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GRB 210827B

GCN Circular 30726

Subject
GRB 210827B: Fermi GBM Final Real-time Localization
Date
2021-08-27T10:20:35Z (4 years ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
The Fermi GBM team reports the detection of a likely LONG GRB

At 10:10:16 UT on 27 Aug 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210827B (trigger 651751821.143562 / 210827424).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 308.8, Dec = -19.3 (J2000 degrees, equivalent to J2000 20h 35m, -19d 18'), with a statistical uncertainty of 2.5 degrees.

The angle from the Fermi LAT boresight is 66.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210827424/quicklook/glg_skymap_all_bn210827424.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/bn210827424/quicklook/glg_healpix_all_bn210827424.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210827424/quicklook/glg_lc_medres34_bn210827424.gif

GCN Circular 30727

Subject
GRB 210827B: BALROG localization (Fermi Trigger 651751821 / GRB 210827424)
Date
2021-08-27T10:28:30Z (4 years ago)
From
Jochen Greiner at MPE,Garching <jcg@mpe.mpg.de>
J. Burgess, F. Kunzweiler, B. Biltzinger, F. Berlato,  & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
651751821 at 10:10:16 on 27 Aug. 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) = 305.1+/-2.9 deg
Decl.(2000.0) = -17.3+/-2.3 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210827424/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210827424/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210827424/json

GCN Circular 30735

Subject
Fermi GRB 210827B: Global MASTER-Net observations report
Date
2021-08-28T12:30:29Z (4 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
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 210827B ( Fermi GBM team, GCN 30726) errorbox  24325 sec after notice time and 24337 sec after trigger time at 2021-08-27 16:55:53 UT, with upper limit up to  18.2 mag. Observations started at twilight.  The observations began at zenith distance = 69 deg. The sun  altitude  is -11.4 deg. 

The galactic latitude b = -32 deg., longitude l = 26 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1701427

