GRB 170810A
GCN Circular 21449
Subject
GRB 170810A: MASTER-NET very bright OT detection
Date
2017-08-10T22:17:00Z (8 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias
V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina,
P.Balanutsa,
A.Kuznetsov, V.V.Chazov, D. Vlasenko
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University
K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk
Irkutsk State University
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
V. Yurkov, A. Gabovich, Yu. Sergienko
Blagoveschensk Educational State University, Blagoveschensk
D. Buckley, S. Potter, A. Kniazev, M. Kotze
South African Astronomical Observatory
R. Podesta, Carlos Lopez and F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA)
Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in IAC was pointed to the GRB170810A 25 sec after notice time
and 45 sec after trigger time at 2017-08-10 22:02:26 UT. On our first (10s
exposure) set we found very bright OT.
Mag: 11.258
Ra: 187.938775
Dec: 3.660714
The message may be cited.
The observations made on zenit distance = 85 degrees, galaxy latitude b =
66 degree.
The moon (90 % bright part) is 4 degrees above the horizon. The distance
between moon and object is 169
The sun altitude is -27.0 degree.
The object can be observed till sunrise at 2017-08-11 06:32:12.
GCN Circular 21450
Subject
GRB 170810A: Swift detection of a burst with a bright optical counterpart
Date
2017-08-10T22:39:41Z (8 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
S. L. Gibson (U Leicester), D. N. Burrows (PSU), J. A. Kennea (PSU),
S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and A. Tohuvavohu (PSU) report on behalf of the
Swift Team:
At 22:01:41 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170810A (trigger=767284). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 187.950, +3.647 which is
RA(J2000) = 12h 31m 48s
Dec(J2000) = +03d 38' 48"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex
structure with a duration of 160 sec. The peak count rate
was ~2600 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 22:02:57.5 UT, 76.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
187.9389, 3.6603 which is equivalent to:
RA(J2000) = 12h 31m 45.33s
Dec(J2000) = +03d 39' 37.0"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 62 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 (2.23 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.2
(+1.98/-1.79) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 4.45e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 876 seconds after the BAT trigger. There is a candidate afterglow in
the list of sources generated on-board at
RA(J2000) = 12:31:45.31 = 187.93881
DEC(J2000) = +03:39:38.9 = 3.66080
with a 90%-confidence error radius of about 1.10 arc sec. This position is 3.5
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.87. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.03.
An earlier UVOT finding chart exposure, starting 85 seconds after the
BAT trigger, showed that the counterpart was much brighter at that time.
However, this brightness precluded automatic analysis.
Results for this early bright detection will be presented later.
The original GCN notice of this burst suggested an association with the
galaxy NGC4496A. However, the apparent separation from this galaxy,
0.295 deg, implies that these two objects are not related.
Burst Advocate for this burst is S. L. Gibson (slg44 AT 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 21451
Subject
GRB 170810A: Enhanced Swift-XRT position
Date
2017-08-11T01:10:17Z (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 1301 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 170810A, 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 = 187.93852, +3.66084 which is equivalent
to:
RA (J2000): 12h 31m 45.24s
Dec (J2000): +03d 39' 39.0"
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 21452
Subject
GRB 170810A: Fermi-LAT detection
Date
2017-08-11T02:24:00Z (8 years ago)
From
Judith Racusin at GSFC <judith.racusin@nasa.gov>
J. L. Racusin (NASA/GSFC), E. Burns (NASA/GSFC), D. Kocevski (NASA/MSFC), F. Longo (University
and INFN, Trieste), J. McEnery (NASA/GSFC), S. Razzaque (Johannesburg), G. Vianello (Stanford),
report on behalf of the Fermi-LAT team:
Fermi-LAT detected high-energy emission from GRB 170810A, which trigger Fermi-GBM (trigger
524095306 / 170810918) and Swift-BAT (Gibson et al, GCN 21450) at 22:01:41 on August, 10, 2017.
The best LAT on-ground location is found to be
RA, Dec = 187.5, 3.33 (J2000)
with an error radius of 0.53 deg (90 % containment, statistical error only), which is consistent with the
Swift BAT, XRT, and UVOT positions (Gibson et al, GCN 21450; Goad et al., GCN 21451), as well as
MASTER-NET (Rebolo et al, GCN 21449).
This was 60 deg from the LAT boresight at the time of the trigger.
The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally
correlated with the trigger with high significance.
The highest-energy photon is a 2.3 GeV event which is observed 34 seconds after the GBM trigger.
The Fermi-LAT point of contact for this burst is Judith Racusin (judith.racusin@nasa.gov).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater
than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and
many scientific institutions across France, Italy, Japan and Sweden.
GCN Circular 21453
Subject
GRB 170810A: Fermi GBM observation
Date
2017-08-11T03:08:08Z (8 years ago)
From
Peter Veres at UAH <veresp@gmail.com>
P Veres and C Meegan (both UAH)
report on behalf of the Fermi GBM Team:
"At 22:01:41.58 UT on 10 August 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170810A (trigger 524095306 / 170810918).
which was also detected by the Swift/BAT (Gibson et al., GCN 21450) and
Fermi LAT (Racusin at al., GCN 21452). The GBM on-ground location is
consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 60 degrees.
The GBM light curve shows multiple pulses
with a duration (T90) of about 137 s (50-300 keV).
The time-averaged spectrum from T0-6.1 s to T0+67.6 s is
adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.79 +/- 0.08 and
the cutoff energy, parameterized as Epeak, is 267 +/- 34 keV.
