GRB 170208B
GCN Circular 20674
Subject
GRB 170208B: SMARTS optical/IR observations
Date
2017-02-14T19:48:17Z (10 years ago)
From
Bethany Cobb at GWU <bcobb@gwu.edu>
B. E. Cobb (GWU) reports:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we
obtained optical/IR imaging of the error region of GRB 170208B
(GCN 20632, Siegel et al.) with a mid-exposure time of about
5.1 hours post-burst (2017-02-09 03:38 UT). Total summed exposure
times amounted to 36 minutes in I and 30 minutes in J.
No source is detected at the position of the X-ray afterglow
(GCN 20635, Goad et al.) to approximate limiting magnitudes
of I > 20.9 and J > 19.4. Magnitudes are calibrated using
Landolt standard stars in I and 2MASS stars in J.
GCN Circular 20673
Subject
GRB 170208B: IRSF upper limits
Date
2017-02-14T07:28:56Z (10 years ago)
From
Katsuhiro L. Murata at Nagoya U <murata@u.phys.nagoya-u.ac.jp>
K. L. Murata (Nagoya U), L. Townsend (UCT), I. Monageng (SAAO), Y. Moritani
(Kavli IPMU), M. Jian (U of Tokyo), S. Chimasu (Tokai U), A. Kawachi (Tokai
U), A. Okazaki (Hokkai-Gakuen U) and T. Nagayama (Kagoshima U)
We observed the field of GRB 170208B (Siegel et al., GCN Circular #20632)
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 2017-02-08 22:49:41 UT (~ 15 min. after the
burst). We could not detect the afterglow within the enhanced XRT error
circle (Goad et al., GCN Circular #20635) in the three bands. We have
obtained the following preliminary upper limits (Vega magnitude system):
J > 16.83
H > 16.31
Ks > 16.30
Given magnitudes were calibrated against 2MASS point sources in this field.
The upper limits were determined as the magnitudes of the faintest star
within 1 arcmin from the enhanced XRT position.
This observation was carried out by IRSF and OISTER collaboration.
GCN Circular 20657
Subject
GRB 170208B: Swift/UVOT Upper Limits
Date
2017-02-10T01:47:01Z (10 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@swift.psu.edu>
M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170208B
127 s after the BAT trigger (Siegel et al., GCN Circ. 20632).
No optical afterglow consistent with the enhanced XRT position
(Goad et al. GCN Circ. 20635) or the GROND position
(Kruehler et al., GCN Circ. 20640)
is detected in the initial UVOT exposures.
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
u_FC 127 377 246 >20.7
v 432 2146 214 >19.6
b 382 2096 233 >20.3
u 127 2211 598 >21.3
w1 482 2195 214 >20.1
m2 457 2171 214 >19.9
w2 408 2122 234 >19.7
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 20655
Subject
GRB 170208B: RATIR Optical and NIR Observations
Date
2017-02-09T23:48:46Z (10 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), Neil Gehrels (GSFC), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy
(UMD) report:
We observed the field of GRB 170208B (Siegel, et al., GCN 20632) 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 2017/02 9.11 to 2017/02 9.47 UTC (3.98 to
12.65 hours after the BAT trigger), obtaining a total of 6.02 hours
exposure in the r and i bands and 2.52 hours exposure in the Z and Y bands.
We do not detect either the GROND (Kruehler, et al., GCN 20640) source or
the WHT (Wiersema, et al., GCN 20647) source. In comparison with the
USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma):
r > 23.56
i > 23.43
Z > 22.64
Y > 22.55
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. The lack of detection of the WHT
source is consistent with this source being reddened due to dust or due to
a high-z origin if the GROND source is not the GRB host galaxy. The first
possibility is also suggested by the significant X-ray column density
relative to the Galactic value (Kennea, et al., GCN 20637).
We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.
