GRB 180914B
GCN Circular 23288
Subject
GRB 180914B: RTT150 optical observations
Date
2018-10-01T20:38:00Z (7 years ago)
From
Rodion Burenin at IKI, Moscow <rodion@hea.iki.rssi.ru>
E. Irtuganov, I. Bikmaev, N. Sakhibullin (KFU/AST),
A. Lyapin, I. Zaznobin, R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
I. Khamitov, S. Ozdemir (TUG), E. Gogus (Sabanci Uni.)
report:
We observed the field of GRB 180914B (Ursi et al., GCN 23226, Bissaldi
et al., GCN 23232, Ai et al., GCN 23236) with the Russian-Turkish
1.5-m optical telescope (RTT150, Bakirlitepe, TUBITAK National
Observatory, Turkey) using the TFOSC instrument.
We obtained direct images in SDSS r filter, on Sep 18, 19 and 21,
2018. The optical transient (Zhen and Filippenko, GCN 23237, Troja et
al., GCN 23238, de Ugarte Postigo et al., GCN 23239) was detected in
all images. We estimated the following magnitudes for the OT:
Sep 18: 21.21 +- 0.03
Sep 19: 21.99 +- 0.05
Sep 21: 22.28 +- 0.10
calibrated against SDSS secondary standards.
Therefore, approximately power law light curve is observed, with a
decay slope near -1.53, which is approximately consistent with the
slope measured earlier by Kann et al., GCN 23256. Note, that some
deviations from simple power law decay at the level of 0.2-0.3 mag are
also observed in our data.
GCN Circular 23287
Subject
GRB 180914B: RTT150 optical observations
Date
2018-10-01T20:36:17Z (7 years ago)
From
Rodion Burenin at IKI, Moscow <rodion@hea.iki.rssi.ru>
A. Lyapin, I. Zaznobin, R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
I. Bikmaev, E. Irtuganov, N. Sakhibullin (KFU/AST),
I. Khamitov, S. Ozdemir (TUG), E. Gogus (Sabanci Uni.)
report:
We observed the field of GRB 180914B (Ursi et al., GCN 23226, Bissaldi
et al., GCN 23232, Ai et al., GCN 23236) with the Russian-Turkish
1.5-m optical telescope (RTT150, Bakirlitepe, TUBITAK National
Observatory, Turkey) using the TFOSC instrument.
We obtained series of exposures in SDSS gri filters, starting at 18:30
UT on Sep 16, 2018. The optical transient (Zhen and Filippenko, GCN
23237, Troja et al., GCN 23238, de Ugarte Postigo et al., GCN 23239)
was detected in all images. We estimated the following magnitudes for
the OT:
g: 20.97 +- 0.02
r: 20.38 +- 0.02
i: 20.04 +- 0.02
calibrated against SDSS secondary standards.
GCN Circular 23278
Subject
INTEGRAL detections of the prompt gamma-ray emission of GRB 180914B
Date
2018-09-28T11:05:12Z (7 years ago)
From
Volodymyr Savchenko at ISDC,U of Geneve <savchenk@in2p3.fr>
J. Rodi, A. Bazzano, P. Ubertini, L. Natalucci (IAPS-Roma)
C. Ferrigno, V. Savchenko (ISDC, University of Geneva, CH)
E. Kuulkers (ESTEC/ESA, The Netherlands)
We have analyzed the public INTEGRAL data of IBIS/PICsIT (200 - 2600 keV)
and SPI-ACS(>75 keV) in coincidence with the long, bright GRB 180914B,
which was initially reported by AGILE/MCAL (GCN 23226), AGILE/GRID (GCN
23231),
and Fermi/LAT(GCN 23232). The INTEGRAL orientation was 98.4 degrees from
the GRB location and implies a near optimal response for SPI-ACS and
a suppressed response for PICsIT (Savchenko et al. 2017, A&A 603, A46).
The GRB was clearly detected in SPI-ACS until about T0+250s
(T0=2018-09-14 18:23:02.22) and shows 8 flaring events, of which 7 show
large variability detected down to the 50 ms time-resolution of the
detector.��
It was also detected in PICsIT until approximately T0+130s, of which 5
flaring
events are clearly seen.�� Because of the unfavorable viewing angle for
PICsIT,
the burst is predominately seen above 460 keV with significant
emission up to 1.2 MeV.
The SPI-ACS light curve can be found at:
https://www.isdc.unige.ch/integral/ibas/cgi-bin/ibas_acs_web.cgi/?trigger=2018-09-14T18-23-01.00-00000-00000-0
GCN Circular 23256
Subject
GRB 180914B: OSN Detection and light curve/SED analysis
Date
2018-09-19T18:33:37Z (7 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC,
DARK/NBI), L. Izzo, C. C. Thoene, M. Blazek, K. Bensch (all
HETH/IAA-CSIC), and A. Sota (IAA/CSIC) report:
We observed the location of the extremely bright AGILE/Fermi GRB 180914B
(Ursi et al., GCN #23226; Bissaldi et al., GCN #23232) with the T150
telescope of the Sierra Nevada Observatory (OSN). We obtained 3 x 180 s
images in the Ic band, centered 3.157 days after the GRB.
