GRB 100628A
GCN Circular 10895
Subject
GRB 100628A: Swift detection of a short hard burst
Date
2010-06-28T08:48:19Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
S. Immler (CRESST/GSFC/UMD), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), S. Campana (INAF-OAB),
C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),
V. Mangano (INAF-IASFPA), J. Mao (INAF-OAB),
P. T. O'Brien (U Leicester), C. Pagani (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
P. Romano (INAF-IASFPA), M. H. Siegel (PSU),
M. Stamatikos (OSU/NASA/GSFC) and R. L. C. Starling (U Leicester)
report on behalf of the Swift Team:
At 08:16:40 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 100628A (trigger=426114). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 225.968, -31.661 which is
RA(J2000) = 15h 03m 52s
Dec(J2000) = -31d 39' 38"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows single hard spike
with a duration of about 0.1 sec. The peak count rate
was ~4500 counts/sec (15-350 keV), at ~0 sec after the trigger. We believe
this trigger to be real because the count rate is above the cosmic ray
shower level, the duration is longer than produced by a shower, and
the signal is distributed across the detector plane.
The XRT began observing the field at 08:18:06.8 UT, 86.0 seconds after
the BAT trigger. No source was detected in the promptly available XRT
data. We are waiting for the full dataset to detect and localise the
XRT counterpart.
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 89 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 25% of
the BAT 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
BAT 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
0.17.
Burst Advocate for this burst is S. Immler (immler AT milkyway.gsfc.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 10896
Subject
GRB 100628A: Swift-BAT refined analysis
Date
2010-06-28T16:16:49Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), T. Sakamoto (GSFC/UMBC),
W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), S. Immler (CRESST/GSFC/UMD),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL),
A. M. Parsons (GSFC), G. Sato (ISAS), M. Stamatikos (ORAU/GSFC),
J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+577 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 100628A (trigger #426114)
(Immler, et al., GCN Circ. 10895). The BAT ground-calculated position is
RA, Dec = 225.943, -31.653 deg, which is
RA(J2000) = 15h 03m 46.2s
Dec(J2000) = -31d 39' 10.2"
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 70%.
The mask-weighted light curve shows two overlapping peaks starting at
~T_zero to ~T+0.04 sec. T90 (15-350 keV) is 0.036 +- 0.009 sec
(estimated error including systematics).
The time-averaged spectrum from T-0.004 to T+0.036 sec is equally well fit
by the exponential cutof powerlaw and a blackbody:
Exponential cutoff: photon index -2.67 +1.8/-3.7, and Epeak of 74.1 +- 11.4 keV
(chi squared 60.5 for 56 d.o.f.). Blackbody: kT = 19.8 +- 2.9
(chi squared 61.0 for 57 d.o.f.).
The total fluence in the 15-150 keV band is 2.5 +- 0.5 x 10^-8 erg/cm2 and
the 1-sec peak flux measured from T-0.48 sec in the 15-150 keV band is
0.5 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.26 +- 0.25 (chi squared 81.3 for 57 d.o.f.). 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/426114/BA/
GCN Circular 10898
Subject
GRB 100628A: INTEGRAL SPI-ACS light curve
Date
2010-06-28T18:45:54Z (15 years ago)
From
Volker Beckmann at APC <beckmann@apc.univ-paris7.fr>
V. Beckmann (APC), M. Beck, C. Ferrigno, V. Savchenko, Ievgen Vovk (ISDC), J.
Borkowski (CAMK/Torun), D. G�tz (CEA/Saclay), S. Mereghetti
(INAF/IASF-Milano), and A. von Kienlin (MPE) report on behalf of the
INTEGRAL SPI-ACS GRB team:
GRB 100628A, detected in Swift/BAT data (Immler et al., GCN 10895;
Barthelmy et al., GCN 10896), is detectable also in the data of the
SPI Anti-Coincidence System (ACS) on-board INTEGRAL. The SPI-ACS light
curve shows the peak of the burst at 2010-06-28T08:16:41 with a
maximum count-rate of ~600
counts/50msec. The duration of the GRB is about 0.05 seconds.
The SPI-ACS light curves are available (both as images and data files)
at http://isdc.unige.ch/Soft/ibas/ibas_acs_web.cgi
The light curves, binned at 50 ms, are derived from 91 independent
detectors with different lower energy thresholds (mainly between 50 keV
and 150 keV) and an upper threshold at about 100 MeV. The ACS response
varies as a function of the GRB incident angle. For these reasons we
caution that the count rates cannot be easily translated into physical
flux units. It is not possible to localize a burst based on the SPI-ACS data.
