GRB 210119A

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

At 02:54:09 UT on 19 Jan 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210119A (trigger 632717654.819782 / 210119121).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 285.8, Dec = -63.1 (J2000 degrees, equivalent to J2000 19h 03m, -63d 06'), with a statistical uncertainty of 7.8 degrees.

The angle from the Fermi LAT boresight is 7.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210119121/quicklook/glg_skymap_all_bn210119121.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/bn210119121/quicklook/glg_healpix_all_bn210119121.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210119121/quicklook/glg_lc_medres34_bn210119121.gif

M. J. Moss (GWU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 02:54:09 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a short burst which would be either an unknown Soft Gamma 
Repeater or GRB 210119A (trigger=1017711). 
The BAT on-board calculated location is 
RA, Dec 282.804, -61.801 which is 
   RA(J2000) = 18h 51m 13s
   Dec(J2000) = -61d 48' 02"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single peak
structure with a duration of 0.128 sec or less.  The peak count rate
was ~8000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 12:54 UT on 2021 January 26. There will thus be no XRT
or UVOT data for this trigger before this time. 

Due to the short timescale of the peak and the location of the source
in the Galactic bulge (lat, lon = 333.99, -23.67) this event may be
from a previously unknown Soft Gamma Repeater, which we would name
SGR Swift J1851.2-6148 . 

Burst Advocate for this burst is M. J. Moss (mikejmoss3 AT gmail.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)

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 210119A ( Fermi GBM team, GCN 29322
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 ) errorbox 45 sec after trigger time at 2021-01-19 02:54:54 UT, with upper limit up to  15.1 mag. Observations started at twilight.  The observations began at zenith distance = 65 deg. The sun  altitude  is -11.3 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 210119A errorbox  57 sec after notice time and 108 sec after trigger time at 2021-01-19 02:55:58 UT, with upper limit up to  12.2 mag. The observations began at zenith distance = 84 deg. The sun  altitude  is -32.3 deg. 

The galactic latitude b = -26 deg., longitude l = 333 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1529080

We obtain a following upper limits.  

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

      50 | 2021-01-19 02:54:54 |         MASTER-SAAO | (18h 32m 27.92s , -60d 49m 23.7s) | P\  |    10 | 15.1 |        
      79 | 2021-01-19 02:55:24 |         MASTER-SAAO | (18h 32m 30.98s , -60d 47m 57.6s) | P\  |    10 | 15.0 |        
     114 | 2021-01-19 02:55:53 |         MASTER-SAAO | (18h 32m 25.77s , -60d 48m 47.0s) | P\  |    20 | 15.1 |        
     119 | 2021-01-19 02:55:58 |         MASTER-OAFA | (19h 56m 18.53s , -62d 36m 50.8s) |   C |    20 | 12.3 |        
     158 | 2021-01-19 02:56:33 |         MASTER-SAAO | (18h 32m 25.96s , -60d 47m 45.1s) | P\  |    30 | 15.0 |        
Filter C is a clear (unfiltred) band. 


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

N.Tiurina, V. Lipunov, V.Kornilov, E.Gorbovskoy, P.Balanutsa,F.Balakin, 
V.Vladimirov, A.Kuznetsov,K.Zhirkov,D. Vlasenko, I.Gorbunov, D.Zimnukhov, 
V.Senik, A.Chasovnikov,A.Pozdnyakov,V.Topolev, D.Cheryasov(Lomonosov 
Moscow State  University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico 
Felix Aguilar, San Huan National University),
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, Yu. Sergienko (Blagoveschensk Educational 
StateUniversity)

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of 
San Juan National University) started inspect of the Fermi GRB 210119A 
errorbox  57 sec after notice time and 108 sec after trigger time at 
2021-01-19 02:55:58 UT (Lipunov et al., GCN #29324
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 ). MASTER autodetection 
system  found  short OT on one of unfiltered image.

    Date/Time UT             RA                Dec        Exp    mag 
2021-01-19 04:20:32 	18h 51m 11.42s  -61d 48m 06s.3 	 180s 	~17

Error is ~1" .
The message may be cited.

J.Mangan (UCD), R.Dunwoody (UCD), S. Lesage (UAH), C. Meegan (UAH)
report on behalf of the Fermi GBM Team:


At 02:54:09.82 UT on 19 January 2021, the Fermi Gamma-Ray Burst
Monitor (GBM) triggered and located GRB 210119A (trigger 632717654 /
210119.121),
which was also detected by the Swift/BAT (M. J. Moss et al. 2021, GCN
29323
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 ). The Fermi GBM Final Real-time Localization (GCN 29322
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 ) is
consistent with the Swift position.


The angle from the Fermi LAT boresight at the GBM trigger time is 8 deg degrees.

