GRB 171123A
GCN Circular 22169
Subject
GRB 171123A: TShAO optical upper limit
Date
2017-11-24T23:05:11Z (8 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (IKI), A. Kusakin (Fesenkov Astrophysical Institute), I.
Reva (Fesenkov Astrophysical Institute), E. Mazaeva (IKI), A.
Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 171123A (Evans et al.,
GCN 22148) with Zeiss-1000 1-m telescope of Tien Shan Astronomical
Observatory starting on Nov., 23 (UT) 23:31:56. We took several images
in R-filter. Within enhanced XRT error circle (Goad et al., GCN 22150)
we do not detect any object. Preliminary photometry of the afterglow
is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s) (3 sigma)
2017-11-23 23:31:56 0.41294 R 38*120 n/d n/d 22.2
Photometry is based on nearby USNO-B1.0 stars, R2 magnitude.
GCN Circular 22166
Subject
GRB 171123A: OSN Upper Limit
Date
2017-11-24T18:52:37Z (8 years ago)
From
Luca Izzo at IAA-CSIC <Luca.Izzo@ICRA.it>
L. Izzo, D. A. Kann, A. de Ugarte Postigo (all HETH/IAA-CSIC), and V. Casanova (IAA-CSIC) report:
We observed the field of GRB 171123A (Evans et al.; GCN Circ. 22148) with the 1.5-m OSN telescope in Granada, Spain.
We began observing at 03:32:53 UT (13.3 hours after the GRB trigger), and obtained 18x300s images in the Ic band. Observations were obtained in inclement conditions (clouds, bad seeing of ~2") and the last four images could not be used.
In our stacked image, we find no source at the position reported by Schmidl et al. (GCN Circ. 22162) down to a a 3-sigma limit of Ic (Vega) > 21. The calibration was performed using nearby stars in the USNO B1 catalog.
GCN Circular 22162
Subject
GRB 171123A: Tautenburg observations
Date
2017-11-24T16:01:55Z (8 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
S. Schmidl, B. Stecklum, S. Klose, A. Nicuesa Guelbenzu, and C. Hoegner
(Thueringer Landessternwarte Tautenburg) report:
We observed the field of GRB 171123A (Evans et al., GCN 22148) in the Rc
band using the Tautenburg Schmidt telescope equipped with the prime focus
CCD camera. Observations started at 04:01 UT, about 14 hr after the burst.
At the SE border of the enhanced XRT error circle (radius 1.9 arcsec; Goad
et al., GCN 22150; 1.5 arcsec acc. to the newest results presented at
http://www.swift.ac.uk/xrt_positions/00791922/) we find a faint source at
coordinates
RA (J2000) : 12:24:59.29,
Dec (J2000): 32:30:03.4 (+/- 0.6 arcsec).
At a midtime of 04:46 UT we measure a preliminary magnitude of Rc (Vega) =
22.7 +/- 0.3, calibrated against SDSS field stars.
The non-detection of this source by RATIR eight hours after our observing
run (Butler et al., GCN 22160) suggests that this was the GRB afterglow.
We caution however that this is only a 3-sigma detection.
GCN Circular 22161
Subject
GRB 171123A: Nanshan-1m optical upper limit
Date
2017-11-24T15:38:53Z (8 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
Z.P. Zhu, H.X. Feng, D. Xu (NAOC), Z. Fan, W. Wang, J. Zheng, N. Song
(NAOC), S.G. Ma, J. Liu (XAO), Y.D. Hu (IAA-CSIC) report
We observed the field of GRB 171123A (Evans et al., GCN 22148) using the
1-m telescope located at Nanshan, Xinjiang, China. We obtained 3x120s,
1x180s SDSS i-band and 1x120s r-band frames, starting at 21:12:40 UT on
2017-11-23, i.e., 6.8 hr after the BAT trigger.
No optical source was detected in the stacked image at the XRT position
(Goad et al., GCN 22150), down to a limiting magnitude of i~20.6 mag, at
the median time of 6.92 hr post-burst, calibrated with the SDSS field.
