Gamma-ray Burst 180703B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Tue 03 Jul 18 22:47:16 UT
  NOTICE_TYPE:     Fermi-GBM Flight Position
  RECORD_NUM:      49
  TRIGGER_NUM:     552350816
  GRB_RA:           90.767d {+06h 03m 04s} (J2000),
                    90.929d {+06h 03m 43s} (current),
                    90.329d {+06h 01m 19s} (1950)
  GRB_DEC:         -36.117d {-36d 07' 00"} (J2000),
                   -36.118d {-36d 07' 05"} (current),
                   -36.114d {-36d 06' 50"} (1950)
  GRB_ERROR:       3.43 [deg radius, statistical plus systematic]
  GRB_INTEN:       5092 [cnts/sec]
  DATA_SIGNIF:     156.70 [sigma]
  INTEG_TIME:      0.512 [sec]
  GRB_DATE:        18302 TJD;   184 DOY;   18/07/03
  GRB_TIME:        82011.32 SOD {22:46:51.32} UT
  GRB_PHI:         300.00 [deg]
  GRB_THETA:        25.00 [deg]
  DATA_TIME_SCALE: 0.5120 [sec]
  HARD_RATIO:      0.73
  LOC_ALGORITHM:   3 (version number of)
  MOST_LIKELY:      97%  GRB
  2nd_MOST_LIKELY:   2%  Generic Transient
  DETECTORS:       1,0,0, 1,0,0, 0,0,0, 0,0,0, 0,0,
  SUN_POSTN:       102.99d {+06h 51m 58s}  +22.90d {+22d 53' 56"}
  SUN_DIST:         60.11 [deg]   Sun_angle= 0.8 [hr] (West of Sun)
  MOON_POSTN:      347.05d {+23h 08m 12s}   -9.18d {-09d 11' 05"}
  MOON_DIST:        95.58 [deg]
  MOON_ILLUM:      73 [%]
  GAL_COORDS:      242.46,-24.80 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       91.22,-59.55 [deg] ecliptic lon,lat of the burst (or transient)
  LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn180703949/quicklook/glg_lc_medres34_bn180703949.gif
  COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
  COMMENTS:        This trigger occurred at longitude,latitude = 177.58,10.90 [deg].  
  COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
  COMMENTS:           
  COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the CALET_GBM event (trignum=1214693124).  
  

• GCN NOTICE
  

  TITLE:          GCN/INTEGRAL NOTICE
  NOTICE_DATE:    Tue 03 Jul 18 22:47:39 UT 
  NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
  TRIGGER_NUM:    8092,   Sub_Num: 0
  GRB_INTEN:      10.85 [sigma]  
  GRB_TIME:       82011.09 SOD {22:46:51.09} UT 
  GRB_DATE:       18302 TJD;   184 DOY;   18/07/03
  COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.
  COMMENTS:       Time_Scale=2.0000 and Time_Error=1.0000.
  COMMENTS:
  COMMENTS:       NOTE: This SPIACS event is temporally(0.0<100sec) coincident with the FERMI_GBM event (trignum=552350816). 
  COMMENTS:
  COMMENTS:       The SPIACS lightcurve can be found at:
  COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2018-07/2018-07-03T22-46-50.9599-16784-111 52-0.lc 
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Wed 04 Jul 18 02:20:12 UT
  NOTICE_TYPE:     Fermi-LAT Offline Position
  TRIGGER_NUM:     552350816
  GRB_RA:           96.920d {+06h 27m 41s} (J2000),
                    97.098d {+06h 28m 24s} (current),
                    96.438d {+06h 25m 45s} (1950)
  GRB_DEC:         -29.880d {-29d 52' 47"} (J2000),
                   -29.892d {-29d 53' 32"} (current),
                   -29.848d {-29d 50' 50"} (1950)
  GRB_ERROR:       24.00 [arcmin radius, 90% containment, statistical only] 
  GRB_DATE:        18302 TJD;   184 DOY;   18/07/03
  GRB_TIME:        82011.31 SOD {22:46:51.31} UT 
  TRIGGER_ID:      0x20000000
  MISC:            0x40000000
  SUN_POSTN:       103.14d {+06h 52m 34s}  +22.89d {+22d 53' 11"}
  SUN_DIST:         53.10 [deg]   Sun_angle= 0.4 [hr] (West of Sun)
  MOON_POSTN:      348.76d {+23h 15m 03s}   -8.61d {-08d 36' 28"}
  MOON_DIST:       101.25 [deg]
  MOON_ILLUM:      72 [%]
  GAL_COORDS:      237.95,-17.88 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      100.01,-53.08 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        Fermi LAT Offline position.
  COMMENTS:        This Notice was ground-generated -- not flight-generated.
  COMMENTS:        It is the result of human-in-the-loop processing.
  COMMENTS:        This is a human generated position of a LAT ground detection GRB 180703B.
  COMMENTS:        This source corresponds to GBM trigger.
  

