Gamma-ray Burst 170307A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Tue 07 Mar 17 20:25:48 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     741528,   Seg_Num: 0
  GRB_RA:           13.535d {+00h 54m 08s} (J2000),
                    13.759d {+00h 55m 02s} (current),
                    12.884d {+00h 51m 32s} (1950)
  GRB_DEC:          +9.537d {+09d 32' 11"} (J2000),
                    +9.629d {+09d 37' 46"} (current),
                    +9.265d {+09d 15' 56"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       0 [cnts]    Image_Peak=1699 [image_cnts]
  TRIGGER_DUR:     72.000 [sec] 
  TRIGGER_INDEX:   20000     E_range: 15-50 keV
  BKG_INTEN:       0 [cnts]
  BKG_TIME:        0.00 SOD {00:00:00.00} UT
  BKG_DUR:         0 [sec]
  GRB_DATE:        17819 TJD;    66 DOY;   17/03/07
  GRB_TIME:        73461.28 SOD {20:24:21.28} UT
  GRB_PHI:         -55.69 [deg]
  GRB_THETA:        33.26 [deg]
  SOLN_STATUS:     0x13
  RATE_SIGNIF:     0.00 [sigma]
  IMAGE_SIGNIF:    7.12 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +6  +1  -3 -100  +0 -87  +0 
  SUN_POSTN:       348.46d {+23h 13m 51s}   -4.95d {-04d 57' 15"}
  SUN_DIST:         29.12 [deg]   Sun_angle= -1.7 [hr] (East of Sun)
  MOON_POSTN:      109.31d {+07h 17m 14s}  +18.51d {+18d 30' 21"}
  MOON_DIST:        92.14 [deg]
  MOON_ILLUM:      76 [%]
  GAL_COORDS:      124.05,-53.33 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       16.15,  3.45 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Coordinates.  
  COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
  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 = 343.83,-9.62 [deg].  
  

• red DSS finding chart ps-file
  
  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Tue 07 Mar 17 20:28:30 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     741528,   Seg_Num: 0
  GRB_RA:           13.535d {+00h 54m 08s} (J2000),
                    13.759d {+00h 55m 02s} (current),
                    12.884d {+00h 51m 32s} (1950)
  GRB_DEC:          +9.537d {+09d 32' 11"} (J2000),
                    +9.629d {+09d 37' 46"} (current),
                    +9.265d {+09d 15' 56"} (1950)
  GRB_DATE:        17819 TJD;    66 DOY;   17/03/07
  GRB_TIME:        73461.28 SOD {20:24:21.28} UT
  TRIGGER_INDEX:   20000
  GRB_PHI:         -55.69 [deg]
  GRB_THETA:        33.26 [deg]
  DELTA_TIME:      0.00 [sec]
  TRIGGER_DUR:     72.000 [sec] 
  SOLN_STATUS:     0x13
  RATE_SIGNIF:     0.00 [sigma]
  IMAGE_SIGNIF:    7.12 [sigma]
  LC_URL:          sw00741528000msb.lc
  SUN_POSTN:       348.47d {+23h 13m 52s}   -4.95d {-04d 57' 12"}
  SUN_DIST:         29.12 [deg]   Sun_angle= -1.7 [hr] (East of Sun)
  MOON_POSTN:      109.34d {+07h 17m 20s}  +18.50d {+18d 30' 15"}
  MOON_DIST:        92.16 [deg]
  MOON_ILLUM:      76 [%]
  GAL_COORDS:      124.05,-53.33 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       16.15,  3.45 [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 an image 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 = 343.83,-9.62 [deg].  
  

  
• GCN Circular #20832
  A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), L. M. Z. Hagen (PSU), J. A. Kennea (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), J. L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU) and E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift Team:
  At 20:24:21 UT, the Swift Burst Alert Telescope (BAT) triggered and located the possible GRB 170307A (trigger=741528). Swift did not slew due to an observing constraint. The BAT on-board calculated location is RA, Dec 13.535, +9.537, which is

     RA(J2000)  =  00h 54m 08s
     Dec(J2000) = +09d 32' 11"
  

  with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows that Swift was emerging from the SAA at this time, giving a quickly-decreasing count rate that would swamp any variation expected from the source at the nominal intensity implied by the image strength.
  Due to a Sun observing constraint, Swift cannot slew to the BAT position until 00:33 UT on 2017 May 24. There will thus be no XRT or UVOT data for this trigger before this time.
  Because of high and variable background rates from the SAA, and in the absence of follow-up observations by the XRT, the immediately-available data does not determine whether this was a true astronomical event or an image fluctuation (with a nominal significance of 7.2 sigma). A determination of the nature of this source will require the full downlinked data set.
  Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT 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.)
• GCN Circular #20835
  C.M. Hui (NASA/MSFC) and O.J. Roberts (USRA/NASA) report on behalf of the Fermi GBM Team:
  At 20:25:17.49 UT on 07 March 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170307A (trigger 510611122 /170307851), which was also detected by Swift BAT (A. Y. Lien et al., GCN 20832). The GBM on-ground location is consistent with the Swift position.
  The angle from the Fermi LAT boresight at the GBM trigger time using the Swift-BAT location is 98 degrees.
  The GBM light curve consists of multiple peaks with a duration (T90) of about 57.9s (50-300 keV). The time-averaged spectrum from T0-27.6s to T0+28.7 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -1.18 +/- 0.26 and the cutoff energy, parameterized as Epeak, is 83.80 +/- 19.90 keV.
  The event fluence (10-1000 keV) in this time interval is (1.85 +/- 0.25)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+8.3 s in the 10-1000 keV band is 1.72 +/- 0.25 ph/s/cm^2.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog.
• GCN Circular #20838
  M. Stamatikos (OSU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
  Using the data set from T-12 to T+963 sec from the recent telemetry downlink, we determine that BAT trigger #741528 (Lien et al., GCN Circ. 20832) is indeed a GRB, which also detected by Fermi GBM (Hui et al., GCN Circ. 20835). We report further analysis of BAT GRB 170307A (trigger #741528). The BAT ground-calculated position is RA, Dec = 13.510, 9.538 deg which is

     RA(J2000)  =  00h 54m 02.5s
     Dec(J2000) = +09d 32' 17.9"
  

  with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 43%.
  The mask-weighted light curve shows a weak structure with several overlapping pulses that starts at ~T+55 s and ends at ~T+125 s. The burst emission might start before it came into the BAT FOV at ~T-12 s. T90 (15-350 keV) is 56.92 +- 27.40 sec (estimated error including systematics).
  The time-averaged spectrum from T+55.33 to T+124.69 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.88 +- 0.23. The fluence in the 15-150 keV band is 1.3 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+69.72 sec in the 15-150 keV band is 1.4 +- 0.3 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/741528/BA/
• GCN Circular #20880
  K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)
  We observed the GRB 170307A detected by Swift (Lien et al., GCN 20832, Stamatikos et al. GCN 20838) and Fermi (Hui et al. GCN 20835) with the AMI Large Array at 15 GHz on 2016 Mar 13.57 (UT). We place a 3sigma upper limit of 90 uJy on the radio afterglow.
  We thank the AMI staff for scheduling this observation. The AMI-GRB database is a log of all GRB follow up observations with the AMI, and is available at http://4pisky.org/ami-grb/.