GCN Circular 20654
Subject
GRB 170208B: Swift-BAT refined analysis
Date
2017-02-09T22:55:28Z (10 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), T. Sakamoto (AGU),
M. H. Siegel (PSU), 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 170208B (trigger #737463)
(Siegel et al., GCN Circ. 20632). The BAT ground-calculated position is
RA, Dec = 127.145, -9.027 deg which is
RA(J2000) = 08h 28m 34.7s
Dec(J2000) = -09d 01' 36.1"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The mask-weighted light curve shows a bright pulse structure with
several overlapping peaks that starts at ~T-5 s and ends at ~T+15 s,
followed by a weaker pulse from ~T+100 s to ~T+160 s. There are also some
weak emissions that start at ~T-20 s, prior to the first bright pulse. The short
spike with duration of ~ 4 ms seen in 15-25 keV at ~T+191.3 s is due to
instrumental noise. T90 (15-350 keV) is 128.07 +- 5.75 sec (estimated error
including systematics).
The time-averaged spectrum from T-18.20 to T+159.30 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.18 +- 0.21,
and Epeak of 97.8 +- 27.4 keV (chi squared 57.4 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 6.1 +- 0.2 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+0.42 sec in the 15-150 keV band is
8.4 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.62 +- 0.05 (chi squared 71.7 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/737463/BA/
GCN Circular 20651
Subject
Correction to GCN 20640: GRB 170208B: GROND observations
Date
2017-02-09T22:12:53Z (10 years ago)
From
Thomas Kruehler at MPE Garching <kruehler@mpe.mpg.de>
T. Kruehler (MPE Garching) reports:
The declination of the source mentioned in my original
GCN 20640 contained an error. The correct position is:
RA (J2000): 08:28:34.55
Dec (J2000): -09:01:46.1
I thank N. R. Tanvir for pointing out the error.
GCN Circular 20647
Subject
GRB 170208B WHT nIR candidate afterglow
Date
2017-02-09T16:50:56Z (10 years ago)
From
Nial Tanvir at U.Leicester <nrt3@star.le.ac.uk>
K. Wiersema, N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick),
R. Karjalainen, F. Riddick (ING) report on behalf of a larger collaboration:
We observed the field of Swift GRB 170208B (Siegel et al. GCN 20632)
with the 4.2m William Herschel Telescope on La Palma.
Images were obtained in the Y,J,H,K filters with LIRIS.
In the K-band exposure, for which the mid-time was 2.54 hr post-burst,
we find a source with magnitude K(AB)=21.1+/-0.1 within the revised
X-ray error circle (Goad et al. GCN 20635).
The source is absent (or very marginally present) in the other infrared
filters, which were observed somewhat earlier, to AB mag limits of
about 22.5 in each band.
The position of this source is:
RA(2000)=08:28:34.55
dec(2000)=-9:01:47.8
This is about 1.8 arcsec south of the steady optical source
seen by GROND and Pan-STARRS (Kruehler GCN 20640;
we note there was a typo in the declination coordinate
reported in GCN 20640, Kruehler priv. comm.).
We suggest that the K-band source is most likely the
afterglow of the GRB, and is not seen in bluer filters
due to dust extinction, while the optical source may be the
host galaxy.
GCN Circular 20646
Subject
GRB 170208B: Fermi GBM Detection
Date
2017-02-09T15:19:35Z (10 years ago)
From
Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>
O.J. Roberts (USRA/NASA) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 22:33:36.53 UT on the 8th of February 2017,
the Fermi Gamma-Ray Burst Monitor triggered and
located GRB 170208B (trigger 508286021 / 170208940),
which was also detected by Konus-Wind
(Svinkin et al. 2017, GCN 20643) and Swift
(Siegel et al. 2017, GCN 20632). The GBM on-ground
location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM
trigger time using the Swift-XRT position is 54 degrees.
The GBM light curve consists of a long GRB with
overlapping episodes of bright emission over a
duration (T90) of about 22 s (50-300 keV). The
time-averaged spectrum from T0-8.0 s to T0+14.0 s is
adequately fit by a Band function with
Epeak = 104.1 +/- 5.5 keV, alpha = -0.83 +/- 0.05, and
beta = -2.33 +/- 0.09
The event fluence (10-1000 keV) in this time interval is
(1.13 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux
measured starting from T0-7.9 s in the 10-1000 keV band
is 12.1 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 20643
Subject
Konus-Wind observation of GRB 170208B
Date
2017-02-09T14:39:18Z (10 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 170208B
(Swift-BAT detection: Siegel et al., GCN Circ. 20632)
triggered Konus-Wind at T0=81222.750 s UT (22:33:42.750).