The GBM light curve consists of a short bright burst
with a duration (T90) of about 0.05 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.064 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.82 +/- 0.18 and
the cutoff energy, parameterized as Epeak, is 515 +/- 168 keV.
Unlikely to be an SGR given Epeak result. The event fluence (10-1000
keV) in this time interval is
(3.432 +/- 0.397)E-7 erg/cm^2. The 64-ms peak photon flux measured
starting from T0-0.064 s in the 10-1000 keV band
is 11.7 +/- 1.3 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.htmlFor Fermi
GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"

Q. B. Yi, S. Xiao, Q. Luo, C. Cai, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, X. F. Lu, A. M. Zhang, Y. F. Zhang, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team: At 2021-01-19T02:54:09.82 (T0), Insight-HXMT/HE detected GRB 210119A (trigger ID: HEB210119120) in a routine search of the data, which was also triggered by Fermi/GBM (GCN #29322
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 ) and Swift/BAT (M. J. Moss. et al., GCN #29323
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 ). The Insight-HXMT/HE light curve mainly consists of a single �� pulse with a duration (T90) of 0.03 s measured from T0+0.01 s. The 1-ms peak rate, measured from T0+0.004 s, is 4418 cnts/sec. The total counts from this burst is 62 counts. URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB210119120_lc.jpg All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org.

Z. H. An, C. Cai, G. Chen, W. Chen, M. Gao, M. Y. Ge, K. Gong, D. Y. Guo,
J. J. He, Y. Huang, B. Li, C. Li, C. Y. Li, J. H. Li, M. S. Li, L. X. Li,
X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang, J.C. Liu, X. J. Liu, Y. Q. Liu,
F. J. Lu, Q. Luo, X. Ma, G. Ou, W. X. Peng, R. Qiao, J. Y. Shi, D. L. Shi,
L. M. Song, X. Y. Song, G. X. Sun, X. L. Sun, Y. L. Tuo, J. Z. Wang,
C. W. Wang, P. Wang, W. S. Wang, X. Y. Wen, S. Xiao, S. L. Xiong, Y. B. Xu,
Y. P. Xu, W. C. Xue, S. Yang, M. Yao, Q. B. Yi, K. Zhang, P. Zhang,
D. L. Zhang, F. Zhang, H. M. Zhang, S. N. Zhang, Y. Q. Zhang, Z. Zhang,
S. Y. Zhao, X. Y. Zhao, Y. Zhao, C. Zheng, S. J. Zheng (IHEP), L. Chang,
Y. M. Chen, X. B. Han, J. Huang, J. P. Yu, K. K. Zhang (IAMCAS), L. Chen,
H. Geng, T. Hu, T. Jing, B. Q. Li, F. L. Ma, X. Meng, H. Y. Wu, J. Wu,
Z. G. Xiao, W. Zhang, Z. M. Zou (NSSC), K. Feng, Y. M. Zhang (AIR),
(The GECAM Mission Team) report:

During the commissioning phase, one satellite of GECAM mission, GECAM-B,
was triggered by a short GRB 210119A or a new SGR candidate
Swift J1851.2-6148 at 2021-01-19T02:54:09.850 (T0).
This burst was also observed by Fermi/GBM (GCN #29322
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 ), Swift/BAT
(GCN #29323
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 ) and Insight-HXMT (GCN #29329
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 ).

According to the GECAM-B light curves in about 8 keV-4 MeV,
this burst consists of a single pulse with a duration (T90) of
38.03 +/- 0.62 ms. The 20-ms peak counts rate is about 7000 cps while the
total counts is about 360 counts. A prominent spectral variation across
the burst duration is evident especially below 25 keV. The spectral
hardness measured by GECAM-B suggests that this bust is more likely
a short GRB rather than a typical SGR.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GECAM-B-tn210119_025409.png

Although the in-flight calibration of energy response and localization
has not been finalized yet, and this burst is rather short and weak,
GECAM-B localized this burst to the following position (J2000):
ra: 284.3 deg
dec: -60.4 deg
err: 6.4 deg
which is consistent with the position given by Swift/BAT 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.

This is the first published burst detected by GECAM mission.

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).

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), M. J. Moss (GWU), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of Swift/BAT trigger #1017711
(Moss, et al., GCN Circ. 29323
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 ).  The BAT ground-calculated position is
RA, Dec = 282.822, -61.767 deg which is 
  RA(J2000)  =  18h 51m 17.4s 
  Dec(J2000) = -61d 45' 59.7" 
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.

The mask-weighted light curve shows a single spike with a FRED-like shape,
rising sharply at T+0 sec and decaying to background by T+0.1 sec. 
T90 (15-350 keV) is 0.06 +- 0.02 sec (estimated error including systematics).

The time-averaged spectrum from T+0.00 to T+0.08 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.41 +- 0.22.  The fluence in the 15-150 keV band is 7.1 +- 0.9 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T-0.46 sec in the 15-150 keV band
is 1.0 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

In the original GCN circular, it was discussed that this event could be either a
previously unknown Soft Gamma Repeater (Swift J1851.2-6148) or short GRB 210119A.
While the BAT data alone is insufficient for us to make a definitive judgement as to the
nature of the source, our assessment of these data suggests that the event was more 
likely a short GRB for the following reasons.  First, the spectrum is rather hard, and the
position of the burst on the T90-hardness diagram is within the population of short GRBs.
Second, the light curve shows a FRED (fast rise, exponential decay) profile, more 
consistent with a GRB than with an SGR flare.  Third, the event location is 35 degrees 
away from the center of the galactic bulge.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/01017711000/BA/