• GCN Circular #22884
  J. L. Racusin (NASA/GSFC), M. Crnogor=C4=8Devi=C4=87 (UMD), A. Barker (George Washington),=20 G. Vianello (Stanford), M. Axelsson (KTH and Stockholm University) report on behalf=20 of the Fermi-LAT team:
  At 22:46:51.32 UTC on July 03, 2018 Fermi-LAT detected high-energy emission from=20 GRB 180703B, which was also detected by Fermi-GBM (trigger 552350816 / 180703949). The best LAT on-ground location is found to be
  RA, Dec =3D 96.92, -29.88 (J2000)
  with an error radius of 0.4 deg (90% containment, statistical error only).
  This was 30 deg from the LAT boresight at the time of the trigger.
  The data from the Fermi-LAT show a significant increase in the event rate that is spatially=20 and temporally correlated with the trigger with high significance.=20
  The highest-energy photon is a ~1 GeV event which is observed 35 seconds after the GBM=20 trigger.
  A Swift ToO has been requested for this burst.=20
  The Fermi-LAT point of contact for this burst is Judith Racusin (judith.racusin@nasa.gov).
  The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20=20 MeV to greater than 300 GeV. It is the product of an international collaboration between=20 NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and=20 Sweden.
• GCN Circular #22888
  I. Takahashi (IPMU), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita, Y. Kawakubo, A. Tezuka, S. Matsukawa, H. Onozawa, T. Ito, H. Morita, Y. Sone (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena) and the CALET collaboration:
  The Fermi-LAT GRB 180703B (Racusin et al. GCN Circ. 22884) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 22:46:51.183 UTC on 3 July 2018. The burst signal was seen by all CGBM detectors.
  The burst light curve shows two short pulses which start at T+0.1 sec, peaks at T+1.4 sec and ends at T+2.1 sec. The T90 and the T50 durations measured by the SGM data are 1.4 +- 0.2 sec and 0.4 +- 0.1 sec (40-1000 keV), respectively.
  Despite its very high brightness the burst spectrum is soft with almost no emission seen in the CGBM data above ~500 keV. So, this is a very bright, short, and soft GRB. The follow-up observations of this interesting event is highly encouraged.
  The ground processed light curve is available at
  http://cgbm.calet.jp/cgbm_trigger/ground/1214693124/
  The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.
• GCN Circular #22897
  S.Poolakkil and C. Meegan (both UAH) report on behalf of the Fermi GBM Team:
  "At 22:46:51.32 UT on 03 July 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180703B (trigger 552350816/ 180703949), which was also detected by the Fermi LAT (Racusin et al. 2018, GCN 22884). The GBM on-ground location is consistent with the LAT position.
  The angle from the Fermi LAT boresight at the GBM trigger time is 31 degrees.
  The GBM light curve shows two peaks with a duration (T90) of about 1.6 s (50-300 keV). The time-averaged spectrum from T0-0.1 s to T0+2.4 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.79 +/- 0.03 and the cutoff energy, parameterized as Epeak, is 138 +/- 3 keV.
  The event fluence (10-1000 keV) in this time interval is (8.281 +/- 0.119)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+1.21 s in the 10-1000 keV band is 103.9 +/- 2.92 ph/s/cm^2.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
• GCN Circular #22908
  K. Hurley, on behalf of the IPN,
  I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
  A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, D. Svinkin, and T. Cline on behalf of the Konus-Wind team,
  A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi GBM team,
  A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
  S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team,
  and
  W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report:
  The short duration GRB 180703B (Fermi-LAT detection: Racusin et al., GCN Circ. 22884; CGBM detection: Takahasi et al., GCN Circ. 22888; Fermi-GBM detection: Poolakkil and Meegan, GCN Circ. 22897) was detected by Fermi (GBM trigger 552350816), Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), CALET (CGBM), and Swift (BAT), at about 82009 s UT (22:46:49). The burst was outside the coded field of view of the BAT.
  We have triangulated it to a Konus-HEND annulus centered at RA(2000)=132.436 deg (08h 49m 45s) Dec(2000)=+22.998 deg (+22d 59' 54"), whose radius is 62.605 +/- 0.326 deg (3 sigma).
  The LAT position reported by Racusin et al. (GCN Circ. 22884) is consistent with the annulus. The annulus combined with the LAT (90 % containment, statistical-only) error circle gives the following error box:

