GRB 170317A
GCN Circular 21001
Subject
GRB 170317A: SAO RAS optical observations
Date
2017-04-07T20:23:42Z (9 years ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
A. Moskvitin (SAO RAS), E. Mazaeva (IKI), A. Pozanenko (IKI),
A. Volnova (IKI), on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 170317A (LaPorte et al. GCN 20885)
with the SAO RAS telescope Zeiss-1000 + CCD photometer on March, 17
(18:12:00--19:58:03 UT). We obtained several images in Rc band.
The optical afterglow (LaPorte et al., GCN 20885;
Mazaeva et al., GCN 20886; Xin et al., GCN 20888;
Mao et al., GCN 20889; Kuroda et al., GCN 20899) is detected
in a stacked frame. Preliminary photometry is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2017-03-17 18:12:00 0.38823 Rc 15*300 22.3 0.3 22.6
Photometry is based on nearby USNO-B1.0 stars
previously used in GCN 20886.
GCN Circular 20966
Subject
DOAO 1m telescope V, R, I observation of GRB 170317A
Date
2017-04-01T02:04:01Z (9 years ago)
From
Changsu Choi at Seoul Nat U <changsu@astro.snu.ac.kr>
Changsu Choi(CEOU/SNU), Tae-Woo Kim(DOAO/NYSC), Myungshin Im(CEOU/SNU), on
behalf of a larger collaboration
We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with 1m
telescope of Deokheung Optical Astronomy Observatory (DOAO) in Korea,
starting from 2017/3/17 10:41:47 to 11:59:41.5 UT which is 0.042 days to
0.093 days after BAT trigger. .
We obtained V, R, I images and clearly detected afterglow on the stacked
images (LaPorte et al., GCN 20885; Mazaeva et al., GCN20886; Xin et al.,
GCN 20888; Mao et al., GCN 20889; Kuroda et al., GCN20899).
The photometric calibration is based on in APASS catalog in the observed
field. No galactic extinction correction is applied.
Date UT start t-T0 Filter Exp. Mag
Err.
(mid, days) (s)
2017-03-17 10:41:47 0.042 I 180*3 18.86 0.10
2017-03-17 10:51:01 0.049 R 300*3 19.66 0.07
2017-03-17 11:06:18 0.057 I 300*5 20.29 0.26
2017-03-17 11:31:41 0.079 V 300*3 20.38 0.15
2017-03-17 11:46:59 0.086 R 300*2 19.98 0.15
2017-03-17 11:57:10 0.093 V 300*2 20.77 0.23
GCN Circular 20955
Subject
GRB 170317A: 15 GHz upper limits from AMI
Date
2017-03-31T13:28:06Z (9 years ago)
From
Kunal Mooley at Oxford U <kunal.mooley@physics.ox.ac.uk>
K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson
(Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J.
Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K.
Grainge, A. Scaife (Manchester)
The AMI Large Array robotically triggered on the Swift alert for GRB
170317A (LaPorte et al., GCN 20885) as part of the 4pisky program, and
subsequent follow up observations were obtained up to 10 days
post-burst. Our observations at 15 GHz on 2016 Mar 17.59, Mar 18.78, Mar
20.79 and Mar 22.78 (UT) do not reveal any radio source at the XRT
location (Beardmore et al., GCN 20887), with 3sigma upper limits of 126
uJy, 246 uJy, 84 uJy and 111 uJy respectively.
We thank the AMI staff for scheduling these observations. The AMI-GRB
database is a log of all GRB follow up observations with the AMI, and is
available at http://4pisky.org/ami-grb/.
GCN Circular 20924
Subject
GRB 170317A: Mondy optical observations
Date
2017-03-20T15:19:06Z (9 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI)
report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with
AZT-33IK telescope of Sayan observatory (Mondy) starting on March, 18
(UT) 14:57:48. We several images in R-filter.
