Gamma-ray Burst 070731

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Tue 31 Jul 07 13:14:57 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     286574,   Seg_Num: 0
  GRB_RA:          328.570d {+21h 54m 17s} (J2000),
                   328.673d {+21h 54m 42s} (current),
                   327.888d {+21h 51m 33s} (1950)
  GRB_DEC:         -15.745d {-15d 44' 41"} (J2000),
                   -15.709d {-15d 42' 31"} (current),
                   -15.982d {-15d 58' 53"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       9380 [cnts]    Image_Peak=1883 [image_cnts]
  TRIGGER_DUR:     0.064 [sec] 
  TRIGGER_INDEX:   307     E_range: 50-350 keV
  BKG_INTEN:       254961 [cnts]
  BKG_TIME:        0.00 SOD {00:00:00.00} UT
  BKG_DUR:         0 [sec]
  GRB_DATE:        14312 TJD;   212 DOY;   07/07/31
  GRB_TIME:        34404.00 SOD {09:33:24.00} UT
  GRB_PHI:         143.96 [deg]
  GRB_THETA:        45.50 [deg]
  SOLN_STATUS:     0x3
  RATE_SIGNIF:     13.80 [sigma]
  IMAGE_SIGNIF:    16.00 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +2  +3  +3  +0  +0 +63  +1 
  SUN_POSTN:       130.38d {+08h 41m 32s}  +18.27d {+18d 16' 29"}
  SUN_DIST:        162.33 [deg]   Sun_angle= 10.8 [hr] (West of Sun)
  MOON_POSTN:      329.96d {+21h 59m 51s}  -13.30d {-13d 17' 58"}
  MOON_DIST:         2.71 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:       39.10,-47.47 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      325.31, -2.83 [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 = 0.00,0.00 [deg].
  COMMENTS:        This Notice was ground-reprocessed from flight-data.  
  COMMENTS:          
  COMMENTS:        This is a delayed distribution (manual generation).  
  COMMENTS:        This burst was missed at T_zero because of a TDRSS outage.  
  COMMENTS:        We have not seen a lightcurve yet, so little is known about this trigger.  
  COMMENTS:        It did not match anything in the catalog.  
  COMMENTS:        The TRIGGER_DUR, BKG, THETA, PHI, INTENS and SIGNIF fields are unknown.  
  

• red DSS finding chart ps-file
  
  
• GCN Circular #6691
  J. Tueller (GSFC), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), P. Romano (INAF/OAB), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), T. Ukwatta (GWU) (i.e. the Swift-BAT team):
  Using the data set from T-240 to T+302 sec from the recent telemetry downlink, we report analysis of BAT GRB 070731 (trigger #286574). The spacecraft did not slew to the location because of a Moon constraint. It will come out of Moon constraint 02 Aug 07 UT. The BAT ground-calculated position is RA, Dec = 328.581, -15.740 deg which is

     RA(J2000)  =  21h 54m 19.5s 
     Dec(J2000) = -15d 44' 23" 
  

