GRB 161004A
GCN Circular 19979
Subject
GRB 161004A: Swift detection of a burst with a possible optical counterpart
Date
2016-10-04T13:10:14Z (9 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
P.A. Evans (U Leicester), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), A. A. Breeveld (UCL-MSSL),
D. N. Burrows (PSU), A. D'Ai (INAF-IASFPA), V. D'Elia (ASDC),
J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), B. Mingo (U Leicester),
K. L. Page (U Leicester), P. Romano (INAF-IASFPA), T. Sakamoto (AGU),
B. Sbarufatti (INAF-OAB/PSU) and E. Troja (NASA/GSFC/UMCP) report on
behalf of the Swift Team:
At 12:58:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 161004A (trigger=715084). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 263.171, -0.928, which is
RA(J2000) = 17h 32m 41s
Dec(J2000) = -00d 55' 41"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a couple of peaks
with a total duration of about 5 sec. The peak count rate
was ~1800 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 12:59:49.3 UT, 80.7 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 263.15298, -0.94831 which is equivalent
to:
RA(J2000) = 17h 32m 36.72s
Dec(J2000) = -00d 56' 53.9"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 97 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 (1.88 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 4.1
(+3.92/-2.99) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 85 seconds after the BAT trigger. There is a candidate afterglow in
the list of sources generated on-board at
RA(J2000) = 17:32:36.59 = 263.15244
DEC(J2000) = -00:57:02.2 = -0.95061
with a 90%-confidence error radius of about 1.10 arc sec. This position is 6.6
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.03. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.25.
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.)
GCN Circular 19980
Subject
GRB 161004A: TSHAO optical observations
Date
2016-10-04T17:44:41Z (9 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), I. Reva (Fesenkov Astrophysical Institute), A. Kusakin
(Fesenkov Astrophysical Institute), A. Volnova (IKI), A. Pozanenko
(IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 161004A (Evans et al., GCN 19979) with
Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory.
We obtained several images in R filter starting on Oct. 04 (UT)
13:36:52. In the XRT error circle we do not detect any new object. Wa
do not detect also candidate afterglow (Evans et al., GCN 19979).
Preliminary photometry of a combined image is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2016-10-04 13:36:52 0.04321 R 15*180 n/d n/d 21.9
Photometry is based on nearby SDSS-DR9 stars (Lupton transformations):
SDSS-DR9_id R(Lupton)
J173243.09-005731.3 17.04
J173250.91-005842.7 16.77
J173251.94-005803.2 15.75
J173253.88-005801.6 15.62
J173253.02-005938.3 16.02
J173232.00-005640.3 16.34
J173227.11-005646.8 16.41
J173227.04-005816.8 16.51
J173227.48-005856.9 16.62
J173236.27-010018.1 16.96
J173241.54-005823.1 16.26
A finding chart can be found at
http://grb.rssi.ru/GRB161004A/GRB161004A_TSHAO_161004_XRT_UVOT.png
GCN Circular 19981
Subject
GRB 161004A: Bassano Bresciano Observatory upper limit
Date
2016-10-04T19:14:38Z (9 years ago)
From
Ulisse Quadri at Bassano Bresciano Obs <oabb@ulisse.bs.it>
U.Quadri, L.Strabla and R.Girelli report:
We imaged the field of GRB 161004A detected by SWIFT(trigger 715084)
with the robotic telescope of (IAU station 565) Bassano Bresciano
Observatory, Italy. Member of:
AAVSO - American Association of Variable Star Observers.
ISSP - Italian Supernovae Search Project.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
The observations started 4.90 hour after the GRB trigger, at the end of twilight,
with our Newton telescope D=250 mm F/D=4.8.
Weather conditions were good.
We co-added 3 series of 10 exposures of 60 sec each.
Start T0+ End T0+ Vlim
4.9 hour 5.5 hour 18
We did not found any optical counterpart in the error box of the XRTcandidate.
P.A. Evans (U Leicester), S. D. Barthelmy (GSFC), et al.
Magnitudes were estimated with the UCAC4 cat. and
are not corrected for galactic dust extinction.
Reference:
http://www.osservatoriobassano.org/GRB.asp
The message may be cited.
GCN Circular 19983
Subject
GRB 161004A: Enhanced Swift-XRT position
Date
2016-10-04T20:50:17Z (9 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team.
Using 4971 s of XRT Photon Counting mode data and 10 UVOT
images for GRB 161004A, 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 = 263.15236, -0.95067 which is equivalent
to:
RA (J2000): 17h 32m 36.57s
Dec (J2000): -00d 57' 02.4"
with an uncertainty of 1.6 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 19984
Subject
GRB 161004A: Swift/UVOT Detection
Date
2016-10-04T21:15:33Z (9 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 161004A
85 s after the BAT trigger (Evans et al., GCN Circ. 19979).
