Gamma-ray Burst 210606B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 07 Jun 21 01:27:38 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     644712030
GRB_RA:           74.033d {+04h 56m 08s} (J2000),
                  74.299d {+04h 57m 12s} (current),
                  73.414d {+04h 53m 39s} (1950)
GRB_DEC:          -4.567d {-04d 34' 00"} (J2000),
                  -4.534d {-04d 32' 02"} (current),
                  -4.645d {-04d 38' 40"} (1950)
GRB_ERROR:       31.87 [deg radius, statistical plus systematic]
GRB_INTEN:       72 [cnts/sec]
DATA_SIGNIF:     4.60 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        19371 TJD;   157 DOY;   21/06/06
GRB_TIME:        81625.32 SOD {22:40:25.32} UT
GRB_PHI:         334.00 [deg]
GRB_THETA:        75.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.86
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      53%  Solar Flare
2nd_MOST_LIKELY:  39%  GRB
DETECTORS:       0,0,0, 1,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        75.39d {+05h 01m 33s}  +22.76d {+22d 45' 22"}
SUN_DIST:         27.31 [deg]   Sun_angle= 0.1 [hr] (West of Sun)
MOON_POSTN:       38.15d {+02h 32m 35s}  +12.07d {+12d 04' 03"}
MOON_DIST:        39.59 [deg]
MOON_ILLUM:      10 [%]
GAL_COORDS:      203.29,-27.65 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       72.07,-27.02 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210606945/quicklook/glg_lc_medres34_bn210606945.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 133.07,7.82 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(42.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=9256).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 07 Jun 21 01:28:31 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      85
TRIGGER_NUM:     644712030
GRB_RA:          109.267d {+07h 17m 04s} (J2000),
                 109.522d {+07h 18m 05s} (current),
                 108.671d {+07h 14m 41s} (1950)
GRB_DEC:          -9.650d {-09d 39' 00"} (J2000),
                  -9.690d {-09d 41' 22"} (current),
                  -9.560d {-09d 33' 33"} (1950)
GRB_ERROR:       14.15 [deg radius, statistical plus systematic]
GRB_INTEN:       292 [cnts/sec]
DATA_SIGNIF:     10.00 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        19371 TJD;   157 DOY;   21/06/06
GRB_TIME:        81625.32 SOD {22:40:25.32} UT
GRB_PHI:         318.00 [deg]
GRB_THETA:       105.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      1.45
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      93%  GRB
2nd_MOST_LIKELY:   5%  Solar Flare
DETECTORS:       0,0,0, 1,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        75.39d {+05h 01m 33s}  +22.76d {+22d 45' 22"}
SUN_DIST:         46.58 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:       38.15d {+02h 32m 36s}  +12.07d {+12d 04' 13"}
MOON_DIST:        74.17 [deg]
MOON_ILLUM:      10 [%]
GAL_COORDS:      224.43,  1.23 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      112.45,-31.60 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210606945/quicklook/glg_lc_medres34_bn210606945.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 133.07,7.82 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(42.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=9256).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 07 Jun 21 01:28:38 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      88
TRIGGER_NUM:     644712030
GRB_RA:           86.350d {+05h 45m 24s} (J2000),
                  86.577d {+05h 46m 18s} (current),
                  85.821d {+05h 43m 17s} (1950)
GRB_DEC:         -21.817d {-21d 49' 00"} (J2000),
                 -21.809d {-21d 48' 33"} (current),
                 -21.836d {-21d 50' 08"} (1950)
GRB_ERROR:       5.35 [deg radius, statistical plus systematic]
GRB_INTEN:       667 [cnts/sec]
DATA_SIGNIF:     58.00 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        19371 TJD;   157 DOY;   21/06/06
GRB_TIME:        81625.32 SOD {22:40:25.32} UT
GRB_PHI:         314.00 [deg]
GRB_THETA:        80.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.25
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,0, 1,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        75.39d {+05h 01m 33s}  +22.76d {+22d 45' 22"}
SUN_DIST:         45.88 [deg]   Sun_angle= -0.7 [hr] (East of Sun)
MOON_POSTN:       38.15d {+02h 32m 37s}  +12.07d {+12d 04' 15"}
MOON_DIST:        58.35 [deg]
MOON_ILLUM:      10 [%]
GAL_COORDS:      226.23,-23.84 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       85.19,-45.20 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210606945/quicklook/glg_lc_medres34_bn210606945.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 133.07,7.82 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(42.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=9256).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 07 Jun 21 01:28:47 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      91
TRIGGER_NUM:     644712030
GRB_RA:           77.767d {+05h 11m 04s} (J2000),
                  77.969d {+05h 11m 53s} (current),
                  77.294d {+05h 09m 11s} (1950)
GRB_DEC:         -31.650d {-31d 38' 59"} (J2000),
                 -31.625d {-31d 37' 29"} (current),
                 -31.710d {-31d 42' 35"} (1950)
GRB_ERROR:       3.88 [deg radius, statistical plus systematic]
GRB_INTEN:       1665 [cnts/sec]
DATA_SIGNIF:     152.90 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        19371 TJD;   157 DOY;   21/06/06
GRB_TIME:        81625.32 SOD {22:40:25.32} UT
GRB_PHI:         306.00 [deg]
GRB_THETA:        70.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.72
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   2%  Generic Transient
DETECTORS:       0,0,0, 1,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        75.39d {+05h 01m 33s}  +22.76d {+22d 45' 22"}
SUN_DIST:         54.44 [deg]   Sun_angle= -0.2 [hr] (East of Sun)
MOON_POSTN:       38.15d {+02h 32m 37s}  +12.07d {+12d 04' 16"}
MOON_DIST:        58.00 [deg]
MOON_ILLUM:      10 [%]
GAL_COORDS:      234.35,-34.09 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       71.98,-54.33 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210606945/quicklook/glg_lc_medres34_bn210606945.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 133.07,7.82 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(42.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=9256).