The afterglow (e.g., Zheng & Filippenko, GCN #23237; Troja et al., GCN
#23238; de Ugarte Postigo et al., GCN #23239) is clearly detected, and
we derive Ic (AB) = 20.28 +/- 0.06 mag vs. several SDSS comparison
stars, using the transformation equations of Lupton (2005).
Using the photometry given in the GCNs so far (Zheng & Filippenko, GCN
#23237; Troja et al., GCN #23238, #23243; de Ugarte Postigo et al., GCN
#23239; Kuin, GCN #23241; Mazaeva et al., GCN #23244, #23249; Lipunov et
al., GCN #23245; D'Avanzo et al., GCN #23246; Ramsay et al., GCN #23252;
Watson et al., GCN #23253, Izzo et al., GCN #23255), we find the optical
afterglow can be fit by an achromatic simple power-law with a decay
slope alpha = 1.65 +/- 0.02 (taking host-galaxy magnitudes from SDSS
into account). The SED (from u to H band) is well-fit with a small
amount of SMC extinction, we find beta = 0.94 +/- 0.11, A_V = 0.09 +/-
0.07 (assuming F_nu ~ t^(-alpha)*nu^(-beta) ). Note the earliest
detection, from MASTER, lies significantly below the back-extrapolation
of the later decay slope, indicating a rebrightening may have taken
place.
GCN Circular 23255
Subject
GRB 180914B: OAJ multi-color follow-up
Date
2018-09-19T18:32:38Z (7 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
L. Izzo, M. Blazek (both HETH/IAA-CSIC), A. de Ugarte Postigo
(HETH/IAA-CSIC, DARK/NBI), D. A. Kann, C. C. Thoene, K. Bensch (all
HETH/IAA-CSIC), R. Martone (U. Ferrara), W. Schoenell (Federal U. of Rio
Grande do Sul), H. Vazquez Radio, M. C. Diaz-Martin, and S.
Rodriguez-Llano (all OAJ) report:
We have continued to monitor GRB 180914B (Ursi et al., GCN 23226;
Verrecchia et al., GCN 23231; Bissaldi et al. GCN 23232; D'Ai et al.,
GCN 23236) with the 0.8m T80 telescope of the Javalambre Astrophysical
Observatory (Teruel, Spain). Observations consisted of a series of 3x300
s griz exposures, starting at 22:47:49 UT on September 16 (2.18 days
after the GRB detection). The afterglow is clearly detected in all
stacked images. We measure the following magnitudes (AB system):
g' = 20.73 +/- 0.05 mag at 2.1875 days,
r' = 20.27 +/- 0.08 mag at 2.2003 days,
i' = 19.94 +/- 0.07 mag at 2.2260 days,
z' = 19.62 +/- 0.07 mag at 2.2413 days,
as compared to nearby PANSTARRS stars.
GCN Circular 23253
Subject
GRB 180914B: DDOTI/OAN Detection and Confirmation of Fading
Date
2018-09-18T00:55:28Z (7 years ago)
From
Alan M. Watson at Instituto de Astronomia UNAM <alan@astro.unam.mx>
Alan M. Watson (UNAM), Nat Butler (ASU), Eleonora Troja (GSFC), Rosa L.
Becerra (UNAM), William H. Lee (UNAM), and Alexander Kutyrev (GSFC)
report:
We observed the field of GRB 180914B (Ursi et al., GCN Circ. 23226) with
the DDOTI/OAN wide-field imager at the Observatorio Astronomico
Nacional on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) from
2018-09-16 02:54 to 06:02 (32.5 to 35.7 hours after burst) and
2018-09-17 02:58 to 04:17 (56.6 to 57.9 after burst) obtaining 7200 and
3060 seconds exposure with no filter.
We detect the optical counterpart (Zheng & Filippenko, GCN Circ. 23237;
Troja, et al., GCN Circ. 23238) with the following magnitudes:
w = 19.45 +/- 0.10 (on 2018-09-16)
w = 20.25 +/- 0.31 (on 2018-09-17)
These AB magnitudes are calibrated against the Pan-STARRS1 catalog and
are not corrected for Galactic extinction in the direction of the GRB.
We confirm the fading reported by de Ugarte Postigo et al. (GCN Circ.
23239), Troja et al. (GCN Circ. 23243), and Mazaeva et al. (GCN Circ.
23249).
DDOTI/OAN imaged the entire Fermi/LAT error region (Bissaldi et al., GCN
Circ. 23232). We confirm that there were no other uncatalogued sources
in the region on 2019-09-16 to a 10-sigma limit of w = 19.4.
