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GCN Circular 33802

Subject
IPN triangulation of GRB 230512A
Date
2023-05-15T10:17:05Z (a year ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko, and
T. Cline on behalf of the Konus-Wind team,

A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,

and

S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, report:

The bright GRB 230512A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 33778Not found
 
 
;
Roberts et al., GCN Circ. 33785Not found
 
 
;
AstroSat-CZTI detection: Navaneeth et al., GCN Circ. 33779Not found
 
 
;
Fermi-LAT detection: Maheso et al., GCN Circ. 33780Not found
 
 
;
GRBAlpha detection: Dafcikova et al., GCN Circ. 33795Not found
 
 
)
was detected by Fermi (GBM trigger 705565670; LAT), AstroSat (CZTI),
Konus-Wind, GRBAlpha, and Swift (BAT) at about 23265 s UT (06:27:45).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a Konus-GBM annulus centered at
RA(2000)=252.326 deg (16h 49m 18s) Dec(2000)=-21.096 deg (-21d 05' 46"),
whose radius is 71.928 +/- 0.057 deg (3 sigma).

The LAT position reported by Maheso et al. (GCN Circ. 33780Not found
 
 
)
is consistent with the annulus. The annulus combined with
the LAT (90 % containment, statistical-only) error circle
gives the following error box:
---------------------------------
 RA(2000), deg   Dec(2000), deg
---------------------------------
  Center:
    295.4160    +38.4139
  Corners:
    295.6484    +38.1720
    295.7385    +38.2604
    295.1883    +38.6501
    295.0849    +38.5708
---------------------------------
The error box area is 242.2 sq. arcmin (a factor of ~4
smaller than that of the LAT error circle), and its maximum
dimension is 0.6 deg (the minimum one is 6.8 arcmin).
The Sun distance was 96 deg.

This box may be improved.

The Swift-XRT sources #2, 4, 8 (https://www.swift.ac.uk/xrt_products/TILED_GRB00111/) are inside the error box.

The OT candidate (Belkin et al., GCN Circ. 33796Not found
 
 
) is outside the error box.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230512_T23265/IPN/

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.