The optical afterglow (LaPorte et al., GCN 20885; Mazaeva et al., GCN
20886; Xin et al., GCN 20888; Mao et al., GCN 20889) is visible in
stacked images. Preliminary photometry of the afterglow is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2017-03-18 14:57:48 1.23738 R 30*120 23.25 0.22 23.6
The photometry is based on nearby USNO-B.10 stars
Ref.stars
USNO_B1_id R2
1405-0167631 15.69
1404-0169027 16.03
1405-0167512 16.85
1404-0169128 16.25
GCN Circular 20922
Subject
GRB 170317A: POLAR observation
Date
2017-03-19T19:12:35Z (9 years ago)
From
Haulin Xiao at PSI/POLAR <hualin.xiao@psi.ch>
H.L. Xiao (PSI), W. Hajdas (PSI) and R. Marcinkowski (PSI) report on behalf of the POLAR collaboration:
At 2017-03-17 09:45:56.0 UT(T0), during a routine on-ground search of data, POLAR detected GRB 170317A
(Swift BAT (trigger # 742866); LaPorte et al., GCN 20885).
The POLAR light curve consists of one peak with duration (T90) of 6.00 � 1.00 s measured from T0.
The 1.00 s peak flux at T0 + 5.50 s is equal to 370 � 50 counts/sec.
POLAR recorded 1500 events from the burst.
Above measurements are in the energy range of about 15 - 300 keV.
LC_URL: http://polar.psi.ch/triggers/GRB_170317A.png
Using the best location from Swift-BAT, which is (J2000):
RA : 93.087 [deg]
Dec: 50.500 [deg]
the incident angle in the POLAR coordinate at T0 is:
Theta: 81.38 [deg]
Phi: 4.61 [deg]
The analysis results presented above are preliminary. POLAR is a dedicated Gamma-Ray Burst polarimeter which was launched on-board the Chinese space
laboratory Tiangong-2 (TG-2) on Sep 15, 2016. The energy detection range of POLAR is ~ 50-500 keV.
More information about POLAR can be found at http://polar.psi.ch/pub ,
http://polar.ihep.ac.cn/en/ and http://isdc.unige.ch/polar/ .
This message is quotable in publications.
GCN Circular 20920
Subject
GRB 170317A: RATIR Optical and NIR Observations
Date
2017-03-19T15:18:09Z (9 years ago)
From
Alan M. Watson at Instituto de Astronomia UNAM <alan@astro.unam.mx>
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 170317A (LaPorte et al., GCN 20885) 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 2017/03 19.13 to 2017/03 19.30
UTC (41.26 to 45.37 hours after the BAT trigger), obtaining a total of
2.84 hours exposure in the r and i bands and 1.19 hours exposure in the
Z, Y, J, and H bands.
For a source within the enhanced Swift-XRT error circle (Beardmore et
al., GCN 20887), in comparison with the USNO-B1 and 2MASS catalogs, we
obtain the following detections and 3-sigma upper limits:
r 23.70 +/- 0.10
i 23.93 +/- 0.26
Z > 23.07
Y > 22.51
J > 22.27
H > 21.75
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
The source has faded by about a magnitude in r and i since our earlier
observations (Watson et al., GCN 20911).
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 20911
Subject
GRB 170317A: RATIR Optical and NIR Observations
Date
2017-03-18T17:10:21Z (9 years ago)
From
Nat Butler at UC berkeley <natxbutler@gmail.com>
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 170317A (LaPorte et al., GCN 20885) 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 2017/03 18.13 to 2017/03 18.30 UTC (17.37 to
21.38 hours after the BAT trigger), obtaining a total of 2.84 hours
exposure in the r and i bands and 1.19 hours exposure in the Z, Y, J, and H
bands.
For a source within the enhanced Swift-XRT error circle (Beardmore et al.,
GCN 20887), in comparison with the USNO-B1 and 2MASS catalogs, we obtain
the following detections and 3-sigma upper limits:
r 22.85 +/- 0.05
i 22.86 +/- 0.09
Z 22.92 +/- 0.30
Y 22.34 +/- 0.26
J 22.41 +/- 0.35
H > 21.95
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 20901
Subject
GRB 170317A: LCO FTN observations
Date
2017-03-18T09:56:26Z (9 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc
(U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large
collaboration report:
We observed Swift GRB 170317A (LaPorte et al. GCN 20885) on March 18,
06:01 UT (0.84 days since the GRB) with the 2-m LCO Faulkes Telescope
North with SDSS r and i filters. We marginally detect the optical
afterglow (LaPorte et al.; Mazaeva et al. GCN 20886, 20893; Xin et al.