----------------------------------------------------------------
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GCN Circular 10899
Subject
GRB 100628A: Swift XRT detection of a possible X-ray afterglow
Date
2010-06-28T20:24:02Z (15 years ago)
From
Rhaana Starling at U of Leicester <rlcs1@star.le.ac.uk>
R.L.C. Starling (U. Leicester) and S. Immler (CRESST/GSFC/UMD) report on
behalf of the Swift-XRT team:
We have analysed 8.7 ks of XRT data for GRB 100628A (Immler et al. GCN
Circ. 10895), from 93 s to 18.8 ks after the BAT trigger. The data are
entirely in Photon Counting (PC) mode. A source is detected at the 3-sigma
confidence level within the BAT refined error circle (Barthelmy et al. GCN
Circ. 10896) at the position:
RA (J2000) = 15 03 52.95
Dec (J2000) = -31 39 41.7
with an error of 5.2 arcsec (radius, 90% containment). This is 91.8 arcsec
from the BAT refined position.
The possible source has a count rate of 0.0023+/-0.0007 count/s. We cannot
determine whether the source is fading at this time.
This circular is an official product of the Swift-XRT team.
GCN Circular 10900
Subject
GRB100628A: RTT150 optical observations
Date
2010-06-28T22:25:30Z (15 years ago)
From
Rodion Burenin at IKI, Moscow <rodion@hea.iki.rssi.ru>
R. Burenin, G. Khorunzhev, S. Sazonov (IKI), I. Khamitov (TUG),
M. Pavlinsky, R. Sunyaev (IKI), I. Bikmaev, N. Sakhibullin (KSU/AST),
Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)
report:
The field of GRB100628A (Immler et al., GCN 10895) was observed with
Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National
Observatory, Turkey). We obtained a serie of Rc images, centered at June 28,
19:10 UT, i.e. approximately 11 hours after the burst.
We do not find any new optical source inside the XRT error circle of
possible X-ray afterglow (Starling et al., GCN 10899) as compared to DSS red
plate.
GCN Circular 10901
Subject
GRB 100628A: Swift/UVOT Upper Limits
Date
2010-06-28T22:48:13Z (15 years ago)
From
Stefan Immler at NASA/GSFC <stefan.m.immler@nasa.gov>
S. Immler (CRESST/GSFC/UMD) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 100628A
90 s after the BAT trigger (Immler et al., GCN Circ. 10895). No optical
afterglow consistent with the XRT position (Starling et al., GCN Circ.
10899) 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 90 239 147 >20.2
u_FC 302 551 246 >19.4
white 90 11409 1498 >21.4
v 631 12968 1099 >19.5
b 557 7133 471 >20.1
u 302 6928 697 >20.2
w1 680 6722 471 >19.6
m2 4882 6517 393 >19.3
w2 607 12315 1176 >20.3
The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.17 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 10902
Subject
GRB 100628A: Magellan near-IR observations
Date
2010-06-29T03:31:31Z (15 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
E. Berger (Harvard), T. Guver (U. of Arizona), W. Fong, R. Chornock
(Harvard) report:
"We observed the location of the potential X-ray afterglow (GCN 18099)
of the short GRB 100628A (GCN 10895) with the PANIC infrared imager on
the Magellan/Baade 6.5-m telescope on 2010 June 29.07 UT (17.4 hours
after the burst). A total of 27 min on source were obtained in the
J-band with seeing of about 1.1 arcsec. We do not detect any sources
within the XRT error circle to a limit of about J>20.6 mag (Vega;
5-sigma).
However, surrounding the XRT error circle are several apparent
galaxies located at the following positions (J2000; astrometry
relative to USNO-B with rms of about 0.25" in each coordinate):
G1: RA = 15:03:53.34, DEC = -31:39:50.2
G2: RA = 15:03:53.61, DEC = -31:39:37.6
G3: RA = 15:03:52.43, DEC = -31:39:44.2
G4: RA = 15:03:52.85, DEC = -31:39:36.9
G5: RA = 15:03:52.85, DEC = -31:39:35.8
A finder marking the location of these objects relative to the XRT
error circle is available from:
http://www.cfa.harvard.edu/~eberger/grb100628_panic_2010June29.jpg
Additional observations are planned to check for variability in any of
the sources."
