GRB 100807A
GCN Circular 11067
Subject
GRB 100807A: Swift detection of a burst
Date
2010-08-07T09:24:29Z (15 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
D. Grupe (PSU), W. H. Baumgartner (GSFC/UMBC), J. M. Gelbord (PSU),
C. Gronwall (PSU), C. Guidorzi (U Ferrara),
S. T. Holland (CRESST/USRA/GSFC), H. A. Krimm (CRESST/GSFC/USRA) and
D. M. Palmer (LANL) report on behalf of the Swift Team:
At 09:13:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 100807A (trigger=431128). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 55.324, +67.679 which is
RA(J2000) = 03h 41m 18s
Dec(J2000) = +67d 40' 43"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single-peaked
structure with a duration of about 10 sec. The peak count rate
was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 09:14:34.4 UT, 80.8 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 55.30004, 67.67171
which is equivalent to:
RA(J2000) = 03h 41m 12.01s
Dec(J2000) = +67d 40' 18.2"
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This
location is 41 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 (3.31e+21
cm^-2, Kalberla et al. 2005), with an excess column of 3.8
(+4.16/-3.25) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 9.12e-10 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 90 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
0.81.
Burst Advocate for this burst is D. Grupe (grupe AT astro.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.)
GCN Circular 11068
Subject
GRB 100807A: ROTSE-III Optical Limits
Date
2010-08-07T09:40:30Z (15 years ago)
From
Heather Flewelling at IfA/Hawaii <flewelling.heather@gmail.com>
GRB 100807A: ROTSE-III Optical Limits
W. Rujopakarn (Steward), H. Flewelling (IfA/Hawaii), B. E. Schaefer
(Louisiana State), W. Zheng (U Mich), and S. B. Pandey (U Mich), report on
behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 100807A
(Swift trigger 431128; Grupe et al., GCN 11067), producing images beginning
5.2 s after the GCN notice time. An automated response took the first image
at 09:13:35.2 UT, 21.6 s after the burst, and during the gamma-ray emission,
under fair conditions. We took 10 5-sec and 10 20-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 15.9-17.2; we set the following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
09:13:35.2 09:13:40.2 5 16.2 21.6 N
09:13:35.2 09:14:42.2 67 16.7 21.6 Y
09:14:55.2 09:19:37.9 282 18.1 101.6 Y
GCN Circular 11069
Subject
GRB 100807A: Swift-BAT refined analysis
Date
2010-08-07T13:13:13Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
N. Gehrels (GSFC), D. Grupe (PSU), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
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+233 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 100807A (trigger #431128)
(Grupe, et al., GCN Circ. 11067). The BAT ground-calculated position is
RA, Dec = 55.283, 67.665 deg, which is
RA(J2000) = 03h 41m 07.9s
Dec(J2000) = +67d 39' 54.2"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 37%.
The mask-weighted light curve a single peak starting around T-20 sec,
peaking at ~T+0, and ending around T+20 sec. T90 (15-350 keV) is
7.9 +- 1.6 sec (estimated error including systematics).
