GRB 180626A
GCN Circular 22870
Subject
GRB 180626A: TSHAO optical upper limit
Date
2018-06-29T16:09:33Z (8 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Pozanenko (IKI), A. Kusakin (FAPHI), I. Reva
(FAPHI), A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger
GRB follow-up collaboration:
We observed the field of GRB 180626A (Evans et al., GCN 22850; Gotz et
al., GCN 22851) with Zeiss-1000 1-m telescope of Tien Shan
Astronomical Observatory starting on June 26 (UT) 16:26:21. We obtained
several images in R-filter. The optical afterglow (Evans et al., GCN
22850; Martone et al. GCN 22854; Troja et al. GCN 22855; Watson et al.
GCN 22859) is not detected in a stacked image. Preliminary photometry
of the field is following.
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2018-06-26 16:26:21 0.41918 R 99*120 n/d n/d 21.5
The photometry is based on several nearby SDSS-DR10 stars.
Ref.stars
SDSS-DR9_id R(Lupton)
J161422.32+144433.2 15.113
J161357.84+144752.0 13.989
J161440.94+144745.0 13.136
GCN Circular 22869
Subject
Konus-Wind observation of GRB 180626A
Date
2018-06-29T10:49:02Z (8 years ago)
From
Anna Kozlova at Ioffe Institute <ann_kozlova@mail.ioffe.ru>
A. Kozlova, S. Golenetskii, R.Aptekar, D. Frederiks,
M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko,
and T. Cline on behalf of the Konus-Wind team, report:
The long GRB 180626A (Swift-BAT trigger #844615: Evans et al.,
GCN 22850; Krimm et al., GCN 22862;
INTEGRAL detection: Gotz et al., GCN 22851)
was detected by Konus-Wind (KW) in the waiting mode.
The burst light curve shows a single emission episode
with a duration of ~ 36 s.
As observed by KW, the burst had a fluence of
7.21(-0.79,+0.97)x10^-6 erg/cm2 and a 2.944-s peak flux,
measured from ~T0(BAT)-3.841 s, of 3.92(-0.49,+0.58)x10^-7 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
Modeling the KW 3-channel time-integrated spectrum
(from ~T0(BAT)-9.7 s to ~T0(BAT)+25.6 s)
by a simple power-law model yields a power law
index of -2.19(-0.04,+0.05), chi2 = 2.5/1 dof.
The KW light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB180626A/
All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.
GCN Circular 22865
Subject
GRB 180626A: RATIR Optical Observations
Date
2018-06-27T05:11:57Z (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 180626A (Evans, et al., GCN Circ. 22850)
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 2018/06 27.16 to
2018/06 27.20 UTC (19.60 to 20.46 hours after the BAT trigger),
obtaining a total of 0.71 hours exposure in the r and i bands.
For a source at the position of the UVOT counterpart, in comparison with
the SDSS DR9 catalog, we obtain the following detections:
r = 22.39 +/- 0.20
i = 21.92 +/- 0.15
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
The source flux has faded approximately as t^-0.35 since our previous
observations (Troja et al., GCN Circ. 22855).
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 22862
Subject
GRB 180626A: Swift-BAT refined analysis
Date
2018-06-26T20:41:06Z (8 years ago)
From
Hans Krimm at NSF/NASA-GSFC <hkrimm@nsf.gov>
H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
P. A. Evans (U Leicester), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+526 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180626A (trigger #844615)
(Evans, et al., GCN Circ. 22850). The BAT ground-calculated position is
RA, Dec = 243.569, 14.759 deg which is
RA(J2000) = 16h 14m 16.6s
Dec(J2000) = +14d 45' 32.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 35%.
The mask-weighted light curve shows a multi-peaked structure. The first peak
is from approximately T-10 to T+5 sec, with a second overlapping peak from T+5
to T+20 sec, followed by a weaker peak from T+20 to T+30 sec.
T90 (15-350 keV) is 30.07 +- 1.42 sec (estimated error including systematics).
The time-averaged spectrum from T-10.01 to T+25.59 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.64 +- 0.27,
and Epeak of 47.7 +- 12.2 keV (chi squared 40.18 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 4.8 +- 0.2 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T-3.69 sec in the 15-150 keV band is
4.1 +- 0.4 ph/cm2/sec. A fit to a simple power law gives a photon index
of 2.01 +- 0.06 (chi squared 46.26 for 57 d.o.f.). All the quoted errors
are at the 90% confidence level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/844615/BA/
GCN Circular 22861
Subject
GRB 180626A: KAIT Optical Upper Limit
Date
2018-06-26T19:58:36Z (8 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 GRB 180626A (Evans et al.,
GCN 22850; Gotz et al., GCN 22851) starting at 08:23:31 UT, 135 s
after the Swift/BAT trigger. Observations were performed with an
automatic sequence in the clear (roughly R), V, and I filters,
and the exposure time was 20 s per image. Since the INTEGRAL trigger
was received earlier than the Swift trigger, KAIT responed to the
INTEGRAL trigger first. Unfortunately the UVOT afterglow location
(Evans et al., GCN 22850) is outside our field of view for the first
few images. We later manually re-pointed to the UVOT afterglow location
starting at 08:52:10 UT about 30 minutes after the Swift/BAT trigger,
with the updated exposure time of 60 s per image.
