GRB 050525B
GCN Circular 3477
Subject
GRB 050525B: INTEGRAL shows it is unrelated to GRB050525A
Date
2005-05-25T13:15:23Z (20 years ago)
From
Sandro Mereghetti at IASF/CNR <sandro@mi.iasf.cnr.it>
S. Mereghetti, D. Gotz (IASF, Milano), N. Mowlavi, S. Shaw, M. Beck (ISDC,
Versoix), J. Borkowski (CAMK, Torun), A. von Kienlin, A. Rau, G. Lichti
(MPE, Garching) on behalf of the IBAS Team report:
The bright event seen by Konus/Wind about 2800 s after GRB 050525 and
reported in GCN 3474 (Golenetskii et al. 2005) has also been detected by
the Anti-Coincidence Shield of the SPI instrument on board INTEGRAL,
starting at 00:49:50 UT and lasting about 16 seconds.
At that time the position of GRB 050525A (GCN Circ. 3466, 3467, 3472) was
inside the field of view of the IBIS imaging instrument. No signal was
detected from this direction, indicating that the event at 00:49:50 UT is
not related with GRB 050525A and is most likely another bright GRB.
This message can be cited.
GCN Circular 3490
Subject
GRB 050525B: Swift-BAT observations
Date
2005-05-26T18:09:33Z (20 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <jayc@milkyway.gsfc.nasa.gov>
J. Cummings (GSFC/NRC), L. Barbier (GSFC), S. Barthelmy (GSFC),
E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (UMD),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), T. Mitani (ISAS),
D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC),
G. Sato (ISAS), M. Suzuki (Saitama), J. Tueller (GSFC),
on behalf of the Swift-BAT team:
From 00:49:50 to approximately 00:50:06 UT Swift-BAT recorded
high rates from GRB 050525B (Mereghetti et al., GCN Circ 3477,
Golenetskii et al. GCN Circ 3474). The burst was not in the BAT
field of view, and was primarily detected in the high energy
band (>100 keV) through the side or bottom of the instrument.
Thus BAT did not find a position, and detailed information
about the flux and spectrum is not available.
The light curve is complex. Peaks occur at 00:49:50, 00:49:52,
00:49:55, and a complex of peaks with the most intense flux from
00:49:59 to 00:50:06. The peak rate in a 64 ms interval was
recorded at 00:50:00.12.
(The association of the small peak at 00:49:39, which initiated
BAT trigger 130094, with the others is uncertain, because GRB
050525B was not coded by the mask and, unlike the other peaks,
the trigger peak's energy profile is not obviously that of
exposure through the side or bottom of the instrument.)
The light curve is available at:
http://swift.gsfc.nasa.gov/docs/swift/results/releases/images/GRB050525b/
We note that GRB 050525A was well below the Earth horizon from
the point of view of Swift at the time of this burst, and
therefore cannot be connected with this GRB 050525B event.