GRB 200815A
GCN Circular 28255
Subject
GRB 200815A: CALET Gamma-Ray Burst Monitor detection of a short burst
Date
2020-08-17T12:01:19Z (5 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
K. Kobayashi (Waseda 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, Y. Akaike (Waseda U),
Y. Shimizu, 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 21:02:43.555 UTC on 15 August 2020, the CALET Gamma-ray Burst Monitor
(CGBM) triggered on short GRB 200815A. The burst signal was seen mainly by
the SGM detector.
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.
The burst light curve shows a short pulse which starts at T-0.056 sec,
peaks at T-0.040 sec and ends at T+0.064 sec. The T90 and T50 durations
measured by the SGM data are 0.104 +- 0.025 sec and 0.056 +- 0.008 sec
(40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1281560544/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.
GCN Circular 28274
Subject
IPN triangulation of GRB 200815A (short)
Date
2020-08-20T18:29:49Z (5 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
K. Hurley, on behalf of the IPN,
I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak,
and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, and
W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:
The short-duration 200815A
(CALET-GBM detection: Kobayashi et al., GCN Circ. 28255)
has been detected by Konus-Wind, INTEGRAL (SPI-ACS),
Mars-Odyssey (HEND), and Swift (BAT), so far,
at about 75764 s UT (21:02:44).
The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
356.686 (23h 46m 45s) -27.798 (-27d 47' 54")
Corners:
356.902 (23h 47m 36s) -27.811 (-27d 48' 41")
356.836 (23h 47m 21s) -28.066 (-28d 03' 58")
356.471 (23h 45m 53s) -27.785 (-27d 47' 05")
356.536 (23h 46m 09s) -27.528 (-27d 31' 39")
---------------------------------------------
The error box area is 357 sq. arcmin, and its maximum
dimension is 36 arcmin (the minimum one is 7 arcmin).
The Sun distance was 148 deg.
This box may be improved.
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB200815_T75768/IPN
The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.
GCN Circular 28275
Subject
GRB 200815A: MASTER optical observations
Date
2020-08-20T20:09:03Z (5 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, K.Zhirkov,P.Balanutsa,A.Kuznetsov,F.Balakin,
V.Vladimirov, A.Chasovnikov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Topolev, V.Senik, T.Pogrosheva,
D.Kuvshinov(Lomonosov Moscow State University, SAI, Physics Department),
D. Buckley(South African Astronomical Observatory),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
R. Podesta, C.Lopez, F. Podesta, C.Francile(Observatorio Astronomico Felix Aguilar OAFA),
H.Levato(Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE),
R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias),
O.A. Gres, N.M. Budnev (Irkutsk State University, API),
A. Gabovich, Yu. Sergienko, V.Yurkov (Blagoveschensk Educational State University)
MASTER Global Robotic Net (Lipunov et al., 2010, Advances in Astronomy, vol. 2010, p.30L)
started GRB 2008015A (IPN triangulation, Hurley et al. GCN 28274) errorbox observations
22881 sec after notice time (1 days 3261 sec after trigger time) at
2020-08-16 21:57:09 UT in MASTER-Tavrida, with upper limit up to 19.0 mag.
The observations began at zenith distance = 76 deg. The sun altitude was -32.5 deg.
MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory)
started inspect of the IPN GRB200815.88 errorbox 26435 sec after notice
time and 1 days 6815 sec after trigger time at 2020-08-16 22:56:23 UT,
with upper limit up to 17.4 mag. The observations began at zenith
distance = 82 deg. The sun altitude is -37.9 deg.
The galactic latitude b = -60 deg., longitude l = 98 deg.
We didn't find OT.
Real time updated cover map is available here:
https://master.sai.msu.ru/site/master2/ligo_1.php?id=11510
We obtained the following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
89752 | 2020-08-16 21:57:09 | MASTER-Tavrida | (23h 39m 20.64s , -28d 07m 25.9s) | C | 180 | 19.0 |
89952 | 2020-08-16 22:00:30 | MASTER-Tavrida | (23h 48m 25.29s , -28d 08m 52.4s) | C | 180 | 18.8 |
90803 | 2020-08-16 22:14:41 | MASTER-Tavrida | (23h 48m 28.58s , -28d 07m 39.8s) | C | 180 | 18.9 |
93305 | 2020-08-16 22:56:23 | MASTER-IAC | (23h 45m 32.32s , -28d 00m 54.2s) | C | 180 | 17.1 |
93915 | 2020-08-16 23:06:33 | MASTER-IAC | (23h 45m 29.43s , -28d 00m 38.4s) | C | 180 | 17.4 |
Filter C is a clear (unfiltred) band.
Cover map is available at
http://master.sai.msu.ru/static/images/MASTERGRB200815Acmap.png
The observation and reduction will continue.
The message may be cited.
GCN Circular 28277
Subject
Konus-Wind observation of GRB 200815A
Date
2020-08-21T13:06:17Z (5 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
Konus-Wind observation of GRB 200815A
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks,
M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:
The short-duration GRB 200815A
(CALET-GBM detection: Kobayashi et al., GCN Circ. 28255;
IPN triangulation: Hurley et al., GCN Circ. 28274)
triggered Konus-Wind at T0=75768.265 s UT (21:02:48.265).
The burst light curve shows a single pulse
which starts at ~T0-0.03 s and has a total duration of ~0.2 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB200815_T75768/
As observed by Konus-Wind, the burst
had a fluence of 3.04(-0.39,+0.43)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.038 s,
of 3.33(-0.73,+0.77)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+0.192 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.37(-0.23,+0.27)
and Ep = 516(-89,+116) keV (chi2 = 35/45 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.3
(chi2 = 35/44 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.