GRB 170705A
GCN Circular 21327
Subject
GRB 170705A: AstroSat CZTI detection
Date
2017-07-12T13:18:15Z (8 years ago)
From
Vidushi Sharma at IUCAA <vidushi@iucaa.in>
V. Sharma (IUCAA), V. Bhalerao (IIT-B), D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:
Analysis of Astrosat CZTI data showed the detection of a long-duration GRB 170705A, which was also detected by Swift/BAT (Starling et al., GCN 21289), Fermi/GBM (Bissaldi et al., GCN 21297), Konus-Wind (Svinkin et al., GCN 21299) and Insight-HXMT (Lu et al., GCN 21301).
The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with the strongest peak at 02:46:00 UT, ~13 s after the Swift Trigger. The measured peak count rate is 635.9 cts/s above the background in combined data of four quadrants, with a total of 3123 cts. The local mean background count rate was 374.1 cts/s. Using cumulative rates, we measure a T90 of 14.9 s.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN Circular 21320
Subject
GRB 170705A: TShAO optical observations
Date
2017-07-11T17:39:03Z (8 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (IKI), E. Mazaeva (IKI), A. Pozanenko (IKI), A. Kusakin
(Fesenkov Astrophysical Institute), I. Reva (Fesenkov Astrophysical
Institute) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 170705A (Starling et al. GCN
21289) which is also detected by GBM/Fermi and Konus-Wind (Bissaldi et
al., GCN 21297; Svinkin et al., GCN 21299) with Zeiss-1000 1-m
telescope of Tien Shan Astronomical Observatory on July 6-8. We took
several images in R-filter. The optical afterglow of GRB 170705A
(Starling et al. GCN 21289, Lipunov et al. GCN 21291, Butler et al. GCN
21293, Emery et al. GCN 21294; Ugarte Postigo et al. GCN 21298) is
visible in a combined image on July 6, and upper limit only for July
7-8. Preliminary photometry of the afterglow is following.
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s) (3 sigma)
2017-07-06 16:28:29 1.61411 R 38*180 20.67 0.24 21.1
2017-07-07 17:30:55 2.63106 R 13*180 n/d n/d 20.6
2017-07-07 17:30:55 3.10501 R 34*180 n/d n/d 21.1
Photometry is based on nearby SDSS DR9 stars listed in GCN 21300.
GCN Circular 21303
Subject
GRB 170705A: Further RATIR Optical and NIR Observations and Steepening of Fading
Date
2017-07-06T18:37:15Z (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 (ASU), and
Vicki Toy (UMD) report:
We observed the field of GRB 170705A (Starling et al., GCN Circ. 21289) 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 2017/07 6.17 to 2017/07 6.26 UTC (25.33
to 27.52 hours after the BAT trigger), obtaining a total of 1.02 hours
exposure in the r and i bands and 0.37 hours exposure in the Z,
Y, J, and H bands.
For a source within the Swift-XRT error circle, in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following detections:
r = 20.62 +/- 0.05
i = 20.35 +/- 0.05
Z = 19.68 +/- 0.07
Y = 19.72 +/- 0.09
J = 19.46 +/- 0.10
H = 19.61 +/- 0.16
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
The source has faded on average by 1.90 +/- 0.17 magnitudes compared to our previous observations (Butler et al., GCN Circ. 21293). This corresponds to a temporal index of -0.72 +/- 0.03, which is steeper than the index of -0.4 we saw during our previous observations.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 21302
Subject
GRB 170705A: KAIT Optical Observations
Date
2017-07-06T18:23:52Z (8 years ago)
From
Max Genecov at UC Berkeley <mgenecov@berkeley.edu>
Max Genecov, WeiKang Zheng, and Alex 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 170705A (Starling, et al.,GCN
21289), starting 1.66 hours after the burst and again 1.08
days after the burst. Observations were performed in the clear
(roughly R) filter, and the exposure time was 60 s per image.
The optical afterglow of GRB 170705A (Starling, et al.,GCN 21289;
Lipunov et al., GCN 21291; Butler et al. GCN 21293,
Emery et al. GCN 21294, Ugarte Postigo et al. GCN 21298, Pozenenko
et al. GCN 21300) was clearly detected in every single image from the
first night and in an image co-added from thirteen frames in the
second night. Preliminary photometry of the afterglow calibrated to
several nearby SDSS stars gives 18.1 +/- 0.2 mag at mean time
1.66 hours and 20.3 +/- 0.3 mag at mean time 1.08 days.
