GRB 160625B
GCN Circular 19683
Subject
GRB 160625B: Global MASTER-Crimea prompt optical emission detection (fwd)
Date
2016-07-12T19:03:59Z (9 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov,
P.Balanutsa, A.Kuznetsov, D.Kuvshinov,
Lomonosov Moscow State University, Sternberg Astronomical Institute
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias
D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory
O.Gres, K.Ivanov, S.Yazev, N.M.Budnev, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Senik
Kislovodsk Solar Station of the Pulkovo Observatory
V.Yurkov, Yu.Sergienko, A.Gabovich, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk
Ricardo Podesta, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)
Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
MASTER-Crimea robotic telescope (testing camera 20 cm) pointing to LAT
error box (Dirirsa et al., GCN 19580) 12 sec after LAT notice time and 66
sec after trigger time at
2016-06-25 22:44:30 UT in unfiltered mode. The OT was about 9.55 +-0.01
mag at this moment ( 0.2B + 0.8R with respect to USNOB1.0 stars)
The automatic photometry and astrometry are:
+id- time coord2000 mag
179841451 22:44:30.055 20h 34m 23.49s , +06d 55m 07s.6 9.55
179890027 22:44:30.055 20h 34m 23.52s , +06d 55m 07s.9 10.11
179845079 22:45:00.899 20h 34m 23.50s , +06d 55m 07s.8 10.03
179878574 22:45:37.806 20h 34m 23.52s , +06d 55m 08s.0 10.54
179909653 22:46:25.105 20h 34m 23.53s , +06d 55m 07s.8 11.46
179883969 22:46:25.105 20h 34m 23.52s , +06d 55m 07s.8 11.04
179895778 22:47:20.57 20h 34m 23.52s , +06d 55m 07s.9 11.52
179901960 22:48:26.68 20h 34m 23.52s , +06d 55m 08s.0 11.91
The delay with internet problems last time .
The message may be cited.
GCN Circular 19680
Subject
GRB 160625B: TSHAO optical observations
Date
2016-07-11T12:56:47Z (9 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), P.
Minaev (IKI), I. Reva (Fesenkov Astrophysical Institute), A. Volnova
(IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up
collaboration:
We observed the field of GRB 160625B (Dirirsa et al., GCN 19580; Burns
et al. GCN 19581) with Zeiss-1000 (East) 1-m telescopes of Tien Shan
Astronomical Observatory. We obtained several images in R filter on July
8 and 10. We detect optical afterglow of GRB 160625B (Troja et al., GCN
19588; Oates et al., GCN 19589). Preliminary photometry of a combined
image is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2016-07-08 19:01:43 12.9172 R 30*300 21.60 0.15 22.7
2016-07-10 18:19:18 14.8713 R 29*300 21.64 0.08 23.3
Photometry is based on nearby USNO-B1.0 stars reported in GCN 19605
(Mazaeva et. al).
GCN Circular 19651
Subject
GRB 160625B: RTT150 optical observations
Date
2016-07-04T13:42:20Z (9 years ago)
From
Rodion Burenin at IKI, Moscow <rodion@hea.iki.rssi.ru>
I. Bikmaev, E. Irtuganov, N. Sakhibullin (KFU/AST),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
I. Khamitov, H. Kirbiyik (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)
report:
We observed field of Fermi GRB 160625B (Dirirsa et al. GCN 19580) at
the position of optical afterglow (Troja et al. ,GCN 19588) with
Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National
Observatory, Turkey) using the TFOSC instrument.
We obtained series of Rc exposures in June 30 / July 01(6 frames x 600
sec, UT = 00:21 - 01:30 ), in July 01 / 02 (4 frames x 900 sec, UT =
00:36 - 01:42), in July 02 / 03 (6 frames x 900 sec, UT = 23:49 -
01:29), and in July 03 / 04, 2016, (14 frames x 600 sec, UT = 22:50 -
01:39). The optical transient (Troja et al. GCN 19588; Oates et
al. GCN 19589; Kuroda et al. GCN 19599; Xu et al. GCN 19600; D'Elia et
al. GCN 19601; Watson at al. GCN 19602; Karpov et al. GCN 19603;
Mazaeva et al. GCN 19605, 19620; Moskvitin et al. GCN 19611;
Gorbovskoy et al. GCN 19612; Batsch et al. GCN 19615; Cobb et al. GCN
19616; Guidorzi et al. GCN 19640; Valeev et al. GCN 19642) is clearly
detected in each images.
Using USNO-B1 0969-0608410 star at RA,DEC = 308.580912 +06.909881
(J2000.0) with R = 16.73 mag as a reference we estimated the
Rc-magnitudes of the afterglow in stacked images:
T-T0, Mag., Mag.err
days
5.09 20.69 +- 0.03
6.10 20.96 +- 0.04
7.08 21.04 +- 0.03
8.06 21.24 +- 0.04
RTT-150 data show that OT is fading at approximately the same power
law rate as it was observed earlier.
GCN Circular 19642
Subject
GRB 160625B: SAO RAS monitoring
Date
2016-07-02T13:55:29Z (9 years ago)
From
Vladimir Sokolov at SAO RAS <sokolov@sao.ru>
A. F. Valeev, A. S. Moskvitin, G. M. Beskin, V. V. Vlasyuk, V. V. Sokolov
(SAO RAS, Russia) report on behalf of the larger GRB follow-up team.
We observed the GRB160625B field (Dirirsa et al. GCNC #19580) with
two optical telescopes of SAO RAS: the 6-m BTA + Scorpio (B, V, Rc, Ic
bands),
and the 1-meter telescope Zeiss-1000 + CCD photometer (Rc band)
at the June 29/30 night.
We clearly detected an OT (Troja et al. ,GCNC #19588; Karpov et al GCNC
#19603;
Alexander et al. GCNC #19606) in our stacked frames.
