GRB 240317A

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

At 09:43:55 UT on 17 Mar 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240317A (trigger 732361440.302272 / 240317405).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 223.9, Dec = 19.1 (J2000 degrees, equivalent to J2000 14h 55m, 19d 06'), with a statistical uncertainty of 4.5 degrees.

The angle from the Fermi LAT boresight is 75.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240317405/quicklook/glg_skymap_all_bn240317405.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240317405/quicklook/glg_healpix_all_bn240317405.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240317405/quicklook/glg_lc_medres34_bn240317405.gif

V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik,  D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(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. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),

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

V. Yurkov, A. Gabovich
(Blagoveschensk Educational State University)

MASTER-Amur robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the Fermi GRB 240317A ( Fermi GBM team, GCN 35939
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 ) errorbox  12523 sec after notice time and 12555 sec after trigger time at 2024-03-17 13:13:10 UT, with upper limit up to  17.8 mag. The observations began at zenith distance = 69 deg. The sun  altitude  is -32.2 deg. 

MASTER-Tunka robotic telescope  located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 240317A errorbox  13217 sec after notice time and 13249 sec after trigger time at 2024-03-17 13:24:45 UT, with upper limit up to  13.5 mag. The observations began at zenith distance = 80 deg. The sun  altitude  is -20.7 deg. 

The galactic latitude b = 60 deg., longitude l = 24 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2400638

We obtain a following upper limits.  

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

   12585 | 2024-03-17 13:13:10 |         MASTER-Amur | (14h 48m 33.06s , +20d 16m 10.5s) |   C |    60 | 17.7 |        
   12665 | 2024-03-17 13:14:30 |         MASTER-Amur | (14h 57m 03.77s , +20d 17m 46.4s) |   C |    60 | 17.4 |        
   12745 | 2024-03-17 13:15:50 |         MASTER-Amur | (14h 59m 54.03s , +22d 11m 46.7s) |   C |    60 | 17.6 |        
   12825 | 2024-03-17 13:17:10 |         MASTER-Amur | (15h 08m 25.81s , +22d 11m 31.4s) |   C |    60 | 17.4 |        
   13067 | 2024-03-17 13:21:11 |         MASTER-Amur | (14h 38m 28.91s , +18d 21m 26.0s) |   C |    60 | 17.8 |        
   13146 | 2024-03-17 13:22:31 |         MASTER-Amur | (14h 46m 52.55s , +18d 23m 18.1s) |   C |    60 | 17.7 |        
   13280 | 2024-03-17 13:24:45 |        MASTER-Tunka | (14h 41m 05.02s , +21d 19m 39.8s) |   C |    60 | 13.5 |        
Filter C is a clear (unfiltred) band. 


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

J. Joshi (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/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., 2021, JApA, 42, 73) showed the detection of a long-duration GRB 240317A which was also detected by Fermi GBM (Fermi-GBM team, GCN Circ. 35939
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 ).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-03-17 09:44:00.50 UTC. The measured peak count rate associated with the burst is 216 (+47, -19) counts/s above the background in the combined data of all quadrants, with a total of 1230 (+201, -216) counts. The local mean background count rate was 383 (+3, -3) counts/s. Using cumulative rates, we measure a T90 of 10 (+2, -4) s. We caution that there is a 0.3 s readout dead time in CZTI data just after the burst. Hence, the T90 can be as large as 13 s for this GRB, with a lower limit of 6 s as estimated above by cumulative rates. 

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-03-17 09:43:58.74 UTC. The measured peak count rate associated with the burst is 408 (+77, -67) counts/s above the background in the combined data of all quadrants, with a total of 2969 (+539, -536) counts. The local mean background count rate was 1833 (+8, -9) counts/s. We measure a T90 of 17 (+3, -4) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb