GRB 100802A
GCN Circular 11031
Subject
GRB 100802A: Swift detection of a burst
Date
2010-08-02T05:56:25Z (15 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
E. Troja (NASA/GSFC/ORAU), J. M. Gelbord (PSU),
C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),
O. M. Littlejohns (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), A. Rowlinson (U Leicester),
T. Sakamoto (NASA/UMBC), M. H. Siegel (PSU),
M. Stamatikos (OSU/NASA/GSFC), R. L. C. Starling (U Leicester) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:
At 05:45:36 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 100802A (trigger=430603). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 2.457, +47.752 which is
RA(J2000) = 00h 09m 50s
Dec(J2000) = +47d 45' 06"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single FRED peak
structure with a duration of about 30 sec. The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 05:46:55.8 UT, 79.7 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 2.4673, +47.7545 which is equivalent to:
RA(J2000) = 00h 09m 52.15s
Dec(J2000) = +47d 45' 16.2"
with an uncertainty of 5.1 arcseconds (radius, 90% containment). This
location is 26 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 2.09e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 88 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 19.6 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 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.12.
Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov).
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 11032
Subject
GRB 100802A: Possible Swift/UVOT Detection of Optical Afterglow
Date
2010-08-02T06:21:36Z (15 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@astro.psu.edu>
M. H. Siegel (PSU) and E. Troya (NASA/GSFC/ORAU) report on behalf of the
Swift/UVOT team:
UVOT took a finding chart exposure of 250 seconds with the U filter
starting
301 seconds after the BAT trigger. There is a candidate afterglow in the
rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 00:09:52.47 = 2.46862
DEC(J2000) = +47:45:19.1 = 47.75531
with a 90%-confidence error radius of about 0.78 arc sec. This
position is 4.3
arc sec. from the center of the XRT error circle. The estimated
magnitude is
19.56 with a 1-sigma error of about 0.21. No correction has been made
for the
expected extinction corresponding to E(B-V) of 0.12.
GCN Circular 11033
Subject
GRB 100802A: ROTSE-III Optical Limits
Date
2010-08-02T06:29:52Z (15 years ago)
From
Shashi Bhushan Pandey at ROTSE <shaship@umich.edu>
S. B. Pandey (U Mich), H. Flewelling (IfA/Hawaii), W. Zheng (U Mich),
report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB
100802A (Swift trigger 430603; Troja, E., GCN 11031), producing images
beginning 9.1 s after the GCN notice time. An automated response took the
first image at 05:46:10.1 UT, 27.9 s after the burst, and during the
gamma-ray emission, under fair conditions. We took 10 5-sec, 10 20-sec and
10 60-sec exposures. These unfiltered images are calibrated relative to
USNO A2.0 (R). Imaging is on going.
Comparison to the DSS (second epoch) reveals no new sources within the
3-sigma Swift/BAT error circle or the XRT error circle, for both single
images and coadding into sets of 10. Individual images have limiting
magnitudes ranging from 15.3-17.6; we set the following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
05:46:10.1 05:46:15.1 5 15.3 27.9 N
05:47:30.9 05:52:12.0 281 18.2 108.7 Y
GCN Circular 11034
Subject
GRB 100802A: Liverpool Telescope observations
Date
2010-08-02T07:11:05Z (15 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
C. Guidorzi (U. Ferrara), A. Gomboc (U. Ljubljana),
report on behalf of a large collaboration:
On 2010 August 02 at 05:51:53 UT the 2-m Liverpool
Telescope automatically began observing the Swift GRB 100802A
(Troja et al., GCN Circ. 11031) using the r' filter,
corresponding to 6.3 minutes after the burst trigger time.
We do not detect any uncatalogued source within the XRT
error circle. We do not detect the possible afterglow
candidate reported by UVOT either (Siegel and Troja,
GCN Circ. 11032) with the following upper limit:
Mid time from Total Exp Filter Magnitude
trigger (s) (s)
-------------------------------------------------
530 6x10 r' > 18.8
-------------------------------------------------
Magnitude has been calibrated from nearby USNOB1.0
R2 stars.
