GRB 110928A
GCN Circular 12394
Subject
GRB 110928A: Swift detection of a burst
Date
2011-09-28T02:03:46Z (14 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
E. A. Hoversten (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
M. M. Chester (PSU), N. Gehrels (NASA/GSFC),
H. A. Krimm (CRESST/GSFC/USRA), C. B. Markwardt (NASA/GSFC),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and
E. Sonbas (GSFC/USRA/Adiyaman Univ.) report on behalf of the Swift
Team:
At 01:51:31 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110928A (trigger=504215). Swift will slew after 52 minutes
after the Earth limb constraint is avoided.
The BAT on-board calculated location is
RA, Dec 257.755, +36.570, which is
RA(J2000) = 17h 11m 01s
Dec(J2000) = +36d 34' 13"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a single FRED-like
pulse with a duration of about 10 sec. The peak count rate
was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger.
Due to an observing constraint, Swift will not slew until
T0+52 minutes. There will be no XRT or UVOT data until
this time.
Burst Advocate for this burst is E. A. Hoversten (hoversten 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 12395
Subject
GRB 110928A: ROTSE-III Optical Limits
Date
2011-09-28T02:32:52Z (14 years ago)
From
Brad Schaefer at LSU <schaefer@grb.phys.lsu.edu>
B. E. Schaefer (Louisiana State), W. Zheng (U Mich), H. Flewelling (IfA/Hawaii), report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 110928A (Swift trigger 504215; Hoversten et al., GCN 12394), producing images beginning 7.1 s after the GCN notice time. An automated response took the first image at 01:52:39.1 UT, 67.3 s after the burst, under excellent 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, for both single images and coadding into sets of 10; the field is not crowded. Individual images have limiting magnitudes ranging from 16.1-17.4; we set the following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
01:52:39.1 01:52:44.1 5 16.1 67.3 N
01:52:39.1 01:54:26.8 107 17.5 67.3 Y
GCN Circular 12396
Subject
GRB 110928A: PAIRITEL NIR Observations
Date
2011-09-28T02:37:03Z (14 years ago)
From
Adam Morgan at U.C. Berkeley <qmorgan@gmail.com>
C. R. Klein and A. N. Morgan (U. C. Berkeley) report:
We observed the field of GRBs 110928A (Hoverston et al., GCN 12394) with the
1.3m PAIRITEL located at Mt. Hopkins, AZ. Observations began at 2011-Sep-28
02h03m59s, 12.5 minutes after the GRB. In mosaics (effective exposure time
of 468s) taken simultaneously in the J, H, and Ks filters, we do not clearly
detect any new sources in the BAT error circle down to the limit of the
2mass catalog.
GCN Circular 12397
Subject
GRB 110928A: Swift/UVOT finding chart observation
Date
2011-09-28T03:09:54Z (14 years ago)
From
Erik Hoversten at Swift/Penn State <hoversten@astro.psu.edu>
E. A. Hoversten (PSU) reports on behalf of the Swift UVOT team:
UVOT took a finding chart exposure of 150 seconds with the white
filter of the field of
GRB 110928A starting 3341 seconds after the BAT trigger (Hoversten et
al., GCN 12394).
No credible afterglow candidate has been found in the initial data
products. The 2.7'x2.7'
sub-image covers none of the XRT error circle. 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 0.03.
GCN Circular 12398
Subject
GRB 110928A: Swift-XRT observations
Date
2011-09-28T03:51:12Z (14 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows
(PSU), J.A. Kennea (PSU), S. Campana (INAF-OAB) and G. Cusumano
(INAF-IASF PA) report on behalf of the Swift-XRT team:
The XRT began observing the field of GRB 110928A at 02:47:09.1 UT,
3337.3 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 257.73360,
36.53636 which is equivalent to:
RA(J2000) = 17h 10m 56.06s
Dec(J2000) = +36d 32' 10.9"
with an uncertainty of 4.3 arcseconds (radius, 90% containment). This
location is 136 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. We cannot determine whether the source is
fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (3.14 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.1
(+2.44/-1.70) x 10^22 cm^-2 (90% confidence).
