GRB 210317A

The Fermi GBM team reports the detection of a likely LONG GRB

At 09:08:29 UT on 17 Mar 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210317A (trigger 637664914.045098 / 210317381).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 154.2, Dec = -64.9 (J2000 degrees, equivalent to J2000 10h 16m, -64d 54'), with a statistical uncertainty of 1.5 degrees.

The angle from the Fermi LAT boresight is 159.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210317381/quicklook/glg_skymap_all_bn210317381.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/bn210317381/quicklook/glg_healpix_all_bn210317381.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210317381/quicklook/glg_lc_medres34_bn210317381.gif

Q. B. Yi, Y. Huang, S. L. Xiong, S. Xiao, C. Cai, 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,
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 triggered a long burst,
GRB 210317A, at 2021-03-17T09:08:28.550 UTC (denoted as T0),
which was also detected by Fermi/GBM (GCN# 29659).

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 70 s.  

An automatic on-ground localization was calculated using the light curves
and counts spectrum in the BDS alert data. 
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: 153.2 deg Dec: -68.1 deg
Err: 3.1 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 location is consistent with the GBM position within the error.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_combine_69671308.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).

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-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 210317A ( Fermi GBM team, GCN 29659
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 ) errorbox  30510 sec after notice time and 30572 sec after trigger time at 2021-03-17 17:38:01 UT, with upper limit up to  18.2 mag. Observations started at twilight.  The observations began at zenith distance = 46 deg. The sun  altitude  is -10.1 deg. 

The galactic latitude b = -7 deg., longitude l = 288 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1570432

We obtain a following upper limits.  

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

   30602 | 2021-03-17 17:38:01 |         MASTER-SAAO | (10h 12m 01.88s , -63d 59m 59.4s) |   C |    60 | 17.3 |        
   30682 | 2021-03-17 17:39:21 |         MASTER-SAAO | (10h 20m 18.77s , -66d 00m 32.2s) |   C |    60 | 17.5 |        
   30842 | 2021-03-17 17:42:00 |         MASTER-SAAO | (10h 05m 27.61s , -62d 00m 11.5s) |   C |    60 | 17.5 |        
   31081 | 2021-03-17 17:45:59 |         MASTER-SAAO | (10h 30m 43.04s , -68d 00m 41.0s) |   C |    60 | 18.2 |        
Filter C is a clear (unfiltred) band. 


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