EventsCirculars
Event: GRB 260313A / All circularsAbout

GRB 260313A — All Circulars

GCN 44047: Fermi Gamma-ray Burst Monitor trigger 795096033/260312500 (GRB 260313A) is unlikely to be a GRB
2026-03-18T15:31:39.425Z | rev 0
O.J. Roberts (Uni. of Galway, Ireland) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

"The Fermi Gamma-ray Burst Monitor (GBM) trigger GRB 260313A (trigger 795096033/260312500) 
at 12:00:28.58 UT on 13 March 2026, tentatively classified as a GRB (GCN 43995, GCN 43987), is in 
fact unlikely to be a GRB. The nature of this trigger is uncertain."
GCN 43998: Fermi GRB 260313A: Global MASTER-Net observations report
2026-03-14T01:16:55.362Z | rev 0
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, 
G.Antipov,  A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile,  F. Podesta, R.Podesta, E. Gonzalez  (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A.Sosnovskij (CrAO),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) 

MASTER-Kislovodsk robotic telescope  [1]  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 260313A ( Fermi GBM team, GCN 43987) errorbox  31381 sec after notice time and 31405 sec after trigger time at 2026-03-13 20:43:54 UT, with upper limit up to  18.7 mag. The observations began at zenith distance = 76 deg. The sun  altitude  is -49.0 deg. 

The galactic latitude b = 39 deg., longitude l = 17 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3184597

We obtain a following upper limits.  