Preliminary Rc band results are shown in the following table.
These estimations are based on the R2 magnitudes of the same nearby
USNO-B1 stars as in our previous GCNC #19611.
Mid_date, UT T-T0,d exp,s R_mag err Telescope
=================================================================
June, 29.827 3.880 3 x 200 20.53 +/- 0.07 BTA
June, 29.983 4.036 8 x 300 20.56 +/- 0.20 Zeiss-1000
GCN Circular 19640
Subject
GRB 160625B: LCOGT FTN observations
Date
2016-07-01T16:43:58Z (9 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath),
A. Gomboc (U. Nova Gorica), on behalf of a large collaboration report:
We observed Fermi GRB 160625B (Dirirsa et al. GCN 19580) with the 2-m
LCOGT Faulkes Telescope North in Hawaii on July 01 from 11:12 UT to
12:46 UT with the SDSS-r filter for a total exposure of 1500 s. We
clearly detect the optical afterglow (Troja et al. GCN 19588; Oates et
al. GCN 19589; Kuroda et al. GCN 19599; Xu et al. GCN 19600; D'Elia et
al. GCN 19601; Karpov et al. GCN 19603; Mazaeva et al. GCN 19605;
Moskvitin et al. GCN 19611; Gorbovskoy et al. GCN 19612; Batsch et al.
GCN 19615; Cobb et al. GCN 19616) with a magnitude of r=21.15 +- 0.15
mag at a mid epoch of 5.5 days post burst, as calibrated against nearby
USNOB1 stars.
GCN Circular 19620
Subject
GRB 160625B: TSHAO optical observations, correction GCN 19619
Date
2016-06-29T15:45:03Z (9 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
Corrected text of the GCN 19619 (Mazaeva et al.) should be as follows.
E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), P.
Minaev (IKI), I. Reva (Fesenkov Astrophysical Institute), A. Volnova
(IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up
collaboration:
We observed the field of GRB 160625B (Dirirsa et al., GCN 19580; Burns
et al. GCN 19581) with Zeiss-1000 (East) 1-m telescopes of Tien Shan
Astronomical Observatory. We obtained several images in R filter
starting on June 28 (UT) 18:12:30. We detect optical afterglow of GRB
160625B (Troja et al., GCN 19588; Oates et al., GCN 19589).
Preliminary photometry of a combined image is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2016-06-28 18:12:30 2.86135 R 63*120 20.32 0.06 22.7
Photometry is based on nearby USNO-B1.0 stars reported in GCN 19605
(Mazaeva et. al).
I thank D. A. Kann who noticed the apparent error.
GCN Circular 19619
Subject
GRB 160625B: TSHAO optical observations
Date
2016-06-29T15:18:38Z (9 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), P.
Minaev (IKI), I. Reva (Fesenkov Astrophysical Institute), A. Volnova
(IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up
collaboration:
We observed the field of GRB 160625B (Dirirsa et al., GCN 19580; Burns
et al. GCN 19581) with Zeiss-1000 (East) 1-m telescopes of Tien Shan
Astronomical Observatory. We obtained several images in R filter
starting on June 27 (UT) 20:15:57. We detect optical afterglow of GRB
160625B (Troja et al., GCN 19588; Oates et al., GCN 19589).
Preliminary photometry of a combined image is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2016-06-27 20:15:57 1.92994 R 54*60 19.56 0.06 22.0
Photometry is based on nearby USNO-B1.0 stars reported in GCN 19605
(Mazaeva et. al).
GCN Circular 19617
Subject
GRB 160625B CALET Gamma-Ray Burst Monitor detection
Date
2016-06-29T08:09:50Z (9 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
S. Nakahira (JAXA), A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
Y. Yamada (AGU), K. Yamaoka (Nagoya U), I. Takahashi (IPMU), Y. Asaoka,
S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR),
M. L. Cherry (LSU), S. Ricciarini (U of Florence) P. S. Marrocchesi (U of Siena)
and the CALET collaboration:
The long-duration GRB 160625B (Burns et al., GCN Circ. 19581;
Dirirsa et al. GCN Circ. 19586; INTEGRAL-ACS #7495) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 22:40:15.49 on 25 June 2016. The burst signal
was seen by all CGBM instruments.
The light curve of the SGM shows a precursor emission starting at T+0.5 sec,
peaking at T+1 sec and ending at T+2 sec. Then, the bright main burst episode
follows starting from T+183 sec and ending at T+233 sec with overlapping
multiple pulses. The T90 duration measured by the SGM data for the main
bright episode is 20.0 +- 0.4 sec (40-1000 keV). The T90 duration of the precursor
emission measured by the SGM data is 0.8 +- 0.1 sec (40-1000 keV).
The light curve is available at
http://cgbm.calet.jp/cgbm_trigger/flight/1150929566/
Furthermore, the main pulse was also detected by Imaging Calorimeter (IMC;
plastic scintillating fibers) and Charge Detector (CHD; plastic scintillators),
which are subsystems of the CALET main instrument Calorimeter (CAL). The
incident angles for this burst was 61 degrees and 67 degrees from the boresight
of CAL at the trigger time and at the main peak, respectively.
The CAL gamma-ray analysis (>1 GeV) is in progress.
The CALET data used in this analysis are provided by the Waseda CALET Operation
Center located at the Waseda University.
GCN Circular 19616
Subject
GRB 160625B: SMARTS optical/IR afterglow observations
Date
2016-06-28T20:56:18Z (9 years ago)
From
Bethany Cobb at GWU <bcobb@gwu.edu>
B. E. Cobb (GWU) reports:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we
obtained optical/IR imaging of the error region of GRB 160625B
(GCN 19580, Dirirsa et al.) with a mid-exposure time of about
32 hours post-burst (2016-06-27 06:51 UT). Total summed exposure
times amounted to 36 minutes in I and 30 minutes in J.
