GRB 171027A
GCN Circular 22053
Subject
GRB 171027A: Swift detection of a burst
Date
2017-10-27T08:40:01Z (8 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
P. D'Avanzo (INAF-OAB), P. A. Evans (U Leicester),
N. P. M. Kuin (UCL-MSSL), K. L. Page (U Leicester),
D. M. Palmer (LANL) and B. Sbarufatti (PSU) report on behalf of the
Swift Team:
At 08:23:06 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 171027A (trigger=783479). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 61.680, -2.606 which is
RA(J2000) = 04h 06m 43s
Dec(J2000) = -02d 36' 21"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a multiple-peaked
structure with a duration of about 120 sec. The peak count rate
was ~4000 counts/sec (15-350 keV), at ~60 sec after the trigger.
The XRT began observing the field at 08:24:34.1 UT, 87.6 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 61.68989, -2.62100
which is equivalent to:
RA(J2000) = 04h 06m 45.57s
Dec(J2000) = -02d 37' 15.6"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 64 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 (1.08 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 2.9
(+2.47/-2.17) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 1.36e-08 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 95 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.14.
Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT brera.inaf.it).
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.)
GCN Circular 22054
Subject
GRB 171027A: Prompt enhanced Swift-XRT position
Date
2017-10-27T09:16:01Z (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-XRT team:
Using promptly downlinked XRT event data for GRB 171027A, we find an
enhanced XRT position of the afterglow: RA, Dec: 61.6907, -2.6223 which
is equivalent to:
RA (J2000) = 04 06 45.78
Dec (J2000) = -02 37 20.4
with an uncertainty of 2.1 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/783479.
Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular 22055
Subject
GRB 171027A: MASTER-OAFA (Argentina) early prompt optical observations
Date
2017-10-27T10:28:03Z (8 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, D.Kuvshinov, P.Balanutsa,
A.Kuznetsov, V.V.Chazov, D. Vlasenko, I.Gorbunov, A.V.Krylov
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University
R. Podesta, Carlos Lopez and F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA)
Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias
K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk
Irkutsk State University
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
V. Yurkov, A. Gabovich, Yu. Sergienko
Blagoveschensk Educational State University, Blagoveschensk
D. Buckley, S. Potter, A. Kniazev, M. Kotze
South African Astronomical Observatory
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in OAFA was pointed to the GRB171027A ( D'Avanzo et al., GCN
Circ 22053 ) 26 sec after notice time
and 71 sec after trigger time at 2017-10-27 08:24:17 UT. On our first (10s
exposure) set we haven`t found optical transient within SWIFT error-box
(ra=61.6708 dec=-2.60556 r=0.05). The 5-sigma upper limit has been about
17.5 mag . This and next 2 images are prompt optical limit because GRB
duration is ~ 120
sec (D'Avanzo et al., GCN Circ 22053 )
The OT limit are:
ID UT Exp Type Limit
103456 08:24:17 10 Alert (SWIFT) 17.5
103463 08:24:17 70 SumAlert (SWIFT) 19.0
103473 08:24:17 550 SumAlert (SWIFT) 20.0
103457 08:25:09 20 Alert (SWIFT) 18.1
103459 08:26:10 40 Alert (SWIFT) 18.6
103467 08:27:34 210 SumAlert (SWIFT) 19.5
103460 08:27:34 50 Alert (SWIFT) 18.6
103461 08:29:07 70 Alert (SWIFT) 18.9
103462 08:31:00 90 Alert (SWIFT) 19.0
103472 08:33:15 450 SumAlert (SWIFT) 19.9
103464 08:33:15 120 Alert (SWIFT) 19.2
103466 08:36:00 150 Alert (SWIFT) 19.2
103468 08:39:15 180 Alert (SWIFT) 19.3
103476 08:43:00 540 SumAlert (SWIFT) 19.5
103470 08:43:00 180 Alert (SWIFT) 19.0
103471 08:46:43 180 Alert (SWIFT) 18.8
103474 08:50:25 180 Alert (SWIFT) 18.4
103477 08:54:08 180 Alert (SWIFT) 18.1
103478 08:57:53 180 Alert (SWIFT) 18.1
The observations made on zenit distance = 41 degrees, galaxy latitude b =
-37 degree. The moon (45 % bright part) below the horizon (The altitude of
the Moon is -33 degree ). Observations started at twilight.