GCN Circular 10904
Subject
GRB100628A : MOA optical upper limit
Date
2010-06-29T05:31:35Z (15 years ago)
From
Suzuki Daisuke at MOA-II <dsuke@stelab.nagoya-u.ac.jp>
D. Suzuki, K. Omori, F. Hayashi, S. Kobara, H. Naito and T. Sako (STE Lab. , Nagoya Univ.)
on behalf of the MOA Collaboration repot :
We searched for an optical afterglow of GRB100628A (GCN 10895, S. Immler et al.)
starting from 08:16:43 UT on 2010 June 28 ( 3 minutes after the burst)
with the MOA-II 1.8m telescope at Mt.John observatory in New Zealand.
In a single image of a 300 sec exposure with a wideband Red filter (center
wavelength ~ 750nm and FWHM ~ 250nm), we did not find any object
within the error circle of the Swift XRT source position (GCN 10899, R.L.C. Starling et al.).
A 3 sigma upper limit is set in the I magnitude at 22.7 mag.
This photometry was done by using the DoPhot and calibrated against the
USNO-B1.0 catalog stars, and not corrected for the Galactic extinction.
GCN Circular 10907
Subject
GRB 100628A: Swift XRT refined position
Date
2010-06-29T14:16:43Z (15 years ago)
From
Rhaana Starling at U of Leicester <rlcs1@star.le.ac.uk>
R.L.C. Starling, A.P. Beardmore (U. Leicester) and S. Immler
(CRESST/GSFC/UMD) report on behalf of the Swift-XRT team:
We have analysed further Swift XRT data totalling 24.77 ks of exposure for GRB
100628A (Immler et al. GCN Circ. 10895), from 93 s to 80.75 ks after the BAT
trigger.
The source reported in Starling & Immler (GCN Circ. 10899) is still detected,
but we cannot confirm any fading at this time. We report a
significantly revised position, incorporating the new data and using an
exposure map corrected psf-centroid fitting method, of
RA (J2000) = 15 03 53.52
Dec (J2000) = -31 39 49.7
with an error of 4.7 arcsec (radius, 90% containment).
This is still within the BAT refined error circle (Barthelmy et al.
GCN Circ. 10896), 10.8 arcsec from the initial XRT position.
This position is 2.3 arcsec from the galaxy G1 reported in Berger et al.
(GCN Circ. 10902).
This circular is an official product of the Swift-XRT team.
GCN Circular 10908
Subject
GRB 100628A: Coincidence of source "G1" with revised XRT error circle
Date
2010-06-29T14:23:29Z (15 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
E. Berger (Harvard) reports:
"Inspection of our PANIC J-band image from 2010 June 29.07 UT (GCN
10902) at the location of the revised XRT error circle (GCN 10907)
reveals that the galaxy designated "G1" is now located within the
error circle, about 2.4 arcsec from its center. A revised finder is
available from:
http://www.cfa.harvard.edu/~eberger/grb100628_panic_2010June29_v2.jpg
Additional observations are planned to check for variability."
GCN Circular 10909
Subject
GRB 100628A: Gemini North Observations
Date
2010-06-29T17:46:37Z (15 years ago)
From
Andrew Levan at U.of Leicester <A.J.Levan@warwick.ac.uk>
A.J. Levan (U. Warwick), N.R. Tanvir, K. Wiersema (U. Leicester),
S.B. Cenko (UC Berkeley) report on behalf of a larger collaboration:
"We obtained two epochs of observations of GRB 100628A (Immler et
al. GCN 10895) with Gemini-North. The first was obtained starting
at 28 Jun, 08:59 UT, approximately 43 minutes after the burst, with
a second obtained on 29 Jun 05:50 UT, ~21.5 hours after the burst.
A total of 1200s of exposure time were obtained in the i-band. Our
images covers ~90% of the BAT refined error circle (Barthelmy et
al GCN 10896), including the position of the candidate X-ray afterglow
identified by Starling et al. (GCN 10899; 10907).
