GRB 180305A
GCN Circular 22476
Subject
GRB 180305A: AstroSat CZTI detection
Date
2018-03-13T16:37:50Z (8 years ago)
From
Vidushi Sharma at IUCAA <vidushi@iucaa.in>
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 bright GRB 180305A, which was also detected by Fermi/GBM (Veres P. et al., GCN 22458), Konus-Wind (Svinkin D. et al., GCN 22461), Swift/XRT (D'Avanzo P. et al., GCN 22462) and CALET (Penacchioni A. V. et al., GCN 22467).
The source was clearly detected in the 40-200 keV energy range. The light curve shows single peak emission with strongest peak at 09:26:12.5 UT, ~4 s after Fermi/GBM trigger. The measured peak count rate is 427.3 cts/s above the background in combined data of four quadrants, with a total of 2358 cts. The local mean background count rate was 490.6 cts/s. Using cumulative rates, we measure a T90 of 8.9 s.
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 22467
Subject
GRB 180305A CALET Gamma-Ray Burst Monitor detection
Date
2018-03-11T05:23:23Z (8 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
A. V. Penacchioni (U of Florence), A. Yoshida, T. Sakamoto, V. Pal'shin,
Y. Kawakubo, M. Moriyama, Y. Yamada, A. Tezuka, S. Matsukawa (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), 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, bright GRB 180305A (Fermi-LAT detection: Axelsson & Bissaldi,
GCN circ. 22457; Fermi-GBM detection: Veres & von Kienlin, GCN circ. 22458;
Konus-Wind detection: Svinkin et al., GCN circ. 22461) triggered the CALET
Gamma-ray Burst Monitor (CGBM) at 09:26:09.218 UTC on 5 March 2018.
No real time CGBM GCN notice was distributed about this trigger because
the real time communication from the ISS was off (loss of signal) between
9:00 and 9:36. The burst signal was seen by all CGBM detectors.
The burst light curve shows a single multi-peaked pulse which starts at T-0.5 sec,
peaks at T+3.4 sec and ends at T+14.6 sec. The T90 and the T50 durations measured
by the SGM data are 10.0 +- 0.8 sec and 3.88 +- 0.13 sec (40-1000 keV), respectively.
CGBM HV was turned off at ~T+95 sec due to entering the radiation belts,
so no CGBM data are available from that time until ~T+1300 sec.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1204276876/
On March 2, the CGBM on-board event data capture end time was changed from
8 sec to 512 sec, so from that time in the Event mode CGBM collects time tagged
events up to T0+512 sec, where T0 is the trigger time.
The CALET data used in this analysis are provided by the Waseda CALET
Operation Center located at the Waseda University.
GCN Circular 22465
Subject
GRB 180305A: RATIR Optical Observations
Date
2018-03-07T14:59:49Z (8 years ago)
From
Alan M. Watson at Instituto de Astronomia UNAM <alan@astro.unam.mx>
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), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jes��s Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and
Vicki Toy (UMD) report:
We observed the field of GRB 180305A (Axelsson, et al., GCN Circ. 22457)
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 2018/03 7.11 to
2018/03 7.20 UTC (41.30 to 43.46 hours after the BAT trigger), obtaining
a total of 1.64 hours exposure in the r and i bands.
The source reported by Troja et al. (GCN Circ. 22460) is still detected,
but has faded to:
r = 23.15 +/- 0.21
i = 22.80 +/- 0.15
These magnitudes are in the AB system, are calibrated against the
USNO-B1 catalog, and are not corrected for Galactic extinction in the
direction of the GRB.
The combination of the optical fading reported here and the X-ray fading
reported by D���Avanzo et al. (GCN Circ. 22462) confirm that this is the
afterglow of the GRB.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 22464
Subject
GRB 180305A: Swift/UVOT Upper Limits
Date
2018-03-06T18:03:54Z (8 years ago)
From
Sam Emery at MSSL-UCL <samuel.emery.15@ucl.ac.uk>
S.W.K. Emery (MSSL-UCL) and M. H. Siegel (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180305A
30621 s after the Fermi/LAT trigger (Axelsson et al., GCN Circ. 22457).