We thank the staff of the Observatorio Astronomico Nacional in San Pedro
Martir.
GCN Circular 23252
Subject
GRB 180914B: GOTO optical detection
Date
2018-09-17T22:22:19Z (7 years ago)
From
Danny Steeghs at U.of Warwick/GOTO <D.T.H.Steeghs@warwick.ac.uk>
G.Ramsay (Armagh O.), K.Ulaczyk, D.Steeghs, J.Lyman (U. Warwick),
M.Dyer (U. Sheffield), B.Gompertz, A.Levan, R.Cutter (U. Warwick)
K. Ackley, D.Galloway, E.Rol (Monash U.), V.Dhillon (U. Sheffield),
P.O'Brien, R.Starling (U. Leicester), S.Poshyachinda (NARIT),
D.Pollacco (U. Warwick), E.Thrane (Monash U.), E.Palle (IAC)
report on behalf of the GOTO collaboration:
The Gravitational-wave Optical Transient Observer observed the field
of the long GRB 180914B (Ursi et al. GCN Circ. 23226, Bissaldi et al. GCN
Circ. 23232) from Roque de los Muchachos Observatory.
In a combined L-band image (400-700nm passband), with a total exposure
time of 600s at a mid-time 2018-09-16 21:57:04 UT, 2.149 days since
burst, we detect the optical counterpart (Zheng et al. GCN
Circ. 23237; Troja GCN Circ. 23238; de Ugarte Postigo et al. GCN
Circ. 23239; Mazaeva et al. GCN Circ. 23244; Lipunov et al. GCN
Circ. 23245) with a preliminary magnitude of g=20.9 +/- 0.2 based on a
comparison to Panstarrs g-band calibrators.
GOTO is operated at the La Palma observing facilities of the University
of Warwick on behalf of a consortium including the University of
Warwick, Monash University, Armagh Observatory, the University of
Leicester, the University of Sheffield, the National Astronomical
Research Institute of Thailand (NARIT) and the Instituto de Astrofisica
de Canarias (IAC) (https://goto-observatory.org/)
GCN Circular 23251
Subject
GRB180914B: Swift UVOT position correction to circ. 23241
Date
2018-09-17T21:25:15Z (7 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N.Paul M. Kuin (MSSL/UCL) reports on behalf of the Swift-UVOT Team:
In GCN Circ. 23241 the position of the transient was correct in sexadecimal
units, but
incorrect in the degree units, where it should read:
The UVOT source position is RA= 332.35638, Dec = 25.06217 (J2000).
My apologies for any confusion caused by this mistake.
GCN Circular 23250
Subject
GRB 180914B: AstroSat CZTI detection
Date
2018-09-17T20:55:04Z (7 years ago)
From
Vidushi Sharma at IUCAA <vidushi@iucaa.in>
T. Khanam, V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data showed the detection of a long GRB 180914B, which was also detected by AGILE (MCAL: Ursi A. et al., GCN 23226 and GRID: Verrecchia F. et al., GCN 23231), Fermi-LAT (Bissaldi E. et al., GCN 23232), Swift-XRT (D'Ai A. et al., GCN 23236) and Konus-Wind (Frederiks D. et al., GCN 23240).
The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 18:23:02.500 UT. The measured peak count rate is 3258 cts/s above the background in combined data of four quadrants, with a total of 105168 cts. The local mean background count rate was 657 cts/s. Using cumulative rates, we measure a T90 of 146.8 s. In preliminary analysis, we find that 7300 compton events are associated with this event.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN Circular 23249
Subject
GRB 180914B : continued TSHAO optical observations
Date
2018-09-17T20:04:01Z (7 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Pozanenko (IKI), I. Reva (FAPHI), A. Kusakin
(FAPHI), A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger
GRB follow-up collaboration:
We observed the field of GRB 180914B (Ursi, et al., GCN 23226; Bissaldi
et al., GCN 23232; Frederiks et al., GCN 23240) with Zeiss-1000 1-m
telescope of Tien Shan Astronomical Observatory starting on September 17
(UT) 14:28:30. We observed the object reported e.g. (Zheng & Filippenko
GCN 23237; Troja et al. GCN 23238; de Ugarte Postigo et al., GCN 23239;
Paul & Kuin, GCN 23241). Preliminary photometry of the object is following.
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2018-09-17 14:28:30 2.87843 R 60*60 20.53 0.07 22.2
The photometry is based on several nearby SDSS-DR9 stars
SDSS-DR9_id R(Lupton)
J220926.80+250130.1 15.705
J220922.87+250206.0 16.156
J220929.88+250257.7 15.812
J220928.05+250309.0 17.230
J220928.90+250327.6 15.524
J220924.12+250415.7 15.485
J220920.37+250610.6 15.050
J220902.04+250312.5 15.321
GCN Circular 23246
Subject
GRB 180914B: VLT/X-shooter spectroscopic redshift
Date
2018-09-17T15:15:17Z (7 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
P. D'Avanzo (INAF/OABr), K. E. Heintz (Univ. Iceland and DAWN/NBI), A.
de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), A. J. Levan (Univ.