Digital image subtraction performed between the two epochs does not
reveal any candidate variable sources between the two epochs, to
an approximate limiting magnitude of i~24. In particular, we do not
find any evidence for variability in any of the galaxies identified
by Berger et al. (GCN 10902) surrounding the XRT location,
including G1, which now lies within the XRT error circle
(Starling et al. GCN 10907; Berger et al. GCN 10908)
We also note the presence of two, apparently point like sources
lying within the refined XRT error circle, at locations of
S1:
RA(J2000) 15:03:53.45
DEC(J2000) -31:39:54.2
S2:
RA(J2000) 15:03:53.73
DEC(J2000) -31:39:48.4
Both are unresolved at the resolution of our observations, but
neither show apparent variability between the two epochs.
An image, showing the field as observed by Gemini-North can be found
at
http://www.star.le.ac.uk/~anl/100628A
We thank the staff of Gemini-North for their assistance with these
observations."
GCN Circular 10910
Subject
GRB 100628A: GROND optical/NIR observations of the host candidate
Date
2010-06-29T22:04:47Z (15 years ago)
From
Adria C. Updike at Clemson U <aupdike@clemson.edu>
A. Updike (Clemson University), M. Nardini, P. Afonso, A. Rau, T.
Kruehler, and J. Greiner (all MPE Garching) report on behalf of the
GROND team:
We observed the field of GRB 100628A (Immler et al., GCN 10895)
simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120,
405) mounted at the 2.2 m MPI/ESO telescope at La Silla
Observatory (Chile).
Observations started at 01:24 UT on June 29, 17.1 hours after the GRB
trigger, and continued for 1.5 hours.
In stacked images of 75 min total integration time in g'r'i'z' and 60
minutes in JHK we detect the possible host galaxy candidate G1 first
noted in Berger et al., GCN #10902 and Berger, GCN #10908 inside the
refined XRT position (Starling et al. GCN 10907) in all filters.
Preliminary photometry yields the following AB magnitudes:
g' = 22.8 +- 0.2
r' = 21.5 +- 0.1
i' = 20.6 +- 0.1
z' = 20.0 +- 0.1
J = 19.4 +- 0.1
H = 19.0 +- 0.1
K = 18.6 +- 0.1
calibrated against the GROND zeropoints and 2MASS field stars, and
uncorrected for the expected mild foreground reddening in the direction
of the burst of E(B-V) = 0.17 (Schlegel et al. 1998).
Galaxy spectral template fitting using the publically available Lephare
code (Arnouts & Ilbert 2009,
http://www.cfht.hawaii.edu/~arnouts/LEPHARE/cfht_lephare/lephare.html)
provides good fits of this very red spectral energy distribution with
starburst or late type galaxies. In this interpretation, a photometric
redshift of z=0.67 (+0.34, -0.12) is indicated. We caution that the error
might be underestimated due to the missing photometric calibration in the
g'r'i'z' bands. We note, however, that at this redshift the absolute
magnitude would be rather bright, M_B ~ -22 mag.
GCN Circular 10911
Subject
GRB 100628A: Second epoch of Magellan near-IR observations
Date
2010-06-30T03:09:37Z (15 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
E. Berger (Harvard), T. Guver (U. of Arizona), W. Fong, R. Chornock
(Harvard) report:
"We re-observed the location of the potential X-ray afterglow (GCNs
18099, 10907) of the short GRB 100628A (GCN 10895) with the PANIC
infrared imager on the Magellan/Baade 6.5-m telescope on 2010 June
29.98 UT (39.2 hours after the burst and 21.8 hours after our previous
observation: GCN 10902). A total of 27 min on source were obtained in
the J-band with seeing of about 0.5 arcsec. Digital image subtraction
of the two epochs does not reveal any variable sources within the XRT
error circle or in coincidence with the galaxy "G1" to a 5-sigma limit
of J=21.6 mag at 17.2 hours after the burst. This result supports the
conclusions of Levan et al. (GCN 10909)."
GCN Circular 10941
Subject
GRB 100628A: Swift XRT/UVOT refined analysis
Date
2010-07-06T21:54:09Z (15 years ago)
From
Rhaana Starling at U of Leicester <rlcs1@star.le.ac.uk>
R.L.C. Starling, P.A. Evans (U. Leicester) and S. Immler (CRESST/GSFC/UMD)
report on behalf of the Swift XRT and UVOT teams,
We have analysed 65.4 ks of Swift XRT data for GRB 100628A (Immler et al. GCN
Circ. 10895). The X-ray source reported in Starling et al. (GCN Circ. 10907)
shows no evidence for fading. We conclude that this source is not the
X-ray afterglow of GRB 100628A.