No optical afterglow consistent with the enhanced XRT position
(D'Avanzo et al., GCN Circ. 22462)
or the RATIR and Mondy detections (Troja et al., GCN Circ. 22460;
Mazaeva et al., GCN Circ. 22463)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) in the
initial exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 30808 52964 961 >21.4
u 30621 52533 2623 >20.7
v 30994 48392 712 >19.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.454 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 22463
Subject
GRB 180305A: Mondy optical observations
Date
2018-03-06T17:07:13Z (8 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova
(IKI) report on behalf of of larger GRB follow-up collaboration:
We observed the field of LAT/Fermi GRB 180305A (Axelsson, et al., GCN
22457) and Konus-Wind (Svinkin et al., GC 22461) with AZT-33IK telescope
of Sayan observatory (Mondy). We obtained several images in R-filter
starting on Mar. 06 (UT) 12:35:17. The afterglow candidate (Troja et
al., GCN 22460) is clearly detected within XRT/Swift error circle
(D'Avanzo et al., GCN 22462). Preliminary photometry is following.
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2018-03-06 12:35:17 1.15219 R 30*120 22.69 0.15 23.7
The photometry is based on nearby USNO-B1.0 stars
USNO-B1_id R2
1221-0050419 18.60
1221-0050432 16.39
1221-0050407 19.31
Since the source has faded in comparison with the previous observation
(Troja et al., GCN 22460) we can confirm the afterglow of GRB 180305A.
GCN Circular 22462
Subject
GRB 180305A: Swift-XRT afterglow detection
Date
2018-03-06T15:38:42Z (8 years ago)
From
Boris Sbarufatti at PSU <bxs60@psu.edu>
P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J.
LaPorte (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester),
A.P. Beardmore (U. Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA)
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 180305A (Axelsson et al. GCN Circ. 22457),
collecting 4.7 ks of Photon Counting (PC) mode data between T0+30.6 ks
and T0+53.0 ks.
Four uncatalogued X-ray sources are detected, of which one ("Source 2")
is above the RASS limit and fading with 3-sigma significance, and is
therefore likely the GRB afterglow. Using 3574 s of PC mode data and 6
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 = 49.61821, +32.10994 which is equivalent to:
RA (J2000): 03h 18m 28.37s
Dec(J2000): +32d 06' 35.8"
with an uncertainty of 1.7 arcsec (radius, 90% confidence). This
position is 2.7 arcmin from the Fermi/LAT position.
The light curve can be modelled with a power-law decay with a decay
index of alpha=2.7 (+0.5, -0.8).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.5 (+/-0.4). The
best-fitting absorption column is 4.7 (+3.2, -2.3) x 10^21 cm^-2,
consistent with the Galactic value of 2.4 x 10^21 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum is 5.4 x 10^-11 (6.9 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 4.7 (+3.2, -2.3) x 10^21 cm^-2
Galactic foreground: 2.4 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.5 (+/-0.4)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020789.
The results of the full analysis of the XRT observations are available
at http://www.swift.ac.uk/ToO_GRBs/00020789.
This circular is an official product of the Swift-XRT team.
GCN Circular 22461
Subject
Konus-Wind observation of GRB 180305A
Date
2018-03-06T14:42:58Z (8 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@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, bright GRB 180305A
(Fermi-LAT detection: Axelsson and E. Bissaldi, GCN Circ. 22457;
Fermi-GBM detection: Veres and von Kienlin, GCN Circ. 22458)
triggered Konus-Wind at T0=33967.647 s UT (09:26:07.647).
The burst light curve shows a single emission episode
which starts at ~T0-2.4 s and has a total duration of ~44 s.
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180305_T33967/
As observed by Konus-Wind, the burst
had a fluence of 8.43(-0.58,+0.59)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+3.168 s,
of 2.02(-0.32,+0.32)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+16.128 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.51(-0.09,+0.10),
the high energy photon index beta = -2.41(-0.17,+0.13),
the peak energy Ep = 348(-27,+30) keV
(chi2 = 139/97 dof).