GCN 20888; Mao et al. GCN 20889, 20890; Kuin et al. GCN 20894) in the r
filter with the following values:
Mid Time Exposure Filter Magnitude (AB)
(days) (s)
-------------------------------------------------------
0.87 10x120 SDSS-R 22.9 +- 0.3
0.88 10x120 SDSS-I > 22.0
-------------------------------------------------------
as calibrated against nearby PanSTARRS-1 DR1 objects.
GCN Circular 20899
Subject
GRB 170317A: MITSuME Okayama Optical Observation
Date
2017-03-18T00:11:10Z (9 years ago)
From
Daisuke Kuroda at OAO/NAOJ <dikuroda@oao.nao.ac.jp>
D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME and OISTER collaboration:
We observed the field of GRB 170317A (LaPorte et al., GCNC 20885)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.
The observation started on 2017-03-17 10:14:19 UT (~28 min after
the burst). We detected the previously reported afterglow (LaPorte
et al., GCNC 20885; Mazaeva et al., GCNC 20886) in Rc and Ic bands.
Three sigma upper limit and photometric results of the OT are
listed below. We used GSC2.3 catalog for flux calibration.
#T0+[day] MID-UT T-EXP[sec] g' Rc Rc_err Ic Ic_err
------------------------------------------------------------------
0.06138 11:14:22 6120.0 >20.5 19.3 0.2 19.2 0.3"
------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
GCN Circular 20896
Subject
GRB 170317A: Swift-BAT refined analysis
Date
2017-03-17T21:02:25Z (9 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
N. Gehrels (GSFC), H. A. Krimm (NSF/USRA),
S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC),
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-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170317A (trigger #742866)
(LaPorte et al., GCN Circ. 20885). The BAT ground-calculated position is
RA, Dec = 93.087, 50.500 deg which is
RA(J2000) = 06h 12m 21.0s
Dec(J2000) = +50d 30' 00.5"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 46%.
The mask-weighted light curve shows a FRED-like pulse that starts at
~T-2 s, peaks at ~ T+2 s, and ends at ~T+18 s. T90 (15-350 keV) is
11.94 +- 4.87 sec (estimated error including systematics).
The time-averaged spectrum from T-0.29 to T+18.29 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 0.80 +- 0.49,
and Epeak of 58.8 +- 10.5 keV (chi squared 75.18 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 1.3 +- 0.1 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+1.28 sec in the 15-150 keV band is
3.5 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.78 +- 0.10 (chi squared 89.59 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/742866/BA/
GCN Circular 20894
Subject
GRB 170317A: Swift/UVOT Detection
Date
2017-03-17T17:00:57Z (9 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and S. J. LaPorte (PSU) report on behalf of
the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB
170317A 87 s after the BAT trigger (LaPorte et al., GCN Circ.20885).
A fading source consistent with the XRT position (Beardmore et al.
GCN Circ. 20887) is detected in the initial UVOT exposures. The GRB
afterglow was also observed by Mazaeva et al. (GCN Circ. 20886) and
Mao et al. (GCN. Circ. 20889) in the R band.
The preliminary UVOT position is:
RA (J2000) = 06:12:14.82 = 93.06173 (deg.)
Dec (J2000) = +50:29:35.2 = 50.49310 (deg.)
with an estimated uncertainty of 0.43 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 87 237 147 17.53 +/- 0.04
v 629 1597 117 18.36 +/- 0.19
b 554 1349 78 19.12 +/- 0.19
u 299 549 246 17.75 +/- 0.07
w1 678 7320 588 20.20 +/- 0.29
m2 653 7115 398 >19.8
w2 604 8141 607 >20.2
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.19 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 20893
Subject
GRB 170317A: Mondy optical observations
Date
2017-03-17T16:48:01Z (9 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova
(IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with
AZT-33IK telescope of Sayan observatory (Mondy) starting on March, 17
(UT) 13:56:13. We obtained 60 of 60 s exposure images in R-filter.
