Gamma-ray Burst 210511B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 11 May 21 11:27:03 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      44
TRIGGER_NUM:     642425204
GRB_RA:          315.183d {+21h 00m 44s} (J2000),
                 315.338d {+21h 01m 21s} (current),
                 314.821d {+20h 59m 17s} (1950)
GRB_DEC:         +54.850d {+54d 51' 00"} (J2000),
                 +54.934d {+54d 56' 04"} (current),
                 +54.653d {+54d 39' 11"} (1950)
GRB_ERROR:       11.77 [deg radius, statistical plus systematic]
GRB_INTEN:       234 [cnts/sec]
DATA_SIGNIF:     10.00 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        19345 TJD;   131 DOY;   21/05/11
GRB_TIME:        41199.26 SOD {11:26:39.26} UT
GRB_PHI:         327.00 [deg]
GRB_THETA:        50.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      1.19
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:        48.57d {+03h 14m 16s}  +18.00d {+18d 00' 15"}
SUN_DIST:         77.16 [deg]   Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN:       45.63d {+03h 02m 32s}  +15.09d {+15d 05' 16"}
MOON_DIST:        77.87 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       93.66,  5.67 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      353.43, 65.73 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210511477/quicklook/glg_lc_medres34_bn210511477.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 173.93,-4.22 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 11 May 21 11:27:12 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      58
TRIGGER_NUM:     642425204
GRB_RA:          306.000d {+20h 24m 00s} (J2000),
                 306.143d {+20h 24m 34s} (current),
                 305.665d {+20h 22m 40s} (1950)
GRB_DEC:         +53.600d {+53d 36' 00"} (J2000),
                 +53.670d {+53d 40' 12"} (current),
                 +53.437d {+53d 26' 13"} (1950)
GRB_ERROR:       4.17 [deg radius, statistical plus systematic]
GRB_INTEN:       1129 [cnts/sec]
DATA_SIGNIF:     68.50 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        19345 TJD;   131 DOY;   21/05/11
GRB_TIME:        41199.26 SOD {11:26:39.26} UT
GRB_PHI:         324.00 [deg]
GRB_THETA:        45.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.93
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      91%  GRB
2nd_MOST_LIKELY:   7%  Cyg X-1
DETECTORS:       0,0,0, 1,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:        48.57d {+03h 14m 16s}  +18.00d {+18d 00' 15"}
SUN_DIST:         82.66 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:       45.64d {+03h 02m 33s}  +15.09d {+15d 05' 18"}
MOON_DIST:        83.38 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       89.38,  9.18 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      340.97, 68.35 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210511477/quicklook/glg_lc_medres34_bn210511477.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 173.93,-4.22 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 11 May 21 11:27:21 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     642425204
GRB_RA:          316.440d {+21h 05m 46s} (J2000),
                 316.557d {+21h 06m 14s} (current),
                 316.166d {+21h 04m 40s} (1950)
GRB_DEC:         +62.390d {+62d 23' 24"} (J2000),
                 +62.476d {+62d 28' 34"} (current),
                 +62.189d {+62d 11' 19"} (1950)
GRB_ERROR:       1.87 [deg radius, statistical only]
DATA_SIGNIF:     50.60 [sigma]
DATA_INTERVAL:   1.024 [sec]
GRB_DATE:        19345 TJD;   131 DOY;   21/05/11
GRB_TIME:        41199.26 SOD {11:26:39.26} UT
GRB_PHI:         337.00 [deg]
GRB_THETA:        49.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:        48.57d {+03h 14m 16s}  +18.00d {+18d 00' 15"}
SUN_DIST:         75.01 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:       45.64d {+03h 02m 33s}  +15.09d {+15d 05' 20"}
MOON_DIST:        76.23 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       99.84, 10.13 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       10.04, 70.06 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210511477/quicklook/glg_lc_medres34_bn210511477.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_642425204.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 11 May 21 11:28:04 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      2
TRIGGER_NUM:     642425204
GRB_RA:          318.250d {+21h 13m 00s} (J2000),
                 318.378d {+21h 13m 31s} (current),
