GRB 210419B

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

At 21:10:28 UT on 19 Apr 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210419B (trigger 640559433.454802 / 210419882).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 307.1, Dec = -0.1 (J2000 degrees, equivalent to J2000 20h 28m, 0d 06'), with a statistical uncertainty of 1.4 degrees.

The angle from the Fermi LAT boresight is 18.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210419882/quicklook/glg_skymap_all_bn210419882.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/bn210419882/quicklook/glg_healpix_all_bn210419882.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210419882/quicklook/glg_lc_medres34_bn210419882.gif

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 210419B ( Fermi GBM team, GCN 29831
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 ) errorbox  8248 sec after notice time and 8274 sec after trigger time at 2021-04-19 23:28:23 UT, with upper limit up to  16.1 mag. The observations began at zenith distance = 71 deg. The sun  altitude  is -27.1 deg. 

The galactic latitude b = -22 deg., longitude l = 45 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1596170

We obtain a following upper limits.  

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

    8305 | 2021-04-19 23:28:23 |   MASTER-Kislovodsk | (20h 27m 02.66s , +00d 07m 45.8s) |   C |    60 | 13.7 |        
    8543 | 2021-04-19 23:32:21 |   MASTER-Kislovodsk | (20h 19m 02.82s , +00d 06m 53.2s) |   C |    60 | 16.1 |        
    8860 | 2021-04-19 23:37:38 |   MASTER-Kislovodsk | (20h 19m 55.36s , +02d 08m 29.6s) |   C |    60 | 14.7 |        
    8940 | 2021-04-19 23:38:58 |   MASTER-Kislovodsk | (20h 27m 46.29s , -01d 51m 11.2s) |   C |    60 | 14.2 |        
    9257 | 2021-04-19 23:44:15 |   MASTER-Kislovodsk | (20h 27m 02.09s , +00d 07m 54.1s) |   C |    60 | 15.1 |        
    9337 | 2021-04-19 23:45:35 |   MASTER-Kislovodsk | (20h 35m 01.94s , +00d 08m 45.7s) |   C |    60 | 15.0 |        
    9496 | 2021-04-19 23:48:14 |   MASTER-Kislovodsk | (20h 19m 07.83s , +00d 07m 34.0s) |   C |    60 | 12.6 |        
Filter C is a clear (unfiltred) band. 


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

P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al, 2020, arxiv:2011.07067) showed detection of a long GRB 210419B, which was also detected by Fermi-GBM (GCN #29831
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 ).

It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed a broad emission peak with the strongest peak at 2021-04-19 21:10:25.625 UT. The measured peak count rate is 1623 (+4 ,-4) cts/s above the background in the combined Veto data of four quadrants, with a total of 3054 (+641, -726) cts. The local mean background count rate was 181 (+89, --3) cts/s. We measure a T90 of 35 (+9, -12) s from the cumulative Veto light curve.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project