The afterglow of GRB 160625B (e.g. GCN 19585, Melandri et al.;
GCN 19588, Troja et al.; GCN 19589, Oates et al.) is detected
in our images. Preliminary comparison to USNO-B1.0 stars in I
and 2MASS stars in J indicates the following afterglow magnitudes:
mid-exposure
time post-burst I mag J mag
1.338 days 18.9+/-0.2 18.6+/-0.1
GCN Circular 19615
Subject
Pi of the Sky detection of an optical flash accompanying GRB 160625B
Date
2016-06-28T19:34:52Z (9 years ago)
From
Lech Wiktor Piotrowski at U Warsaw <lewhoo@fuw.edu.pl>
T. Batsch, A.J. Castro-Tirado, R. Cunniffe, H. Czyrkowski, A. ��wiek, M. ��wiok, R. D��browski,
M. Jel��nek, G. Kasprowicz, A.Majcher, K. Ma��ek, L. Mankiewicz, K. Nawrocki, ��. Obara,
R. Opiela, M. Siudek, M. Soko��owski, L. W. Piotrowski, R. Wawrzaszek, G. Wrochna,
A Zadro��ny, M. Zaremba, A.F. ��arnecki (Pi of the Sky Collaboration)
Following GCN 19603 we present the reconstructed light curve of GRB 160625B.
One of four Pi of the Sky North detectors located at INTA - El Arenosillo
observatory in Mazag��n near Huelva, Spain imaged the region of GRB 160625B
(Swift-XRT error circle (Melandri, et al., GCN 19585), at a position RA, Dec =
20:34:23.50, +6:55:8.1) before, during and after the GRB with 10s exposures
(the exposures were taken in white light, IR-cut and UV-cut filters only,
to achieve deepest detection limit).
Cameras of the Pi of the Sky North observatory were observing the position of the GRB160625B
48s after Fermi GBM trigger 488587220 time (Jun 25 22:40:16.28 UT) 140 seconds
before the LAT 488587408 trigger (Jun 25 22:43:24.82 UT). We observed optical emission
at the position given by Swift XRT recording a bright light curve starting -5.9 s
before the LAT trigger. The first 10 s exposure shows initial magnitude of ~9.18 (unfiltered)
brightening to ~8.04 on the second exposure, than becoming gradually dimmer.
It is important to note that both cameras, 35 and 39, identified a new object
on exposures starting just before the time of the trigger. Below we give the light curve of
GRB 160625B separately for two cameras:
For camera id = 35
t - t0 MagV ErrV
-5.90351900 9.17858000 0.01979590
7.30034010 8.04185240 0.00692530
20.50411000 8.85256720 0.01464740
33.70891000 9.16411390 0.01958250
46.91391000 9.35221170 0.02310580
60.12562000 9.48356820 0.02605830
73.33060000 9.76273220 0.03348310
86.53484000 9.88869010 0.03764580
110.75906000 10.36167800 0.05831040
123.96549000 10.36315500 0.05835510
137.17366000 10.65792100 0.07717340
150.37855000 10.78365300 0.08672800
163.58296000 10.90103300 0.09643880
176.79191000 11.10503700 0.11532510
190.00141000 11.27645400 0.13539200
203.20498000 11.43088800 0.15646540
216.40969000 11.52125300 0.16944510
229.59719000 11.66219300 0.19535900
242.80196000 11.97388500 0.26215110
255.98556000 11.44272600 0.15893520
269.18835000 12.22780400 0.33061590
282.39288000 11.70644300 0.20138410
295.59737000 12.10355100 0.29637090
308.80171000 12.01954200 0.27279960
348.41412000 12.14943500 0.30407830
388.02095000 12.20940300 0.32526530
For camera id = 39
t-t0 MagV ErrV
-0.21738000 8.08332450 0.00848860
15.13208000 8.39624730 0.01125160
30.48032000 9.30388780 0.02600590
45.83497000 9.38090950 0.02766380
61.69324000 9.60060770 0.03356240
77.04026000 9.76118030 0.03894990
92.38808000 10.00068600 0.04923380
107.71683000 10.23761200 0.05958340
123.06963000 10.43917000 0.07335490
138.42439000 10.63567700 0.08856020
153.77331000 10.78614800 0.10097800
169.12145000 10.99128200 0.12175100
184.46995000 11.23445500 0.15126550
199.82483000 11.04686000 0.12786780
215.17292000 11.27135000 0.15866670
232.56505000 11.47398300 0.19109480
247.89472000 11.99905600 0.31466480
263.75136000 11.78799000 0.25153010
279.09823000 12.08530200 0.33607390
294.44611000 11.95412600 0.30025650
325.14680000 12.14188100 0.35312590
432.59537000 12.18551500 0.36922680
Indicated errors are statistical only. Estimated systematic uncertainty of the image calibration is around 0.06-0.08 mag.
T0 is the Fermi GBM trigger 488587408 time (Jun 25 22:43:24.82 UT) and t is the time of shutter oppening. Each image taken covers approximately 400 square degrees. The
magnitudo limit was about 12.5 mag.
Pi of the Sky observations are performed in wide visible band, with IR-cut and UV-cut filters only. We calibrate our observations to the reference stars from Tycho 2 using
the transformation from Tycho to Pi of the Sky system given by:
VPi = VT + 0.235313 - 0.292266*(BT - VT)
Due to the proximity of the burst to the edge of our FoV, the transient was not detected automatically. However, this allowed us to record it with two cameras, with
exposures slightly shifted in time.
The light curve is available at: http://grb.fuw.edu.pl/results/gamma-ray-bursts/grb160625b/.
