (UAH) report on behalf of the Fermi GBM Team:
  "At 20:18:22.89 UT on 13 spetember 2012, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 120913A (trigger369260305 / 120913846), which was also detected by the Swift/BAT (E.A. Helder et al. 2008, GCN 13762). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 97 degrees.
  The GBM light curve consists of 2 peaks at T0 and T0+20s with a duration (T90) of about 41s (50-300 keV).
  The event fluence (10-1000keV) from T0-3.584 s to T0+33.280 s is (1.8 +/- 0.3)E-06 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+21.568 s in the 10-1000 keV band is 3.8 +/- 0.2 ph/s/cm^2.
  The first peak is harder but fainter than the second peak, which is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.25 +/- 0.38 and the cutoff energy, parameterized as Epeak, is 26 +/- 4 keV (C-stat 372 for 366 d.o.f.).
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
• GCN Report 389.1
  GCN_Report 389.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_389_1.pdf by E.A. Helder at PSU titled: "Swift Observations of GRB 120913A"