GCN Circular 11035
Subject
GRB 100802A: Swift-BAT refined analysis
Date
2010-08-02T12:53:03Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD),
D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU),
E. Troja (NASA/GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 100802A (trigger #430603)
(Troja, et al., GCN Circ. 11031). The BAT ground-calculated position is
RA, Dec = 2.482, 47.752 deg, which is
RA(J2000) = 00h 09m 55.6s
Dec(J2000) = +47d 45' 05.5"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 84%.
The mask-weighted light curve shows a FRED peak starting at ~T-7 sec and
peaking at ~T+1sec. There is a second peak on the tail of the first
at ~T+90 sec. There is also a long peak starting around T+250, peaking
at ~T+450 sec, and ending at ~T+700 sec. T90 (15-350 keV) is 487 +- 30 sec
(estimated error including systematics).
The time-averaged spectrum from T-3.3 to T+531.7 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.85 +- 0.10. The fluence in the 15-150 keV band is 3.6 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.08 sec in the 15-150 keV band
is 0.9 +- 0.1 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/430603/BA/
GCN Circular 11036
Subject
GRB 100802A: Enhanced Swift-XRT position
Date
2010-08-02T13:49:26Z (15 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 794 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 100802A, 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 = 2.46849, +47.75479 which is equivalent
to:
RA (J2000): 00h 09m 52.44s
Dec (J2000): +47d 45' 17.3"
with an uncertainty of 2.0 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 11038
Subject
GRB 100802A: Swift/UVOT Possible Optical Afterglow
Date
2010-08-02T15:59:42Z (15 years ago)
From
Alice Breeveld at MSSL-UCL <aab@mssl.ucl.ac.uk>
A. Breeveld (MSSL/UCL) and E. Troja (NASA/GSFC/ORAU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 100802A
89 s after the BAT trigger (Troja et al., GCN Circ. 11031). Using the
data from the most recent telemetry, there is a tentative detection of
an optical afterglow at the position given by Siegel et al., GCN Circ.
11032, in the early white and u exposures.
Preliminary detections and later 3-sigma upper limits using the UVOT
photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first
finding chart (FC) exposures and subsequent summed exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 89 238 147 20.7 � 0.24
u_FC 301 551 246 19.57 � 0.22
white 581 5566 327 21.85 � 0.48
(2.4 sigma sig)
v 632 5977 432 >20.6
b 557 6754 388 >21.2
u 706 6593 412 >20.92
w1 682 6388 432 >20.9
m2 657 6183 432 >20.6
w2 608 5772 432 >21.0
The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.12 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 11039
Subject
GRB 100802A: XRT refined analysis
Date
2010-08-02T17:37:31Z (15 years ago)
From
Antonia Rowlinson at U.of Leicester <bar7@star.le.ac.uk>
A. Rowlinson (U. Leicester) and E. Troja (NASA/GSFC/ORAU) report on
behalf of the Swift-XRT team:
We have analysed 10 ks of XRT data for GRB 100802A (Troja et al. GCN
Circ. 11031), from 69 s to 24.0 ks after the BAT trigger. The data
comprise 804 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 Evans et al.
(GCN. Circ 11036).
The light curve can be modelled with an initial power-law decay with an
index of alpha=1.64 (+0.03, -0.03) and a flare peaking at 515 s which is
consistent with a BAT peak (Baumgartner et al. GCN Circ. 11035). At
T+11500 s, the light curve breaks to a decay with alpha=0.06 (+0.26,
-0.21).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.88 (+/-0.03). The
best-fitting absorption column is 1.93 (+/-0.09) x 10^21 cm^-2, in
excess of the Galactic value of 9.7 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 4.0 x 10^-11 (5.4 x 10^-11) erg
cm^-2 count^-1. The PC mode spectrum can be fitted with an absorbed
power-law with a photon spectral index of 2.21 (+0.23, -0.33). The
best-fitting absorption column is 1.39 (+0.82, -0.42) x 10^21 cm^-2, in
excess of the Galactic value. The counts to observed (unabsorbed) 0.3-10
keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11
(5.2 x 10^-11) erg cm^-2 count^-1.