The event fluence (10-1000 keV) in this time interval is
(1.0 +/- 0.6)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+38.4 s in the 10-1000 keV band
is 2.6 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 21454
Subject
GRB 170810A: Swift/UVOT Detection
Date
2017-08-11T04:04:43Z (8 years ago)
From
Sam LaPorte at PSU <sjl5346@psu.edu>
GRB 170810A: Swift/UVOT Detection
S. J. LaPorte (PSU) and S. L. Gibson (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170810A
85 s after the BAT trigger (Gibson et al., GCN Circ. 21450).
A source consistent with the XRT position
(Goad et al. GCN Circ. 21451)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 12:31:45.33 = 187.93889 (deg.)
Dec (J2000) = +03:39:38.9 = 3.66081 (deg.)
with an estimated uncertainty of 0.42 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 14.64 +/- 0.02
v 628 648 20 15.88 +/- 0.13
b 554 574 20 16.62 +/- 0.10
u 299 1493 281 >19.3
w1 677 1473 97 >18.9
w2 604 623 19 >18.0
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 21455
Subject
GRB 170810A: Swift-XRT refined Analysis
Date
2017-08-11T06:05:07Z (8 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
B. Mingo (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri
(INAF-OAB), A. Cholden-Brown (PSU), S. J. LaPorte (PSU), J.A. Kennea
(PSU) and S.L. Gibson report on behalf of the Swift-XRT team:
We have analysed 6.8 ks of XRT data for GRB 170810A (Gibson et al. GCN
Circ. 21450), from 66 s to 18.7 ks after the BAT trigger. The data
comprise 387 s in Windowed Timing (WT) mode (the first 9 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. 21451).
The late-time light curve (from T0+4.6 ks) can be modelled with a
power-law decay with a decay index of alpha=1.33 (+/-0.13).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.60 (+/-0.04). The
best-fitting absorption column is 3.5 (+1.0, -0.9) x 10^20 cm^-2, in
excess of the Galactic value of 2.2 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.93 (+0.11, -0.10)
and a best-fitting absorption column of 5.5 (+2.4, -2.3) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.4 x 10^-11 (3.8 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 5.5 (+2.4, -2.3) x 10^20 cm^-2
Galactic foreground: 2.2 x 10^20 cm^-2
Excess significance: 2.4 sigma
Photon index: 1.93 (+0.11, -0.10)
If the light curve continues to decay with a power-law decay index of
1.33, the count rate at T+24 hours will be 0.012 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.0 x
10^-13 (4.6 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/00767284.
This circular is an official product of the Swift-XRT team.
GCN Circular 21458
Subject
GRB 170810A: Swift-BAT refined analysis
Date
2017-08-11T15:26:06Z (8 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
S. L. Gibson (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), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170810A (trigger #767284)
(Gibson, et al., GCN Circ. 21450). The BAT ground-calculated position is
RA, Dec = 187.928, 3.664 deg which is
RA(J2000) = 12h 31m 42.8s
Dec(J2000) = +03d 39' 49.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 93%.
The mask-weighted light curve shows a complex multi-peaked structure that
starts at ~T-20 s and ends at ~T+180 s. The brightest peak occurs at ~T+0.5 s.
T90 (15-350 keV) is 152.4 +- 21.5 sec (estimated error including systematics).
The time-averaged spectrum from T-24.33 to T+157.74 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.24 +- 0.07. The fluence in the 15-150 keV band is 4.8 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.15 sec in the 15-150 keV band
is 1.2 +- 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/767284/BA/
GCN Circular 21471
Subject
GRB 170810A: AbAO optical upper limit
Date
2017-08-13T19:29:38Z (8 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (IKI), A. Pozanenko (IKI), R. Inasaridze (AbAO), V. Ayvazian
(AbAO), O. Kvaratskhelia (AbAO), G. Inasaridze (AbAO), E. Mazaeva (IKI),
I. Molotov (KIAM) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 170810A (Gibson et al., GCN 21450)
with AS-32 (0.7m) telescope of Abastumani Observatory starting on August, 11
(UT) 17:02:09. We obtained several unfiltered images of the field. Within
enhanced XRT error circle (Goad et al., GCN 21451) we do not detect the
afterglow (Rebolo et al, GCN 21449; Gibson et al., GCN 21450). Preliminary
photometry of the field is following
Date UT start t-T0 Filter Exp. OT Err UpLim (3
sigma)
(mid, days) (s)
2017-08-11 17:02:09 0.80915 CR 33*20 n/d n/d 18.2
Photometry is based on nearby SDSS stars (Lupton transformation)
SDSS id R_Lupton
J123141.98+033552.6 15.637 0.013
J123153.09+033552.7 14.800 0.012
J123154.00+033945.4 15.540 0.013
GCN Circular 21492
Subject
GRB 170810A: VLA Detection
Date
2017-08-16T00:22:47Z (8 years ago)
From
Kate Alexander at Harvard <kalexander@cfa.harvard.edu>
K. D. Alexander (Harvard), T. Laskar (NRAO / UC Berkeley), and E. Berger
(Harvard) report on behalf of a larger collaboration:
We observed the Swift GRB 170810A (Gibson et al., GCN 21450) at multiple
frequencies with the Karl G. Jansky Very Large Array (VLA) beginning 2017
August 12.77 UT (1.85 days after the burst). At a mean frequency of 7.1
GHz, we detect a radio source with a preliminary flux density of ~0.1 mJy.
In follow-up observations on 2017 August 15.03 UT the source had faded to
~half its original brightness, confirming this as the radio afterglow of
GRB 170810A.
The best-fit radio position is
RA (J2000) = 12:31:45.346
Dec (J2000) = +03:39:38.61
with an uncertainty of 0.4��� in each coordinate. This is consistent with the
refined Swift/XRT position (Goad et al. GCN 21451) and the position of the
Swift/UVOT afterglow (LaPorte et al. GCN 21454).
We thank the VLA staff for rapidly executing these observations.