- GCN Circular #16596
J. R. Cummings reports on behalf of the Swift science team:
At2014-07-16T10:27:57.3 Swift-BAT rate-triggered on the first episode of GRB 140716.
A sub-threshold peak in the image was found for trigger # 604792 at
RA, Dec 108.146,-60.130.
At 2014-07-16T10:29:26.4, BAT triggered on a second episode. A sub-threshold peak in
the image for trigger # 604793 was found at RA, Dec 108.175,-60.153.
A combined image shows a bright peak at RA, Dec 108.133 -60.150, which is
RA (J2000) 07h 12m 31.9s
Dec (J2000) -60d 08' 59"
with an estimated 90% confidence radius of 1.5 arcmin. This is consistent with
the Fermi GBM position for trigger 427199280 reported at
http://gcn.gsfc.nasa.gov/fermi_grbs.html
The burst had three main episodes, the first 2 seconds long, the second 4 seconds long
at T+90, and the third 6 seconds long at T+100.
A Swift TOO request has been submitted.
- GCN Circular #16598
J. R. Cummings, S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC),
M. Stamatikos (OSU/NASA/GSFC), J. Tueller (GSFC), T. N. Ukwatta (GWU)
on behalf of the Swift-BAT team:
We report further analysis of the ground-detected GRB 140716A (Cummings,
GCN # 16596) using 20 seconds of photon-event data that cover the first and third
peaks, and BAT survey data covering the entire burst.
The best BAT position remains RA, Dec 108.133 -60.150, which is
RA (J2000) 07h 12m 31.9s
Dec (J2000) -60d 08' 59"
with an estimated 90% confidence radius of 1.5 arcmin. The source was 3% coded
in BAT.
The burst had three peaks with similar maximum flux, the first 2 seconds long, the
second 4 seconds long at T+90, and the third about 8 seconds long at T+100. The
emission was undetectable between the first and second peaks, while there was a
slight overlap between peaks 2 and 3. The total T90 was about 104 +- 2 seconds.
At T+112 seconds, Swift executed a preplanned slew, putting the source completely
out of the BAT coded field of view, but we can say that there was no bright
emission above about 50 keV after this time.
The average spectrum from 15 to 150 keV is best fit by a simple power law function
with a photon index of 1.61 +- 0.33. The total fluence was
(5.9 +- 1.2) x 10^-6 ergs/cm^2. The peak 1-second flux was
5.2 +- 1.5 photons/sec/cm^2 from T+0.2 to T+1.2 seconds. All the quoted errors are
at the 90% confidence level.
A Swift TOO request has been approved and is being executed with the target number
20390.
- GCN Circular #16599
P. Jenke (UAH) and H.-F. Yu (MPE) report on behalf of the Fermi GBM Team:
"At 10:27:57.66 UT on July 16 2014, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 140716A (trigger 427199280/140716436),
which was also detected by
Swift (J. R. Cummings et al. 2014, GCN 16596).
The GBM on-ground location, using the Fermi GBM trigger
data, is consistent with the Swift/BAT location.
The angle of the burst direction to the Fermi LAT boresight
is 137 degrees.
The GBM light curve consists of one FRED-like short peak near T0 and a
longer double peak at ~T0+100s with a duration (T90) of about
106 s (50-300 keV).
The time-averaged spectrum from T0+89s to T0+108s
is well fit by a Band function with Epeak = 92 +/- 13 keV,
Alpha = -0.8 +/- 0.2 and Beta = -2.07 +/- 0.07.
The event fluence (10-1000 keV) in this time interval is
(1.03 +/- 0.04)E-05 ergs/cm^2. The 1.0-sec peak photon flux measured
starting from T0+100s in the 10-1000 keV band
is 11.3 +/- 0.6 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
- GCN Circular #16600
K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:
We have analysed 3.4 ks of XRT data for the Swift/BAT ground-detected
burst: GRB 140716A (Cummings, GCN Circ 16596; Cummings et al., GCN Circ.
16598), from 34.1 to 56.8 ks after the first of the ground-detected BAT
triggers. This burst was also detected by Fermi-GBM (Jenke & Yu, GCN Circ.
16599). The data are entirely in Photon Counting (PC) mode. We detect an
uncatalogued X-ray source with a mean count rate of 0.024 (+/- 0.003)
count s^-1, at a position of RA, Dec = 108.1731, -60.1757, which is
equivalent to:
RA (J2000): 07h 12m 41.53s
Dec (J2000): -60d 10' 32.7"
with an uncertainty of 4.7" (radius, 90% confidence). This is 1.95' from
the BAT position, a little outside the 1.5' 90% BAT error circle. We
cannot determine at the present time whether the source is fading.
This circular is an official product of the Swift-XRT team.