GCN Circular 22160
Subject
GRB 171123A: RATIR Optical and NIR Observations
Date
2017-11-24T15:06:18Z (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 observed the field of GRB 171123A (Evans, et al., GCN 22148) 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 2017/11 24.47 to 2017/11 24.54 UTC (21.06 to
22.77 hours after the BAT trigger), obtaining a total of 1.07 hours
exposure in the r and i bands and 0.45 hours exposure in the Z, Y, J, and H
bands.
For a source within the Swift-XRT error circle (Goad, et al., GCN 22150),
in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following
upper limits (3-sigma):
r > 23.60
i > 23.39
Z > 22.23
Y > 21.69
J > 21.43
H > 21.02
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 22158
Subject
GRB 171123A: Swift/UVOT Upper Limits
Date
2017-11-24T13:06:31Z (8 years ago)
From
Sam Emery at MSSL-UCL <samuel.emery.15@ucl.ac.uk>
S.W.K. Emery (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 171123A
94 s after the BAT trigger (Evans et al., GCN Circ. 22148).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 22150)
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 94 243 147 >20.9
u_FC 308 557 246 >20.5
white 94 2397 489 >21.0
v 637 2447 214 >18.8
b 563 2373 194 >19.7
uvw1 13669 18855 1209 >20.7
uvm2 12763 13663 886 >20.6
uvw2 23870 35081 1032 >21.1
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 22157
Subject
GRB 171123A: GMG observation limit
Date
2017-11-24T12:55:39Z (8 years ago)
From
Jirong Mao at Yunnan Obs <jirongmao_obs@ynao.ac.cn>
J. Mao, C.-J. Wang and J.-M. Bai (YNAO) report:
We observed the field of GRB 171123A (Evans et al., GCN 22148) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG) station of Yunnan Observatories. Observations began from 21:02:44 UT, about 6.8 hours after the trigger. We did not detect any source within the X-ray afterglow position error circle (Goad et al. GCN 22150), down to a limit of R~21.6 mag.
GCN Circular 22154
Subject
GRB 171123A: MITSuME Akeno optical upper limits
Date
2017-11-24T07:02:25Z (8 years ago)
From
Katsuhiro L. Murata at Nagoya U <murata@u.phys.nagoya-u.ac.jp>
K. Morita, R. Itoh, K. L. Murata, T. Yoshii, Y. Tachibana, S. Harita, T.
Ozawa, H. Mamiya, K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We searched for the optical counterpart of GRB 171123A (P. A. Evans et
al., GCN Circular #22148) with the optical three color (g', Rc, and Ic) CCD
cameras attached to the MITSuME 50 cm telescope of Akeno Observatory,
Yamanashi, Japan.
The observation started on 2017-11-23 16:24:30.61 UT. We did not find any
new point source within enhanced XRT circle (M.R. Goad et al., GCN Circular
#22150) in all three bands.
We obtained following limits for the magnitudes.
T0+[hour] MID-UT T-EXP[sec] g' Rc Ic
-------------------------------------------------------------------------------------------------------
~3.15 18:56:14.59 9360 >21.1 >20.7 >19.6
-------------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.
GCN Circular 22153
Subject
GRB 171123A: Swift-BAT refined analysis
Date
2017-11-24T00:14:52Z (8 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), P. A. Evans (U Leicester),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 171123A (trigger #791922)
(Evans et al., GCN Circ. 22148). The BAT ground-calculated position is
RA, Dec = 186.198, 32.503 deg which is
RA(J2000) = 12h 24m 47.6s
Dec(J2000) = +32d 30' 12.5"
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 86%.
The mask-weighted light curve shows a weak pulse that starts at ~T-1 s and ends
at ~T+20 s, with a tail lasting till ~T+60 s. In addition, there is a weak
precursor from ~T-25 s to ~T-20 s. T90 (15-350 keV) is 58.5 +- 27.1 sec
(estimated error including systematics).