Warwick), L. Izzo (HETH/IAA-CSIC), D. B. Malesani (DAWN/NBI and
DARK/NBI), D. A. Kann (HETH/IAA-CSIC), N. R. Tanvir (Univ. Leicester),
report on behalf of the Stargate collaboration:
We observed the optical counterpart (e.g. Zheng & Filippenko, GCN 23237)
of GRB 180914B, detected by AGILE (Ursi et al., GCN 23226; Verrecchia et
al., GCN 23231), Fermi/LAT (Bissaldi & Longo, GCN 23232), and Konus-Wind
(Frederiks et al., GCN 23240). We used the X-shooter spectrograph on the
ESO VLT UT2 (Kueyen), for a total exposure of 2x600 s, starting on 2018
September 17.07 UT (2.30 days after the GRB). The covered wavelength
range is 3000-21000 AA, and the seeing was relatively poor, around 1.5".
From a 15-s acquisition image, we measure the magnitude of the
afterglow as r = 20.37 +- 0.04 (AB), calibrated against the Pan-STARRS
catalog.
Several absorption features are detected superimposed on the afterglow
continuum. Among them, we identify Mn II, Al III, Fe II, Mg II, Mg I, Ca
II, all at the common redshift of z = 1.096. At the same redshift,
fine-structure lines from Fe II are also identified, thus firmly
establishing this value as the GRB redshift. A few emission lines from
the underlying host are also visible. We identify the [O II] doublet and
[O III] 5008, while other commonly observed features lie at this
redshift in regions of poor atmospheric transparency or low S/N.
We note that our spectroscopic value is larger than the photometric
redshift of the putative host galaxy as listed in the SDSS catalog
(https://skyserver.sdss.org/dr14/en/tools/explore/Summary.aspx?id=1237680331629267013),
which is however based on low-S/N photometry. At z = 1.096, the
isotropic-equivalent energy radiated in gamma-rays is 3.6*10^54 erg,
using the Konus-Wind fluence (1.15*10^-3 erg cm^-2; Frederiks et al.,
GCN 23240). This ranks among the highest measured values for GRBs.
We acknowledge the ESO staff at Paranal for their support, in particular
Willem-Jan de Wit, Romain Thomas and Rodrigo Palominos.
GCN Circular 23245
Subject
GRB 180914B: MASTER OT automatic dtection
Date
2018-09-17T11:10:54Z (7 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, E. Gorbovskoy, N.Tiurina, D. Vlasenko,
V.Kornilov, A.Kuznetsov, V.Chazov, I. Gorbunov,
D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov,
Lomonosov Moscow State University,SAI
D.Svinkin (Ioffe Institute, Sankt Petersburg)
A. Tlatov, V.Senik, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
D. Buckley,
South African Astronomical Observatory (SAAO)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias (IAC)
R. Podesta, F. Podesta, C. Lopez, C.Francile
Observatorio Astronomico Felix Aguilar (OAFA)
H.Levato,
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
O. Gres, N.M.Budnev , Yu.Ishmuhametova
Irkutsk State University (ISU)
A. Gabovich, V. Yurkov, Yu. Sergienko
Blagoveschensk Educational State University (BSPU)
MASTER-Tunka robotic telescope (MASTER-Net: http://observ.pereplet.ru,
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in
Tunka Astrophysical Center (Baykal Lake, Applied Physics Institute,
Irkutsk State University, Russia) was starting
survey on the LAT GRB180914.77 error-box (ra=22 09 47 dec=+24 52 47
r=0.33) 9409 sec after notice time and 79012 sec after trigger time at
2018-09-15 16:19:55 UT. The 5-sigma upper limit on our first (180s
exposure) set is about 19.7 mag
MASTER OT J220925.53+250343.3 - Afterglow
MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 22h
09m 25.53s +25d 03m 43.3s on 2018-09-15 16:19:55.393UT. Error is 0.7
arcsec. This position is coincident with late XRT (P. A. Evans, GCN 23234)
and KAIT (WeiKang Zheng and Alexei V. Filippenko, GCN 23237) positions.
The OT magnitude in clear filter is 19.2m (limit 19.7m).
This is the first optical magnitude ( see also Eleonora Troja GCN 23238,
A. de Ugarte Postigo et al., GCN 23239; N. Paul M. Kuin et al., GCN 23241;
Eleonora Troja et al., GCN 23243).
The OT is seen in 2 images. There is no minor planet at this place.
We have reference image without OT on 2011-12-15.46200 UT with unfiltered
magnitude limit 20.0m.