The sun altitude is -16.5 degree.
The object can be observed till sunrise at 2017-10-27 09:44:50
The message may be cited.
GCN Circular 22056
Subject
GROND observations of GRB 171027A
Date
2017-10-27T11:17:03Z (8 years ago)
From
Patricia Schady at MPE/Swift <pschady@mpe.mpg.de>
P. Schady (MPE) reports:
Observations of the field of GRB 171027A (Swift trigger 783479; D'Avanzo
et al., GCN #22053) were carried out simultaneously in g'r'i'z' with GROND
(Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at
ESO La Silla Observatory (Chile).
Observations started at 08:51 UT on 27-10-2017, 28.4 mins after the GRB
trigger. They were performed during astronomical twilight, at an average
seeing of 1.4" and at an average airmass of 1.4.
Using a total exposure of 4.4 min, no source is detected within the 2.1"
enhanced Swift/XRT error circle (Evans et al., GCN 22054) down to the
following 3 sigma upper limits (all in AB):
g' > 23.1
r' > 23.1
i' > 22.3
z' > 22.2
Given magnitudes are calibration against PanSTARRS and are not corrected
for the expected Galactic foreground extinction corresponding to a
reddening of E_(B-V)=0.12 mag in the direction of the burst (Schlafly &
Finkbeiner 2011).
I acknowledge the excellent support provided by Angela Hempel in obtaining
these data.
GCN Circular 22057
Subject
GRB 171027A: RATIR Detection of a NIR Afterglow Candidate
Date
2017-10-27T11:20:05Z (8 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 (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 GRB 171027A (D'Avanzo et al., GCN Circ. 22053)
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 2017/10 27.35 to
2017/10 27.37 UTC (0.04 to 0.51 hours after the BAT 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.
For a source within the Swift-XRT error circle, in comparison with the
USNO-B1 and 2MASS catalogs, we obtain the following detections and upper
limits (3-sigma):
r > 23.17
i > 23.12
Z > 20.66
Y > 21.09
J = 20.95 +/- 0.26
H = 19.12 +/- 0.06
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. The source position is at RA,
Dec (J2000) = 04:06:45.77 -02:37:18.9 (+/- 0.5 arcsec). We currently
have no evidence for fading.
The very red colors suggest that this might be at high redshift or
dusty.
Further observations are planned.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 22058
Subject
GROND observations of GRB 171027A: correction
Date
2017-10-27T11:49:56Z (8 years ago)
From
Patricia Schady at MPE/Swift <pschady@mpe.mpg.de>
P. Schady (MPE) reports:
The upper limits reported in GCN #22056 were in fact calibrated against
GROND zeropoints. The 3-sigma upper limits (AB) calibrated against
PanSTARRS are in fact:
g' > 22.2
r' > 22.2
i' > 21.2
z' > 21.0
The reported magnitudes are not corrected for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V)=0.12 mag in
the direction of the burst (Schlafly & Finkbeiner 2011).
GCN Circular 22059
Subject
GRB 171027A: LCO 1-m telescope observations
Date
2017-10-27T11:51:22Z (8 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), I.A. Steele (LJMU) on behalf of a large
collaboration report:
We began observing Swift GRB171027A (D'Avanzo et al. GCN 22053) on
October 27, from 08:39:29 to 09:06:37 UT (16 minutes since the GRB
trigger time) with one of the 1-m LCO McDonald telescopes in the SDSS
gri filters. Within the enhanced Swift-XRT error circle (Evans et al.
22054) and in particular at the position of the NIR afterglow candidate
(Watson et al. GCN 22057) we do not see any optical source down to the
following limits in agreement with previous reports (Lipunov et al. GCN
22055; Schady et al. GCN 22056):
Mid Time���� Exposure������ Filter������ Magnitude (AB)
(hrs)�������� (s)
-------------------------------------------------------
0.5��������� 5x60���������� SDSS-G��������� > 19.5
0.5��������� 5x60���������� SDSS-R��������� > 19.3
0.5��������� 5x60���������� SDSS-I��������� > 18.8
-------------------------------------------------------
as calibrated against nearby USNO URAT1 objects.