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

      91 | 2026-03-13 12:01:49 |             MASTER- | (16h 26m 25.94s , +10d 37m 52.9s) |   C |    20 | 19.1 |        
      91 | 2026-03-13 12:01:49 |             MASTER- | (16h 27m 45.04s , +10d 04m 45.6s) |   C |    20 | 19.3 |        
     121 | 2026-03-13 12:02:19 |             MASTER- | (16h 26m 25.91s , +10d 36m 25.9s) |   C |    20 | 19.0 |        
     121 | 2026-03-13 12:02:19 |             MASTER- | (16h 27m 45.05s , +10d 03m 19.4s) |   C |    20 | 19.2 |        
     156 | 2026-03-13 12:02:49 |             MASTER- | (16h 26m 28.86s , +10d 38m 02.1s) |   C |    30 | 19.3 |        
     156 | 2026-03-13 12:02:49 |             MASTER- | (16h 27m 48.04s , +10d 04m 55.7s) |   C |    30 | 19.6 |        
     201 | 2026-03-13 12:03:29 |             MASTER- | (16h 26m 23.44s , +10d 37m 13.5s) |   C |    40 | 19.6 |        
     201 | 2026-03-13 12:03:29 |             MASTER- | (16h 27m 42.65s , +10d 04m 07.8s) |   C |    40 | 19.7 |        
     256 | 2026-03-13 12:04:19 |             MASTER- | (16h 26m 22.44s , +10d 38m 13.7s) |   C |    50 | 19.7 |        
     256 | 2026-03-13 12:04:19 |             MASTER- | (16h 27m 41.66s , +10d 05m 08.4s) |   C |    50 | 19.8 |        
     321 | 2026-03-13 12:05:19 |             MASTER- | (16h 26m 30.02s , +10d 37m 13.3s) |   C |    60 | 19.8 |        
     321 | 2026-03-13 12:05:19 |             MASTER- | (16h 27m 49.26s , +10d 04m 08.7s) |   C |    60 | 19.9 |        
     397 | 2026-03-13 12:06:30 |             MASTER- | (16h 26m 22.89s , +10d 36m 13.8s) |   C |    70 | 19.9 |        
     397 | 2026-03-13 12:06:30 |             MASTER- | (16h 27m 42.12s , +10d 03m 09.8s) |   C |    70 | 19.9 |        
     914 | 2026-03-13 12:15:13 |             MASTER- | (16h 27m 20.26s , +10d 02m 33.4s) |   C |    60 | 19.9 |        
     914 | 2026-03-13 12:15:13 |             MASTER- | (16h 26m 01.06s , +10d 35m 40.9s) |   C |    60 | 19.7 |        
    1058 | 2026-03-13 12:17:36 |             MASTER- | (16h 21m 46.15s , +08d 09m 04.5s) |   C |    60 | 19.8 |        
    1058 | 2026-03-13 12:17:36 |             MASTER- | (16h 20m 27.41s , +08d 42m 10.1s) |   C |    60 | 19.7 |        
    1131 | 2026-03-13 12:18:49 |             MASTER- | (16h 29m 54.57s , +08d 10m 15.0s) |   C |    60 | 19.9 |        
    1131 | 2026-03-13 12:18:49 |             MASTER- | (16h 28m 35.81s , +08d 43m 20.6s) |   C |    60 | 19.7 |        
    1644 | 2026-03-13 12:27:23 |             MASTER- | (16h 27m 24.44s , +10d 02m 47.0s) |   C |    60 | 19.9 |        
    1644 | 2026-03-13 12:27:23 |             MASTER- | (16h 26m 05.20s , +10d 35m 52.9s) |   C |    60 | 19.7 |        
    1787 | 2026-03-13 12:29:45 |             MASTER- | (16h 21m 44.33s , +08d 09m 55.3s) |   C |    60 | 19.8 |        
    1787 | 2026-03-13 12:29:45 |             MASTER- | (16h 20m 25.58s , +08d 42m 59.8s) |   C |    60 | 19.7 |        
    1859 | 2026-03-13 12:30:57 |             MASTER- | (16h 29m 49.96s , +08d 10m 36.5s) |   C |    60 | 19.8 |        
    1859 | 2026-03-13 12:30:57 |             MASTER- | (16h 28m 31.19s , +08d 43m 41.1s) |   C |    60 | 19.7 |        
    2387 | 2026-03-13 12:39:45 |             MASTER- | (16h 26m 07.46s , +10d 36m 46.3s) |   C |    60 | 19.4 |        
    2387 | 2026-03-13 12:39:45 |             MASTER- | (16h 24m 53.49s , +11d 09m 55.3s) |   C |    60 | 19.5 |        
    2530 | 2026-03-13 12:42:08 |             MASTER- | (16h 19m 23.33s , +09d 16m 12.3s) |   C |    60 | 19.2 |        
    2530 | 2026-03-13 12:42:08 |             MASTER- | (16h 20m 36.37s , +08d 43m 04.5s) |   C |    60 | 19.1 |        
    2601 | 2026-03-13 12:43:19 |             MASTER- | (16h 27m 22.55s , +09d 14m 45.8s) |   C |    60 | 19.3 |        
    2601 | 2026-03-13 12:43:19 |             MASTER- | (16h 28m 35.59s , +08d 41m 38.2s) |   C |    60 | 19.0 |        
    3152 | 2026-03-13 12:52:30 |             MASTER- | (16h 26m 13.15s , +10d 36m 57.7s) |   C |    60 | 18.0 |        
    3152 | 2026-03-13 12:52:30 |             MASTER- | (16h 24m 59.66s , +11d 10m 07.2s) |   C |    60 | 18.2 |        
    3298 | 2026-03-13 12:54:56 |             MASTER- | (16h 20m 35.88s , +08d 42m 46.2s) |   C |    60 | 17.7 |        
    3298 | 2026-03-13 12:54:56 |             MASTER- | (16h 19m 23.36s , +09d 15m 54.5s) |   C |    60 | 17.8 |        
    3370 | 2026-03-13 12:56:08 |             MASTER- | (16h 27m 25.46s , +09d 16m 34.4s) |   C |    60 | 17.7 |        
    3370 | 2026-03-13 12:56:08 |             MASTER- | (16h 28m 38.01s , +08d 43m 26.8s) |   C |    60 | 17.4 |        
   31435 | 2026-03-13 20:43:54 |   MASTER-Kislovodsk | (15h 57m 41.97s , +04d 46m 40.9s) |   C |    60 | 18.1 |        
   31540 | 2026-03-13 20:45:38 |   MASTER-Kislovodsk | (16h 01m 07.45s , +06d 40m 48.5s) |   C |    60 | 18.1 |        
   31645 | 2026-03-13 20:47:24 |   MASTER-Kislovodsk | (15h 48m 59.18s , +06d 43m 14.5s) |   C |    60 | 18.1 |        
   31753 | 2026-03-13 20:49:11 |   MASTER-Kislovodsk | (15h 55m 31.20s , +02d 53m 04.3s) |   C |    60 | 18.2 |        
   31853 | 2026-03-13 20:50:52 |   MASTER-Kislovodsk | (15h 53m 31.18s , +08d 36m 59.4s) |   C |    60 | 18.3 |        
   31960 | 2026-03-13 20:52:39 |   MASTER-Kislovodsk | (15h 54m 36.75s , +08d 36m 58.4s) |   C |    60 | 12.5 |        
   41297 | 2026-03-13 23:28:15 |   MASTER-Kislovodsk | (16h 09m 55.10s , +04d 56m 04.0s) |   C |    60 | 17.9 |        
   41401 | 2026-03-13 23:29:59 |   MASTER-Kislovodsk | (16h 05m 46.45s , +08d 42m 26.9s) |   C |    60 | 18.5 |        
   41506 | 2026-03-13 23:31:44 |   MASTER-Kislovodsk | (16h 07m 41.96s , +03d 01m 52.5s) |   C |    60 | 18.3 |        
   41604 | 2026-03-13 23:33:22 |   MASTER-Kislovodsk | (16h 13m 25.35s , +06d 48m 48.5s) |   C |    60 | 18.4 |        
   41707 | 2026-03-13 23:35:05 |   MASTER-Kislovodsk | (15h 59m 05.81s , +10d 38m 10.3s) |   C |    60 | 18.7 |        
   41820 | 2026-03-13 23:36:58 |   MASTER-Kislovodsk | (15h 43m 40.10s , +03d 02m 39.4s) |   C |    60 | 18.1 |        
   42252 | 2026-03-13 23:44:10 |   MASTER-Kislovodsk | (15h 54m 29.49s , +01d 08m 26.1s) |   C |    60 | 18.5 |        
   42360 | 2026-03-13 23:45:58 |   MASTER-Kislovodsk | (15h 41m 30.91s , +08d 43m 08.7s) |   C |    60 | 18.6 |        
   42478 | 2026-03-13 23:47:56 |   MASTER-Kislovodsk | (15h 37m 05.30s , +06d 50m 16.8s) |   C |    60 | 18.6 |        
   42581 | 2026-03-13 23:49:39 |   MASTER-Kislovodsk | (15h 46m 50.58s , +10d 36m 59.0s) |   C |    60 | 18.6 |        
   42681 | 2026-03-13 23:51:19 |   MASTER-Kislovodsk | (16h 06m 25.20s , +01d 06m 49.4s) |   C |    60 | 18.4 |        
   42802 | 2026-03-13 23:53:20 |   MASTER-Kislovodsk | (16h 11m 16.05s , +10d 36m 20.0s) |   C |    60 | 18.4 |        
   42914 | 2026-03-13 23:55:12 |   MASTER-Kislovodsk | (16h 12m 12.42s , +10d 36m 20.3s) |   C |    60 | 13.0 |        
   43021 | 2026-03-13 23:56:59 |   MASTER-Kislovodsk | (16h 13m 46.32s , +10d 36m 17.0s) |   C |    60 | 12.9 |        
   43195 | 2026-03-13 23:59:53 |   MASTER-Kislovodsk | (16h 19m 39.08s , +03d 02m 31.4s) |   C |    60 | 18.3 |        
   43305 | 2026-03-14 00:01:43 |   MASTER-Kislovodsk | (15h 33m 51.88s , +04d 55m 55.3s) |   C |    60 | 18.1 |        
   43425 | 2026-03-14 00:03:43 |   MASTER-Kislovodsk | (15h 42m 27.14s , +01d 09m 22.2s) |   C |    60 | 18.2 |        
   43540 | 2026-03-14 00:05:39 |   MASTER-Kislovodsk | (15h 53m 26.55s , +12d 31m 34.8s) |   C |    60 | 18.3 |        
   43643 | 2026-03-14 00:07:21 |   MASTER-Kislovodsk | (16h 25m 31.18s , +06d 50m 11.1s) |   C |    60 | 17.6 |        
   43748 | 2026-03-14 00:09:06 |   MASTER-Kislovodsk | (16h 05m 42.64s , +12d 31m 14.8s) |   C |    60 | 18.1 |        
   43962 | 2026-03-14 00:12:40 |   MASTER-Kislovodsk | (15h 54m 17.96s , -00d 44m 27.8s) |   C |    60 | 12.1 |        
   46601 | 2026-03-14 00:56:39 |   MASTER-Kislovodsk | (16h 06m 19.90s , -00d 45m 06.5s) |   C |    60 | 17.9 |        
   46699 | 2026-03-14 00:58:17 |   MASTER-Kislovodsk | (16h 18m 28.04s , +01d 10m 17.3s) |   C |    60 | 18.1 |        
Filter C is a clear (unfiltred) band. 