The discovery and refernces images are available at
http://master.sai.msu.ru/static/OT/MASTEROTJ220925.53+250343.3.jpg
The galactic latitude b = -25 deg.
The observations made on zenit distance = 28 deg.The moon (38 % bright
part) below the horizon (The altitude of the Moon is -17 deg. ).
The sun altitude is -34.5 deg.
The object can be observed till sunrise at 2018-09-15 22:42:06
GCN Circular 23244
Subject
GRB 180914B : TSHAO optical observations
Date
2018-09-17T10:26:49Z (7 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Pozanenko (IKI), I. Reva (FAPHI), A. Kusakin
(FAPHI), A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger
GRB follow-up collaboration:
We observed the field of GRB 180914B (Ursi, et al., GCN 23226; Bissaldi
et al., GCN 23232; Frederiks et al., GCN 23240) with Zeiss-1000 1-m
telescope of Tien Shan Astronomical Observatory starting on September 16
(UT) 19:44:34, obtaining a total of 46.5 minutes exposure in the
Rc-band. Within XRT position (D'Ai et al., GCN 23236) we detect the
object reported by Zheng & Filippenko (GCN 23237), Troja et al. (GCN
23238), (Paul & Kuin, GCN 23241). Preliminary photometry of the objext
is following.
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2018-09-16 19:44:34 2.07692 R 31*90 19.89 0.05 21.9
The photometry is based on several nearby SDSS-DR9 stars.
SDSS-DR9_id R(Lupton)
J220926.80+250130.1 15.705
J220922.87+250206.0 16.156
J220929.88+250257.7 15.812
J220928.05+250309.0 17.230
J220928.90+250327.6 15.524
J220924.12+250415.7 15.485
J220920.37+250610.6 15.050
J220902.04+250312.5 15.321
--
�������� ��������������
GCN Circular 23243
Subject
GRB 180914B: Continued RATIR Optical and NIR Observations
Date
2018-09-17T07:20:02Z (7 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 (UVI), , Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jesus Gonzalez (UNAM), Carlos Roman-Zuniga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.),
and Vicki Toy (UMD) report:
We re-observed the field of GRB 180914B (Ursi, et al., GCN�� 23226)
with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the
Observatorio Astronomico Nacional on Sierra San Pedro Martir from
2018/09 17.12 to 2018/09 17.28 UTC (56.53 to 60.22 hours after the
burst), obtaining a total of 2.49 hours exposure in the r and i
bands and 1.04 hours exposure in the Z, Y, J, and H bands.
At the position of the optical/nIR counterpart (Zheng & Filippenko,
GCN 23237; Troja, et al., GCN 23238), in comparison with the
SDSS DR9 and 2MASS catalogs, we obtain the following detections:
r = 20.46 +/- 0.01
i = 20.08 +/- 0.01
z = 19.74 +/- 0.02
Y = 19.57 +/- 0.02
J = 19.33 +/- 0.02
H = 19.08 +/- 0.03
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
Compared to our first night of observations (Troja, et al., GCN 23238),
the source significantly faded at an approximate decay rate of t^(-1.4),
shallower than the value found by De Ugarte Postigo, et al. (GCN 23239)
at earlier times.
Further observations are planned.
We thank the staff of the Observatorio Astronomico Nacional in San Pedro
Martir.
GCN Circular 23242
Subject
GRB 180914B: AGILE/MCAL refined analysis
Date
2018-09-16T18:26:38Z (7 years ago)
From
Alessandro Ursi at INAF/IAPS <alessandro.ursi@gmail.com>
GRB 180914B: AGILE/MCAL refined analysis
A. Ursi (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), M. Tavani
(INAF/IAPS, and Univ. Roma Tor Vergata), F. Longo (Univ. Trieste and INFN
Trieste), A. Argan, M. Cardillo, Y. Evangelista, G. Piano (INAF/IAPS), F.
Lucarelli, C. Pittori (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, F.
Fuschino, N. Parmiggiani (INAF/OAS), M. Marisaldi (INAF/OAS, and Bergen
University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), A.
Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team:
We present a refined analysis of the long GRB 180914B detected by
AGILE/MCAL (Ursi et al., GCN #23226), AGILE/GRID (Verrecchia et al., GCN
#23231), Fermi/LAT (Bissaldi et al., GCN #23232), and Konus-Wind (Frederiks
et al., GCN #23240), whose afterglow has been so far detected by Swift/XRT
(D'Ai et al., GCN #23236) and Swift/UVOT (Kuin et al., GCN #23241), KAIT
(Zheng & Filippenko, GCN #23237), RATIR (Troja et al., GCN #23238), and OAJ
(de Ugarte Postigo et al., GCN #23239).
The AGILE Mini-CALorimeter (MCAL) detector high time resolution data
acquisition was triggered twice by the GRB on sub-millisecond and 16 ms
timescales.