More information will be published at http://grb.fuw.edu.pl and http://grb.fuw.edu.pl/results/gamma-ray-bursts/grb160625b/
[GCN OPS NOTE(04jul16): Per author's request, the GRB name in the 2nd paragraph was corrected,
and RC was added to the author list.]
GCN Circular 19612
Subject
GRB 160625B: Global MASTER-Net prompt optical emission detection
Date
2016-06-28T14:05:38Z (9 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
E. Gorbovskoy, V. Lipunov, N.Tyurina, V.Kornilov,
P.Balanutsa, A.Kuznetsov, D.Kuvshinov,
Lomonosov Moscow State University, Sternberg Astronomical Institute
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias
D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory
O.Gres, K.Ivanov, S.Yazev, N.M.Budnev, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Senik
Kislovodsk Solar Station of the Pulkovo Observatory
V.Yurkov, Yu.Sergienko, A.Gabovich, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk
Ricardo Podesta, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)
Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
MASTER-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru)
was pointed to the GRB 160625B (Burns et al., GCN19581) 31 sec after GBM
notice time and 57 sec after GBM trigger (131 sec before LAT Trigger,
Dirirsa et al., GCN 19580) at 2016-06-25 22:41:13UT .
Starting from this time we continiously observed Swift X-ray
error box (Melandri et al., GCN 19585) by MASTER-IAC wide field camera
with 5 sec unfiltered exposition. We have several thousands frames.
The OT appears at 22 43 30 (+- 2.5 sec) UT and rised to maximum ~8 mag
after ~5 sec at RATIR position (Troja et al., GCN 19588).
The prompt optical emission strongly correlated with Konus Wind gamma ray
light curve ( Svinkin et al., GCN 19604 ).
MASTER-IAC robotic telescope started OT error box observation 43
sec after LAT notice time and 95 sec after trigger time at 2016-06-25 22:44:59
in two polarisations. The OT was about ~ 9.7 mag at this moment ( 0.2B +
0.8R with respect to USNOB1.0 stars)
The delay with publication connected with installation new MASTER
telescope at Argentina (http://master.sai.msu.ru/masternet/).
The message may be cited.
GCN Circular 19611
Subject
GRB 160625B: SAO RAS optical observations
Date
2016-06-28T14:00:13Z (9 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
A. Moskvitin (SAO RAS, Russia) report on behalf of the larger team.
After fruitful multiband observations of the GRB 160625B optical
counterpart by several telescopes including Mini-MegaTORTORA
system located at SAO RAS (Karpov et al. GCNC #19603)
we observed the GRB160625B field (Dirirsa et al. GCNC #19580)
with the 1-meter telescope Zeiss-1000 of SAO RAS on June, 27.923
(1.976 days after the trigger). 7 x 300 sec. images in Rc band
were obtained under good weather conditions.
The OT is clearly visible in separate frames and in the stacked frame.
It's position is perfectly consistent with the coordinates reported by
Troja et al. (GCNC #19588) and Alexander et al. (GCNC #19606).
During our observations the OT magnitude was R = 19.87 +/- 0.07.
This estimation is based on the R2 magnitudes of nearby USNO-B1 stars,
without any correction for the Galactic extinction in the GRB direction.
The finding chart can be found at
ftp://ftp.sao.ru/pub/grb/GRB160625B/GRB160625B_z1000.jpg
GCN Circular 19610
Subject
GRB 160625B: 15 GHz detection from AMI
Date
2016-06-28T13:15:59Z (9 years ago)
From
Kunal Mooley at Oxford U <kunal.mooley@physics.ox.ac.uk>
K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson
(Curtin), T. Cantwell (Manchester), C. Rumsey, D. Titterington, S. H.
Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge),
K. Grainge, A. Scaife (Manchester)
We observed the Fermi/LAT GRB 160625B (Dirirsa et al., GCN 19580) with
the AMI Large Array at 15 GHz on 2016 Jun 28.06 (UT), 2.1 days
post-burst, as part of the 4pisky program. We detect a radio source
consistent with the VLA location (Alexander et al., GCN 19606) at
640+/-40 uJy.
Monitoring of this source is underway. We thank the AMI staff for
scheduling these observations. The AMI-GRB database is a log of all GRB
follow up observations with the AMI, and is available at
http://4pisky.org/ami-grb/.
GCN Circular 19606
Subject
GRB 160625B: VLA Detection
Date
2016-06-27T20:43:24Z (9 years ago)
From
Kate Alexander at Harvard <kalexander@cfa.harvard.edu>
K. D. Alexander (Harvard), T. Laskar (NRAO / UC Berkeley), W. Fong
(University of Arizona) and E. Berger (Harvard) report on behalf of a
larger collaboration:
We observed the Fermi/LAT GRB 160625B (Diririsa et al., GCN 19580) at
multiple frequencies with the Karl G. Jansky Very Large Array (VLA)
beginning 2016 June 27.28 UT (1.34 days after the burst). At a mean
frequency of 9.8 GHz, we detect a radio source with a preliminary flux
density of ~400 uJy at
RA (J2000) = 20:34:23.507 +/- 0.003
Dec (J2000) = +06:55:07.89 +/- 0.03
consistent with the position of the optical afterglow (Troja et al., GCN
19588; Oates et al., GCN 19589) and the Swift/XRT position (Melandri et
al., GCN 19585). Follow-up observations are planned.
We thank the VLA staff for rapidly executing these observations.
GCN Circular 19605
Subject
GRB 160625B: TSHAO optical observations
Date
2016-06-27T19:59:50Z (9 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), P.
Minaev (IKI), I. Reva (Fesenkov Astrophysical Institute), A. Volnova
(IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up
collaboration:
We observed the field of GRB 160625B (Dirirsa et al., GCN 19580; Burns
et al. GCN 19581) with Zeiss-1000 (East) 1-m telescopes of Tien Shan
Astronomical Observatory. We obtained several images in R filter
starting on June 26 (UT) 19:39:18. We detect optical afterglow of GRB
160625B (Troja et al., GCN 19588; Oates et al., GCN 19589).