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   15633 | 2021-08-27 14:30:38 |             MASTER- | (20h 28m 55.00s , -19d 15m 45.0s) |   C |    20 | 15.2 |        
   16581 | 2021-08-27 14:46:27 |             MASTER- | (20h 28m 52.92s , -19d 12m 38.6s) |   C |    20 | 14.9 |        
   17531 | 2021-08-27 15:02:16 |             MASTER- | (20h 28m 53.96s , -19d 13m 34.5s) |   C |    20 | 15.0 |        
   18829 | 2021-08-27 15:23:55 |             MASTER- | (20h 31m 16.41s , -17d 19m 29.2s) |   C |    20 | 14.8 |        
   18829 | 2021-08-27 15:23:55 |             MASTER- | (20h 23m 01.74s , -18d 44m 06.1s) |   C |    20 | 13.7 |        
   19755 | 2021-08-27 15:39:20 |             MASTER- | (20h 31m 06.85s , -17d 19m 50.6s) |   C |    20 | 12.6 |        
   19755 | 2021-08-27 15:39:20 |             MASTER- | (20h 22m 54.22s , -18d 43m 23.5s) |   C |    20 | 13.5 |        
   20653 | 2021-08-27 15:54:19 |             MASTER- | (20h 31m 05.17s , -17d 20m 21.3s) |   C |    20 | 14.9 |        
   20653 | 2021-08-27 15:54:19 |             MASTER- | (20h 22m 55.05s , -18d 42m 04.8s) |   C |    20 | 13.2 |        
   24368 | 2021-08-27 16:55:53 |   MASTER-Kislovodsk | (20h 27m 37.06s , -17d 37m 30.7s) |   C |    60 | 16.9 |        
   24368 | 2021-08-27 16:55:53 |   MASTER-Kislovodsk | (20h 32m 08.17s , -18d 03m 02.3s) |   C |    60 | 17.1 |        
   24528 | 2021-08-27 16:58:34 |   MASTER-Kislovodsk | (20h 25m 24.24s , -19d 31m 47.6s) |   C |    60 | 17.0 |        
   24528 | 2021-08-27 16:58:34 |   MASTER-Kislovodsk | (20h 29m 57.78s , -19d 57m 21.8s) |   C |    60 | 17.4 |        
   25329 | 2021-08-27 17:11:55 |   MASTER-Kislovodsk | (20h 27m 35.57s , -17d 37m 16.0s) |   C |    60 | 17.3 |        
   25329 | 2021-08-27 17:11:55 |   MASTER-Kislovodsk | (20h 32m 08.08s , -18d 02m 47.5s) |   C |    60 | 17.9 |        
   25489 | 2021-08-27 17:14:35 |   MASTER-Kislovodsk | (20h 25m 19.62s , -19d 33m 12.5s) |   C |    60 | 17.3 |        
   25489 | 2021-08-27 17:14:35 |   MASTER-Kislovodsk | (20h 29m 54.59s , -19d 58m 46.9s) |   C |    60 | 17.9 |        
   26292 | 2021-08-27 17:27:57 |   MASTER-Kislovodsk | (20h 27m 38.37s , -17d 37m 26.2s) |   C |    60 | 17.4 |        
   26292 | 2021-08-27 17:27:57 |   MASTER-Kislovodsk | (20h 32m 11.64s , -18d 02m 59.8s) |   C |    60 | 18.2 |        
   26452 | 2021-08-27 17:30:37 |   MASTER-Kislovodsk | (20h 25m 25.65s , -19d 31m 23.4s) |   C |    60 | 17.5 |        
   26452 | 2021-08-27 17:30:37 |   MASTER-Kislovodsk | (20h 30m 01.38s , -19d 56m 58.4s) |   C |    60 | 18.1 |        
   27014 | 2021-08-27 17:39:59 |   MASTER-Kislovodsk | (20h 31m 11.23s , -15d 44m 54.0s) |   C |    60 | 17.5 |        
   27014 | 2021-08-27 17:39:59 |   MASTER-Kislovodsk | (20h 35m 43.24s , -16d 10m 21.8s) |   C |    60 | 18.2 |        
   27174 | 2021-08-27 17:42:40 |   MASTER-Kislovodsk | (20h 24m 24.36s , -21d 25m 55.7s) |   C |    60 | 17.5 |        
   27174 | 2021-08-27 17:42:40 |   MASTER-Kislovodsk | (20h 29m 03.61s , -21d 51m 33.9s) |   C |    60 | 18.1 |        
   27575 | 2021-08-27 17:49:20 |   MASTER-Kislovodsk | (20h 41m 31.97s , -19d 31m 13.5s) |   C |    60 | 17.5 |        
   27575 | 2021-08-27 17:49:20 |   MASTER-Kislovodsk | (20h 46m 07.89s , -19d 56m 48.7s) |   C |    60 | 18.2 |        
   27816 | 2021-08-27 17:53:21 |   MASTER-Kislovodsk | (20h 43m 33.76s , -17d 38m 08.2s) |   C |    60 | 17.5 |        
   27816 | 2021-08-27 17:53:21 |   MASTER-Kislovodsk | (20h 48m 07.55s , -18d 03m 38.8s) |   C |    60 | 18.1 |        
   27976 | 2021-08-27 17:56:02 |   MASTER-Kislovodsk | (20h 31m 16.12s , -15d 44m 00.6s) |   C |    60 | 17.6 |        
   27976 | 2021-08-27 17:56:02 |   MASTER-Kislovodsk | (20h 35m 48.31s , -16d 09m 26.7s) |   C |    60 | 18.2 |        
   28137 | 2021-08-27 17:58:42 |   MASTER-Kislovodsk | (20h 24m 31.19s , -21d 26m 25.0s) |   C |    60 | 17.5 |        
   28137 | 2021-08-27 17:58:43 |   MASTER-Kislovodsk | (20h 29m 10.79s , -21d 52m 01.6s) |   C |    60 | 18.2 |        
   28537 | 2021-08-27 18:05:23 |   MASTER-Kislovodsk | (20h 46m 07.24s , -19d 56m 31.8s) |   C |    60 | 18.0 |        
   28537 | 2021-08-27 18:05:23 |   MASTER-Kislovodsk | (20h 41m 30.66s , -19d 30m 59.4s) |   C |    60 | 17.4 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.

GCN Circular 30774

Subject
GRB 210827B: GECAM detection
Date
2021-09-05T15:56:03Z (4 years ago)
From
Y Q Zhang at IHEP <yqzhang@ihep.ac.cn>
J. C. Liu, S. L. Xiong, X. Y. Zhao, Y. Huang, X. Y. Song, C. Cai, S. Xiao,
S. L. Xie, Y. Q. Zhang, Y. Zhao, Z. W. Guo, C. Zheng, W. C. Xue, C. Y. Li,
C. W. Wang, Q. B. Yi, B. X. Zhang, P. Zhang, W. X. Peng, R. Qiao, D. Y. Guo,
X. B. Li, X. Ma, P. Wang, J. Wang, Z. Zhang, S. J. Zheng, W. Chen, J. J. He, 
G. Y. Zhao, Y. Q. Du, H. Wu, J. Liang, Q. Luo, X. L. Zhang,
L. M. Song, F. J. Lu, S. N. Zhang (IHEP), report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by a long
burst, GRB 210827B, at 2021-08-27T10:10:16.60 UTC (denoted as T0), 
which was also observed by Fermi/GBM (GCN #30726). 
GECAM alert data was downlinked to the ground through the short message
service of BeiDou Navigation Satellite System (BDS) within ~60 s after T0.

According to the BDS alert data, this burst mainly consists of a broad pulse
with a duration of about 20 s. 

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_combine_83758216.png

Using the automatic on-ground localization pipeline with the BDS alert data, 
GECAM-B localized this burst to the following position (J2000): 
Ra: 307.5 deg 
Dec: -19.2 deg
Err: 3.5 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.

The GECAM preliminary location could be found here: 
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_skymap_bdm_83758216_V01.png

GECAM location is consistent with the Fermi/GBM position within the error.

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).

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