The spectrum near the maximum count rate
(measured from T0+0.256 to T0+4.352 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.25(-0.15,+0.17),
the high energy photon index beta = -2.59(-0.44,+0.23),
the peak energy Ep = 467(-56,+64) keV
(chi2 = 113/81 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 22460
Subject
GRB 180305A: RATIR Optical Afterglow Candidate
Date
2018-03-06T11:24:41Z (8 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), Jes��s Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and
Vicki Toy (UMD) report:
We observed the field of the LAT GRB 180305A (Axelsson, et al., GCN 22457)
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 2018/03 6.11 to 2018/03 6.20 UTC
(17.28 to 19.45 hours after the burst), obtaining a total of 1.36 hours
exposure in the r and i bands.
At the position of source #2 found by Swift-XRT�� (Evans, et al., GCN
22459),
we detect a faint uncatalogued optical source. In comparison with the
USNO-B1 catalog, we obtain the following detections:
�� r������ = 21.95 +/- 0.12
�� i������ = 21.48 +/- 0.08
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
The source is located at RA,Dec = 03:18:28.33,+32:06:36.2 (J2000, +/-0.5").
Further observations to establish fading of the optical source are planned.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 22459
Subject
GRB 180305A: Swift ToO observations
Date
2018-03-05T18:06:15Z (8 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 ToO observation of the Fermi/LAT GRB 180305A.
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020789
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Fermi/LAT event. 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 22458
Subject
GRB 180305A: Fermi GBM detection
Date
2018-03-05T17:10:52Z (8 years ago)
From
Peter Veres at UAH <veresp@gmail.com>
P. Veres (UAH) and A. von Kienlin (MPE)
report on behalf of the Fermi GBM Team:
"At 09:26:08.66 UT on 05 March 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180305A (trigger 541934773 / 180305393) which
was also detected by the Fermi LAT (Axelsson et al., GCN 22457).
The GBM on-ground location is consistent with the LAT position.
The angle from the Fermi LAT boresight at the GBM trigger time is 70 degrees.
The GBM light curve consists of a single bright pulse
with a duration (T90) of about 12.5 s (50-300 keV).
The time-averaged spectrum from T0 to T0+24.1 s is best fit by
a Band function with Epeak= 334 +/- 10 keV, alpha = -0.48 +/- 0.02
and beta = 2.29 +/- 0.07.
The event fluence (10-1000 keV) in this time interval is
(3.302 +/- 0.023)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+3.65 s in the 10-1000 keV band
is 32.2 +/- 0.5 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 22457
Subject
GRB 180305A: Fermi-LAT detection
Date
2018-03-05T15:32:53Z (8 years ago)
From
Magnus Axelsson at Stockholm U. <magaxe@kth.se>
M. Axelsson (KTH and Stockholm Univ.) and E. Bissaldi (Politecnico and INFN Bari), report on behalf of the Fermi-LAT team:
At 09:26:08.66 UT on March 05, 2018, Fermi-LAT detected high-energy emission from GRB 180305A, which was also detected by Fermi-GBM (trigger 541934773 / 180305393).
The best LAT on-ground location is found to be
RA, Dec = 49.7, 32.1 (J2000)
with an error radius of 0.12 deg (90 % containment, statistical error only).
This location was a few degrees outside the LAT field of view at the time of the trigger. It entered the FoV approximately 200s later, and remained visible until around 2600s after the trigger time.
The data from the Fermi-LAT show a significant increase in the event rate that is spatially correlated with the trigger with high significance. More than 10 events above 100 MeV are detected. The highest-energy photon is a 9 GeV event which is observed ~1630 seconds after the GBM trigger.
A Swift ToO has been approved for this burst.
The Fermi-LAT point of contact for this burst is Magnus Axelsson (magaxe@kth.se<mailto:magaxe@kth.se>).
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.