The optical afterglow (LaPorte et al., GCN 20885; Mazaeva et al., GCN
20886; Xin et al., GCN 20888; Mao et al., GCN 20889) is clearly visible
in stacked images. Preliminary photometry of the afterglow is following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2017-03-17 13:56:13 0.18073 R 20*60 20.94 0.10 22.5
The photometry is based on nearby USNO-B.10 stars
Ref.stars
USNO_B1_id R2
1405-0167493 16.10
1405-0167631 15.69
1404-0169027 16.03
1405-0167512 16.85
1404-0169128 16.25
GCN Circular 20892
Subject
GRB 170317A: MITSuME Okayama Ks-band upper-limit
Date
2017-03-17T16:39:39Z (9 years ago)
From
Kenshi Yanagisawa at OAO/NAOJ <yanagi@oao.nao.ac.jp>
K. Yanagisawa, D. Kuroda, Y. Shimizu, H. Izumiura (OAO/NAOJ),
M. Yoshida (Hiroshima), K. Ohta(Kyoto) and N. Kawai (Tokyo Tech.)
report on behalf of the MITSuME collaboration:
We observed the field of GRB 170317A (LaPorte et al., GCN 20885)
in Ks-band with a wide-field near infrared imager at Okayama
Astrophysical Observatory (Japan). The imager has effective
aperture of 0.91 m.
Observations started from 09:54 UT on 17th March, 8 min after
the BAT trigger, to 10:38 UT. The total exposure of 17.0 min
was successfully obtained.
In our co-add image, we did not find any new point source within
the XRT error circle (Beardmore et al., GCN 20887) down to
the limiting magnitude of Ks=16.1 (Vega, S/N=5). The photometric
calibration was made against 2MASS field stars.
T0+[sec] MID-UT T-EXP[sec] Ks
---------------------------------------------------
+1,819 10:16 1020.0 >16.1
---------------------------------------------------
T0+ : Elapsed time after the burt [sec]
T-EXP: Total Exposure time [sec]
GCN Circular 20891
Subject
GRB 170317A: Swift-XRT refined Analysis
Date
2017-03-17T15:46:59Z (9 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A. Cholden-Brown (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), B.
Mingo (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia
(ASDC) and report on behalf of the Swift-XRT team: report on behalf of
the Swift-XRT team:
We have analysed 6.9 ks of XRT data for GRB 170317A, from 68 s to 13.5
ks after the BAT trigger. The data comprise 8 s in Windowed Timing
(WT) mode (taken while Swift was slewing), with the remainder in Photon
Counting (PC) mode.
The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=3.8 (+4.2, -1.4). At T+105 s the decay
flattens to an alpha of 0.58 (+0.07, -0.09) before breaking again at
T+3006 s to a final decay with index alpha=1.4 (+0.4, -0.3).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.05 (+0.10, -0.07). The
best-fitting absorption column is consistent with the Galactic value
of 2.5 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum is 3.5 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.5 (+/-0.3) x 10^21 cm^-2
Galactic foreground: 2.5 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.05 (+0.10, -0.07)
If the light curve continues to decay with a power-law decay index of
1.4, the count rate at T+24 hours will be 2.2 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.9 x
10^-14 (1.1 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/00742866.
This circular is an official product of the Swift-XRT team.
GCN Circular 20889
Subject
GRB 170317A: GMG observation
Date
2017-03-17T14:58:21Z (9 years ago)
From
Jirong Mao at Yunnan Obs <jirongmao_obs@ynao.ac.cn>
J. Mao, Y. Xin and J.-M. Bai (YNAO) report:
We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with the 2.4-meter
optical telescope at Gao-Mei-Gu (GMG) station of Yunnan Observatories. Observations began
from 13:58:18 UT, about 4.2 hours after the trigger. We detected the afterglow with
R~19.96+/-0.10 mag, calibrated by a nearby USNO-B1.0 star.