The time-averaged spectrum from T-6.1 to T+3.1 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.32 +- 0.23. The fluence in the 15-150 keV band is 3.4 +- 0.5 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.35 sec in the 15-150 keV band
is 1.8 +- 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/431128/BA/
GCN Circular 11070
Subject
GRB 100807A: Enhanced Swift-XRT position
Date
2010-08-07T13:25:45Z (15 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 960 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 100807A, 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 = 55.30042, +67.67158 which is equivalent
to:
RA (J2000): 03h 41m 12.10s
Dec (J2000): +67d 40' 17.7"
with an uncertainty of 1.9 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 11072
Subject
GRB 100807A: Swift/UVOT Upper Limits
Date
2010-08-07T15:57:36Z (15 years ago)
From
Craig Swenson at PSU/Swift <cswenson@astro.psu.edu>
C. A. Swenson and D. Grupe (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 100807A
91 s after the BAT trigger (Grupe et al., GCN Circ. 11067). No optical
afterglow consistent with the enhanced XRT position (Osborne et al.,
GCN Circ. 11070) is detected in the initial UVOT exposures. Preliminary
3-sigma upper limits using the UVOT photometric system (Poole et al. 2008,
MNRAS, 383, 627) for the first finding chart (FC) exposure and subsequent
exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 91 240 147 >20.9
u_FC 304 553 246 >20.4
white 91 5947 530 >21.8
v 634 6358 255 >19.6
b 559 7063 319 >21.1
u 304 6973 659 >21.1
w1 683 6768 413 >20.8
m2 6363 6563 197 >20.7
w2 609 6153 255 >20.8
The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.81 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 11073
Subject
GRB 100807A: P60 Optical Afterglow Discovery
Date
2010-08-07T20:55:56Z (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 GRB 100807A (Grupe et al., GCN 11067) with the
automated Palomar 60 inch telescope. Observations were obtained in the
Sloan r', i', and z' filters beginning at 9:16 UT on 7 August (~ 3 min
after the Swift trigger).
At the edge of the enhanced XRT position (Osborne et al., GCN 11070), we
detect a fading point source with coordinates (J2000.0):
RA: 03:41:12.43 Dec: +67:40:17.4
Using several nearby objects in the USNO-B1 catalog for reference, we
report the following photometry for this object:
UT (mid-point) t_burst (min) Filter Magnitude
---------------------------------------------------------------
09:16:55 3.7 R 20.47 +/- 0.17
09:18:21 5.1 I 19.80 +/- 0.14
09:47:07 33.9 R 21.57 +/- 0.20
09:49:58 36.8 I 20.96 +/- 0.20
The above magnitudes have not been corrected for the large Galactic
extinction along the line of sight.
The fading behavior confirms this source is the optical afterglow of GRB
100807A.
GCN Circular 11074
Subject
GRB 100807A: Swift XRT refined analysis
Date
2010-08-08T00:29:22Z (15 years ago)
From
Dirk Grupe at PSU/Swift-XRT <grupe@astro.psu.edu>
D. Grupe (PSU) reports on behalf of the Swift-XRT team:
We have analyzed 9.7 ks of XRT data for GRB 100807A (Grupe et al.
GCN Circ. 11067), from 125 s to 24882 s after the BAT trigger. The
data comprise 36 s in Windowed Timing (WT) mode with the remainder
in Photon Counting (PC) mode. The light curve can be modeled
with a broken power-law model. After an initial flare the light
curve decays with a slope of 6.4+0.6-1.9. The light curve breaks at
173+/-10s followed by a flatter decay slope of 0.82+/-0.08.
A spectrum formed from the WT mode data can be fitted with an
absorbed power-law with a photon spectral index of 2.12 (+/-0.22).
The best-fitting absorption column is consistent with the Galactic
value of 3.3 x 10^21 cm^-2 (Kalberla et al. 2005). A fit to the pc
mode data is also consistent with the Galactic absorption column
density, but the spectrum is slightly flatter with a photon index
of 1.79+/-0.37. The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from the WT spectrum is 4.38 x 10^-11
(7.54 x 10^-11) erg cm^-2 count^-1.
If the light curve continues to decay with a power-law decay index
of 0.8, the count rate at T+48 hours will be in the order of
1.3 x 10^-3 count s^-1, corresponding to an observed (unabsorbed)
0.3-10 keV flux of 5.7 x 10^-14 (9.8 x 10^-14) erg cm^-2 s^-1.
Note that we are currently in the plateau phase which is followed by
a steeper decay slope.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00431128.
This circular is an official product of the Swift-XRT team.