A first GRB peak triggered complete MCAL data acquisition, starting at T1 =
2018-09-14 18:23:02.22 +/- 0.01 s (UTC) and ending at about T1+6.4 s, and
lasted the whole duration of the acquisition. The time-integrated spectrum
measured between T1 and T1+6.4 s can be fitted in the energy range 0.5-40
MeV with a power law with photon index 1.74 -0.13/+0.06 and a cut-off
energy of 2.35 -2.2/+1.54 MeV, with a reduced chi-square of 1.13 (66
d.o.f.). The burst fluence in the same energy range and time interval is
2.4e-04 erg/cm^2 (90% confidence level).
After ~85 s, a second GRB peak triggered complete MCAL data acquisition,
starting at T2 = 2018-09-14 18:24:27.84 +/- 0.01 s and ending at about
T2+6.4, and lasted about 2.7 s. The time-integrated spectrum measured
between T2 and T2+2.7 s can be fitted in the 0.5-40 MeV energy range with a
simple power law with ph.ind. = 2.13 -0.07/+0.08 and a reduced chi-square
of 1.23 (68 d.o.f.). The corresponding fluence is 1.94e-05 erg/cm^2 (90%
confidence level).
The AGILE-MCAL detector has a full solid angle acceptance, and is
operational in the range 0.4 - 100 MeV. This observation was done with the
MCAL trigger capability set to a reduced mode with substantial TM
constraints, and the Super-AGILE imaging being turned-off. A substantially
enhanced AGILE instrument configuration is foreseen to be implemented
shortly.
GCN Circular 23241
Subject
GRB180914B: Swift UVOT detection of an optical afterglow
Date
2018-09-16T16:05:06Z (7 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. Paul M. Kuin reports on behalf of the Swift-UVOT team:
Swift-UVOT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 180914B (Bissaldi et al. GCN Circ. 23232)
in a series of observations tiled on the sky.
Within the error of the location of the XRT source (D'Ai, GCN Circ. 23236)
we detect a source that appears to be fading.
The UVOT source location is RA = 332.2609, Dec = 24.5823 deg which is
RA = 22:09:25.53 (J2000)
Dec = +25:03:43.8 (J2000)
which is consistent with Zheng and Filipenko (GCN Circ. 23237).
The preliminary magnitude using the UVOT photometric calibration
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) is
filter Tstart Tend exposure magnitude
u 8.35e4 8.37e4 76.5 18.90 +- 0.23
u 8.70e4 8.74e4 373.0 18.87 +- 0.11
u 9.27e4 9.29e4 1.93.8 19.05 +- 0.17A
Times in seconds since Tzero=2018-09-14 18:22:40 UT.
No correction has been made for Galactic interstellar reddening of
E(B-V) = 0.07 (Schlafy&Finkbeiner, 2011 ApJ 737, 103).
GCN Circular 23240
Subject
Konus-Wind of the very bright GRB 180914B
Date
2018-09-16T14:34:47Z (7 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
D. Frederiks, S. Golenetskii, R.Aptekar, A. Kozlova,
A.Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The long, very bright GRB 180914B
(Agile/MCAL detection: Ursi et al., GCN 23226;
Fermi-LAT detection: Bissaldi & Longo, GCN 23232,
Agile/GRID detection: Verrecchia et al., GCN 23233)
triggered Konus-Wind (KW) at T0=66182.692 s UT (18:23:02.692).
The burst light curve shows multiple pulses in the interval from
T0 - 30 s to T0+250 s. A total duration of the burst (T100)
is ~280 s. The emission is seen up to ~15 MeV.
As observed by Konus-Wind, the burst had a fluence of
(1.15 �� 0.05)x10^-3 erg/cm2 and a 64-ms peak energy flux,
measured from T0+5.824, of (1.14 �� 0.24)x10^-4 erg/cm2
(both in the 20 keV - 10 MeV energy range).
The fluence of GRB 180914B is among the highest measured
for the Konus-Wind sample of >3000 GRBs detected since 1994.
The time-integrated spectrum (measured from T0 to T0+168.192 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.81 (-0.04,+0.04),
the high energy photon index beta = -2.12 (-0.7,+0.08),
the peak energy Ep = 466 (-27,+29) keV
(chi2 = 104/97 dof).
The spectrum near the peak count rate (measured from T0+5.632 s
to T0+6.144 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
alpha = -0.64 (-0.08,+0.10),
beta = -1.98 (-0.16,+0.12),
Ep = 1285 (-249,+287) keV
(chi2 = 68/69 dof).
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180914_T66182/
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.