We do not detect the afterglow at the reported UVOT location
(Evans et al., GCN 22850) in our single image, nor in the co-added
images. The typical limiting magnitude of our single clear image is
about 19.5 mag calibrated to the PS1 catalog.
GCN Circular 22860
Subject
GRB 180626A: Swift-XRT refined Analysis
Date
2018-06-26T18:28:59Z (8 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), S.L. Gibson (U.
Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo
(INAF-OAB), A. Tohuvavohu (PSU), S. J. LaPorte (PSU) and P.A. Evans
report on behalf of the Swift-XRT team:
We have analysed 6.6 ks of XRT data for GRB 180626A (Evans et al. GCN
Circ. 22850), from 129 s to 22.4 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Osborne et al. (GCN Circ. 22852).
The light curve can be modelled with an initial power-law decay with an
index of alpha=0.21 (+0.14, -0.15), followed by a break at T+2992 s to
an alpha of 0.90 (+0.11, -0.10).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.01 (+/-0.11). The
best-fitting absorption column is 2.2 (+/-0.4) x 10^21 cm^-2, in
excess of the Galactic value of 3.5 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 3.5 x 10^-11 (4.9 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.2 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 3.5 x 10^20 cm^-2
Excess significance: 8.0 sigma
Photon index: 2.01 (+/-0.11)
If the light curve continues to decay with a power-law decay index of
0.90, the count rate at T+24 hours will be 0.028 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x
10^-12 (1.4 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00844615.
This circular is an official product of the Swift-XRT team.
GCN Circular 22859
Subject
GRB 180626A: COATLI Optical Detection
Date
2018-06-26T17:10:10Z (8 years ago)
From
Alan M. Watson at Instituto de Astronomia UNAM <alan@astro.unam.mx>
Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), William
H. Lee (UNAM), Carlos Rom��n-Z����iga (UNAM), Alexander Kutyrev (GSFC), and
Eleonora Troja (GSFC) report:
We observed the field of GRB 180626A (Evans et al., GCN 22850) with the
COATLI 50-cm telescope and interim imager at the Observatorio
Astron��mico Nacional on the Sierra de San Pedro M��rtir
(http://coatli.astroscu.unam.mx) from 2018-06-20 08:21:50.6 to
11:18:41.7 UTC (from 33.7 seconds after the trigger or 17.9 seconds
after the alert to 2.95 hours after the trigger), obtaining a total of
7020 seconds of exposure in the w filter.
Within the enhanced XRT error region (Osborne et al., GCN Circ. 22852),
we detect the afterglow previously reported by Evans et al. (GCN Circ.
22850), Martone et al. (GCN Circ. 22854), and Breeveld et al. (GCN Circ.
22857) with
w = 21.4 +/- 0.9
In our first set of 30 images each of 5 seconds of exposure, from
08:21:50.6 to 08:27:10.1 UTC, we do not detect the afterglow with a
10-sigma limiting magnitude of
w > 19.2
These magnitudes are calibrated against the Pan-STARRS1 catalog and the
USNO-B1 catalog (adjusted to an approximate AB system) and are not
corrected for Galactic extinction in the direction of the GRB.
We thank the COATLI technical team (Fernando ��ngeles, Oscar Chapa,
Salvador Cuevas, Alejandro Farah, Jorge Fuentes, Rosal��a Langarica,
Fernando Quir��s, and Carlos Tejada) and the staff of the Observatorio
Astron��mico Nacional.
GCN Circular 22857
Subject
GRB 180626A: Swift/UVOT Detection
Date
2018-06-26T15:22:56Z (8 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180626A
123 s after the BAT trigger (Evans et al., GCN Circ. 22850).
A fading source consistent with the XRT position (Osborne et al. GCN
Circ. 22852) and also seen by Martone et al. (GCN Circ. 22854) and Troja
et al. (GCN Circ. 22855) is detected in the initial UVOT exposures.
Preliminary detections and 3-sigma upper limits using the UVOT
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for
the finding chart (FC) and early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 123 273 147 20.57 �� 0.22
white 633 1033 190 >21.4
v 665 6473 452 >20.2
b 591 5858 246 >20.4
u 336 6936 529 >20.7
w1 714 6882 432 >21.0
m2 5043 6677 393 >20.1
w2 641 6268 432 >21.3
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.04 in the direction of the
burst (Schlegel et al. 1998).
GCN Circular 22855
Subject
GRB 180626A: RATIR Optical Detection
Date
2018-06-26T12:36:12Z (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), 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 180626A (Evans, et al., GCN 22850) 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 2018/06 26.42 to 2018/06 26.43 UTC (1.61
to 2.06 hours after the BAT trigger), obtaining a total of 0.36 hours
exposure in the r and i bands.