                 317.951d {+21h 11m 48s} (1950)
GRB_DEC:         +61.520d {+61d 31' 12"} (J2000),
                 +61.609d {+61d 36' 32"} (current),
                 +61.313d {+61d 18' 46"} (1950)
GRB_ERROR:       1.70 [deg radius, statistical only]
DATA_SIGNIF:     66.60 [sigma]
DATA_INTERVAL:   6.144 [sec]
GRB_DATE:        19345 TJD;   131 DOY;   21/05/11
GRB_TIME:        41199.26 SOD {11:26:39.26} UT
GRB_PHI:         336.00 [deg]
GRB_THETA:        50.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:        48.57d {+03h 14m 16s}  +18.00d {+18d 00' 16"}
SUN_DIST:         74.31 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:       45.64d {+03h 02m 34s}  +15.09d {+15d 05' 27"}
MOON_DIST:        75.47 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       99.76,  8.92 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        9.31, 68.87 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210511477/quicklook/glg_lc_medres34_bn210511477.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_642425204.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=9207).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 11 May 21 11:28:36 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      3
TRIGGER_NUM:     642425204
GRB_RA:          318.230d {+21h 12m 55s} (J2000),
                 318.358d {+21h 13m 26s} (current),
                 317.930d {+21h 11m 43s} (1950)
GRB_DEC:         +61.450d {+61d 27' 00"} (J2000),
                 +61.539d {+61d 32' 20"} (current),
                 +61.243d {+61d 14' 34"} (1950)
GRB_ERROR:       1.38 [deg radius, statistical only]
DATA_SIGNIF:     73.00 [sigma]
DATA_INTERVAL:   9.216 [sec]
GRB_DATE:        19345 TJD;   131 DOY;   21/05/11
GRB_TIME:        41199.26 SOD {11:26:39.26} UT
GRB_PHI:         336.00 [deg]
GRB_THETA:        50.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:        48.57d {+03h 14m 16s}  +18.00d {+18d 00' 16"}
SUN_DIST:         74.33 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:       45.65d {+03h 02m 35s}  +15.09d {+15d 05' 33"}
MOON_DIST:        75.48 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       99.70,  8.88 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        9.13, 68.84 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210511477/quicklook/glg_lc_medres34_bn210511477.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_642425204.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=9207).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 11 May 21 11:36:02 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     642425204
GRB_RA:          316.180d {+21h 04m 43s} (J2000),
                 316.301d {+21h 05m 12s} (current),
                 315.897d {+21h 03m 35s} (1950)
GRB_DEC:         +61.690d {+61d 41' 24"} (J2000),
                 +61.776d {+61d 46' 33"} (current),
                 +61.490d {+61d 29' 23"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
GRB_DATE:        19345 TJD;   131 DOY;   21/05/11
GRB_TIME:        41199.26 SOD {11:26:39.26} UT
GRB_PHI:         336.00 [deg]
GRB_THETA:        49.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:        48.57d {+03h 14m 17s}  +18.01d {+18d 00' 21"}
SUN_DIST:         75.25 [deg]   Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN:       45.71d {+03h 02m 50s}  +15.11d {+15d 06' 52"}
MOON_DIST:        76.44 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       99.22,  9.76 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        8.14, 69.78 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210511477/quicklook/glg_lc_medres34_bn210511477.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210511477/quicklook/glg_locplot_all_bn210511477.png
COMMENTS:        Fermi-GBM Final Position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
COMMENTS:        This notice was generated completely by automated pipeline processing.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=9207).

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Tue 11 May 21 11:27:30 UT
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
TRIGGER_NUM:    9207,   Sub_Num: 0
GRB_INTEN:      9.05 [sigma]
GRB_TIME:       41198.72 SOD {11:26:38.72} UT
GRB_DATE:       19345 TJD;   131 DOY;   21/05/11
COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.  
COMMENTS:       Time_Scale=2.0000 and Time_Error=1.0000.  
COMMENTS:
COMMENTS:       NOTE: This SPIACS event is temporally(1.0<100sec) coincident with the FERMI_GBM event(trignum=642425204).  
