GRB 211201A

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

At 20:42:52 UT on 1 Dec 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 211201A (trigger 660084177.881018 / 211201863).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 355.4, Dec = 2.6 (J2000 degrees, equivalent to J2000 23h 41m, 2d 36'), with a statistical uncertainty of 5.0 degrees.

The angle from the Fermi LAT boresight is 108.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211201863/quicklook/glg_skymap_all_bn211201863.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/bn211201863/quicklook/glg_healpix_all_bn211201863.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211201863/quicklook/glg_lc_medres34_bn211201863.gif

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, 
D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina,
A.Chasovnikov, V.Topolev, V.Grinshpun, 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
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(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 211201A ( Fermi GBM team, GCN 31155
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 ) errorbox  1138 sec after notice time and 1166 sec after trigger time at 2021-12-01 21:02:19 UT, with upper limit up to  12.7 mag. The observations began at zenith distance = 75 deg. The sun  altitude  is -68.9 deg. 

The galactic latitude b = -56 deg., longitude l = 92 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1801667

We obtain a following upper limits.  

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

    1197 | 2021-12-01 21:02:19 |   MASTER-Kislovodsk | (23h 49m 38.72s , +01d 09m 30.8s) |   C |    60 | 12.7 |        
Filter C is a clear (unfiltred) band. 


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

James DeLaunay (UAlabama), Aaron Tohuvavohu (U Toronto), Gayathri
Raman (PSU), Jamie A. Kennea (PSU), report:

Swift/BAT did not trigger on GRB 211201A (T0: 2021-12-01T20:42:52 UTC,
Fermi/GBM GCN 31155
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 ).

The Fermi/GBM notice, distributed in near real-time, triggered the
Swift Mission Operations Center operated Gamma-ray Urgent Archiver for
Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).

Upon trigger by this notice, GUANO sent a command to the Swift Burst
Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from
[-50,+150] seconds around the time of the burst. All the requested
event mode data was delivered to the ground.

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu,
arXiv:2111.01769
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 ), detects the burst with a sqrt(TS) of 13.1 in a
16.384 s analysis time bin.
Estimated T90 in the detector is 30.5 +/- 0.5 s (15-350 keV).

NITRATES results, independently, are ambiguous with respect to whether
this burst originates from in or outside the BAT FOV, with a
borderline DeltaLLHOut of 9.57.
An out of FOV origin is more consistent with the Fermi/GBM
localization, and the Fermi/GBM spectral fit (private comm.) is
consistent with the best fit OFOV model from NITRATES.
Therefore we think it likely that this burst originates from outside
the coded FOV.

See Section 9.1 and Figure 20 in the NITRATES paper for brief
descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and
DeltaLLHOut.

GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/

G. Y. Zhao, S. L. Xiong,X. L. Zhang, S. Xiao, Yi Zhao, C. Cai, J. J. He, 
Y. Huang, Z. W. Guo, C. Y. Li, X. B. Li, J. C. Liu, X. Y. Song, P. Wang,
S. L. Xie, W. C. Xue, Q. B. Yi, Y. Q. Zhang,  X. Y. Zhao, C. Zheng,
Y. Q. Du, D. Y. Guo, J. Liang, F. J. Lu, Q. Luo, X. Ma, W. X. Peng,
R. Qiao, L. M. Song, J. Wang, H. Wu, P. Zhang, S. N. Zhang,
C. W. Wang,Z. Zhang, S. J. Zheng (IHEP),report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered on-ground by a 
long bright burst, GRB 211201A, at 2021-12-01T20:43:06.000 UTC (denoted as T0)���
which was also observed by Fermi/GBM (GCN #31155
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 ).

This burst mainly consists of multiple pulses with duration of about 50 s.

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