GCN Circular 21301
Subject
GRB 170705A: Insight-HXMT observation
Date
2017-07-06T18:10:53Z (8 years ago)
From
Shaolin Xiong at IHEP <xiongsl@ihep.ac.cn>
F. J. Lu, C. K. Li, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li,
X. B. Li, J. Y. Liao, Y. Huang, Y. H. Wang, Z. Chang, X. F. Lu,
J. L. Zhao, A. M. Zhang, Y. F. Zhang, C. L. Zou (IHEP), Y. J. Jin,
Z. Zhang (THU), Y. P. Chen, M. Gao (IHEP), T. P. Li (IHEP/THU),
G. Li, M. S. Li, H. W. Liu, L. M. Song, W. H. Tao, H. Y. Wang,
X. Y. Wen, M. Wu, H. Xu, Y. P. Xu, C. M. Zhang, F. Zhang, J. Zhang,
T. Zhang, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team:
During the commissioning phase, at 2017-07-05T02:45:59.00 (T0),
Insight-HXMT detected GRB 170705A (trigger ID: HEB170705115)
in a routine search of the data, which was also observed by
the Swift/BAT (Starling et al. 2017, GCN 21289), Fermi/GBM
(Bissaldi et al. 2017, GCN 20297) and Konus-Wind (Svinkin et al. 2017,
GCN 21299).
The Insight-HXMT light curve consists of single pulse
with a duration (T90) of 7.0 s measured from T0-1.30 s.
The 1-second peak rate, measured from T0+1 s, is 928.3 cnts/sec.
The total counts from this burst is 3458 counts.
All measurements above are made with the CsI detectors in the energy range
of about 80-840 keV (record energy) in the regular mode. Only gamma-rays
with
energy greater than about 200 keV can penetrate the spacecraft and leave
signals in the CsI detectors installed on the inside of the telescope.
URL_LC: http://www.hxmt.org/images/GRB/HEB170705115_lc.jpg
The time-averaged spectrum from T0-2 s to T0+8 s is
adequately fit by a Power Law model with spectral index = -2.16 +/- 0.10.
The energy fluence is (1.42 +/- 0.30)E-05 erg/cm^2 in 200 - 5000 keV
in this time interval.
The analysis results presented above are preliminary;
final results will be published elsewhere.
Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .
GCN Circular 21300
Subject
GRB 170705A: ISON/Terskol optical observations
Date
2017-07-06T13:28:01Z (8 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Pozanenko (IKI), V. Agletdinov (KIAM), A. Volnova
(IKI), A. Mokhnatkin (KIAM), I. Molotov (KIAM) report on behalf of
larger GRB follow-up collaboration:
We observed the field of the Swift GRB 170705A (Starling et al. GCN 21289)
which is also detected by GBM/Fermi and Konus-Wind (Bissaldi et al., GCN
21297; Svinkini et al., GCN 21299) with K-800 (0.8m) telescope of
ISON/Terskol observatory starting on July, 05 (UT) 18:30:54. We obtained
several unfiltered images of 20 s exposure. The optical afterglow of GRB
170705A (Starling et al. GCN 21289, Lipunov et al. GCN 21291, Butler et al.
GCN 21293, Emery et al. GCN 21294; Ugarte Postigo et al. GCN 21298) is
clearly visible in a combined image. Preliminary photometry of the
afterglow is following
Date UT start t-T0 Filter Exp. OT Err.
UL
(mid, days) (s)
2017-07-05 18:30:54 0.70649 CR 358*20 19.84 0.08 22.2
Photometry is based on nearby SDSS DR9 stars
SDSS id R_Lupton
J124702.82+181926.7 17.63
J124700.96+181851.9 19.15
J124653.35+182058.9 17.08
J124641.28+182043.7 16.61
J124646.57+181522.1 17.45
J124645.71+181510.4 17.18
J124650.58+182306.3 18.18
J124624.60+181820.0 16.34
J124647.75+181330.6 16.05
J124644.99+181414.3 18.79
GCN Circular 21299
Subject
Konus-Wind observation of GRB 170705A
Date
2017-07-06T11:16:24Z (8 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 170705A
(Swift-BAT observation: Starling et al., GCN Circ. 21289;
Fermi-GBM observation: Bissaldi and Meegan, GCN Circ. 21297)
triggered Konus-Wind at T0=9956.188 s UT (02:45:56.188).