GCN Circular 12399
Subject
GRB 110928A: Swift-BAT refined analysis
Date
2011-09-28T04:17:24Z (14 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), E. A. Hoversten (PSU), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 110928A (trigger #504215)
(Hoversten, et al., GCN Circ. 12394). The BAT ground-calculated position is
RA, Dec = 257.745, 36.547 deg, which is
RA(J2000) = 17h 10m 58.7s
Dec(J2000) = +36d 32' 49.3"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 37%.
The mask-weighted light curve shows a single FRED-like peak starting at ~T_zero
and ending at ~T+30 sec. T90 (15-350 keV) is 26.7 +- 4.8 sec (estimated error
including systematics).
The time-averaged spectrum from T-0.53 to T+27.88 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.09 +- 0.30. The fluence in the 15-150 keV band is 6.9 +- 1.1 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+6.84 sec in the 15-150 keV band
is 0.9 +- 0.3 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/504215/BA/
GCN Circular 12400
Subject
GRB 110928A: Further PAIRITEL NIR Observations
Date
2011-09-28T04:28:47Z (14 years ago)
From
Adam Morgan at U.C. Berkeley <qmorgan@gmail.com>
A. N. Morgan, C. R. Klein and J. S. Bloom (UC Berkeley) report:
We observed the field of GRB 110928A (Hoversten et al., GCN 12394)
with the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations
began at 2011-Sep-28 02h03m59s UT, ~12.5 min after the Swift trigger.
In mosaics (effective exposure time of 678.6 s) taken simultaneously
in the J, H, and Ks filters, we do not detect any source within the
XRT error circle (Evans et al. GCN 12398).
post burst
t_mid (hr) exp.(hr) filt U. Limit (3 sig)
0.36 0.19 J > 18.2
0.36 0.19 H > 17.5
0.36 0.19 Ks > 15.9
Deeper NIR observations are underway. All magnitudes are given in the
Vega system, calibrated to 2MASS. No correction for Galactic
extinction has been made to the above reported values.
GCN Circular 12401
Subject
GRB 110928A: P60 Observations
Date
2011-09-28T05:59:37Z (14 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 110928A (Hoversten et al., GCN 12394) with
the automated Palomar 60 inch telescope. Observations were obtained in
the Sloan r', i', and z' filters beginning at 4:11 UT on 2011 September 28
(~ 2.3 hours after the Swift trigger).
We do not detect any sources within the XRT error circle (Evans et al.,
GCN 12398). Using nearby point sources from the Sloan Digital Sky Survey
for reference, we calculate the following upper limits (AB):
r' > 22.1
i' > 21.6
z' > 20.3
We note the presence on the northern edge of the XRT error circle of one
(possibly two) extended sources present in SDSS. The large size of the
current X-ray localization precludes any firm association with GRB
110928A, however.
GCN Circular 12402
Subject
GRB 110928A: Enhanced Swift-XRT position
Date
2011-09-28T06:01:13Z (14 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 1477 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 110928A, 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 = 257.73295, +36.53571 which is equivalent
to:
RA (J2000): 17h 10m 55.91s
Dec (J2000): +36d 32' 08.5"
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 12404
Subject
GRB 110928A: Swift-XRT refined Analysis
Date
2011-09-28T18:02:01Z (14 years ago)
From
Chris Wolf at PSU <cwolf@swift.psu.edu>
C. A. Wolf (PSU), E. A. Hoversten (PSU), and K. L. Page (U Leicester)
report on behalf of the Swift-XRT team:
We have analysed 12 ks of XRT data for GRB 110928A (Hoversten et al.
GCN Circ. 12394), from 3.3 ks to 44.3 ks after the BAT trigger. The
data was collected in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Osborne et al. (GCN. Circ 12402).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.55 (+0.17, -0.19).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.07 (+0.34, -0.27). The
best-fitting absorption column is 4.8 (+2.5, -1.7) x 10^21 cm^-2, in
excess of the Galactic value of 3.1 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 4.4 x 10^-11 (8.1 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 4.8 (+2.5, -1.7) x 10^21 cm^-2
Galactic foreground: 3.1 x 10^20 cm^-2
Excess significance: 4.7 sigma
Photon index: 2.07 (+0.34, -0.27)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00504215.
This circular is an official product of the Swift-XRT team.
