GRB 120701A
GCN Circular 13404
Subject
GRB 120701A: Swift-BAT refined analysis
Date
2012-07-03T03:41:43Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), E. Sonbas (GSFC),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-61 to T+242 sec from recent telemetry downlinks,
we report analysis of BAT GRB 120701A (trigger #525477).
There was no initial set of GCN Notices nor a rapid-response circular
because of the power outage at GSFC when this burst occurred.
The BAT ground-calculated position is
RA, Dec = 80.338, -58.531 deg which is
RA(J2000) = 05h 21m 21.0s
Dec(J2000) = -58d 31' 52.3"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 60%.
The mask-weighted light curve shows several overlapping peaks starting
at ~T-2 sec and ending at ~T-20 sec. T90 (15-350 keV) is 13.8 +- 0.7 sec
(estimated error including systematics).
The time-averaged spectrum from T-0.0 to T+15.4 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.05 +- 0.10. The fluence in the 15-150 keV band is 1.4 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+10.36 sec in the 15-150 keV band
is 1.6 +- 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/525477/BA/
[GCN OPS NOTE(03jul12): Per author's request: "It should be noted that the
trigger_time for trigger 525477 is 07:50:41.57 UT on 01 July 2012."]
GCN Circular 13406
Subject
GRB 120701A: Swift-XRT afterglow detection and analysis
Date
2012-07-03T12:20:14Z (13 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
We have analysed 19 ks of XRT data for GRB 120701A (Barthelmy et al. et
al. GCN Circ. 13404), from 61 s to 58.8 ks after the BAT trigger. The
data comprise 69 s in Windowed Timing (WT) mode (the first 9 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode. We find an uncatatalogued, fading X-ray source inside the
BAT error circle. Using 7344 s of PC mode data and 5 UVOT images, we
find an enhanced XRT position (using the XRT-UVOT alignment and
matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
80.34740, -58.54973 which is equivalent to:
RA (J2000): 05h 21m 23.38s
Dec(J2000): -58d 32' 59.0"
with an uncertainty of 1.8 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.078 (+0.031, -0.030).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.06 (+0.22, -0.21). The
best-fitting absorption column is 1.6 (+0.6, -0.5) x 10^21 cm^-2, in
excess of the Galactic value of 2.5 x 10^20 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 3.7 x 10^-11 (5.2 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.6 (+0.6, -0.5) x 10^21 cm^-2
Galactic foreground: 2.5 x 10^20 cm^-2
Excess significance: 4.0 sigma
Photon index: 2.06 (+0.22, -0.21)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00525477.
This circular is an official product of the Swift-XRT team.
GCN Circular 13409
Subject
GRB 120701A: GROND detection of the afterglow
Date
2012-07-03T18:15:59Z (13 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
J. Elliott (MPE Garching), S. Schmidl, S. Klose (both TLS Tautenburg), and
J. Greiner (MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 120701A (Swift trigger 525477; Barthelmy et
al., GCN #13404) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla
Observatory (Chile).
Observations started at 09:11 UT on 2012-07-01, 1.34 hr after the GRB
trigger. They were performed at an average seeing of 1.6 arcsec and at an
average airmass of 2.5. A second epoch observation was performed 25.3 hr
after the the trigger.
Inside the 1.8 arcsec XRT error circle (Evans et al., GCN #13406) we
detect a fading object in all bands at coordinates RA(J2000) =
05:21:23.52, DEC(J2000) = -58:32:58.3 (+/- 0.3 arcsec).
During the first night we obtained exposures of 3120s in JHK and 2550s in
g'r'i'z'. At a mid time of 2.08 hrs after the trigger we measure the
following preliminary magnitudes (all in the AB system)
g' = 21.7 +- 0.1,
r' = 21.3 +- 0.1,
i' = 20.8 +- 0.1,
z' = 20.8 +- 0.1,
J = 20.3 +- 0.1,
H = 20.5 +- 0.2,
K = 20.1 +- 0.3.
The object faded in r' by about 1.0 mag between the first and the second
epoch. We therefore propose this source to be the afterglow of GRB
120701A.
All magnitudes are derived based on calibrating the images against GROND
zeropoints and 2MASS field stars. The Galactic reddening along the line of
sight is E(B-V) =0.02 mag (Schlegel et al. 1998).
GCN Circular 13410
Subject
GRB 120701A: Swift/UVOT Detection
Date
2012-07-03T21:34:12Z (13 years ago)
From
Alice Breeveld at MSSL-UCL <aab@mssl.ucl.ac.uk>
A. A. Breeveld (MSSL-UCL) and T. N. Ukwatta(MSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 120701A
89 s after the BAT trigger (Barthelmy et al. GCN Circ. 13404).
A fading source consistent with the XRT and GROND positions (Evans et
al., GCN Circ. 13406 and Elliott et al., GCN Circ. 13409) is detected in
the initial UVOT exposures in white and U.
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 and summed exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 89 239 147 18.27 � 0.06
white 880 1030 147 20.01 � 0.36
v 6603 6809 197 >18.8
b 5994 18439 494 >20.3
u_FC 303 553 245 19.16 � 0.23
u 5788 5988 197 >19.9
w1 11812 12668 842 >20.6
m2 6815 22538 969 >20.7
w2 6405 6605 197 >19.8
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).