GCN Circular 11075
Subject
GRB100807A: MITSuME optical upper limits
Date
2010-08-08T08:36:56Z (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 100807A (Grupe et al., GCN 11067)
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 2010-08-07 13:29:46 UT (~4.3 h after
the burst). We did not find any new point source within the
enhanced XRT error circle (Osborne et al., GCNC 11070) in all
the three bands. We could not detect the previously reported
afterglow (Cenko, GCN 11073).
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
------------------------------------------------------
0.21418 14:21:39 4620.0 >20.1 >19.7 >19.1
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
GCN Circular 11078
Subject
GRB100807A: optical observation in CrAO
Date
2010-08-09T15:05:23Z (15 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB
follow-up collaboration:
We observed the field of the Swift GRB 100807A (Grupe et al., GCN 11067)
with Shajn telescope of CrAO in filter R between (UT) Aug. 07 22:58:14 --
Aug. 08 01:17:44 under descending seeing with mean value of ~ 2.1". We do
not detect the afterglow (Cenko, GCN 11073). The extended object ~ 8" was
detected in coordinates (J2000) center RA: 03 41 12.92 Dec: +67 40 19.4.
The position of optical afterglow (Cenko, GCN 11073) is in the edge of the
extended object.
The photometry is based on USNO-B1.0 star 1576-0084708 (J2000) RA= 03 41
11.50 Dec= +67 39 58.1 (assuming R=16.37):
T0+ Filter, Exposure, Ext. Object mag. Upper Limit
(mid, d) (s)
0.6214 R 97x60 23.0 +/- 0.2 23.8
With upper limit of R=23.8 we confirm the fading nature of afterglow of GRB
100807A (Grupe et al., GCN 11067). The extended object might be a host
galaxy of GRB 100807A.
The combined images can be found
http://grb.rssi.ru/GRB100807A/GRB100807a_100807_R_ZTSh.gif
GCN Circular 11080
Subject
GRB 100807A: P200 Infrared Observations
Date
2010-08-11T15:01:54Z (15 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
R. Chary and J. Davies (Caltech) report:
We have imaged the field of GRB 100807A (Grupe et al., GCN 11067) with
the WIRC instrument on the Palomar 200 inch telescope in the J and H bands
beginning at 9:47 UT on 7 August (~ 35 mins after the Swift trigger). The
fading transient reported in Cenko et al. (GCN 11073) is clearly
detected. Using 2MASS stars for relative photometry, we measure the
following photometry for the object:
UT (mid-point) t_burst (min) Filter Magnitude
---------------------------------------------------------------
09:55 41 J 19.76 +/- 0.1
10:10 56 H 19.05 +/- 0.1
12:16 183 J 21.10 +/- 0.2
The red colors of the source compared to the optical photometry can be
attributed to the A_V=2.5 mag of Galactic extinction in this region.
A nearby object 3" to the SE is also quite red with H=18.75+/-0.1 and
J-H=1.5 mag and could potentially be the host galaxy.
All magnitudes are in the Vega system.
GCN Circular 11147
Subject
GRB100807A: R band observations
Date
2010-08-25T15:22:51Z (15 years ago)
From
Janos Kelemen at Konkoly Obs/Hungary <kelemen@konkoly.hu>
J. Kelemen on behalf of the GRB OT observing program at the Konkoly Observatory.
On 08 august 2010 21:29:00 UT (130547 s after the burst) we observed the field
of GRB 100807A detected by Swift (trigger=431128; Grupe et al., GCN 11067)
with a 60/90 cm Schmidt telescope located at the Mountain Station of the
Konkoly Observatory using R filter. The total exposure of the coadded CCD
images were 1800 s. We examined the position reported Cenko et al., GCN 11073.
No fading object brighter than 21.6 +/- 0.2 was detected.
Time Mag Error. Flag.
[s] [R] [1-sigma]
-------------------------------------
130547 21.6 0.2 Upper Limit
-------------------------------------
The above magnitudes have not been corrected for the Galactic extinction.