GCN Circular 23239
Subject
GRB 180914B: Optical counterpart observation from OAJ
Date
2018-09-16T08:58:16Z (7 years ago)
From
Antonio de Ugarte Postigo at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), L. Izzo (HETH/IAA-CSIC),
D.A. Kann (HETH/IAA-CSIC), C.C. Thoene (HETH/IAA-CSIC), H. Vazquez
Ramio (CEFCA), N. Maicas (CEFCA) and V. Tilve (CEFCA) report:
We have observed the field of GRB 180914B (Ursi et al., GCN 23226;
Verrecchia et al., GCN 23231; Bissaldi et al. GCN 23232; D���Ai et al., GCN 23236)
with the 0.8m T80 telescope of the Javalambre Astrophysical Observatory
(Teruel, Spain). The observation consisted of 12x300s i-band exposures, each
covering the complete LAT error box. The exposures started at 22:03:46 UT of
the 15th September, 27.68 hr after the burst. The counterpart identified by Zheng
& Filippenko (GCN 23237) and Troja et al. (GCN 23238) is well detected in the
individual images. Photometry of the first epoch, as compared with SDSS
reference stars yields i(AB)=18.84+/-0.03.
Comparing with the RATIR photometry (roja et al. GCN 23238), our photometry
implies a decay rate of alpha ~ -1.9 (where F_nu ~ t^alpha), indicating that the
afterglow has possibly entered a post-jet-break regime evolution.
GCN Circular 23238
Subject
GRB 180914B: RATIR Optical and NIR Observations
Date
2018-09-16T05:48:12Z (7 years ago)
From
Eleonora Troja at GSFC <eleonora.troja@nasa.gov>
Eleonora Troja (GSFC), Alan M. Watson (UNAM), 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 (UVI), , Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jesus Gonzalez (UNAM), Carlos Roman-Zuniga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.),
and Vicki Toy (UMD) report:
We observed the field of GRB 180914B, detected by AGILE/MCAL (Ursi,
et al., GCN 23226) AGILE/GRID (Verrecchia, et al., GCN 23231), and
Fermi/LAT (Bissaldi, et al., GCN 23232) with the Reionization and
Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold
Johnson Telescope at the Observatorio Astronomico Nacional on Sierra
San Pedro Martir from 2018/09 16.14 to 2018/09 16.16 UTC (32.90 to
33.43 hours after the burst), obtaining 0.36 hours exposure in the
r and i bands and 0.15 hours exposure in the Z, Y, J, and H bands.
Within the Swift-XRT error circle (D'Ai, et al., GCN 23236),
we detect the object reported by Zheng & Filippenko (GCN 23237).
In comparison with the SDSS DR9 and 2MASS catalogs, we obtain
the following detections:
r = 19.51 +/- 0.01
i = 19.20 +/- 0.01
z = 18.93 +/- 0.03
Y = 18.75 +/- 0.03
J = 18.60 +/- 0.05
H = 18.28 +/- 0.04
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
The source position is consistent with a catalogued SDSS galaxy with
photometric redshift z~0.58. However, its brightness is significantly
higher than the values reported in the catalogue,suggesting that the
emission may be dominated by the GRB afterglow and that the SDSS
object may be the GRB host galaxy.
Further observations to establish the source variability are planned.
We thank the staff of the Observatorio Astronomico Nacional in San Pedro
Martir.
GCN Circular 23237
Subject
GRB 180914B: KAIT Optical Afterglow Candidate
Date
2018-09-16T04:23:18Z (7 years ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to AGILE/MCAL GRB 180914B (Ursi et al.,
GCN 23226 starting at Sep. 16, 03:47:39 UT, namely ~1.392 days
after the burst. Observations were performed with a sequence in the
clear (roughly R), B, V, R, and I filters, and the exposure time was
60 s per image. Inside the reported Swift/XRT afterglow error circle
(D'Ai et al., GCN 23236) we detected an optical afterglow candidate
at position:
RA: 22:09:25.55 (J2000)
Dec: +25:03:43.90 (J2000)
We estimate the clear band magnitude ~19.2. At this time, we can not
estimate the changes of the brightness. But the object was not presented
in the SDSS image, we therefore suggest it to be the optical afterglow of
GRB 180914B.
Observation are on going, multi-band follow-ups are encouraged.
GCN Circular 23236
Subject
GRB 180914B: Swift-XRT afterglow detection
Date
2018-09-15T22:21:41Z (7 years ago)
From
Paolo D'Avanzo at INAF-OAB <paolo.davanzo@brera.inaf.it>
A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), S. J. LaPorte (PSU),
J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), S.L. Gibson (U.
Leicester), Z. Liu (NAOC / U. Leicester), J.P. Osborne (U. Leicester),
P. D'Avanzo (INAF-OAB) 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 180914B (Bissaldi et al. GCN Circ. 23232)
in a series of observations tiled on the sky. The total exposure time
is 4.1 ks, distributed over 6 tiles; the maximum exposure at a single
sky location was 1.3 ks. The data were collected between T0+82.8 ks and
T0+93.8 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. Using 579 s of PC mode data
and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 332.35648, +25.06314 which is equivalent to:
RA (J2000): 22h 09m 25.56s
Dec(J2000): +25d 03' 47.3"
with an uncertainty of 3.4 arcsec (radius, 90% confidence). This
position is 12.1 arcmin from the Fermi/LAT position. The source has a
mean count rate of 6.2e-02 ct/sec; we cannot determine at the present
time whether it is fading.