GCN Circular #30138
C. Cai, Y. Huang, S. L. Xiong, S. L. Xie, S. Xiao, Y. Zhao, J. C. Liu, C. Y. Li, Y. Q. Zhang, W. C. Xue, C. Zheng, Z. W. Guo, X. Y. Zhao, Z. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo, J. J. He, B. Li, C. Li, J. H. Li, Q. X. Li, X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang, J. Y. Liao, J. C. Liu, X. J. Liu, Y. Q. Liu, F. J. Lu, Q. Luo, X. Ma, G. Ou, W. X. Peng, R. Qiao, D. L. Shi, J. Y. Shi, L. M. Song, X. Y. Song, G. X. Sun, X. L. Sun, Y. L. Tuo, C. W. Wang, J. Z. Wang, P. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, S. Yang, M. Yao, Q. B. Yi, B. X. Zhang, C. Y. Zhang, D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang, K. Zhang, P. Zhang, S. N. Zhang, Z. Zhang, S. Y. Zhao, S. J. Zheng, X. Zhou (IHEP), report on behalf of GECAM team:
During the commissioning phase, GECAM-B was triggered by a long GRB 210606B at 2021-06-06T22:41:08.100 UTC (denoted as T0), which was also observed by Fermi/GBM (trigger #644712030); AGILE (trigger #550104073); INTEGRAL/SPIACS (trigger #9256).
GECAM alert data was promptly downlinked to the ground through the short message service of BeiDou Navigation Satellite System (BDS). The time latency of the first BeiDou message relative to the trigger time is about 1 minute.
According to the BDS alert data, this burst mainly consists of multiple pulses with a duration of about 35s.
An automatic on-ground localization was calculated using the light curves and spectrum. Although the in-flight calibration of energy response and localization has not been finalized yet, GECAM-B localized this burst to the following position (J2000):
```
ra: 85.89 deg
dec: -18.63 deg
err: 1.39 deg (1-sigma, statistical only)
```
The current systematic error of location is estimated to be several degrees which could be minimized by the ongoing calibration.
This position is consistent with the Fermi GBM team localization (trigger #644712030) within the error.
The GECAM light curve could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_combine_76718468.png
As the detailed science data are downloaded, all analyses would be improved.
Please note that all GECAM results here are preliminary. The final analysis will be published in journal papers or GECAM online catalog.
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time), which was funded by the Chinese Academy of Sciences (CAS).
GCN Circular #30139
F. Kunzweiler, B. Biltzinger, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 644712030 at 22:40:25 on 06 June 2021 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60).
The best-fit position (1 sigma statistical errors) is: RA(2000.0) = 87.9+/-0.5 deg Decl.(2000.0) = -15.9+/-0.6 deg We estimate an additional systematic error of 1 deg.
Further details are available at: https://grb.mpe.mpg.de/grb/GRB210606945/
The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB210606945/healpix
The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB210606945/json
GCN Circular #30142
A. Ursi (INAF/IAPS), F. Verrecchia, C. Pittori (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C. Casentini, Y. Evangelista, G. Piano (INAF/IAPS), F. Lucarelli (SSDC, and INAF/OAR), A. Bulgarelli, A. Di Piano, V. Fioretti, F. Fuschino, N. Parmiggiani (INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo (Univ. Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team:
The AGILE satellite detected the long GRB 210606B at T0 = UTC 2021-06-06 22:41:03 s (UTC), reported by Fermi/GBM (Trigger no. 644712030), GECAM (GCN #39138), and BALROG (GCN #39139).
The burst is visible in the AGILE scientific ratemeters of the SuperAGILE (SA; 20-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and AntiCoincidence (AC; 50-200 keV) detectors. The event lasted ~35 s and released a total number of 3120 counts in the SA detector (above a background rate of 66 Hz), 43110 counts in the MCAL detector (above a background rate of 1250 Hz), and 125100 counts in the AC detector (above a background rate of 3660 Hz). The AGILE ratemeter light curves can be found at http://www.agilescienceapp.it/notices/GRB210606B_AGILE_RM.png .
