Gamma-ray Burst 210708B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/SWIFT NOTICE                                                                 
  NOTICE_DATE:     Thu 08 Jul 21 13:35:00 UT                                                         
  NOTICE_TYPE:     Swift-BAT GRB Position                                                            
  TRIGGER_NUM:     1059494,   Seg_Num: 0                                                            
  GRB_RA:          142.579d {+09h 30m 19s} (J2000),                                                 
                   142.873d {+09h 31m 30s} (current),                                               
                   141.894d {+09h 27m 35s} (1950)                                                   
  GRB_DEC:         +14.471d {+14d 28' 16"} (J2000),                                                 
                   +14.376d {+14d 22' 33"} (current),                                               
                   +14.691d {+14d 41' 29"} (1950)                                                   
  GRB_ERROR:       3.00 [arcmin radius, statistical only]                                           
  GRB_INTEN:       0 [cnts]    Image_Peak=1813 [image_cnts]                                         
  TRIGGER_DUR:     64.000 [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:        19403 TJD;   189 DOY;   21/07/08                                                 
  GRB_TIME:        48204.66 SOD {13:23:24.66} UT                                                    
  GRB_PHI:         -72.95 [deg] 
  GRB_TIME:        48204.66 SOD {13:23:24.66} UT
  GRB_PHI:         -72.95 [deg]
  GRB_THETA:        19.85 [deg]
  SOLN_STATUS:     0x13
  RATE_SIGNIF:     0.00 [sigma]
  IMAGE_SIGNIF:    10.51 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +6  +1  +0 -100  +0 -83  +0 
  SUN_POSTN:       108.02d {+07h 12m 04s}  +22.40d {+22d 24' 10"}
  SUN_DIST:         33.95 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
  MOON_POSTN:       89.94d {+05h 59m 45s}  +25.08d {+25d 04' 47"}
  MOON_DIST:        50.65 [deg]
  MOON_ILLUM:      2 [%]
  GAL_COORDS:      217.52, 41.65 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      140.26, -0.27 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Coordinates.  
  COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger integration interval;  
  COMMENTS:        probably due to it occurring during a Malindi downlink session.  
  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 = 14.64,-17.83 [deg].  
  

• red DSS finding chart ps-file
  
  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Thu 08 Jul 21 13:35:25 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     1059494,   Seg_Num: 0
  GRB_RA:          142.579d {+09h 30m 19s} (J2000),
                   142.873d {+09h 31m 30s} (current),
                   141.894d {+09h 27m 35s} (1950)
  GRB_DEC:         +14.471d {+14d 28' 16"} (J2000),
                   +14.376d {+14d 22' 33"} (current),
                   +14.691d {+14d 41' 29"} (1950)
  GRB_DATE:        19403 TJD;   189 DOY;   21/07/08
  GRB_TIME:        48204.66 SOD {13:23:24.66} UT
  TRIGGER_INDEX:   20000
  GRB_PHI:         -72.95 [deg]
  GRB_THETA:        19.85 [deg]
  DELTA_TIME:      0.00 [sec]
  TRIGGER_DUR:     64.000 [sec] 
  SOLN_STATUS:     0x13
  RATE_SIGNIF:     0.00 [sigma]
  IMAGE_SIGNIF:    10.51 [sigma]
  LC_URL:          sw01059494000msb.lc
  SUN_POSTN:       108.02d {+07h 12m 04s}  +22.40d {+22d 24' 10"}
  SUN_DIST:         33.95 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
  MOON_POSTN:       89.94d {+05h 59m 46s}  +25.08d {+25d 04' 48"}
  MOON_DIST:        50.65 [deg]
  MOON_ILLUM:      2 [%]
  GAL_COORDS:      217.52, 41.65 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      140.26, -0.27 [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 = 14.64,-17.83 [deg].  
  

  
• GCN Circular #30417
  B. Sbarufatti (PSU), P. A. Evans (U Leicester), H. A. Krimm (NSF), K. L. Page (U Leicester), D. M. Palmer (LANL) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
  At 13:23:24 UT, the Swift Burst Alert Telescope (BAT) triggered and located possible GRB 210708B (trigger=1059494). The BAT on-board calculated location is RA, Dec 142.579, +14.471 which is

     RA(J2000) = 09h 30m 19s
     Dec(J2000) = +14d 28' 16"
  

  with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 100 sec. The peak count rate was ~1400 counts/sec (15-350 keV), at ~6 sec after the trigger.
  Due to a Sun observing constraint, Swift cannot slew to the BAT position until 05:03 UT on 2021 September 30. There will thus be no XRT or UVOT data for this trigger before this time.
  Due to a discrepancy between the on-board and ground analysis with the limited data available, we cannot definitively determine whether this is an astrophysical event. Further analysis will be done after the ground telemetry pass.
  Burst Advocate for this burst is B. Sbarufatti (bxs60 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/)
• GCN Circular #30426
  V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department),
  R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
  R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
  D. Buckley (South African Astronomical Observatory),
  O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API),
  A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
  V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University)
  MASTER-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) was pointed to the Swift GRB 210708B ( B. Sbarufatti et al., GCN 30417) errorbox 27094 sec after notice time and 27800 sec after trigger time at 2021-07-08 21:06:45 UT, with upper limit up to 16.5 mag. Observations started at twilight. The observations began at zenith distance = 79 deg. The sun altitude is -13.0 deg.
  MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB 210708B errorbox 34540 sec after notice time and 35247 sec after trigger time at 2021-07-08 23:10:51 UT, with upper limit up to 17.2 mag. The observations began at zenith distance = 77 deg. The sun altitude is -17.6 deg.
  The galactic latitude b = 42 deg., longitude l = 218 deg.
  Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1655856
  We obtain a following upper limits.

  Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
  _________|_____________________|_____|_______|______|________
  
     27891 |          MASTER-IAC |   C |   180 | 16.5 |        
     35337 |         MASTER-OAFA |   C |   180 | 17.2 |        
  

  Filter C is a clear (unfiltred) band.
  The observation and reduction will continue. The message may be cited.
• GCN Circular #30429
  M. Stamatikos (OSU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), B. Sbarufatti (PSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
  Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210708B (trigger #1059494) (Sbarufatti, et al., GCN Circ. 30417). The BAT ground-calculated position is RA, Dec = 142.594, 14.523 deg which is

     RA(J2000)  =  09h 30m 22.5s 
     Dec(J2000) = +14d 31' 22.6" 
  

  with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 74%.
  The mask-weighted light curve shows a broad peak with some sub-structure. Emission begins around T-100 sec, peaks near the trigger time and decays to background by T+200 sec. The burst position was not in the field of view of the BAT until about T-150 sec. T90 (15-350 keV) is 298.43 +- 47.32 sec (estimated error including systematics).
  The time-averaged spectrum from -99.8 to 263.7 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.62 +- 0.26. The fluence in the 15-150 keV band is 2.2 +- 0.4 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+2.84 sec in the 15-150 keV band is 0.0 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
  We note that in the original GCN circular, the event was described as a possible burst. Analysis of the full data set shows that the event is indeed a GRB.
  The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1059494/BA/