COMMENTS:          
COMMENTS:       The SPIACS lightcurve can be found at:  
COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2021-05/2021-05-11T11-26-38.5762-22656-31632-0.lc

GCN Circular #29988
The Fermi GBM team reports the detection of a likely LONG GRB
At 11:26:39 UT on 11 May 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210511B (trigger 642425204.260366 / 210511477).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 316.2, Dec = 61.7 (J2000 degrees, equivalent to J2000 21h 04m, 61d 42'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 49.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210511477/quicklook/glg_skymap_all_bn210511477.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210511477/quicklook/glg_healpix_all_bn210511477.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210511477/quicklook/glg_lc_medres34_bn210511477.gif
GCN Circular #29989
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 642425204 at 11:26:39 on 11 May 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) = 314.1+/-1.4 deg Decl.(2000.0) = 56.3+/-0.6 deg We estimate an additional systematic error of 1 deg.
Further details are available at: https://grb.mpe.mpg.de/grb/GRB210511477/
The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB210511477/healpix
The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB210511477/json
GCN Circular #29990
C. Cai, S. L. Xie, Y. Huang, S. L. Xiong, 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 210511B at 2021-05-11T11:26:40.600 UTC (denoted as T0), which was also observed by Fermi/GBM (GCN #29988).
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 a single pulse with a duration of about 10s.
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: 317.99 deg
dec: 59.53 deg
err: 3.19 deg (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 (GCN 29988) within the error.
The GECAM light curve could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_combine_74431600.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 #29991
A. Ursi (INAF/IAPS), V. Fioretti (INAF/OAS-Bologna), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C. Casentini, Y. Evangelista, G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori, F. Verrecchia (SSDC, and INAF/OAR), A. Bulgarelli, A. Di Piano, 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 210511B at T0 = 2021-05-11 11:26:37 s (UTC), reported by Fermi/GBM (GCN #29988) and GECAM (GCN #29990).
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 ~12 s and released a total number of 2120 counts in the SA detector (above a background rate of 64 Hz), 15630 counts in the MCAL detector (above a background rate of 1260 Hz), and 48375 counts in the AC detector (above a background rate of 3865 Hz). The AGILE ratemeter light curves can be found at http://www.agilescienceapp.it/notices/GRB210511_AGILE_RM.png .
Additional analysis of AGILE data is in progress.
GCN Circular #29992
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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 210511B ( Fermi GBM team, GCN 29988) errorbox 24287 sec after notice time and 24402 sec after trigger time at 2021-05-11 18:13:21 UT, with upper limit up to 18.0 mag. The observations began at zenith distance = 68 deg. The sun altitude is -17.1 deg.
The galactic latitude b = 10 deg., longitude l = 99 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1611119
We obtain a following upper limits.
```
Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   24492 | 2021-05-11 18:13:21 |   MASTER-Kislovodsk | (21h 04m 20.43s , +61d 44m 35.3s) |   C |   180 | 17.6 |        
   24493 | 2021-05-11 18:13:21 |   MASTER-Kislovodsk | (21h 04m 10.88s , +61d 20m 40.1s) |   C |   180 | 18.0 |        
   24693 | 2021-05-11 18:16:41 |   MASTER-Kislovodsk | (21h 04m 27.56s , +61d 43m 35.1s) |   C |   180 | 17.5 |        
   24693 | 2021-05-11 18:16:41 |   MASTER-Kislovodsk | (21h 04m 18.29s , +61d 19m 37.6s) |   C |   180 | 18.0 |        
   24893 | 2021-05-11 18:20:02 |   MASTER-Kislovodsk | (20h 54m 20.98s , +62d 42m 45.4s) |   C |   180 | 17.4 |        
   24893 | 2021-05-11 18:20:02 |   MASTER-Kislovodsk | (20h 54m 12.62s , +62d 18m 48.3s) |   C |   180 | 17.9 |        
   25093 | 2021-05-11 18:23:22 |   MASTER-Kislovodsk | (20h 54m 27.35s , +62d 43m 01.4s) |   C |   180 | 17.4 |        
   25093 | 2021-05-11 18:23:22 |   MASTER-Kislovodsk | (20h 54m 19.40s , +62d 19m 03.9s) |   C |   180 | 17.8 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #29996
E. Bissaldi (Politecnico and INFN Bari) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 11:26:39.26 UT on 11 May 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210511B (trigger 642425204 / 210511477), which was also detected by GECAM (Cai et al., GCN 29990) and by AGILE (Ursi et al., GCN 29991). The Fermi GBM Final Real-time Localization was reported in GCN 29988.