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

[1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023,  Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp.
http : // www.pereplet.ru/lipunov/625.html
GCN 43995: GRB 260313A: A Correction to the Fermi GBM Final Localization
2026-03-13T18:31:37.768Z | rev 0
O.J. Roberts (Uni. of Galway, Ireland) reports on behalf of the Fermi
Gamma-ray Burst Monitor Team.

"At 12:00:28.58 UT on 13 March 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260313A (trigger 795096033/260312500). An on-ground
calculated location, using the Fermi GBM trigger data, was initially reported
in GCN 43987 by the GBM Team.

Further analysis found the location of the short GRB to be inaccurate. We 
report the updated/refined location to be RA = 241.16, Dec = 5.80 (J2000 degrees, 
equivalent to J2000 16h 05m, 05d 48'), with a statistical uncertainty of 5.8 degrees.

The angle from the Fermi LAT boresight with this new position is 15 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260312500/quicklook/glg_skymap_all_bn260312500.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260312500/quicklook/glg_healpix_all_bn260312500.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260312500quicklook/glg_lc_medres34_bn260312500.gif"
GCN 43987: GRB 260313A: Fermi GBM Final Real-time Localization
2026-03-13T12:11:03.637Z | rev 0
The Fermi GBM team reports the detection of a likely LONG GRB

At 12:00:28 UT on 13 Mar 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260313A (trigger 795096033.584074 / 260313500).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 53.4, Dec = 33.3 (J2000 degrees, equivalent to J2000 03h 33m, 33d 17'), with a statistical uncertainty of 14.1 degrees.

The angle from the Fermi LAT boresight is 152.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260313500/quicklook/glg_skymap_all_bn260313500.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260313500/quicklook/glg_healpix_all_bn260313500.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260313500/quicklook/glg_lc_medres34_bn260313500.gif