Preliminary photometry of a combined image is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2016-06-26 19:39:18 0.91784 R 50*120 19.07 0.05 22.0
Photometry is based on nearby USNO-B1.0 stars
USNO-B.1_id R2
0969-0608423 16.38
0969-0608416 16.28
0969-0608335 15.00
0969-0608366 16.05
0969-0608449 17.38
0969-0608443 16.78
0969-0608456 16.79
The GRB 160625B triggered Fermi LAT and GBM (Dirirsa et al., GCN 19580;
Burns et al. GCN 19581), Konus-Wind (Svinkin et al. GCN 19604) and D.
Kann (GCN 19579) reported about CALET and SPI-ACS/INTEGRAL trigger.
A light curve of SPI-ACS/INTEGRAL can be found in
http://grb.rssi.ru/GRB160625B/GRB160625B_API-ACS.png
The SPI-ACS time profile of GRB 160625B consists of 3 episodes of total
duration about 750 seconds and compatible with time profiles reported by
GBM (Burns, GCN 19581) and Konus-Wind (Svinkin et al. GCN 19604).
GCN Circular 19604
Subject
Konus-Wind observation of GRB 160625B
Date
2016-06-27T16:30:09Z (9 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration, extremely bright GRB 160625B
(Fermi-LAT detection: Dirirsa et al., GCN Circ. 19580;
Fermi-GBM detection: Burns, GCN Circ. 19581)
triggered Konus-Wind at T0=81619.875 s UT (22:40:19.875).
The burst light curve starts, at ~T0-0.3 s, with a short soft
initial pulse (precursor) which had a duration of about 1 s.
The precursor is followed, starting at ~T0+180 s, by the main, extremely
bright and spectrally-hard episode with a duration of
about 40 s. This episode evolves into a weak emission traceable
up to ~T0+680 s.
The emission in the main episode is seen up to ~20 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB160625_T81619/
As observed by Konus-Wind, the burst
had a fluence of 9.44(-0.16,+0.16)x10^-4 erg/cm2,
and a 256-ms peak flux, measured from T0+188.928 s,
of 1.26(-0.10,+0.10)x10^-4 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the initial pulse
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 1 MeV range
by a simple power law model with
the photon index alpha = -2.34(-0.22,+0.25)
(chi2 = 38/61 dof)
The time-averaged spectrum of the main episode
(measured from T0+180.480 to T0+229.632 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.79(-0.02,+0.02),
the high energy photon index beta = -2.25(-0.04,+0.04),
the peak energy Ep = 554(-19,+20) keV
(chi2 = 353/97 dof)
The spectrum near the maximum count rate
(measured from T0+188.928 to T0+189.184 s)
is best fit in the 20 keV - 20 MeV range
by the Band model with the following parameters:
the low-energy photon index alpha = -0.77(-0.08,+0.10),
the high energy photon index beta = -2.22(-0.25,+0.17),
the peak energy Ep = 937(-179,+195) keV
(chi2 = 62/67 dof)
Assuming the redshift z=1.406 (Xu, et al., GCN Circ. 19600)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.27, and Omega_Lambda = 0.73,
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~5.0x10^54 erg,
the peak luminosity L_iso is ~1.6x10^54 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~1.3 MeV.
This Eiso is the highest one measured by Konus-Wind for
more than 21 years of its GRB observations and, probably,
the highest Eiso recorded for a GRB ever.
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 19603
Subject
GRB 160625B: Mini-MegaTORTORA detection of bright optical flash simultaneous with LAT event
Date
2016-06-27T15:37:31Z (9 years ago)
From
Sergey Karpov at SAO RAS <karpov@sao.ru>
S.Karpov, G.Beskin (SAO RAS and Kazan Federal University, Russia), S.Bondar,
E.Ivanov, E.Katkova, N.Orekhova, A.Perkov (OJS RPC PSI, Russia), A.Biryukov
(SAI MSU and Kazan Federal University, Russia), V.Sasyuk (Kazan Federal
University, Russia)
The on-sky position of GRB 160625B (Dirirsa et al., GCN Circ. 19580) has
been observed by Mini-MegaTORTORA nine-channel wide-field monitoring system
with high temporal resolution (http://mmt.favor2.info) before, during and
just after the LAT trigger time (T0 = 2016-06-25 22:43:24).
Mini-MegaTORTORA reacted to Fermi GBM trigger 488587220 and started
observing its error box at 2016-06-25 22:41:07, 52 seconds after GBM
trigger and 136 seconds before LAT trigger. Due to large size of error box,
the observations have been performed in "widefield+deep" regime, with
channels simultaneously covering ~30x30 deg field of view with 30 s
exposures in white light to achieve deepest detection limit. The system
acquired 20 frames in such regime, covering time interval from T0-136 to
T0+466 s.
The system detected a bright optical flash on a frame coincident with LAT
trigger time (T0-15.9 - T0+14.1 s) at position reported by Troja et al.
(GCN Circ. 19588), with a magnitude of about V=8.8 mag. Next frame
displayed a slight rebrightening of about 0.1 mag, and then the light curve
followed nearly smooth power-law decay with slope of about -1.6, down to
V=12.2 at last acquired frame. The images acquired prior to LAT trigger do
not display any object at that position down to about V=13.5 mag.
The system also reacted to second GBM trigger 488587880 with slightly
different coordinates, and due to large field of view again covered the
position of a transient, acquiring 20 more frames from T0+1691 to T0+2264
s. No object is seen in these frames down to about V=13.5 mag.
Snapshots of a frames from first follow-up (20 arcmin fields around the
transient) is available at
http://vo.astronet.ru/~karpov/grb160625b_mosaic.png
Further analysis and calibration of the data is ongoing.