The burst light curve shows a single emission episode
started at ~T0-5 s with a total duration of ~11 s.
The emission is seen up to ~1 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170208_T81222/
As observed by Konus-Wind, the burst
had a fluence of 8.17(-0.44,+0.46)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+1.072 s,
of 2.55(-0.82,+0.82)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 1 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.78(-0.23,+0.25)
and Ep = 105(-7,+8) keV (chi2 = 40/51 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.0
(chi2 = 39/50 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 20640
Subject
GRB 170208B: GROND observations
Date
2017-02-09T14:08:32Z (10 years ago)
From
Thomas Kruehler at MPE Garching <kruehler@mpe.mpg.de>
T. Kruehler (MPE Garching) reports:
I observed the field of GRB 170208B (Swift trigger 737463; Siegel
et al. GCN 20632) simultaneously in g'r'i'z'JHK with GROND
(Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG
telescope at the ESO La Silla Observatory (Chile).
Observations started at 01:22 UT on 2017-02-09, 2.8 hr after the
GRB trigger and reveal a faint optical source centered at:
RA (J2000): 08:28:34.55
Dec (J2000): -09:01:38.1
which is 2.0" away from the center of the XRT error circle
(Goad et al. GCN 20635, current 90% error radius of 1.6").
Based on combined images with 66 min of total exposures in g'r'i'z'
and 60.0 min in JHK at a mid-time of 02:39 UT on 2017-02-09, this
source has the following preliminary magnitudes and upper limits
(all in the AB system):
g' = 24.5 +- 0.4 mag
r' = 24.4 +- 0.3 mag
i' = 23.4 +- 0.2 mag
z' = 23.1 +- 0.2 mag
J > 21.3 mag
H > 21.0 mag
K > 19.0 mag
Given magnitudes are calibrated against Pan-STARRS and 2MASS field
stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V)=0.042 mag in the
direction of the burst (Schlafly & Finkbeiner 2011).
This source is marginally detected already in the archival Pan-STARRS
imaging of the field, so it is not the GRB 170208B afterglow. It is,
however, a possible host galaxy candidate (the chance coincidence
probability of finding a similarly bright object at 2" from the XRT
position is around 6%).
I acknowledge excellent help in obtaining these data from the
supporting astronomers on La Silla, Sam Kim and Simon Steinmassl.
GCN Circular 20638
Subject
GRB 170208B: NOT upper limits
Date
2017-02-09T11:33:49Z (10 years ago)
From
Kasper Elm Heintz at Univ. of Iceland and DARK/NBI <heintz@dark-cosmology.dk>
K. E. Heintz (Univ. Iceland and DARK/NBI), D. Malesani (DARK/NBI and DTU Space), N. R. Tanvir (Univ. Leicester), A. de Ugarte Postigo (IAA-CSIC and DARK/NBI), A. J. Korn (Uppsala Univ.) and I. R. Losada (NOT, NORDITA, and Stockholm Univ.) report on behalf of a larger collaboration:
We observed the field of GRB 170208B (Siegel et al., GCN 20632) using the ALFOSC instrument equipped at the 2.56-m Nordic Optical Telescope (NOT). Observations started at 23:24:13.1 UT on 2017-02-08 (i.e., 50.5 min after the trigger). We obtained SDSS r- and z-band images with 3x300 s and 4x200 s exposures, respectively. The weather conditions were good with a measured seeing of 1.6 and 1.3 arcsec in the r- and z-band, respectively.
In the stacked r- and z-bands no optical afterglow of the burst is detected within the XRT error circle (Goad et al., 20635) at limiting magnitudes of m(r) < 22.5 and m(z) < 22.2 (all AB) mag, calibrated with nearby stars from the Pan-STARRS survey.