  with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 49%.
  The mask-weighted lightcurve shows a single peak starting at ~T-0.5 sec, peaking at ~T+0.7, and ending at ~T+3 sec. There is no indication of any other emission prior and past the trigger. We note that there is a gap in the currently downloaded data set from T+120 to T+190 sec. T90 (15-350 keV) is 2.9 +- 0.2 sec (estimated error including systematics).
  The time-averaged spectrum from T-0.1 to T+3.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.65 +- 0.23. The fluence in the 15-150 keV band is 1.6 +- 0.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.14 sec in the 15-150 keV band is 1.2 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
  This burst occurred during a 42-min outage in the TDRSS service and so all the normal real-time messages were not sent to the ground.
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Wed 01 Aug 07 14:03:14 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     286574,   Seg_Num: 0
  GRB_RA:          328.570d {+21h 54m 17s} (J2000),
                   328.673d {+21h 54m 42s} (current),
                   327.888d {+21h 51m 33s} (1950)
  GRB_DEC:         -15.745d {-15d 44' 41"} (J2000),
                   -15.709d {-15d 42' 31"} (current),
                   -15.982d {-15d 58' 53"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       0 [cnts]    Image_Peak=133 [image_cnts]
  TRIGGER_DUR:     0.000 [sec] 
  TRIGGER_INDEX:   40     E_range: 15-25 keV
  BKG_INTEN:       0 [cnts]
  BKG_TIME:        0.00 SOD {00:00:00.00} UT
  BKG_DUR:         0 [sec]
  GRB_DATE:        14312 TJD;   212 DOY;   07/07/31
  GRB_TIME:        34404.00 SOD {09:33:24.00} UT
  GRB_PHI:           0.00 [deg]
  GRB_THETA:         0.00 [deg]
  SOLN_STATUS:     0x3
  RATE_SIGNIF:     0.00 [sigma]
  IMAGE_SIGNIF:    33522.00 [sigma]
  MERIT_PARAMS:     +0  +0  +0  +0  +0  +0  +0  +0  +0  +0 
  SUN_POSTN:       131.39d {+08h 45m 33s}  +18.02d {+18d 01' 02"}
  SUN_DIST:        163.31 [deg]   Sun_angle= 10.8 [hr] (West of Sun)
  MOON_POSTN:      343.17d {+22h 52m 41s}   -6.80d {-06d 48' 03"}
  MOON_DIST:        16.76 [deg]
  MOON_ILLUM:      92 [%]
  GAL_COORDS:       39.10,-47.47 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      325.31, -2.83 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Coordinates.  
  COMMENTS:           
  COMMENTS:        Since all the BAT_Pos_Ack & BAT_LC & BAT_ScaledMap messages were missing in the real-time TDRSS stream,  
  COMMENTS:        this Notice was reconstructed from the (delayed) Malindi-pass ground-generated BAT_Pos SERS message.  
  COMMENTS:        As such, many of the fields above are undefined -- they are not available in the limited SERS messages.  
  COMMENTS:        However, the GRB_RA/DEC, GRB_DATE/TIME, IMAGE_SIGNIF, and a few other fields are defined and valid.  
  COMMENTS:           
  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 = 0.00,0.00 [deg].
  COMMENTS:        This Notice was ground-reprocessed from flight-data.  
  COMMENTS:          
  COMMENTS:        This is a delayed distribution (manual generation).  
  COMMENTS:        This burst was missed at T_zero because of a TDRSS outage.  
  COMMENTS:        We have not seen a lightcurve yet, so little is known about this trigger.  
  COMMENTS:        It did not match anything in the catalog.  
  COMMENTS:        The TRIGGER_DUR, BKG, THETA, PHI, INTENS and SIGNIF fields are unknown.  
  

• GCN Report 79.1
  GCN_Report 79.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_79_1.pdf by A. Moretti at INAF-OAB titled: "Swift observations of GRB 070731"
• GCN Circular #6765
  F.E. Marshall (NASA/GSFC) and A. Moretti (INAF-OAB) report on behalf of the Swift team:
  The Swift/UVOT observed the field of GRB 070731 starting 144 ks after the BAT trigger (Tueller et al., GCN Circ. 6691), which occurred at 09:33:22 UT (Moretti et al., GCN Report 79.1). All of the UVOT exposures used the White (160-650 nm) filter, and the final exposure started 219 ks after the trigger. No XRT source was detected (Moretti et al., GCN Report 79.1) inside the BAT error circle, and we do not find any afterglow candidate inside the BAT error circle in the UVOT observations. The first long (1154 s) exposure that covered the entire BAT error circle started 155 ks after the BAT trigger. The 3-sigma upper limit for detecting a source is 20.9 mag. (uncorrected for the expected Galactic extinction corresponding to a reddening of E(B-V) = 0.04 mag in the direction of the burst (Schlegel et al. 1998)).