Mini-MegaTORTORA belongs to Kazan Federal University and is located at
Special Astrophysical Observatory near Russian 6-m telescope.
GCN Circular 19602
Subject
GRB 160625B: RATIR Optical and NIR Observations
Date
2016-06-27T14:12:33Z (9 years ago)
From
Alan M. Watson at Instituto de Astronomia UNAM <alan@astro.unam.mx>
Alan M. Watson (UNAM), Eleonora Troja (GSFC), Nat Butler (ASU),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer
(UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB),
Antonino Cucchiara (GSFC/STScI), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos�� A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jes��s Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM), Neil Gehrels (GSFC),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and
Vicki Toy (UMD) report:
We observed the field of the Fermi LAT GRB 160625B (Dirirsa, et al., GCN
19580) with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
Astron��mico Nacional on Sierra San Pedro M��rtir from 2016/06 27.36 to
2016/06 27.47 UTC (33.89 to 36.56 hours after the BAT trigger),
obtaining a total of 1.73 hours exposure in the r and i bands and 0.73
hours exposure in the Z, Y, J, and H bands.
We detect the afterglow reported by Troja et al. (GCN Circ. 19588) and,
in comparison with the USNO-B1 and 2MASS catalogs, obtain the following
magnitudes:
r = 19.63 +/- 0.01
i = 19.52 +/- 0.01
Z = 19.34 +/- 0.02
Y = 19.17 +/- 0.02
J = 19.11 +/- 0.02
H = 18.98 +/- 0.03
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
The afterglow has faded by about 1.20 magnitude in all bands compared to
our earlier epoch, confirming the fading seen during the first epoch.
The fading is consistent with a temporal index of -0.90.
More observations are planned.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
[GCN OPS NOTE(27jun16): Per author's request, the GRB name in the Title
was changed from "A" to "B". The name in the text was/is correct.]
GCN Circular 19601
Subject
GRB 160625B: TNG redshift confirmation
Date
2016-06-27T09:51:06Z (9 years ago)
From
Valerio D'Elia at ASDC <delia@asdc.asi.it>
V. D�Elia (INAF-OAR/ASI-ASDC), A. Melandri (INAF-OAB) and D. Malesani (DARK/NBI) report on behalf of the CIBO collaboration:
We observed the afterglow of GRB 160625B (Dirirsa et al., GCN 19580) with the TNG equipped with DOLORES and the LR-B grism. The spectrum was acquired on 2016-06-26 and covers the range between 3000 and 7800 AA. The observation consisted of 2400 s exposure, starting at 23:04:20.836 (24 hr after the trigger).
The optical counterpart is clearly detected in the acquisition images with a magnitude r = 19.0 +/- 0.3 at the position reported by Troja et al. (GCN 19588) and Oates and D'A� (GCN 19589).
The spectrum shows a clear continuum. We detect absorption features consistent with Mg I, Mg II, Mn II and Fe II lines a redshift of z = 1.41 +/- 0.01, thus confirming the redshift reported by Xu et al. (GCN 19600).
We thanks the TNG staff for excellent support, in particular Luca di Fabrizio and Albar Garcia.
GCN Circular 19600
Subject
GRB 160625B: VLT/X-shooter redshift
Date
2016-06-27T09:50:38Z (9 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
D. Xu (NAOC/CAS), D. Malesani (DARK/NBI), J. P. U. Fynbo (DARK/NBI), N.
R. Tanvir (Univ. Leicester), A. J. Levan (Univ. Warwick), D. A. Perley
(DARK/NBI), report on behalf of a larger collaboration:
We observed the optical afterglow of the Fermi GRB 160625B (Dirirsa et
al., GCN 19580; Burns, GCN 19581; Troja et al., GCN 19588) with the ESO
VLT UT2 (Kueyen) equipped with the X-shooter spectrograph. Observations
started on 2016 June 27.19 UT (1.25 days after the Fermi trigger) and
consisted of 4 spectra by 600 s each, covering the wavelength range
3500-20000 AA.
The afterglow is well detected in the acquisition image with R ~ 19.1 +-
0.3, where the large error is due to scatter in the USNO magnitudes used
as reference, and the r versus R filter transformation.
The continuum trace is well detected in our exposures, down to ~3100 AA.
The lack of any drop sets an upper limit to the redshift z < 1.55. A
number of superimposed absorption features are visible; among others, we
detect Mg I, Mg II, Fe II, C IV, Si IV, O I, Si II, Zn II, Al II, and Al
III, all at a common redshift z = 1.406, which we conclude to be the
redshift of GRB 160625B. We also detect an intervening Mg II absorption
system at z = 1.319.
At z = 1.406, the fluence in the 10-1000 keV Fermi band (Burns, GCN
19587) corresponds to an isotropic-equivalent energy of ~2.5*10^54 erg.
We acknowledge excellent support from the ESO observing staff in
Paranal, in particular Juan Carlos Munoz, Elizabeth (Liz) Bartlett,
Dimitri Gadotti and Francisco Caceres.
GCN Circular 19599
Subject
GRB 160625B: MITSuME Ishigakijima Optical Observation
Date
2016-06-27T02:51:23Z (9 years ago)
From
Daisuke Kuroda at OAO/NAOJ <dikuroda@oao.nao.ac.jp>
D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ),
K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima),
K. Ohta (Kyoto) and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME and OISTER collaboration:
We observed the field of GRB 160625B (Dirirsa et al., GCNC 19580;
Melandri et al., GCNC 19585) with the optical three color (g', Rc
and Ic) CCD camera attached to the Murikabushi 1m telescope of
Ishigakijima Astronomical Observatory.
The observation started on 2016-06-26 14:03:44 UT (~15.3 h after
the burst). We detected the previously reported afterglow
(Troja et al., GCNC 19588) in in all the three bands.