GCN Circular 20888
Subject
GRB 170317A : Xinglong TNT optical observation
Date
2017-03-17T13:39:57Z (9 years ago)
From
L.P. Xin at NAOC <xlp@nao.cas.cn>
L. P. Xin, T. M. Zhang, J. Y. Wei, Y. L. Qiu, J. S. Deng,
J. Wang, X. H. Han���C. Wu and E. W. Liang reports:
We began to observe GRB 170317A (LaPorte et al., GCN 20885)
with Xinglong 0.8-m TNT telescope at 2017-03-17,11:39:17 (UT),
about 1.9 hours after the Swift trigger time.
The optical afterglow reported ( LaPorte et al., GCN 20885;
Mazaeva et al., GCN 20886) was clearly detected in the
stacked 11*300 sec R-band image.
Preliminary analysis shows that the brightness of the optical afterglow
in R band is about 19.8+/-0.1 mag, calibrated by nearby USNO B1.0 objects
at the mid time of 2.3 hours after the burst.
This message could be cited.
We thank the excellent support of the Xinglong 80cm TNT staff, particularly S. Liu
GCN Circular 20887
Subject
GRB 170317A: Enhanced Swift-XRT position
Date
2017-03-17T13:22:50Z (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 2369 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 170317A, 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 = 93.06206, +50.49305 which is equivalent
to:
RA (J2000): 06h 12m 14.89s
Dec (J2000): +50d 29' 35.0"
with an uncertainty of 1.7 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 20886
Subject
GRB 170317A: ISON-Ussuriysk aferglow confirmation
Date
2017-03-17T13:06:50Z (9 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), A. Pozanenko (IKI), A. Kochergin (UAFO), A. Volnova
(IKI), E. Chornaya (UAFO), A. Matkin (UAFO, ISON), I. Molotov
(KIAM) report on behalf of larger GRB follow-up collaboration:
We observed the field of the GRB 170317A (LaPorte et al., GCN 20885)
with SANTEL-650 (0.65m) telescope of UAFO/ISON-Ussuriysk observatory
starting on March, 17 (UT) 10:20:37. We obtained series of unfiltered
images of 60 s exposure. In a first combined images we detected optical
afterglow (LaPorte et al., GCN 20885). Preliminary photometry of some
initial combined image is following
Date UT start t-T0 Filter Exp. OT err UL (3sigma)
(mid, days) (s)
2017-03-17 10:20:37 0.0321 none 20*60 18.95 0.08 21.5
In comparison with early reported photometry (LaPorte et al., GCN
20885) the OT is faded, and we confirm the afterglow of the GRB 170317A.
Photometry is based on nearby USNO-B1.0 stars
USNO_B1_id R2
1405-0167482 15.08
1405-0167474 15.43
1405-0167493 16.10
1405-0167484 16.14
1404-0169177 15.93
1405-0167639 15.62
1405-0167631 15.69
GCN Circular 20885
Subject
GRB 170317A: Swift detection of a burst with an optical counterpart
Date
2017-03-17T10:01:55Z (9 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
S. J. LaPorte (PSU), A. P. Beardmore (U Leicester),
B. Mingo (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf
of the Swift Team:
At 09:45:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170317A (trigger=742866). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 93.088, +50.520 which is
RA(J2000) = 06h 12m 21s
Dec(J2000) = +50d 31' 13"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a FRED
structure with a duration of about 10 sec. The peak count rate
was ~3000 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 09:47:22.4 UT, 83.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 93.06317, 50.49431 which is equivalent
to:
RA(J2000) = 06h 12m 15.16s
Dec(J2000) = +50d 29' 39.5"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 109 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 consistent with the Galactic value of 2.53
x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 86 seconds after the BAT trigger. There is a candidate afterglow in
the list of sources generated on-board at
RA(J2000) = 06:12:14.78 = 93.06160
DEC(J2000) = +50:29:34.8 = 50.49300
with a 90%-confidence error radius of about 1.10 arc sec. This position is 5.7
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.05. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.19.
Burst Advocate for this burst is S. J. LaPorte (extragsam AT gmail.com).
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.)