GCN Circular 22060
Subject
GRB 171027A: VLT optical upper limits
Date
2017-10-27T12:01:58Z (8 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
D. Malesani (DARK/NBI), N. R. Tanvir (Univ. Leicester), P. Schady (MPE),
A. de Ugarte Postigo (IAA/CSIC and DARK/NBI), K. E. Heintz (Univ.
Iceland and DARK/NBI), G. Pugliese (API, Univ. Amsterdam), report on
behalf of the Stargate collaboration:
We observed the field of GRB 171027A (D'Avanzo et al., GCN 22053) with
the ESO Very Large Telescope (VLT) UT2 equipped with X-shooter.
Observations started on 2017 Oct 27.379 UT (42.8 min after the trigger)
using the acquisition camera, entirely during twilight. For this reason,
only short exposures could be secured (45 s in r, 60 s in z).
Within the prompt-enhanced XRT position (Evans, GCN 22054) we find no
new sources down to r > 23, z > 22.7 mag (all AB, calibrated against the
Pan-STARRS catalog). Our results are consistent with the lack of optical
detection by GROND (Schady, GCNs 22056, 22058), RATIR (Watson et al.,
GCN 22057), and LCO (Guidorzi, GCN 22059). In particular, we confirm
that no object is visible at the position of the NIR candidate reported
by Watson et al. (GCN 22057).
We acknowledge excellent support from the ESO staff, in particular
Michael Hilker and Francisco Labrana.
GCN Circular 22061
Subject
GRB 171027A: RATIR Confirmation of Fading and Photo-z
Date
2017-10-27T14:50:03Z (8 years ago)
From
Nat Butler at Az State U <natbutler@asu.edu>
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), 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 continued to observe the field of GRB 171027A (D'Avanzo et al., et al.,
GCN 22053) 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 2017/10 27.35 to
2017/10 27.53 UTC (0.04 to 4.24 hours after the BAT trigger), obtaining a
total of 2.82 hours exposure in the r and i bands and 1.18 hours exposure
in the Z, Y, J, and H bands.
At late time, the source is only detected in the H-band, with H = 19.12 +/-
0.06. This magnitude is calibrated relative to 2MASS and is in the AB
system, not corrected for Galactic extinction in the direction of the GRB.
We measure a fade in the H-band flux in time as t^(-1.0+/-0.1).
Using all bands (see, Watson et al., GCN 22057), we find high A_V photo-z
solutions nearby (z<3.85, 90% conf.) and a high-z solution which assumes
A_V=0 (z=9+/-1). We note that the XRT N_H constraints (D'Avanzo et al., et
al., GCN 22053) point toward the high A_V solution, although with low
statistical significance.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 22062
Subject
GRB 171027A: Enhanced Swift-XRT position
Date
2017-10-27T14:59:05Z (8 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team.
Using 3587 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 171027A, 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 = 61.69071, -2.62207 which is equivalent
to:
RA (J2000): 04h 06m 45.77s
Dec (J2000): -02d 37' 19.5"
with an uncertainty of 1.4 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 22063
Subject
GRB 171027A: Swift-XRT refined Analysis
Date
2017-10-27T15:09:38Z (8 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
S. J. LaPorte (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester),
P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), V. D'Elia
(ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti
(INAF-OAB/PSU) and P. D'Avanzo report on behalf of the Swift-XRT team:
We have analysed 6.8 ks of XRT data for GRB 171027A (D'Avanzo et al.
GCN Circ. 22053), from 81 s to 18.6 ks after the BAT trigger. The data
comprise 191 s in Windowed Timing (WT) mode (the first 5 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Goad et al.
(GCN Circ. 22054).