For a source at the position of the UVOT counterpart, in comparison
with the SDSS DR9 catalog, we obtain the following detections:
�� r������ = 21.57 +/- 0.22
�� i������ = 20.91 +/- 0.13
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. These magnitudes are fainter
than the values reported by Martone et al. (GCN 22854) suggesting that
the source is indeed the fading GRB afterglow.
We thank the staff of the Observatorio Astronomico Nacional in San Pedro
Martir.
GCN Circular 22854
Subject
GRB 180626A: LCO Haleakala observations
Date
2018-06-26T12:13:43Z (8 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
R. Martone, C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell
(U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU), A. Cucchiara
(U. of Virgin Islands) on behalf of a large collaboration report:
The LCO 2-m unit at Haleakala Observatory (Hawaii), former FTN, began
observing Swift and INTEGRAL GRB 180626A (Evans et al. GCN 22850; Gotz
et al. GCN 22851) on June 26, 08:41:11 UT (20 min after the GRB trigger
time) with the SDSS ri filters. The optical counterpart (Evans et al.)
is clearly detected� with the following magnitudes:
Mid Time since GRB��� Exposure�������� Filter������� Magnitude
(hrs)����������������� (s)
------------------------------------------------------------------
0.424���������������� 5x120����������� SDSS-R������� 20.96 +- 0.12
0.617���������������� 5x120����������� SDSS-I������� 20.53 +- 0.12
------------------------------------------------------------------
as calibrated against nearby SDSS objects.
GCN Circular 22853
Subject
GRB 180626A: ISON-MN optical observations
Date
2018-06-26T11:25:47Z (8 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
L. Elenin (KIAM), E. Mazaeva (IKI), A. Pozanenko (IKI), A. Volnova
(IKI), I. Molotov (KIAM) report on behalf of larger GRB follow-up
collaboration:
We observed the field of the Swift GRB 180626A (Evans et al., GCN
22850) with ISON-NM observatory. Observation started 51 s after burst
trigger. We do not find optical afterglow (Evans et al., GCN 22850) in
a combined image of first 5 frames. Preliminary photometry of the filed
is following.
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2018-06-26 08:22:07 0.00146 CR 5* 20 n/d n/d 17.3
The photometry is based on several nearby USNO-B1.0 stars.
GCN Circular 22852
Subject
GRB 180626A: Enhanced Swift-XRT position
Date
2018-06-26T10:07:10Z (8 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 804 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 180626A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 243.57603, +14.75692 which is equivalent
to:
RA (J2000): 16h 14m 18.25s
Dec (J2000): +14d 45' 24.9"
with an uncertainty of 1.8 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.
GCN Circular 22851
Subject
GRB 180626A: A long GRB detected by INTEGRAL
Date
2018-06-26T09:34:14Z (8 years ago)
From
Diego Gotz at CEA <diego.gotz@cea.fr>
D.Gotz (CEA, Saclay), S.Mereghetti (IASF-Milano), C.Ferrigno, E. Bozzo, V.Savchenko (ISDC, Versoix), L. Ducci (IAAT/ISDC) and J.Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report:
a gamma ray burst lasting about 40 s has been detected by IBAS in the IBIS/ISGRI data at 08:21:04 UT of June 26, 2018
The refined coordinates (J2000) are:
R.A.= 243.5715 deg
DEC.= 14.7486 deg
with an uncertainty of 1.1 arcmin (90% c.l.).
The burst had a measured peak flux of about 2.7 counts/cm2/s (20-200 keV, 1-s integration time) and a fluence in the same energy range of about 2e-6 erg/cm2. We note that both those values are lower limits, due to telemetry saturation at satellite level.
This burst was also detected by the Swift/BAT, XRT and UVOT (Evans et al., GCN 22850), and the IBIS position is at 33 arc seconds from the UVOT one.
A plot of the light curve will be posted at http://ibas.iasf-milano.inaf.it/IBAS_Results.html
GCN Circular 22850
Subject
GRB 180626A: Swift detection of a burst with an optical counterpart
Date
2018-06-26T08:34:26Z (8 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
P. A. Evans (U Leicester), A. P. Beardmore (U Leicester),
J.D. Gropp (PSU), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC) and
K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 08:21:16 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180626A (trigger=844615). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 243.567, +14.764 which is
RA(J2000) = 16h 14m 16s
Dec(J2000) = +14d 45' 52"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a multi-peaked
structure with a duration of about 50 sec. The peak count rate
was ~3400 counts/sec (15-350 keV), at ~-2 sec after the trigger.
The XRT began observing the field at 08:23:16.9 UT, 120.0 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 243.57544, 14.75598 which is equivalent
to:
RA(J2000) = 16h 14m 18.11s
Dec(J2000) = +14d 45' 21.5"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 41 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (3.47 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.2
(+2.28/-2.05) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 123 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 16:14:18.12 = 243.57551
DEC(J2000) = +14:45:25.5 = 14.75707
with a 90%-confidence error radius of about 0.81 arc sec. This position is 5.1
arc sec. from the center of the XRT error circle. The estimated magnitude is
20.71 with a 1-sigma error of about 0.23. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.04.
Burst Advocate for this burst is P. A. Evans (pae9 AT star.le.ac.uk).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)