The event also triggered a partial high time resolution MCAL data acquisition at T = UTC 2021-06-06 22:41:13.18 +/- 0.01 s, whose light curve can be found at: http://www.agilescienceapp.it/notices/073374_GRB_550104073.181294.png .
Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html.
GCN Circular #30147
C. Malacaria (USRA) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 22:40:25.32 UT on 6 June 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210606B (trigger 644712030 / 210606945). This burst was also independently detected by INTEGRAL SPI-ACS, GECAM (GCN 30138) and AGILE (GCN 30142).
The on-ground calculated location, using the GBM trigger data, is RA = 87.48, DEC = -18.41 (J2000 degrees, equivalent to 05 h 49 m, -18 d 24 '), with a statistical uncertainty of 1.20 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).
The angle from the Fermi LAT boresight at the GBM trigger time is 82 degrees.
The GBM light curve consists of three main peaks taking place about 40 s after the initial trigger, plus one weaker peak showing 250 s after the initial trigger. The full event has a duration (T90) of about 244 s (50-300 keV).
The time-averaged spectrum from T0+42 s to T0+52 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.04 +/- 0.01 and the cutoff energy, parameterized as Epeak, is 397 +/- 13 keV. A Band function fits the spectrum equally well with Epeak= 394 +/- 14 keV, alpha = -1.04 +/- 0.01 and beta = -3.7 +/- 1.5 .
The event fluence (10-1000 keV) in this time interval is (3.45 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+49 s in the 10-1000 keV band is 35.6 +/- 0.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular #30154
K. Hurley, on behalf of the IPN,
I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
D. Svinkin, S. Golenetskii, D. Frederiks, A. Ridnaia, A. Lysenko, 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, D. Palmer, and A. Tohuvavohu 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 bright, long-duration 210606B (GECAM detection: Cai et al., GCN Circ. 30138; BALROG localization: Kunzweiler et al., GCN Circ. 30139; AGILE detection: Ursi et al., GCN Circ. 30142; Fermi-GBM detection: The Fermi GBM team, GCN Circ. 30147) was detected by Fermi (GBM trigger 644712030), Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), GECAM, AGILE (SA, MCAL, and AC) and Swift (BAT) at about 81625 s UT (22:40:25) The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:
```
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    87.986 (05h 51m 57s) -16.689 (-16d 41' 19")
  Corners:
    86.597 (05h 46m 23s) -15.596 (-15d 35' 45")
    89.249 (05h 57m 00s) -17.675 (-17d 40' 30")
    89.394 (05h 57m 35s) -17.719 (-17d 43' 07")
    86.742 (05h 46m 58s) -15.651 (-15d 39' 05")
  ---------------------------------------------
```
The error box area is 588 sq. arcmin, and its maximum dimension is 3.4 deg (the minimum one is 3 arcmin). The Sun distance was 40 deg.
This box may be improved.
The IPN localization is consistent with, but reduces the area of, the Fermi RoboBA and BALROG localizations (GCN Circ. 30147 and 30139).
A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB210606_T81665/IPN/
The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
GCN Circular #30157
D. Frederiks, S. Golenetskii, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The long GRB 210606B (GECAM detection: Cai et al., GCN 30138; BALROG localization: Kunzweiler et al., GCN Circ. 30139; AGILE detection: Ursi et al., GCN 30142; Fermi GBM detection: Malacaria & Meegan, GCN 30147; IPN localization: Hurley et al., GCN Circ. 30154;) triggered Konus-Wind (KW) at T0=81665.249 s UT (22:41:05.249).
The burst light curve contains two major emission episodes: a bright, multi-peaked emission complex in the interval from ~T0-2 s to ~T0+30 s; and the second, much weaker episode, which starts at ~T0+195 s, and has a duration of ~70 s. The emission in the main episode is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB210606_T81665/
As observed by Konus-Wind, the burst had a fluence of (8.1 � 0.7)x10^-5 erg/cm^2 and a 64-ms peak energy flux, measured from T0 + 4.224 s, of (1.7 � 0.2)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The spectrum of the main episode (measured from T0 to T0+33.024 s) is best fit in the 20 keV - 20 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.04 (-0.06,+0.07), the high energy photon index beta = -2.61 (-0.54,+0.24), the peak energy Ep = 309 (-27,+31) keV, chi2 = 80/97 dof.
The spectrum of the second episode (measured from T0+193.536 to T0+259.072 s) is best fit in the 20 keV - 20 MeV range by the a simple power law with the photon index of 2.1 (-0.14,+0.15), chi2 = 94/99 dof.
The spectrum near the peak count rate (measured from T0+0.256 to T0+13.824 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.08 (-0.07,+0.08), the high energy photon index beta = -2.67 (-1.76,+0.33), the peak energy Ep = 345 (-42,+48) keV, chi2 = 84/97 dof.
All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.

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Jochen Greiner, last update: 09-Jun-2021 [Disclaimer]