GCN Circular 33466

M.J. Liu, Y.L. Wang, Y. Liu, C. Zhang, Z.X. Ling, H.Q. Cheng, C.Z. Cui, D.W. Fan, 
H.B. Hu, J.W. Hu, M.H. Huang, C.C. Jin, D.Y. Li, J.Q. Li, H.Y. Liu, H. Sun, H.W. Pan, 
W.X. Wang, Q.Y. Wu, X.P. Xu, Y.F. Xu, H.N. Yang, M. Zhang, W.D. Zhang, Z. Zhang, 
D.H. Zhao, and W. Yuan (NAOC, CAS), report on behalf of the LEIA and Einstein Probe team:

The prompt emission of the extremely bright long-duration GRB 230307A (Fermi/GBM 
detection: GCN 33405
Not found
 
 
, 33407
Not found
 
 
, 33411
Not found
 
 
, 33414
Not found
 
 
; GECAM-B detection: GCN 33406
Not found
 
 
; 
Solar Orbiter STIX detection: GCN 33410
Not found
 
 
; AGILE/MCAL detection: GCN 33412
Not found
 
 
, 33444
Not found
 
 
; 
IPN triangulation: GCN 33413
Not found
 
 
; AstroSat detection: GCN 33415
Not found
 
 
; BALROG
localization: GCN 33416
Not found
 
 
; GRBAlpha detection: 33418, VZLUSAT-2: GCN 33424
Not found
 
 
,
Konus-Wind GCN 33427
Not found
 
 
, AstroSat CZIT: 33415, Swift/BAT upper limits: GCN 33431
Not found
 
 
, 
AstroSat LAXPC detection: GCN 33437
Not found
 
 
, ASO-S/HXI detection: GCN 33438
Not found
 
 
, MAXI/GSC 
upper limit: GCN 33448
Not found
 
 
) was detected by LEIA (Lobster Eye Imager for Astronomy) 
in the soft X-ray 0.5-4 keV band during one of its monitoring observations of 
the Large Magellanic Cloud. 

The observation was conducted from 2023-03-07T15:43:41 (25 s earlier than the 
Fermi GBM trigger time at 2023-03-07T15:44:06) to 2023-03-07T16:02:00 with 
a net exposure of 761 s. The GRB was detected within the extended FoV 
(about 0.6 deg outside the nominal 18.6deg x 18.6deg FoV) of LEIA, and the 
on-ground calculated position is RA=60.6, Dec=-75.4, with an estimated 3-sigma 
error of 10 arcmin, which is consistent with the IPN localizaition (GCN 33461
Not found
 
 
). 
The lightcurve shows a burst profile which peaked at 2023-03-07T15:44:13 
in 0.5 - 4.0 keV, and droped quickly to a level comparable to the detection 
sensitivity within about 200 s. Given that the source is outside the nominal FoV, 
the estimation of the source flux is complex and subject to further 
investigation and will be published later.  

LEIA also conducted follow-up observations in 6 successive orbits covering 
the entire IPN error box from 2023-03-09UT00:47:26 to 2023-03-09UT10:32:34. 
The total good exposure is around 4000 s and no significant emission was detected. 
The derived upper limit of the LEIA is around 1e-11 erg/cm^2/s 
in the energy band of 0.5 - 4.0 keV.
 
LEIA (Zhang et al, ApJL, 941, 2) is a soft X-ray monitor (0.5 - 4.0 keV)
with a FoV of 340 square degrees aboard the SATech-01 satellite of the CAS,
launched on July 27, 2022. The above result is preliminary and the final
result will be published elsewhere.