The angle from the Fermi LAT boresight at the GBM trigger time is 49 degrees.
The GBM light curve consists of a bright emission episode with a duration (T90) of about 6 s (50-300 keV). The time-averaged spectrum from T0 to T0+8 s is best fit by a Band function with Epeak = 128 +/- 5 keV, alpha = -0.72 +/- 0.04, and beta = -2.47 +/- 0.10.
The event fluence (10-1000 keV) in this time interval is (1.04 +/- 0.02)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+4.2 s in the 10-1000 keV band is 23.3 +/- 0.3 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 #29998
Oc�lotl Lopez (UNAM), Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Simone Dichiara (GSFC/UMD), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Diego Gonzalez (UNAM), Margarita Pereyra (UNAM), Srihari Ravi (ASU), and Eleonora Troja (GSFC/UMD) report:
We observed the field of the Fermi - GBM event GRB 210511B (Fermi Collaboration, GCN Circ. 29988) with the DDOTI wide-field imager at the Observatorio Astron�mico Nacional on Sierra San Pedro Martir ( http://ddoti.astroscu.unam.mx) from 2021-05-11 11:49:26 to 12:01:38 UTC (0.38 to 0.58 hours after the trigger) and obtained 6 minutes of exposure in the w filter. The images were obtained after the astronomical twilight.
We observed a region covering approximately 14 degrees in RA and 10 degrees in declination, with a 2 x 1 grid, including the entire initial uncertainty region distributed in the GCN Notice (Fermi Collaboration, GCN Circ. 29988)
Comparing to the Pan-STARRS DR1 catalog, we detect no uncatalogued point sources to a 10-sigma limiting magnitude of w = 18.39.
We thank the staff of the Observatorio Astron�mico Nacional in San Pedro Martir.
GCN Circular #30002
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,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report:
The long-duration GRB 210511B (Fermi-GBM detection: The Fermi GBM team, GCN Circ. 29988; Bissaldi and Meegan, GCN Circ. 29996; BALROG localization: Kunzweiler et al., GCN Circ. 29989; GECAM detection: Cai et al., GCN Circ. 29990; AGILE detection: Ursi et al., GCN Circ. 29991) was detected by Fermi (GBM trigger 642425204), Konus-Wind, Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), AGILE and GECAM-B at about 41199 s UT (11:26:39).
We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:
```
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   312.914 (20h 51m 39s) +58.375 (+58d 22' 31")
  Corners:
   306.385 (20h 25m 33s) +59.894 (+59d 53' 39")
   306.250 (20h 25m 00s) +60.029 (+60d 01' 45")
   318.903 (21h 15m 37s) +56.519 (+56d 31' 10")
   318.984 (21h 15m 56s) +56.371 (+56d 22' 16")
  ---------------------------------------------
```
The error box area is 2687 sq. arcmin, and its maximum dimension is 7.6 deg (the minimum one is 6.0 arcmin). The Sun distance was 75 deg.
This box may be improved.
This error box is consistent with, but reduces the areas of, the Fermi (RoboBA and BALROG), and GECAM localizations.
A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB210511_T41201/IPN
The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
GCN Circular #30007
A. Ridnaia, D. Frederiks, S. Golenetskii, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, report:
The long-duration GRB 210511B (Fermi GBM detection: Fermi GBM team, GCN 29988; Bissaldi and Meegan, GCN 29996; BALROG localization: Kunzweiler et al., GCN 29989; GECAM detection: Cai et al., GCN 29990; AGILE detection: Ursi et al., GCN 29991; IPN triangulation: Hurley et al., GCN 30002) triggered Konus-Wind at T0=41201.35 s UT (11:26:41.350).
The burst light curve shows a multi-peaked structure which starts at ~T0-1.7 s and has a total duration of ~6 s. The emission is seen up to ~4 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB210511_T41201/
As observed by Konus-Wind, the burst had a fluence of 1.10(-0.15,+0.18)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+0.512 s, of 4.76(-1.24,+1.34)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 4 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.98(-0.15,+0.18), the high energy photon index beta = -2.48(-0.43,+0.23), the peak energy Ep = 154(-22,+25) keV (chi2 = 86/71 dof).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.

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Jochen Greiner, last update: 13-May-2021 [Disclaimer]