The photometric results of the OT are listed below.
We used GSC2.3 catalog for flux calibration.
#T0+[day] MID-UT T-EXP[sec] g' g'_e Rc Rc_e Ic Ic_e
-------------------------------------------------------------------
0.64273 14:08:57 540.0 19.16 0.10 18.59 0.05 18.08 0.10
0.73075 16:15:41 540.0 19.27 0.08 18.78 0.06 18.28 0.08
-------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
GCN Circular 19589
Subject
GRB 160625B: Swift/UVOT Detection
Date
2016-06-26T11:15:45Z (9 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
GRB 160625B: Swift/UVOT Detection
S. R. Oates (U. Warwick) and A. D'A� (INAF-IASFPA)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160625B
9616 s after the LAT trigger (Dirirsa et al., GCN Circ. 19580).
A source consistent with the RATIR position (Troja et al. GCN Circ. 19588)
and the edge of the XRT position (Melandri et al. GCN Circ. 19585)
is detected in the initial UVOT exposures.
Preliminary detections using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
u 9616 9978 353 16.41 +/- 0.04
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.12 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 19588
Subject
GRB 160625B: RATIR Optical and NIR Afterglow Detection
Date
2016-06-26T08:18:57Z (9 years ago)
From
Eleonora Troja at GSFC <eleonora.troja@nasa.gov>
Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM),
Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB),
Antonino Cucchiara (GSFC/STScI), Owen Littlejohns (ASU),
Enrico Ramirez-Ruiz (UCSC), Jos�� A. de Diego (UNAM), Leonid Georgiev
(UNAM), Jes��s Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM), Neil
Gehrels (GSFC), Harvey Moseley (GSFC), John Capone (UMD), V. Zach
Golkhou (ASU), and Vicki Toy (UMD) report:
We observed the field of the Fermi LAT GRB 160625B (Dirirsa, et al., GCN
19580)
with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio Astron��mico
Nacional
on Sierra San Pedro M��rtir from 2016/06 26.30 to 2016/06 26.32 UTC (8.53
to 9.02 hours after the LAT trigger), obtaining a total of 0.36 hours
exposure in the r and i bands and 0.15 hours exposure in the Z, Y, J
and H bands.
We detect a bright, fading and uncatalogued source at the edge of the
Swift-XRT
error circle (Melandri, et al., GCN 19585), at a position RA, Dec =
20:34:23.50,
+6:55:8.1 (J2000, +/-0.5"). In comparison with the USNO-B1 and 2MASS
catalogs,
we obtain the following values:
r = 18.28 +/- 0.01
i = 18.08 +/- 0.01
Z = 17.95 +/- 0.01
Y = 17.78 +/- 0.01
J = 17.77 +/- 0.02
H = 17.65 +/- 0.02
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
Further observations are on-going.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 19587
Subject
GRB 160625B: Fermi GBM refined analysis
Date
2016-06-26T08:01:15Z (9 years ago)
From
Eric Burns at U of Alabama <eb0016@uah.edu>
E. Burns (UAH) reports on behalf of the Fermi GBM Team:
"We report temporal and spectral analysis on GRB 160625B, covering
all three Fermi trigger times (LAT trigger 488587408 / 160625947
GBM triggers 488587220 / 160625945 and 488587880 / 160625952).
All times are relative to the first GBM trigger time.
The GBM light curve consists of multiple peaks
with a total duration (T90) of about 460 s (50-300 keV).
The 1.024-sec peak photon flux of the main peak measured starting
from T0+188.707 s in the 10-1000 keV band is 167 +/- 1 ph/s/cm^2.
The soft peak that initially triggered GBM is about 1 second long.
The time-averaged spectrum from T0+0.002 s to T0+1.056 s is
well fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.2 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 68 +/- 1 keV.
The event fluence (10-1000 keV) in this time interval is
(1.65 +/- 0.03)E-06 erg/cm^2.
The main peak that triggered the LAT is about 25 seconds long.
The time-averaged spectrum from T0+187.427 s to T0+212.003 s is
well fit by a Band function with Epeak = 657 +/- 5 keV,
alpha = -0.74 +/- 0.00, and beta = 2.36 +/- 0.01.
The event fluence (10-1000 keV) in this time interval is
(5.00 +/- 0.01)E-04 erg/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 19586
Subject
GRB 160625B: Fermi-LAT refined analysis
Date
2016-06-26T07:55:38Z (9 years ago)
From
Judith Racusin at GSFC <judith.racusin@nasa.gov>
F. Dirirsa (U. Johannesburg), G. Vianello (Stanford), J. Racusin (NASA/GSFC), and
M. Axelsson (KTH Stockholm) report on behalf of the Fermi-LAT team:
We report the on-ground localization and analysis of GRB 160625B, which triggered
the LAT onboard (Dirisa et al., GCN 19580). All times are relative to the initial GBM
trigger (Burns et al, GCN 19581).
The best LAT on-ground location is found to be:
RA, Dec = 308.56, 6.93 deg (J2000)
with an error radius of 0.06 deg (90 % containment, statistical error only). This is fully
compatible with the position of the afterglow detected by Swift/XRT (Melandri et al.,
GCN 19585).
This was 42 deg from the LAT boresight at the time of the GBM trigger and triggered
an autonomous repoint of the spacecraft.
More than 300 photons were detected above 100 MeV. The LAT emission became
detectable during the second bright pulse observed by GBM at ~T0+181 s. The
highest-energy photon is a 15 GeV event which is observed ~345 seconds after
the GBM trigger. The GRB was detectable by the LAT up to ~1 ks after the
trigger. Data are still being collected, and pointed mode observations are continuing
to maximize exposure to the GRB location.
