GRB 171001A
GCN Circular 21946
Subject
GRB 171001A: Swift detection of a burst
Date
2017-10-01T18:38:25Z (8 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
A. Y. Lien (GSFC/UMBC), P. D'Avanzo (INAF-OAB), J.D. Gropp (PSU),
J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), D. M. Palmer (LANL),
M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report on behalf of the
Swift Team:
At 18:25:40 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 171001A (trigger=775553). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 22.088, -11.893 which is
RA(J2000) = 01h 28m 21s
Dec(J2000) = -11d 53' 35"
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 30 sec. The peak count rate
was ~900 counts/sec (15-350 keV), at ~20 sec after the trigger.
The XRT began observing the field at 18:28:53.9 UT, 193.7 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 22.0774, -11.8940 which
is equivalent to:
RA(J2000) = 01h 28m 18.59s
Dec(J2000) = -11d 53' 38.5"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 37 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. We
cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (3.56 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.9
(+3.76/-3.10) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 197 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
0.03.
Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT nasa.gov).
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 21952
Subject
GRB 171001A: Enhanced Swift-XRT position
Date
2017-10-01T20:57:34Z (8 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1293 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 171001A, 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 = 22.07740, -11.89417 which is equivalent
to:
RA (J2000): 01h 28m 18.58s
Dec (J2000): -11d 53' 39.0"
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 21953
Subject
GRB171001A: D50 optical limit
Date
2017-10-01T22:50:08Z (8 years ago)
From
Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek@asu.cas.cz>
Martin Jelinek, Jan Strobl and Rene Hudec (ASU CAS Ondrejov)
We observed the field of the Swift GRB171001A (trigger #775553, Lien et al.
GCNC 21946) with the 0.5m telescope of Ondrejov observatory, the obseration
started at 21:17UT, i.e. about 2.9h after trigger and lasted for 30 miutes,
when the field became observable. On a series of unfiltered exposures we do
not detect any new object within or in the vicinity of the XRT errorbox
(Evans et al., GCNC 21952) down to the USNO-B/R2 calibrated limit of
R>20.0.
GCN Circular 21954
Subject
GRB 171001A: IRSF Observation
Date
2017-10-02T01:07:51Z (8 years ago)
From
Katsuhiro L. Murata at Nagoya U <murata@u.phys.nagoya-u.ac.jp>
R. Itoh (Tokyo Tech), K. L. Murata (Tokyo Tech), K. Morihana (Nagoya U.)
and T. Nagayama (Kagoshima U)
We observed the field of GRB 171001A (Lien et al., GCNCircular #21946) with
the near-infrared (J, H, Ks) simultaneous imaging camera SIRIUS attached to
1.4 m telescope IRSF (InfraRed Survey Facility) in Sutherland observatory,
South Africa.
The observations started on 2017-10-01 19:16:51 UT. We detected the
afterglow within the enhanced XRT error circle (Evans et al., GCN Circular
#21952) in J band. The measured magnitudes (Vega magnitude system) were
listed as below.
T0+[min] MID-UT T-EXP[sec] J H
Ks
-------------------------------------------------------------------------------------------------
~48 19: 31 1270 17.0+-1.1 >16.3
>16.0
-------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
Given magnitudes were calibrated against 2MASS point sources in this field.
This observation was carried out by IRSF and OISTER collaboration.
GCN Circular 21955
Subject
GRB 171001A: Swift/UVOT Detection
Date
2017-10-02T09:52:10Z (8 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and A. Y. Lien (GSFC/UMBC) report on behalf of
the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 171001A
198 s after the BAT trigger (Lien et al., GCN Circ. 21946). The source
was found in the IR J band by Itoh et al. (GCN. Circ. # 21954). We find
a source consistent with the XRT position (Evans et al. GCN Circ. 21952) 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 early exposures
are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 198 1359 373 21.23 +/- 0.30
v 686 1409 58 >18.2
b 612 1503 93 >19.8
u 356 780 265 >20.3
w1 736 1458 58 >20.4
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 21956
Subject
GRB 171001A: Swift-XRT refined Analysis
Date
2017-10-02T11:19:25Z (8 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore
(U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P.
D'Avanzo (INAF-OAB), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J.
