GRB 200805A

Y. Shimizu (Kanagawa U),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka (ICRR), S. Torii (Waseda U), T. Tamura (Kanagawa U),
N. Cannady (GSFC/UMBC), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

At 13:31:12.629 UTC on 5 August 2020, the CALET Gamma-ray Burst Monitor
(CGBM) triggered on short GRB 200805A. The burst signal was seen
by the SGM detector only.
Because of a problem in one of the ground alert processing script,
the GCN notice was not distributed automatically for this event.

This short GRB is also clearly seen by the publicly available
INTEGRAL SPI-ACS light curve and was detected by Konus-Wind
(see the GCN IPN_RAW Notices).

The burst light curve shows a short pulse which starts at T-0.192 sec,
peaks at -0.144 sec and ends at T-0.032 sec. The T90 and T50 durations
measured by the SGM data are 0.144 +- 0.045 sec and 0.064 +- 0.036 sec
(40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1280669472/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.

T. Tamura (Kanagawa U),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka (ICRR), S. Torii (Waseda U), Y. Shimizu (Kanagawa U),
N. Cannady (GSFC/UMBC), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:


Using the CALET Gamma-Ray Burst Monitor (CGBM) event data and
publicly available INTEGRAl-SPI-ACS light curve data we have triangulated
the short GRB 200805A (Shimizu et al., GCN Circ. 28217
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to a preliminary CGBM-SPI-ACS annulus centered at
RA(J2000)=57.359 deg (03h 49m 26s) Dec(J2000)=-49.453 deg (-49d 27' 10"),
whose radius is 37.65(-5.06,+4.54) deg (3 sigma).

The portion of the annulus within 69.8 deg from
RA, Dec(J2000) = 315.5 deg, -33.3 deg was below the horizon for CALET.

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.

The INTEGRAL public data used for this analysis provided by
INTEGRAL Science Data Centre through
http://isdc.unige.ch/~savchenk/spiacs-online/
maintained by Volodymir Savchenko.

A. Ridnaia, S. Golenetskii, R. Aptekar, D. Frederiks, D. Svinkin,
and T. Cline on behalf of the Konus-Wind team,

K. Hurley, on behalf of the IPN,

and

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, report:

The short-duration GRB 200521A
(CALET-CGBM detection: Shimizu et al., GCN Circ. 28217
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 ;
CGBM-SPI-ACS triangulation: Tamura et al., GCN Circ. 28219
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was detected by CALET (CGBM), Konus-Wind, and
INTEGRAL (SPI-ACS) at about 48670 s UT (13:31:10).

We have triangulated it to a preliminary, 3 sigma error arc whose
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
  97.601 (06h 30m 24s) -31.467 (-31d 28' 01")
  Corners:
  97.403 (06h 29m 37s)  -31.623 (-31d 37' 23")
  121.103 (08h 04m 25s) -44.012 (-44d 00' 43")
  120.592 (08h 02m 22s) -43.397 (-43d 23' 49")
  97.798 (06h 31m 11s)  -31.310 (-31d 18' 36")
  84.870 (05h 39m 29s)  -13.195 (-13d 11' 43")
  84.208 (05h 36m 50s)  -12.881 (-12d 52' 52")
  ---------------------------------------------
The error arc area is 20.3 sq. deg, and its maximum
dimension is ~43.7 deg (the minimum one is ~27.6 arcmin).
The Sun distance was ~58 deg.

This arc may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB200805_T48670/IPN/

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