The Fermi-LAT point of contact for this burst is Feraol Dirirsa (fdirirsa@uj.ac.za <mailto:fdirirsa@uj.ac.za>).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from
20 MeV to greater than 300 GeV. It is the product of an international collaboration
between NASA and DOE in the U.S. and many scientific institutions across France,
Italy, Japan and Sweden.
GCN Circular 19585
Subject
GRB 160625B: Swift-XRT afterglow detection
Date
2016-06-26T06:54:13Z (9 years ago)
From
Antonino D'Ai at IASF-PA <antonino.dai@ifc.inaf.it>
A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), D.N.
Burrows (PSU), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), S.L. Gibson
(U. Leicester), J.P. Osborne (U. Leicester) and P.A. Evans (U.
Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 160625B (Dirirsa et al. GCN Circ. 19580)
in a series of observations tiled on the sky. The total exposure time
is 2.7 ks, distributed over 8 tiles; the maximum exposure at a single
sky location was 1.1 ks. The data were collected between T0+9.6 ks and
T0+10.0 ks, and are entirely in Photon Counting (PC) mode.
An uncatalogued X-ray source is detected and is above the RASS limit,
and is therefore likely the GRB afterglow. The position of this source
is RA, Dec=308.5969, +6.9196 which is equivalent to:
RA (J2000): 20:34:23.25
Dec(J2000): +06:55:10.5
with an uncertainty of 3.8 arcsec (radius, 90% confidence). This
position is 19.7 arcmin from the Fermi/LAT position.
The light curve can be modelled with a power-law decay with a decay
index of alpha=3.156 (+0.011, -2.764).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.09 (+0.20, -0.19). The
best-fitting absorption column is 1.6 (+/-0.6) x 10^21 cm^-2, in
excess of the Galactic value of 9.8 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 3.1 x 10^-11 (4.3 x 10^-11) erg
cm^-2 count^-1.
A summary of the WT-mode spectrum is thus:
Total column: 1.6 (+/-0.6) x 10^21 cm^-2
Galactic foreground: 9.8 x 10^20 cm^-2
Excess significance: 1.8 sigma
Photon index: 2.09 (+0.20, -0.19)
If the light curve continues to decay with a power-law decay index of
3.156, the count rate at T+24 hours will be 6.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x
10^-13 (2.6 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/xrt_products/TILED_GRB00056/index_1.php.
The results of the full analysis of the tiled XRT observations are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00056.
This circular is an official product of the Swift-XRT team.
GCN Circular 19582
Subject
GRB 160625B: Tiled Swift observations
Date
2016-06-26T01:18:16Z (9 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a series of observations, tiled on the sky, of the
Fermi/LAT GRB 160625B. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00056
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular 19581
Subject
GRB 160625B: Fermi GBM initial observations
Date
2016-06-26T00:53:38Z (9 years ago)
From
Eric Burns at U of Alabama <eb0016@uah.edu>
E. Burns (UAH) reports on behalf of the Fermi GBM Team:
"At 22:40:16.28 UT on 25 June 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 160625B for the first time
(trigger 488587220 / 160625945).
The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux of the GRB.
This ARR was accepted and the spacecraft slewed to the GBM in-flight
location. The initial angle from the Fermi LAT boresight to
the GBM ground location is 40 degrees.
At 22:43:24.82 the Fermi LAT triggered on a bright
pulse from the same GRB (Dirirsa et al. 2016, GCN 19580). Owing to
the ARR the initial angle from the Fermi LAT boresight to the
LAT position at LAT trigger time was 12 degrees.
At 22:51:16.03 GBM triggered again on GRB 160625B
(trigger 488587880 / 160625952).
GRB 160625B is distinct from the Swift BAT GRB 160625A
(Maselli et al. 2016, GCN 19577).
The GBM light curve consists of multiple peaks over
approximately 700 seconds. The first peak is soft with a
duration of about 1 second. The main peak, corresponding
to the LAT trigger, is about 25 seconds long and is very
hard. The peak that triggered GBM for the second time is
about 30 seconds long and soft.
Standard GBM temporal and spectral analysis is awaiting
downlink of the full dataset and will be reported when
available."
GCN Circular 19580
Subject
GRB 160625B: Fermi-LAT detection of a bright burst
Date
2016-06-26T00:23:32Z (9 years ago)
From
Judith Racusin at GSFC <judith.racusin@nasa.gov>
F. Dirirsa (U. Johannesburg), J. Racusin (NASA/GSFC), J. McEnery (NASA/GSFC),
and R. Desiante (INFN Torino) report on behalf of the Fermi-LAT team:
At 22:43:24 on June 25, 2016, Fermi/LAT detected a sharp increase in the rate of
high-energy photons, resulting in an onboard trigger on GRB 160625B. Fermi/GBM
triggered on this object two separate times (160625945/488587220,
160625952/488587880), with emission evident between triggers, including the time
at which LAT triggered.
Note that all of these triggers are distinct from the Swift/BAT trigger on GRB160625A
(Maselli et al., GCN 19577) that occurred 15 seconds after the first GBM trigger, and
was occulted by the Earth to Fermi at the time, and >100 degrees away on the sky.
The onboard location is:
RA, Dec = 308.3, +6.9 (J2000)
with an error radius of 0.5 deg (90% containment, systematic error only).
This was 12.3 deg from the LAT boresight at the time of the LAT trigger.
We anticipate providing a refined location within the next 8 hours when the LAT
science data for this burst is downlinked and processed.
A Swift TOO request has been approved, and given the unusual nature of this trigger,
a Fermi TOO will extended the pointed-mode observations to T0+24 hours beyond the
initial autonomous repoint.
The Fermi-LAT point of contact for this burst is Feraol Dirirsa (fdirirsa@uj.ac.za).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band
from 20 MeV to greater than 300 GeV. It is the product of an international collaboration
between NASA and DOE in the U.S. and many scientific institutions across France,
Italy, Japan and Sweden.