A source consistent with the enhanced XRT position (Beardmore et al.,
GCN Circ. 19983) is detected in the initial UVOT exposures in the white
and u filters only.
The preliminary UVOT position is:
RA (J2000) = 17:32:36.54 = 263.15224 (deg.)
Dec (J2000) = -00:57:02.7 = -0.95075 (deg.)
with an estimated uncertainty of 0.56 arc sec. (radius, 90% confidence).
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 85 235 147 19.47 �� 0.16
v 627 6121 432 >20.1
b 552 10926 1144 >21.8
u 297 547 246 19.55 �� 0.29
w1 848 6531 413 >20.2
m2 4690 6326 393 >20.3
w2 602 12506 1063 >20.8
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.25 in the direction of the
burst (Schlegel et al. 1998).
GCN Circular 19985
Subject
GRB 161004A: Swift-XRT refined Analysis
Date
2016-10-04T21:47:28Z (9 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), B. Sbarufatti (INAF-OAB/PSU),
D.N. Burrows (PSU), T.G.R. Roegiers (PSU), A.P. Beardmore (U.
Leicester), S.L. Gibson (U. Leicester), A. D'Ai (INAF-IASFPA) and P.A.
Evans report on behalf of the Swift-XRT team:
We have analysed 6.1 ks of XRT data for GRB 161004A (Evans et al. GCN
Circ. 19979), from 84 s to 18.2 ks after the BAT trigger. The data
comprise 112 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Beardmore et al. (GCN Circ. 19983).
The late-time light curve (from T0+4.3 ks) can be modelled with a
power-law decay with a decay index of alpha=1.3 (+0.5, -0.4).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.94 (+0.11, -0.09). The
best-fitting absorption column is consistent with the Galactic value
of 1.9 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has
a photon index of 1.59 (+0.18, -0.16) and a best-fitting absorption
column of 2.2 (+0.9, -0.4) x 10^21 cm^-2. The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum is 4.6 x 10^-11 (5.5 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.2 (+0.9, -0.4) x 10^21 cm^-2
Galactic foreground: 1.9 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.59 (+0.18, -0.16)
If the light curve continues to decay with a power-law decay index of
1.3, the count rate at T+24 hours will be 1.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.9 x
10^-14 (5.9 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00715084.
This circular is an official product of the Swift-XRT team.
GCN Circular 19986
Subject
GRB 161004A: SAO RAS optical upper limit
Date
2016-10-04T23:02:45Z (9 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
A. Moskvitin (SAO RAS), A. Volnova (IKI), and A. Pozanenko (IKI)
report on behalf of the larger GRB follow-up team.
We observed the field of GRB 161004A (Evans et al., GCN 19979)
with Zeiss-1000 - the 1-meter telescope of Special Astrophysical
Observatory of Russian Academy of Sciences. We obtain several
images with filter Rc starting on October, 4 (UT) 15:44:35.
In the refined XRT error circle (Beardmore et al., GCN 19983)
we do not detect the optical counterpart (Breeveld and Evans,
GCN 19984). Preliminary photometry of a combined image is following
Date UT start t-T0 Filter Exp. OT UL
(mid, days) (s)
2016-10-04 15:44:35 0.1396 Rc 12*300 n/d 22.4
Photometry is based on nearby SDSS-DR9 stars reported
by Mazaeva et al. (GCN 19980).
GCN Circular 19993
Subject
GRB 161004A: RATIR Optical and NIR Observations
Date
2016-10-05T12:32:05Z (9 years ago)
Edited On
2024-11-07T19:42:21Z (7 months ago)
From
Eleonora Troja at GSFC <eleonora.troja@nasa.gov>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@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), José A. de Diego (UNAM), Leonid Georgiev
(UNAM), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Neil
Gehrels (GSFC), Harvey Moseley (GSFC), John Capone (UMD), V. Zach
Golkhou (ASU), and Vicki Toy (UMD) report:
We observed the field of GRB 161004A (Evans, et al., GCN 19979) with
the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico
Nacional on Sierra San Pedro Mártir from 2016/10 5.10 to 2016/10 5.22
UTC (13.49 to 16.23 hours after the BAT trigger), obtaining a total
of 1.73 hours exposure in the r and i bands and 0.65 hours exposure in
the Z, Y, J, and H bands.
For a source within the Swift-UVOT error circle (Breeveld & Evans,
GCN 19984), in comparison with the USNO-B1 and 2MASS catalogs, we
obtain the following upper limits (3-sigma):
r > 23.3
i > 23.2
Z > 22.4
Y > 21.8
J > 21.3
H > 19.4
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 Astronómico Nacional in San Pedro
Mártir.
GCN Circular 20001
Subject
GRB 161004A: Swift-BAT refined analysis
Date
2016-10-06T09:03:15Z (9 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
P. A. Evans (U Leicester), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), J. P. Norris (BSU),
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+242 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 161004A (trigger #715084)
(Evans, et al., GCN Circ. 19979). The BAT ground-calculated position is
RA, Dec = 263.127, -0.947 deg which is
RA(J2000) = 17h 32m 30.6s
Dec(J2000) = -00d 56' 50.7"
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.