The time-averaged spectrum from T-1.39 to T+60.29 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.35 +- 0.34. The fluence in the 15-150 keV band is 4.8 +- 1.0 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.27 sec in the 15-150 keV band
is 0.8 +- 0.2 ph/cm2/sec. 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/791922/BA/
GCN Circular 22152
Subject
GRB 171123A: Swift-XRT refined Analysis
Date
2017-11-23T22:04:20Z (8 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), B.
Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), S.L. Gibson (U.
Leicester), J.P. Osborne (U. Leicester), V. D'Elia (ASDC) and P.A.
Evans report on behalf of the Swift-XRT team:
We have analysed 6.5 ks of XRT data for GRB 171123A (Evans et al. GCN
Circ. 22148), from 98 s to 19.7 ks after the BAT trigger. The data are
entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Goad et al. (GCN Circ. 22150).
The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=3.4 (+0.7, -0.6). At T+306 s the decay
flattens to an alpha of -0.33 (+0.25, -0.45) before breaking again at
T+1892 s to a final decay with index alpha=0.68 (+0.13, -0.14).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.21 (+0.22, -0.21). The
best-fitting absorption column is 8.8 (+5.1, -4.4) x 10^20 cm^-2, in
excess of the Galactic value of 1.9 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 2.9 x 10^-11 (3.8 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 8.8 (+5.1, -4.4) x 10^20 cm^-2
Galactic foreground: 1.9 x 10^20 cm^-2
Excess significance: 2.6 sigma
Photon index: 2.21 (+0.22, -0.21)
If the light curve continues to decay with a power-law decay index of
0.68, the count rate at T+24 hours will be 0.010 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x
10^-13 (3.8 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00791922.
This circular is an official product of the Swift-XRT team.
GCN Circular 22151
Subject
GRB 171123A: Confirmation of the X-ray afterglow
Date
2017-11-23T16:41:02Z (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:
We have now received the full dataset from the early Swift-XRT
observations of GRB 171123A (Evans et al. GCN Circ. 22148). In these
data, the afterglow is clearly detected, and the light curve shows an
initial decay and plateau, typical of GRB afterglows. The best position
currently available was given by Goad et al. (GCN Circ. 22150). This
position is ~15 arcsec from that reported in GCN 22148. This is because
the object lay ~14 arcsec outside the field of view of the
promptly-available XRT data, so only the edges of the PSF were available for
source localisation.
As ever, the automated XRT analysis can be viewed at
http://www.swift.ac.uk/xrt_products/00791922.
This circular is an official product of the Swift-XRT team.
GCN Circular 22150
Subject
GRB 171123A: Enhanced Swift-XRT position
Date
2017-11-23T15:57:18Z (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 1128 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 171123A, 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 = 186.24641, +32.50104 which is equivalent
to:
RA (J2000): 12h 24m 59.14s
Dec (J2000): +32d 30' 03.7"
with an uncertainty of 1.9 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 22148
Subject
GRB 171123A: Swift detection of a burst
Date
2017-11-23T14:54:37Z (8 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P. A. Evans (U Leicester), D. N. Burrows (PSU), A. Deich (PSU),
J.D. Gropp (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report on behalf of the
Swift Team:
At 14:14:47 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 171123A (trigger=791922). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 186.190, +32.531 which is
RA(J2000) = 12h 24m 46s
Dec(J2000) = +32d 31' 51"
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 40 sec. The peak count rate
was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 14:16:17.8 UT, 90.2 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
possible X-ray source with an enhanced position: RA, Dec 186.2425, 32.5032
which is equivalent to:
RA(J2000) = 12h 24m 58.19s
Dec(J2000) = +32d 30' 11.4"
with an uncertainty of 3.5 arcseconds (radius, 90% containment). This
location is 188 arcseconds from the BAT onboard position, just outside the
BAT error circle. This possible source is weak and at the edge of the
region of the XRT which is promptly downlinked; we are not completely
certain that this is an astrophysical object. We are awaiting the full
dataset to confirm the nature of this source.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.90 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 9.4
(+9.50/-2.54) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 93 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 none of
the XRT error circle. 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 0.02.
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.)