The burst light curve shows a bright, multipeaked pulse,
which starts at ~T0-6 s and has a total duration of ~25 s,
followed by a weaker emission seen up to ~T0+300 s.
The emission in the main episode is seen up to ~1 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170705_T09956/
As observed by Konus-Wind, the burst
had a fluence of 1.76(-0.19,+0.20)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+2.384 s,
of 4.21(-0.94,+0.96)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the main episode
(measured from T0 to T0+24.832 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.31(-0.17,+0.20)
and Ep = 155(-22,+31) keV (chi2 = 53/62 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.7
(chi2 = 59/61 dof).
The spectrum near the maximum count rate
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
with alpha = -1.16(-0.15,+0.16)
and Ep = 166(-18,+23) keV (chi2 = 69/61 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3
(chi2 = 69/60 dof).
Assuming the redshift z=2.010 (de Ugarte Postigo et al.,
GCN Circ. 21298) and a standard cosmology model
with H_0 = 70 km/s/Mpc, Omega_M = 0.27, and Omega_Lambda = 0.73,
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~1.8x10^53 erg,
the peak luminosity L_iso is ~1.3x10^53 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~466 keV.
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 21298
Subject
GRB 170705A: Redshift from 10.4m GTC/OSIRIS
Date
2017-07-05T23:48:25Z (8 years ago)
From
Antonio de Ugarte Postigo at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D.A. Kann (IAA-CSIC),
L. Izzo (IAA-CSIC), C.C. Thoene (IAA-CSIC) report on behalf of the
HETH group:
We observed the afterglow of GRB 170705A (Starling et al. GCN 21289,
Lipunov et al. GCN 21291, Butler et al. GCN 21293, Emery et al.
GCN 21294) with OSIRIS at the 10.4m GTC telescope. The observation
consisted of 3x900s using grism R1000B, covering the range between
3700 and 7880 AA at a mean epoch of July 5.9350 2017 UT (19.68 hr
after the burst).
The acquisition shows the afterglow at a magnitude of r(AB) = 20.20
+/- 0.10 mag, as compared to SDSS field stars. The spectrum shows
continuum across all the spectral range, although the signal to noise
ratio of the bluest part is low because of the bright sky due of the nearby
almost full Moon. We detect weak spectral absorption features due to
CIV, AlII, AlIII, FeII and FeII* at a common redshift of 2.010, which we
identify as the redshift of the GRB.
GCN Circular 21297
Subject
GRB 170705A: Fermi GBM observation
Date
2017-07-05T18:03:09Z (8 years ago)
From
Elisabetta Bissaldi at U.Innsbruk/IAPP <Elisabetta.Bissaldi@uibk.ac.at>
E. Bissaldi (Politecnico & INFN Bari) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 02:45:51.03 UT on 5 July 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170705A (trigger 520915556 / 170705115),
which was also detected by the Swift/BAT (Starling et al. 2017, GCN 21289).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 118
degrees.
The GBM light curve shows two peaks
with a duration (T90) of about 22 s (50-300 keV).
The time-averaged spectrum from T0-2 s to T0+20 s is
adequately fit by a Band function with Epeak = 100 +/- 10 keV,
alpha = -0.88 +/- 0.07, and beta = -2.38 +/- 0.09.
The event fluence (10-1000 keV) in this time interval is
(1.37 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+9.4 s in the 10-1000 keV band
is 22.5 +/- 0.5 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 21296
Subject
GRB 170705A: Swift-BAT refined analysis
Date
2017-07-05T16:14:33Z (8 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
R. L. C. Starling (U Leicester), 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 170705A (trigger #760064)
(Starling et al., GCN Circ. 21289). The BAT ground-calculated position is
RA, Dec = 191.708, 18.298 deg which is
RA(J2000) = 12h 46m 50.0s
Dec(J2000) = +18d 17' 51.3"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 83%.
The mask-weighted light curve shows a multi-peaked structure that starts
at ~ T0 and ends at ~ T+300 s. The main emission occurs at ~ T0 to ~ T+40 s,
with the major peak at ~ T+14 s. T90 (15-350 keV) is 217.3 +- 18.0 sec
(estimated error including systematics).
The time-averaged spectrum from T+0.44 to T+304.86 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.65 +- 0.05. The fluence in the 15-150 keV band is 9.5 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+13.41 sec in the 15-150 keV band
is 13.9 +- 0.4 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/760064/BA/
[GCN OPS NOTE(06jul17): Per author's request, the last paragaph was added.]