LaPorte (PSU) and A.Y. Lien report on behalf of the Swift-XRT team:
We have analysed 6.0 ks of XRT data for GRB 171001A (Lien et al. GCN
Circ. 21946), from 176 s to 52.2 ks after the BAT trigger. The data
comprise 11 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Evans et al. (GCN Circ.
21952).
The light curve can be modelled with an initial rise, with a power-law
index of alpha=-0.13 (+0.19, -0.21), followed by a break at T+1318 s
to an alpha of 1.88 (+0.24, -0.18).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.09 (+0.21, -0.19). The
best-fitting absorption column is 6.2 (+4.6, -2.7) x 10^20 cm^-2,
consistent with the Galactic value of 3.6 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 3.1 x 10^-11 (3.7 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 6.2 (+4.6, -2.7) x 10^20 cm^-2
Galactic foreground: 3.6 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.09 (+0.21, -0.19)
If the light curve continues to decay with a power-law decay index of
1.88, the count rate at T+24 hours will be 2.1 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.6 x
10^-15 (7.8 x 10^-15) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00775553.
This circular is an official product of the Swift-XRT team.
GCN Circular 21957
Subject
GRB 171001A: Nanshan-0.36m optical afterglow detections
Date
2017-10-02T12:21:09Z (8 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
H.J. Tan (CCU), H.X. Feng, D. Xu, Z.P. Zhu (NAOC), Y.D. Hu (IAA-CSIC),
Y. Qin (Geneva Obs.), X. Gao (Urumqi No.1 Senior High School) report:
We observed the field of GRB 171001A (Lien et al., GCN 21946) using the
0.36m robotic telescope located at Nanshan, Xinjiang, China.
Observations started at 18:37:21 UT on 2017-10-01, i.e, 701 sec after
the BAT trigger, and all imaged were taken without filter.
The optical afterglow was detected at the XRT position (Evans et al.,
GCN 21952) with coordinates
R.A. (J2000) = 01:28:18.67
Dec. (J2000) = -11:53:39.0
with an uncertainty of ~0.5 arcsec.
Our photometry was summarized as follows:
========================================
Tmid(s)+T0 Exptime(s) Mag(R) MagErr
741 40*2 >17.60
902 60*2 17.93 0.13
1102 60*3 18.00 0.11
1328 90*2 18.55 0.11
1522 90*2 18.60 0.20
3327 90*8 >18.75
========================================
Note: (1) Photometry is calibrated with stars in the USNO B1 catalogue
in the R-filter, although images were taken without filter. (2) MagErr
is the only statistical error of the measurement. (3) The magnitudes are
not corrected for the Galactic extinction.
GCN Circular 21958
Subject
GRB 171001A: Swift-BAT refined analysis
Date
2017-10-02T14:11:12Z (8 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 171001A (trigger #775553)
(Lien et al., GCN Circ. 21946). The BAT ground-calculated position is
RA, Dec = 22.080, -11.928 deg which is
RA(J2000) = 01h 28m 19.2s
Dec(J2000) = -11d 55' 39.6"
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 72%.
The mask-weighted light curve shows a multi-peaked structure that starts
at ~T+11 s and ends at ~T+37 s. The major peaks occur at ~T+13 s, ~T+17 s,
and ~T+32 s, respectively. T90 (15-350 keV) is 22.8 +- 2.0 sec (estimated
error including systematics).
The time-averaged spectrum from T+11.40 to T+37.02 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.48 +- 0.19. The fluence in the 15-150 keV band is 6.4 +- 0.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+31.42 sec in the 15-150 keV band
is 0.9 +- 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/775553/BA/
GCN Circular 21959
Subject
GRB 171001A: RATIR Optical and NIR Observations
Date
2017-10-02T15:46:07Z (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 171001A (Lien, et al., GCN 21946) 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 2.17 to 2017/10 2.51 UTC (9.63 to
17.69 hours after the BAT trigger), obtaining a total of 5.31 hours
exposure in the r and i bands and 2.24 hours exposure in the Z, Y, J, and H
bands.
We do not detect a source within the XRT error region (Evans, et al., GCN
21952) or at the position of the Nanshan optical transient (Tan, et al.,
GCN 21957). In comparison with the USNO-B1 and 2MASS catalogs, we obtain
the following upper limits (3-sigma):
r > 24.15
i > 23.98
Z > 22.96
Y > 22.77
J > 22.43
H > 22.03
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.