If the light curve continues to decay with a power-law decay index of
0.06, the count rate at T+24 hours will be 1.6 x 10^-2 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.6 x
10^-13 (8.3 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/00430603.
This circular is an official product of the Swift-XRT team.
GCN Circular 11040
Subject
GRB 100802A: P60 Observations
Date
2010-08-02T18:23:13Z (15 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. B. Cenko (UC Berkeley) reports on behalf of a larger collaboration:
We have imaged the field of GRB100802A (Troja et al., GCN 11031) with the
automated Palomar 60 inch telescope. Observations were taken in the Sloan
r', i', and z' filters beginning at 05:51 UT on 2 August (~ 6 minutes
after the BAT trigger).
In a co-added r'-band image (mid-point 06:02 UT, or ~ 17 minutes after
the burst trigger), we detect a marginal source at the location of the
candidate UVOT afterglow (Siegel and Troja, GCN 11032; Breeveld and Troja,
GCN 11038). Calibrating with respect to several USNO-B1 catalog objects,
we measure R = 21.3 +/- 0.3 mag. No object is detected at this location
in a co-added i'-band image (mid-point 06:04 UT, or ~ 18.5 minutes after
the burst trigger) to a limiting magnitude of I > 20.6.
The values quoted above are not corrected for Galactic extinction.
GCN Circular 11041
Subject
GRB100802A: MITSuME optical upper limits
Date
2010-08-03T05:46:22Z (15 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 collaboration:
We observed the field of GRB 100802A (Troja et al., GCNC 11031)
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 2010-08-02 11:43:26 UT (~6 h after
the burst). We did not find any new point source within the XRT
error circle and the enhanced XRT error circle (Evans et al.,
GCNC 11036) in all the three bands. Also, we could not detect the
previously reported afterglow (Siegel and Troya, GCN 11032).
Three sigma upper limits of the OT are listed below. We used
GSC 2.3 catalog for flux calibration.
T0+[day] MID-UT T-EXP[sec] g' Rc Ic
------------------------------------------------------
0.29658 12:52:41 9480.0 >19.9 >19.8 >19.3
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
GCN Circular 11042
Subject
GRB 100802A: NOT optical observation
Date
2010-08-03T10:09:43Z (15 years ago)
From
Dong Xu at DARK,NBI <dong@astro.ku.dk>
D. Xu (Weizmann Inst.), D. Malesani (DARK/NBI), P. Jakobsson (Univ. of
Iceland), P. A. Wilson, R. Nilsson (NOT), report on behalf of a larger
collaboration:
We have imaged the field of GRB100802A (Troja et al., GCN #11031) with
the Nordic Optical Telescope equipped with ALFOSC. Observations
started at 02:49 UT, 3rd August (~21.06 hrs after the BAT trigger) and
four 900 s frames in the R band were obtained.
We detect an optical source localised at
RA(J2000) = 00:09:52.38
Dec(J2000) = +47:45:18.8
with an error radius of 0.4". This position is 0.96" +/- 0.85" S-W of
the UVOT position (Siegel & Troja, GCN #11032). We therefore identify
this source as the afterglow of GRB100802A. A finding chart is visible
at the following URL:
http://www.astro.ku.dk/~malesani/GRB/100802A/GRB100802A_NOT.jpg.
Based on the USNO-B1 catalog (R1 magnitudes), we find R=22.9+/-0.3 at
a mean epoch of 21.6 hr after the BAT trigger. Compared with the P60
detection (Cenko, GCN #11040), our measurement confirms a clear
fading, and implies a rather shallow decay of the afterglow light
curve with alpha = 0.34 +/- 0.08 assuming an unbroken power-law decay
F(t) propto t^-alpha. This might suggest some contribution from an
underlying host galaxy.