GCN Circular 20637
Subject
GRB 170208B: Swift-XRT refined Analysis
Date
2017-02-09T09:00:40Z (10 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), B. Mingo (U. Leicester), A.
Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), D.N.
Burrows (PSU) and M.H. Siegel report on behalf of the Swift-XRT team:
We have analysed 6.4 ks of XRT data for GRB 170208B (Siegel et al. GCN
Circ. 20632), from 50 s to 24.0 ks after the BAT trigger. The data
comprise 260 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. 20635).
The late-time light curve (from T0+5.4 ks) can be modelled with a
power-law decay with a decay index of alpha=0.81 (+0.19, -0.20).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.46 (+/-0.05). The
best-fitting absorption column is 4.34 (+/-0.21) x 10^21 cm^-2, in
excess of the Galactic value of 5.3 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.07 (+0.15, -0.14)
and a best-fitting absorption column of 3.7 (+0.7, -0.6) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.7 x 10^-11 (5.9 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 3.7 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 5.3 x 10^20 cm^-2
Excess significance: 8.5 sigma
Photon index: 2.07 (+0.15, -0.14)
If the light curve continues to decay with a power-law decay index of
0.81, the count rate at T+24 hours will be 0.020 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.6 x
10^-13 (1.2 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/00737463.
This circular is an official product of the Swift-XRT team.
GCN Circular 20636
Subject
GRB 170208B: Etelman observatory optical observations
Date
2017-02-09T05:22:46Z (10 years ago)
From
Bruce Gendre at ASDC <bruce.gendre@gmail.com>
B. Gendre (UVI), N. Orange (OrangeWave Innovative Science, LLC), D.
Morris (UVI), A. Cucchiara (UVI), D. Drost (UVI), T. Giblin (USAF
Academy), J. Hakkila (College of Charleston), A. Klotz (IRAP), J. Neff
(NSF), D. Smith (UVI), J. Staff (UVI), P. Thierry (Auragne Observatory),
R. Watlington (UVI), and L. Wentlent (UVI) report:
We observed the field of GRB 170208B (Siegel et al., GCN 20632) with the
0.5m Virgin Island Robotic Telescope (VIRT) on February the 9th,
starting at 3:10 UT (4.7 hours after the trigger). We
performed a series of exposures in the clear filter. The weather
conditions were good during the first hour of observation.
We co-added the exposures taken between 3h10UT and 4h17UT. At the
position of the X-ray afterglow reported by Goad et al. (GCN 20635), we
do not detect any optical emission, with an upper limit of R ~ 19
(estimated from nearby USNO-B1 stars).
Magnitudes have not been corrected for Galactic extinction. The VIRT is
still in its commissioning phase.
This message can be cited.
GCN Circular 20635
Subject
GRB 170208B: Enhanced Swift-XRT position
Date
2017-02-09T02:43:34Z (10 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 1870 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 170208B, 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 = 127.14385, -9.03002 which is equivalent
to:
RA (J2000): 08h 28m 34.52s
Dec (J2000): -09d 01' 48.1"
with an uncertainty of 2.2 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 20632
Subject
GRB 170208B: Swift detection of a burst
Date
2017-02-08T22:50:18Z (10 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
M. H. Siegel (PSU), S. D. Barthelmy (GSFC), A. Cholden-Brown (PSU),
J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC)
and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:
At 22:33:38 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170208B (trigger=737463). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 127.155, -9.027 which is
RA(J2000) = 08h 28m 37s
Dec(J2000) = -09d 01' 35"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows several overlapping peaks
with a total duration of about 40 sec. The peak count rate
was ~14,500 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 22:34:40.6 UT, 61.8 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 127.14389,
-9.02979 which is equivalent to:
RA(J2000) = 08h 28m 34.53s
Dec(J2000) = -09d 01' 47.2"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 40 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 (5.32 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 2.9
(+2.27/-2.01) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 7.16e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 250 seconds with the U filter starting
126 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 19.2 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 18.0 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.05.
Burst Advocate for this burst is M. H. Siegel (siegel AT swift.psu.edu).
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.)