The mask-weighted light curve shows a single peak starting at T-0.1 sec,
peaking at T+0.5 sec and ending at T+5 sec. T90 (15-350 keV) is 1.08 +- 0.21 sec
(estimated error including systematics).
The time-averaged spectrum from T-0.11 to T+1.06 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.26 +- 0.33. The fluence in the 15-150 keV band is 9.5 +- 1.6 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T+0.06 sec in the 15-150 keV band
is 1.0 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
Due to a low signal-to-noise of the data, the lag analysis is not possible.
Therefore, it is not clear whether this burst belongs to a short GRB or not.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/715084/BA/
GCN Circular 20011
Subject
GRB 161004A: refined analysis of TSHAO optical observations
Date
2016-10-07T23:58:37Z (9 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), I. Reva (Fesenkov Astrophysical Institute), A. Kusakin
(Fesenkov Astrophysical Institute), A. Volnova (IKI), A. Pozanenko
(IKI) report on behalf of larger GRB follow-up collaboration:
We present a refined analysis of our observations (Mazaeva et al., GCN
19980) of the field of GRB 161004A (Evans et al., GCN 19979) with
Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory.
We obtained several images in R filter starting on Oct. 04 (UT)
13:36:52. In a combined image of the first 30 minutes of our
observations we detect the afterglow (Breeveld et al., GCN 19984).
Preliminary photometry of a combined image is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2016-10-04 13:36:52 0.03632 R 9*180 21.65 0.25 21.7
Photometry is based on nearby SDSS-DR9 stars used in GCN 19980.
GCN Circular 20012
Subject
GRB 161004A: Maidanak optical observations
Date
2016-10-08T00:26:58Z (9 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Pozanenko (IKI), B. Hafizov (UBAI), A. Volnova
(IKI), O. Burhonov (UBAI) report on behalf of larger GRB follow-up
collaboration:
We observed the field of GRB 161004A (Evans et al., GCN 19979) with
AZT-22 telescope of Maidanak observatory equipped with SNUCAM in R
filter starting on Oct. 04 (UT) 14:25:10. We clearly detected optical
afterglow (Evans et al., GCN 19979; Breeveld et al., GCN 19984;
Mazaeva et al., GRB 20011). Preliminary photometry of the afterglow in
a combined image is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2016-10-04 14:25:10 0.06981 R 15*120 22.0 0.15 22.7
Photometry is based on nearby SDSS-DR9 stars used in GCN 19980.
GCN Circular 20053
Subject
GRB161004A: Further analysis of the burst nature
Date
2016-10-16T00:06:51Z (9 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
S. D. Barthelmy (GSFC), P.A. Evans (U Leicester), N. Gehrels (GSFC),
A. Y. Lien (GSFC/UMBC), J. P. Norris (BSU), P. O'Brien (U Leicester),
K. L. Page (U Leicester), J. L. Racusin (NASA/GSFC),
and H. Ziaeepour report on behalf of the Swift Team:
We performed further analysis of GRB161004A (trigger #715084;
Evans et al., GCN Circ. 19979), to explore the possibility to
clarify its short/long nature.
Using the full BAT event data set from T-240 to T+962 sec,
the updated T90 is 3 +/- 1.4 s (using the 1-s binned light curve).
This T90 is longer than the 1.08 +- 0.21 s originally reported
(Palmer et al, GCN Circ. 20001). However, we note that due to
the weakness of the burst, the standard pipeline finds a T90 that
varies from ~ 1.3 s to ~ 3 s when using light curves with different
bin sizes.
The image analysis with the BAT data in 15-150 keV finds no significant
detections for extended emission within several hundred seconds
after the trigger. However, the BAT image from T+250 s to T+350 s,
which is the time period around the peak of the XRT flare,
does show a slight increase of significance of 3.8 sigma (comparing
to ~ 1 to 2 sigma detections for other periods). Therefore, it is possible
that the XRT flare might be the second peak of the prompt emission, but
was close to the detection limit of the BAT.
The time averaged spectrum is best fit by a simple power-law model,
with an index of 1.3 +/- 0.33. This value is consistent with the average
value of the short GRB distribution, and slightly on the harder side of the
long burst distribution, but still within the majority (Lien & Sakamoto et al.
2016).
The lag analysis is still unavailable due to the weakness of the burst
(Palmer et al, GCN Circ. 20001).
The bright flare in the XRT light curve around T+300 s is unusual
for short GRBs. However, Swift have detected short GRBs with
flares before (e.g., GRB 070724A, GRB 100816A; Margutti et al., 2011,
MNRAS, 417, 2144), and thus we cannot rule out the short-burst
possibility base on this.
Therefore, we conclude that the burst nature remains ambiguous
with current information.