The light curve can be modelled with an initial power-law decay with an
index of alpha=3.53 (+/-0.12), followed by a break at T+274 s to an
alpha of 0.96 (+/-0.03).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.43 (+/-0.07). The
best-fitting absorption column is 2.8 (+/-0.4) x 10^21 cm^-2, in
excess of the Galactic value of 1.1 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.02 (+0.13, -0.12)
and a best-fitting absorption column of 3.6 (+0.6, -0.5) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.8 x 10^-11 (5.8 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 3.6 (+0.6, -0.5) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 7.7 sigma
Photon index: 2.02 (+0.13, -0.12)
If the light curve continues to decay with a power-law decay index of
0.96, the count rate at T+24 hours will be 0.026 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.7 x
10^-13 (1.5 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/00783479.
This circular is an official product of the Swift-XRT team.
GCN Circular 22064
Subject
GRB 171027A: Swift/UVOT Upper Limits
Date
2017-10-28T10:59:30Z (8 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates (U. Warwick) and P. D'Avanzo (INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 171027A
96 s after the BAT trigger (D'Avanzo et al., GCN Circ. 22053).
No optical afterglow consistent with the optical position
(Watson et al. GCN Circ. 22057)
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) for the first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 96 246 147 >20.6
u_FC 308 558 246 >20.0
white 96 6148 428 >21.2
v 639 6558 432 >19.7
b 564 5943 236 >20.3
u 308 5737 462 >20.3
w1 688 6835 282 >19.8
m2 5126 6763 393 >19.8
w2 4716 6354 393 >20.1
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.14 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 22066
Subject
GRB 171027A, Swift-BAT refined analysis
Date
2017-10-28T16:22:47Z (8 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), P. D'Avanzo (INAF-OAB),
H. A. Krimm (NSF/USRA), 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-61 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 171027A (trigger #783479)
(D'Avanzo et al., GCN Circ. 22053). The BAT ground-calculated position is
RA, Dec = 61.683, -2.601 deg which is
RA(J2000) = 04h 06m 43.8s
Dec(J2000) = -02d 36' 02.0"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 91%.
The mask-weighted light curve shows a multi-peaked structure that starts
at ~T-2 s and ends at ~T+150 s. The main peak occurs at ~ T+63 s.
T90 (15-350 keV) is 96.6 +- 4.8 sec (estimated error including systematics).
The time-averaged spectrum from T-2.0 to T+132.0 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.25 +- 0.18,
and Epeak of 150.4 +- 95.1 keV (chi squared 33.21 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 7.5 +- 0.2 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+62.29 sec in the 15-150 keV band is
3.0 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.53 +- 0.04 (chi squared 40.62 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/783479/BA/
GCN Circular 22070
Subject
Konus-Wind observation of GRB 171027A
Date
2017-10-29T17:43:50Z (8 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:
The long GRB 171027A (Swift-BAT trigger #783479: (D'Avanzo et al.,
GCN 22053; Lien et al., GCN 22066; T0(BAT)=08:23:06.623 UT)
was detected by Konus-Wind (KW) in the waiting mode.
The light curve shows a muli-peaked structure with a duration of ~103 s.
Modeling the KW 3-channel time-integrated spectrum
(from T0(BAT)-1.661 s to T0(BAT)+101.379 s) by
a power law with exponential cutoff (CPL) model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -1.21(-0.35,+0.20) and Ep = 176(-35,+47) keV.
The energy fluence for this time interval is (1.78 �� 0.21)x10^-5
erg/cm2, and the peak energy flux, measured on a 2.944 s scale from
T0(BAT)+63.107 s is (6.6 �� 0.12)x10^-7 erg/cm2/s, both in the
20 keV-10 MeV range.
Assuming the GRB photo-z < 3.85 (90%, Butler et al., GCN 22061)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.30, and Omega_Lambda = 0.70, our analysis sets
the following upper limits on the burst isotropic energy release
and rest-frame peak energy: E_iso < 5.2x10^53 erg and
Ep,z < 854 keV.
The K-W light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB171027A/
All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.
GCN Circular 22073
Subject
GRB 171027A: KAIT Optical Upper Limit
Date
2017-10-30T23:39:12Z (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 Swift GRB 171027A (D'Avanzo et al.,
GCN 22053) starting at 08:26:07 UT, 181 s after the burst.
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. We do not detect the optical source (Watson et al., GCN 22057;
Butler et al., GCN 22061) in our images. The typical limiting magnitude
of our single clear image is about 19.0 calibrated to USNO B1.0.