Further inspection of these data reveal another possible X-ray source close
to the persistant source, detected in the first two orbits of data only
(totalling 3.8 ks from T0+92 s to T0+7200 s).
This source comprises just 7 counts, however the predicted background
level is only 0.7 counts in this time interval. Using the Bayesian method
described in Kraft, Burrows & Nousek (1991) we find a detection
significance >99.999%. The 0.3-10 keV count rate during this interval is
0.0017 (+0.0008, -0.0006) counts/s. The source position is
RA, Dec (J2000) = 225.96837, -31.65839, which is equivalent to:
RA (J2000.0) = 15 03 52.41
Dec (J2000.0) = -31 39 30.2
with an uncertainty of 7 arcseconds (radius, 90% containment).
In the subsequent XRT data (>T0+7200 s) the source is not detected; a
3-sigma upper limit on the 0.3-10 keV count rate is 5.7E-5 count/s.
Therefore, if this source was real it has faded and can be considered a
candidate X-ray afterglow.
We caution that with so few total counts a background fluctuation or other
spurious detection cannot be completely ruled out.
No UVOT afterglow candidate is seen in any of the UVOT images at the XRT
position down to the limits reported in GCN 10901.
This circular is an official product of the Swift team.
GCN Circular 10942
Subject
GRB 100628A: Chandra observations
Date
2010-07-06T22:27:15Z (15 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
E. Berger (Harvard) reports:
"We observed the field of the short GRB 100628 (GCN 10895) with the
Chandra X-ray Observatory starting on 2010 July 2.79 UT for a total of
19.8 ksec. Within the XRT error circle (GCN 10907) we detect a single
point source at the following coordinates (J2000):
RA = 15:03:53.33
DEC = -31:39:50.5
This object is coincident with the bright core of the galaxy "G1"
(GCNs 10902,10908). The flux of the object is about 4.8e-14
erg/cm^2/s, in good agreement with the flux measured with the
Swift/XRT of about 4.6e-14 erg/cm^2/s (see Swift/XRT GRB lightcurve
repository: http://www.swift.ac.uk/xrt_curves/00426114/). Given the
position of the source and its constant flux we conclude that it is
due to AGN activity and is therefore not related to GRB 100628 (see
also GCN 10941).
Furthermore, we do not detect any emission at the location of the new
and possibly fading XRT source (GCN 10941) to a 3-sigma limit of
<5e-15 erg/cm^2/s, about a factor of 15 times fainter than the initial
XRT detection.
We thank Harvey Tananbaum and the CXO scheduling staff for rapidly
approving and executing this observation."
GCN Circular 10943
Subject
GRB 100628A: Near-IR sources coincident with the possible X-ray afterglow
Date
2010-07-06T22:58:34Z (15 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
E. Berger (Harvard) reports:
"We inspected the location of the new and possibly fading XRT source
(GCN 10941) associated with the short GRB 100628 (GCN 10895) in our
Magellan/PANIC images (GCNs 10902,10908,10911). Within the 7" radius
circle we detect two extended sources at the following positions (J2000):
G6: RA = 15:03:52.02, DEC = -31:39:32.5
G7: RA = 15:03:52.78, DEC = -31:39:33.7
Neither source shows any evidence for fading between our two PANIC
observations from 0.65 and 21.8 hours after the burst."
GCN Circular 10946
Subject
GRB 100628A: Keck/LRIS Spectroscopy of Host Galaxy Candidate
Date
2010-07-08T13:54:02Z (15 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. B. Cenko, D. A. Perley, J. S. Bloom, A. N. Morgan (UC Berkeley), and A.
Cucchiara (UCB/LBNL/UCSC) report on behalf of a larger collaboration:
We have obtained spectra of the galaxy dubbed "G7" (Berger, GCN 10943)
inside the possible X-ray afterglow error circle (Starling et al., GCN
10941) of the short GRB 100628A (Immler et al., GCN 10895) with the Low
Resolution Imaging Spectrometer mounted on the 10 m Keck I telescope. Our
observations began at 6:25 UT on 8 July 2010 and cover the wavelength
range from 3500-10000 A.
The spectrum is comprised of a series of narrow emission lines, clearly
resolved into two spatially distinct components and joined by a bridge of
faint continuum emission, possibly indicating an interacting or disturbed
system. We identify the emission lines in both components as [O II], [O
III], H-alpha, and H-beta at a common redshift of z = 0.102, which we
therefore take to be the redshift of the galaxy "G7".