GCN Circular 12406
Subject
GRB 110928A: Swift/UVOT Upper Limits
Date
2011-09-28T20:38:28Z (14 years ago)
From
Erik Hoversten at Swift/Penn State <hoversten@astro.psu.edu>
E. A. Hoversten (PSU) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 110928A
3342 s after the BAT trigger (Hoversten et al., GCN Circ. 12394).
No optical afterglow consistent with the XRT position (Osborne et al.,
GCN Circ. 12402) 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 3342 3492 147 >20.2
white 3342 4723 344 >21.0
v 3499 3698 197 >19.1
b 4319 4518 197 >21.0
u 4114 4313 197 >20.8
w1 3909 4108 197 >20.3
m2 3704 3903 197 >19.9
w2 4729 4929 197 >21.6
The magnitudes in the table are not corrected for the Galactic
extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 12407
Subject
GRB 110928A: RAPTOR Limits During Gamma-ray Emitting Interval
Date
2011-09-28T21:11:25Z (14 years ago)
From
James Wren at LANL <jwren@nis.lanl.gov>
J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis,
of Los Alamos National Laboratory report:
The RAPTOR network of robotic optical telescopes made observations of Swift
trigger 504215 (Hoversten et al., GCN 12394). The burst location was within
the field of our wide-field monitors which began a 10 s integration of the
location at 01:51:33.0 UT, 1.2 s after the Swift trigger time and during the
gamma-ray emitting interval. The next wide-field 10 s integration begins at
01:51:52.1 UT, and is also within the gamma-ray emitting interval. Neither
image shows a counterpart at the Swift XRT location (Evans et al., GCN 12398)
to an unfiltered 3-sigma limiting magnitude of 10.1 based on comparison to
the Tycho-2 V-band. Our narrow-field instruments began imaging at
01:52:40.2 UT, 68.4 s after the Swift trigger. The initial 5 s exposures
show no counterpart to a 3-sigma limiting magnitude of 16.1 when compared to
the USNO-B1 R-band. The following table gives a sample of our observations.
The start time is given as the seconds between the start of the exposure and
the initial Swift trigger time.
start(s) exp(s) mag limit
------------------------------
1.22 10.0 > 10.1
20.32 10.0 > 10.1
68.44 5.0 > 16.1
153.55 10.0 > 16.5
413.45 30.0 > 17.2
GCN Circular 12408
Subject
Skynet observations of GRB 110928A
Date
2011-09-29T04:14:54Z (14 years ago)
From
Aaron LaCluyze at U.North Carolina <lacluyze@email.unc.edu>
J. Haislip, K. Ivarsen, A. LaCluyze, K. McLin, D. Reichart, J. Moore, T.
Cromartie, R. Egger, A. Foster, M. Nysewander, A. Oza, E. Speckhard, A.
Trotter, and J. A. Crain report:
Skynet observed the field of GRB 110928A (Hoverston et al., GCN 12394)
with the GLAST Optical Robotic Telescope (GORT) at the Hume observatory
in California beginning roughly 75 minutes after the burst. We do not
detect any uncatalogued sources. Stacking only images that increase the
limiting magnitude yields:
mean mean
time
time 3-sigma
since
since limiting
trigger trigger (days) telescope exposures filter mag
3.186 h 0.13277 GORT 19 x 80 s Ic 20.0
3.400 h 0.14166 GORT 23 x 80 s Rc 21.0
This message may be cited.
GCN Circular 12409
Subject
Skynet/Dolomiti observations of GRB 110928A
Date
2011-09-30T04:19:07Z (14 years ago)
From
Aaron LaCluyze at U.North Carolina <lacluyze@email.unc.edu>
J. Haislip, K. Ivarsen, A. LaCluyze, M. Maturi, D. Reichart, J. Moore, T.
Cromartie, R. Egger, A. Foster, N. Frank, M. Nysewander, A. Oza, E.
Speckhard, A.Trotter, and J. A. Crain report:
Skynet observed the field of GRB 110928A (Hoverston et al., GCN 12394)
with the 16" Dolomites Astronomical Observatory telescope (DAO) in Italy
beginning roughly 16.3 hours after the burst. We do not detect any
uncatalogued sources. Stacking only images that increase the limiting
magnitude yields:
Mean Time 3-sigma limiting
Since trigger Tel Exposures Filter magnitude
17.244 h DAO 37 x 160 s g' 21.0
(0.71850 days)
This message may be cited.