GCN Circular 21295
Subject
GRB 170705A: MITSuME Akeno Optical Observation
Date
2017-07-05T15:27:51Z (8 years ago)
From
Taketoshi Yoshii at Tokyo Tech <yoshii.t.ac@m.titech.ac.jp>
S. Harita, Y. Saito, R. Itoh, Y. Tachibana, T. Yoshii,
K. Morita, 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 170705A (R. L. C. Starling et al.,
GCN Circular #21289) with the optical three color (g', Rc, and Ic) CCD cameras
attached to the MITSuME 50cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started on 2017-07-05 11:21:20.84 UT.
We did not find any new point source within XRT circle in all three bands.
We obtained following limits for the magnitudes.
T0+[hour] MID-UT T-EXP[sec] g' Rc Ic
-------------------------------------------------------------------------------------------------------
~8.59 12:29:51 1320 >18.5 >17.9 >17.8
-------------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.
GCN Circular 21294
Subject
GRB 170705A: Swift/UVOT Detection
Date
2017-07-05T15:08:53Z (8 years ago)
From
Sam Emery at MSSL-UCL <samuel.emery.15@ucl.ac.uk>
S.W.K. Emery (UCL-MSSL) and R. L. C. Starling (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170705A
82 s after the BAT trigger (Starling et al., GCN Circ. 21289).
We detect a fading source consistent with the XRT position
(Goad et al., GCN Circ. 21290) and the MASTER (Lipunov et al., GCN Circ. 21291)
and RATIR (Butler et al., GCN Circ. 21293) detections in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 12:46:48.97 = 191.70404 (deg.)
Dec (J2000) = +18:18:26.4 = 18.30733 (deg.)
with an estimated uncertainty of 0.45 arc sec. (radius, 90% confidence).
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 82 231 147 18.55 +/- 0.06
white 573 1020 186 19.23 +/- 0.11
u 294 543 246 19.43 +/- 0.19
v 623 1070 58 >18.3
b 549 741 39 18.92 +/- 0.26
uvw1 672 692 19 >18.1
uvm2 4617 12950 996 >20.7
uvw2 5644 11420 1137 >21.0
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 21293
Subject
GRB 170705A: RATIR Optical and NIR Observations
Date
2017-07-05T14:58:02Z (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 (ASU), and Vicki Toy (UMD) report:
We observed the field of GRB 170705A (Starling, et al., GCN 21289) 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 2017/07 5.17 to 2017/07 5.26 UTC (1.34 to 3.41
hours after the BAT trigger), obtaining a total of 1.42 hours exposure in
the r and i bands and 0.59 hours exposure in the Z, Y, J, and H bands.
We detect the optical transient found by Swift and observed MASTER-OAFA
(Lipunov, et al., GCN 21291). In comparison with the SDSS DR9 and 2MASS
catalogs, we obtain the following detections:
r = 18.60 +/- 0.01
i = 18.30 +/- 0.01
Z = 18.03 +/- 0.01
Y = 17.79 +/- 0.01
J = 17.79 +/- 0.01
H = 17.56 +/- 0.01
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. The source fades as in time as
t^(-0.4) during our observation.
We note that the Swift-UVOT detection makes this GRB unlikely to be at very
high redshift. Our photo-z calculations, using RATIR data alone, suggest
z<4.
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 21292
Subject
GRB 170705A: Swift-XRT refined Analysis
Date
2017-07-05T10:34:21Z (8 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai
(INAF-IASFPA), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU) and R.L.C. Starling report on behalf of the Swift-XRT
team:
We have analysed 8.4 ks of XRT data for GRB 170705A (Starling et al.
GCN Circ. 21289), from 62 s to 22.1 ks after the BAT trigger. The data
comprise 424 s in Windowed Timing (WT) mode (the first 8 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. 21290).
The late-time light curve (from T0+4.6 ks) can be modelled with a
power-law decay with a decay index of alpha=0.83 (+/-0.09).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.53 (+/-0.03). The
best-fitting absorption column is 8.4 (+1.1, -1.0) x 10^20 cm^-2, in
excess of the Galactic value of 1.5 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.87 (+0.09, -0.08)
and a best-fitting absorption column of 1.29 (+0.26, -0.24) x 10^21
cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 3.6 x 10^-11 (4.5 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.29 (+0.26, -0.24) x 10^21 cm^-2
Galactic foreground: 1.5 x 10^20 cm^-2
Excess significance: 7.7 sigma
Photon index: 1.87 (+0.09, -0.08)
If the light curve continues to decay with a power-law decay index of
0.83, the count rate at T+24 hours will be 0.11 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.0 x
10^-12 (5.0 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/00760064.