  ---------------------------------------------
    RA(2000), deg  Dec(2000), deg
  ---------------------------------------------
  Center:
       97.0594 -29.7187
  Corners:
       96.9223 -29.8774
       97.2925 -30.1165
       97.1962 -29.5599
       96.5548 -29.6361
  ---------------------------------------------
  

  The error box area is 894.7 sq. arcmin (a factor of 2 smaller than that of the LAT error circle).
  This box may be improved.
  A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB180703_T82008/IPN
• GCN Circular #22914
  D. Frederiks, S. Golenetskii, R.Aptekar, A. Kozlova, A.Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
  GRB 180703B (IPN Triangulation: Hurley et al., GCN 22908; Fermi-LAT detection: Racusin et al., GCN 22884; Fermi-GBM detection: Poolakkil & Meegan, GCN 22897) triggered Konus-Wind at T0=3D82008.633 s UT (22:46:48.633)
  The burst light curve shows two prominent peaks, with a total duration of ~2.0 s. The emission in the main peak is seen up to ~2 MeV.
  As observed by Konus-Wind, the burst had a fluence of (6.4 =B1 0.4)x10^-6 erg/cm2 and a 64-ms peak energy flux, measured from T0+1.088, of (1.60 =B1 0.09)x10^-5 erg/cm2 (both in the 20 keV - 10 MeV energy range).
  The time-integrated spectrum (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 2 MeV range by a cutoff power-law (CPL) function with the following model parameters: the photon index alpha =3D -0.74(-0.18,+0.19), and the peak energy Ep =3D 131(-9,+11) keV, chi2 =3D 55/57 dof. Fitting this spectrum with the GRB (Band) function yields the same alpha and Ep, and only an upper limit on beta (<-3.3).
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180703_T82008/
  All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.
• GCN Circular #22932
  V. Pal'shin, Y. Kawakubo, A. Yoshida, T. Sakamoto, S. Sugita, A. Tezuka, S. Matsukawa, H. Onozawa, T. Ito, H. Morita, Y. Sone (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena) and the CALET collaboration:
  Using the CALET Gamma-ray Burst Monitor (CGBM) event data we report further analysis of the bright, short-duration, soft spectrum GRB 180703B (Fermi-LAT detection: Racusin et al. GCN Circ. 22884; CGBM detection: Takahashi et al. GCN Circ. 22888; Fermi-GBM detection: Poolakkil and Meegan GCN Circ. 22897; IPN localization: Hurley et al. GCN Circ. 22908; Konus-Wind observation: Frederiks et al. GCN Circ. 22914).
  Using a 16-ms binned light curve of the sum of HXM1 and HXM2 detectors, the estimated spectral lag for the 25-50 keV to 100-300 keV bands is 43 ± 30 ms (68% CL). This value is more consistent with lags of long rather than short GRBs.
  We also obtained more precise estimates of T90 and T50 using the SGM 16-ms lc: 1.44 s +- 0.10 s and 0.34 +- 0.06 sec (40-1000 keV), respectively.
  The time-averaged spectrum of the burst (measured by the SGM from T0+0.032 sec to T0+1.856 sec, where T0=22:46:51.183 UTC) is best fit in the 30-1000 keV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.83(-0.32, +0.36) and Ep = 143(-13, +15) keV (chi2 = 62/59 dof). The resulting fluence in this energy range is 5.98(-0.43, +0.46)x10^-6 erg/cm2. The quoted errors are at 90% CL.
  All the quoted values are preliminary.
• GCN Circular #23058
  K. Yoshikawa, Y. Asaoka (Waseda U), N. Cannady (LSU), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita, Y. Kawakubo, A. Tezuka, S. Matsukawa, H. Onozawa, T. Ito, H. Morita, Y. Sone (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU), S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena) and the CALET collaboration:
  Using the CALET CALorimeter (CAL) data, we report GeV gamma-ray search analysis associated to GRB 180703B (Racusin et al. GCN Circ. 22884; Takahashi et al. GCN Circ. 22888; Poolakkil and Meegan GCN Circ. 22897; Hurley et al. GCN Circ. 22908; Frederiks et al. GCN Circ. 22914).
  The CAL was operating in low energy trigger mode at the trigger time of the CALET Gamma-ray Burst Monitor (CGBM). We have searched for gamma-ray events in the 1-10 GeV band from -60 sec to +60 sec from the CGBM trigger time using the Fermi-LAT position (Racusin et al. GCN Circ. 22884) and found no candidates. The 90% upper limit of CAL is 1.5e-6 erg/cm2/s (1-10 GeV) assuming a power-law spectrum of a photon index of -2.
  All the quoted values are preliminary.