- GCN Circular #16601
F. Knust, J. Bolmer (both MPE Garching), S. Schmidl (TLS Tautenburg), and
J. Greiner (MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 140716A (Swift trigger 604792; Cummings et al.,
GCN 16596) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla
Observatory (Chile).
Observations started at 10:16 UT on July 17, 2014, 23.8 hrs after
the GRB trigger. They were performed at an average seeing of 1.8" and at
an average airmass of 2.3.
We find a faint source inside the XRT error circle given in Page et al.
(GCN 16600) at coordinates
RA (J2000.0) = 07:12:41.20
DEC (J2000.0) = -60:10:35.3
with an uncertainty of 0.5" in each coordinate.
Based on a total exposures of 264 seconds in g'r'i'z' and 240 seconds in
JHK, at a mid-time of 23.9 hrs after the burst, we measure the following
preliminary magnitudes (all in AB):
g' = 21.5 +/- 0.1,
r' = 21.0 +/- 0.1,
i' = 20.9 +/- 0.1,
z' = 20.6 +/- 0.1,
J > 20.1,
H > 19.6 and
K > 18.7.
At present we cannot decide if the source is fading.
Given magnitudes are calibrated against GROND zeropoints as well as
2MASS field stars and are not corrected for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V) = 0.13 mag
in the direction of the burst (Schlegel et al. 1998).
- GCN Circular #16604
L. M. Z. Hagen (PSU) and K. L. Page (U. Leicester) report on behalf
of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 140716A
34072 s after the BAT trigger (Cummings, GCN Circ. 16596). No optical
afterglow consistent with the XRT candidate (Page, GCN Circ. 16600) or
GROND candidate (Knust et al., GCN Circ. 16601) 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 initial exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
u (fc) 34072 34367 291 >19.17
u 40452 56904 1860 >20.20
v 40559 57641 1125 >19.52
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.131 in the direction of the burst
(Schlegel et al. 1998).
- GCN Circular #16605
S. Golenetskii, R. Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:
A long duration GRB 140716A (Swift-BAT: Cummings, GCN 16596; GCN 16598;
Fermi-GBM: Jenke and Yu, GCN 16599) triggered Konus-Wind at
T0=37676.966 s UT (10:27:56.966).
The burst light curve shows three emission episodes, the first at ~T0,
the second double pulse episode at ~T0+90 s, and the third weak at
~T0+167 s. The total duration of the burst is ~170 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/GRB140716_T37676/
As observed by Konus-Wind, the burst
had a fluence of 9.4(-1.6,+2.2)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+0.354 s,
of 2.8(-0.8,+1.1)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+114.944 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 = -1.09 (-0.38,+0.51)
and Ep = 157 (-41,+84) keV (chi2 = 60/58 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.2
(chi2 = 60/57 dof)
The spectrum near the maximum count rate
(measured from T0 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 = -1.09 (-0.41,+0.68)
and Ep = 196 (-72,+174) keV (chi2 = 58/58 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
- GCN Circular #16614
J. Bolmer, F. Knust (both MPE Garching), S. Schmidl (TLS Tautenburg), and
J. Greiner (MPE Garching) report on behalf of the GROND team:
We re-observed the field of GRB 140716A (Swift trigger 604792; Cummings et
al., GCN 16596) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla
Observatory (Chile).
Observations started on July 20, 2014, at 09:47 UT, 3.97 days after the
GRB trigger. They were performed at an average seeing of 1.8" and at an
average airmass of 2.3.
Based on a total exposure of 1782 seconds in g'r'i'z', we measure for the
optical afterglow candidate reported by Knust et al. (GCN
#16601) the following preliminary magnitudes (all AB):
g' = 22.9 +/- 0.2 mag,
r' = 22.0 +/- 0.1 mag,
i' = 21.7 +/- 0.2 mag and
z' = 21.2 +/- 0.2 mag.
Compared to the first-epoch observations the source has faded in all
bands, confirming that this is the optical afterglow of GRB 140716A.
Given magnitudes are calibrated against GROND zeropoints and are not
corrected for the expected Galactic foreground extinction corresponding to
a reddening of E_(B-V) = 0.13 mag in the direction of the burst (Schlegel
et al. 1998).
- GCN Circular #16616
K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:
Following the detection of an X-ray afterglow candidate for GRB 140716A
(Page, GCN Circ. 16600), Swift obtained a second epoch of observations
starting 357 ks after the BAT detection.
The X-ray source has now faded to a level of (1.4 +0.8/-0.6) x 10^-3 count
s^-1, and the light curve can be modelled with a power-law decay with a
decay index of alpha=1.16 (+0.39, -0.27). We therefore confirm that this
is the X-ray afterglow of GRB 140716A.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020390.
This circular is an official product of the Swift-XRT team.
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