GCN Circular 11046
Subject
GRB 100802A: Fermi GBM observation
Date
2010-08-04T08:54:53Z (15 years ago)
From
Elisabetta Bissaldi at MPE <ebs@mpe.mpg.de>
Elisabetta Bissaldi (MPE) reports on behalf of the Fermi GBM Team:
"At 05:45:35.68 UT on 2 August 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100802A (trigger 302420737 / 100802240),
which was also detected by the Swift-BAT (Troja et al. 2010, GCN 11031).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 76 degrees.
The GBM light curve consists of an initial peak
followed by a softer tail with a duration (T90) of about 100 s (50-300 keV).
The time-averaged spectrum from T0 to T0+40 s is
adequately fit by a power law function with an exponential
high energy cutoff. The power law index is -1.17 (+0.21/-0.25) and
the cutoff energy, parameterized as Epeak, is 149 (+41/-96) keV
(Castor C-STAT 669 for 479 d.o.f.).
The event fluence (10-1000 keV) in this time interval is
(2.24 +/- 0.28)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+62 s in the 10-1000 keV band
is 3.2 +/- 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 11061
Subject
GRB 100802A: WIYN observations
Date
2010-08-05T16:13:08Z (15 years ago)
From
Adria C. Updike at Clemson U <aupdike@clemson.edu>
Adria C. Updike, Ginger Bryngelson, Dieter H. Hartmann (Clemson
University) and Peter A. Milne (Steward Observatory) report:
We observed the field of GRB 100802A (Troja et al., GCN 11031) with the
3.5m WIYN telescope at KPNO equipped with WHIRC on August 3, 2010
beginning 26 hours and 13 minutes after the trigger and continuing for 26
minutes in the K band under good conditions. We do not detect the
afterglow (Siegel & Troja, GCN 11032; Cenko, GCN 11040) or any source
within the enhanced XRT position (Evans et al., GCN 11036) to limiting
magnitude of K > 18.8 upon comparison to the 2MASS catalog and field
stars. No further observations are planned.
GCN Circular 11082
Subject
GRB 100802A: further NOT observation
Date
2010-08-12T10:37:13Z (15 years ago)
From
Dong Xu at DARK,NBI <dong@astro.ku.dk>
Nis B. Andreasen, Maria Cavallius, Louise Dyregaard Nielsen,
Christopher Groenbech, Simone J. Jakobsen, Jonatan Selsing,
Lasse Oedegaard (Niels Bohr Inst.), Johan P.U. Fynbo,
Daniele Malesani (DARK/NBI), Dong Xu (Weizmann Inst.),
and Pall Jakobsson (Univ. Iceland), report on behalf
of a larger collaboration:
We observed the field of GRB 100802A (Troja et al., GCN 11031, Siegel
& Troja, GCN 11032) with the NOT equipped with ALFOSC. Observations
were carried out with mean time Aug 11.10 UT (212.7 hr after the GRB).
The object seen in our early-time NOT image (Xu et al., GCN 11042) is
barely detected in the new stacked image, and has decayed by 1.3 +/-
0.4 mag between the two epochs.
We note that the NOT object is slightly offset (by ~1.1" W) with
respect to the UVOT position (GCN 11032; also confirmed by P60
imaging; B. Cenko, priv. comm.). Coupled to the slow decay, this may
indicate the presence of an underlying constant source of light, which
could be the host galaxy or a foreground, unrelated object.
An image showing the two epochs is available at the following URL:
http://www.astro.ku.dk/~malesani/GRB/100802A/GRB100802A_epoch2.jpg
Given the relative brightness of the underlying source (R ~ 23.7), we
encourage further photometric and spectroscopic observations.
[GCN OPS NOTE (12aug10): Per author's request, MC was added to the author list.]