The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/xrt_products/TILED_GRB00075/Source2.php.
The results of the full analysis of the tiled XRT observations are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00075.
This circular is an official product of the Swift-XRT team.
GCN Circular 23234
Subject
GRB 180914B: Tiled Swift observations
Date
2018-09-15T17:34:21Z (7 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 180914B. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00075
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 23232
Subject
GRB 180914B: Fermi-LAT detection
Date
2018-09-15T14:32:01Z (7 years ago)
From
Elisabetta Bissaldi at INFN,Bari <elisabetta.bissaldi@ba.infn.it>
E. Bissaldi (Politecnico & INFN Bari) and F. Longo (Univ & INFN Trieste)
report on behalf of the Fermi-LAT team:
At 18:23:02 UT on September 14, 2018 Fermi-LAT detected high-energy emission
from GRB 180914B, which was also detected by AGILE/MCAL (Ursi et al., GCN #23226)
and by AGILE/GRID (Verrecchia et al., GCN #23231).
The best LAT on-ground location is found to be
RA, Dec = 332.45, 24.88 (J2000)
with an error radius of 0.33 deg (90 % containment, statistical error only).
This was 94 deg from the LAT boresight at the time of the trigger.
The Fermi-LAT position is consistent with the AGILE/GRID one.
The data from the Fermi-LAT show a significant increase in the event rate
that is spatially correlated with the trigger with high significance.
The highest-energy photon is a 12.6 GeV event
which is observed 1662 s after the AGILE trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is
Elisabetta Bissaldi (elisabetta.bissaldi@ba.infn.it).
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 23231
Subject
GRB 180914B: AGILE/GRID detection
Date
2018-09-15T14:06:01Z (7 years ago)
From
Alessandro Ursi at INAF/IAPS <alessandro.ursi@gmail.com>
GRB 180914B: AGILE/GRID detection
F. Verrecchia (SSDC, and INAF/OAR), A. Ursi (INAF/IAPS), M. Tavani
(INAF/IAPS, and Univ. Roma Tor Vergata), F. Longo (Univ. Trieste and INFN
Trieste), A. Argan, M. Cardillo, A. Giuliani (INAF/IASF-Mi), Y.
Evangelista, G. Minervini, G. Piano (INAF/IAPS), F. Lucarelli, C.
Pittori (SSDC,
and INAF/OAR), A. Bulgarelli, V. Fioretti, F. Fuschino, M. Marisaldi
(INAF/OAS, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari),
I. Donnarumma (ASI),
report on behalf of the AGILE Team:
The Gamma-Ray Imaging Detector (GRID) of AGILE detected the long bright
GRB 180914B reported Ursi et al., GCN 23226.
A preliminary GRID analysis in the energy range 30 - 420 MeV shows a
detection
with a statistical significance of about 9 sigma, at the sky position
L,B: 85,-26 +/- 5 deg.
The gamma-ray emission detected by the AGILE-GRID lasted about 16 seconds,
and the preliminary estimated position is between 50 and 70 deg off-axis
angle.
These measurements were obtained with AGILE observing a large portion of
the sky in spinning mode. Additional analysis of AGILE data is in progress.
GCN Circular 23226
Subject
GRB 180914B: AGILE/MCAL detection of a burst
Date
2018-09-14T22:37:55Z (7 years ago)
From
Alessandro Ursi at INAF/IAPS <alessandro.ursi@gmail.com>
GRB 180914B: AGILE/MCAL detection of a burst
A. Ursi (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata),
A. Argan, M. Cardillo, Y. Evangelista, G. Minervini, G. Piano (INAF/IAPS),
F. Lucarelli, C. Pittori, F. Verrecchia (SSDC, and INAF/OAR),
A. Bulgarelli, V. Fioretti, F. Fuschino, N. Parmiggiani (INAF/OAS), M.
Marisaldi (INAF/OAS, and Bergen University), M. Pilia, A. Trois
(INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo (Univ. Trieste and INFN
Trieste), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team:
The AGILE Mini-CALorimeter (MCAL) detected a long burst at T0 = 2018-09-14
18:23:02.22 +/- 0.01 s (UTC).
The event lasted T90 = 5.8 s (in the 0.4-100 MeV energy range), consisting
of two broad pulses, and released a total number of ~25,000 counts in the
detector, above an average background rate of ~1250 counts / s.
Further analysis is still in progress.
The AGILE-MCAL detector has a full solid angle acceptance, and is
operational in the range 0.4 - 100 MeV.