This circular is an official product of the Swift-XRT team.
GCN Circular 21291
Subject
GRB 170705A: MASTER-OAFA early OT observations
Date
2017-07-05T09:26:46Z (8 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, D.Kuvshinov, A.V.Krylov,
I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko
Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU
R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA),
National University of San Juan, Argentina
H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina
K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, O. Ershova
Irkutsk State University
V.Yurkov, Yu.Sergienko
Blagoveschensk Educational State University, Blagoveschensk
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in OAFA was pointed to the GRB170705A (Starling et al.,GCN #21289)
24 sec after notice time and 38 sec after trigger time at 2017-07-05
02:46:27 UT at high zenit distance.
On our first (10s exposure) unfiltered exposition we haven`t found
optical transient within SWIFT error-box (ra=191.704 dec=18.2928 r=0.05)
brighter than 15.0.
We marginally found OT at Swift UVOT position (Starling et al.,GCN #21289)
on coaded image ID=79921 with m ~ 17.0.
ID DATE UT Exp Type Limit Note
79817 2017-07-05 02:46:27 10 Alert (SWIFT) 15.0 no
79921 2017-07-05 02:46:27 190 SumAlert (SWIFT) 16.9 79817+79825+79820+79818
79818 2017-07-05 02:47:20 20 Alert (SWIFT) 15.8 yes
79819 2017-07-05 02:48:24 30 Alert (SWIFT) 15.9 no
79820 2017-07-05 02:49:38 50 Alert (SWIFT) 16.2 yes
79822 2017-07-05 02:51:13 60 Alert (SWIFT) 16.3 no
79824 2017-07-05 02:52:57 90 Alert (SWIFT) 16.5 no
79825 2017-07-05 02:55:11 110 Alert (SWIFT) 16.4 yes
79826 2017-07-05 02:57:46 140 Alert (SWIFT) 16.4 no
79827 2017-07-05 03:00:48 180 Alert (SWIFT) 16.7 no
79829 2017-07-05 03:04:32 180 Alert (SWIFT) 16.3 no
79830 2017-07-05 03:08:12 180 Alert (SWIFT) 16.0 no
The unfiltered magnitude is about ~17 m .
The big differences with UVOT magnitude may be connected with high GRB
redshift because our CCD is more red.
The observations made on zenit distance = 79 degrees, galaxy latitude b =
81 degree. The moon (86 % bright part) is 66 degrees above the horizon.
The distance between moon and object is 56
The sun altitude is -63.1 degree.
The object can be observed till 2017-07-05 03:46:20 .
The message may be cited.
GCN Circular 21290
Subject
GRB 170705A: Enhanced Swift-XRT position
Date
2017-07-05T05:26:47Z (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 569 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 170705A, 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 = 191.70427, +18.30741 which is equivalent
to:
RA (J2000): 12h 46m 49.02s
Dec (J2000): +18d 18' 26.7"
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 21289
Subject
GRB 170705A: Swift detection of a burst with an optical counterpart
Date
2017-07-05T03:08:15Z (8 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
R. L. C. Starling (U Leicester), A. Cholden-Brown (PSU),
J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and M. Stamatikos (OSU/NASA/GSFC) report on behalf
of the Swift Team:
At 02:45:47 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170705A (trigger=760064). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 191.705, +18.293 which is
RA(J2000) = 12h 46m 49s
Dec(J2000) = +18d 17' 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 40 sec. The peak count rate
was ~17000 counts/sec (15-350 keV), at ~13 sec after the trigger.
The XRT began observing the field at 02:46:59.3 UT, 72.3 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 191.70472, 18.30811 which
is equivalent to:
RA(J2000) = 12h 46m 49.13s
Dec(J2000) = +18d 18' 29.2"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 54 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 (1.46 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.6
(+3.03/-2.52) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 1.57e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 81 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 12:46:48.97 = 191.70406
DEC(J2000) = +18:18:26.2 = 18.30727
with a 90%-confidence error radius of about 0.76 arc sec. This position is 3.7
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.65 with a 1-sigma error of about 0.15. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.02.
Burst Advocate for this burst is R. L. C. Starling (rlcs1 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.)