GRB 100728B
GCN Circular 11009
Subject
GRB 100728B: Swift detection of a burst with an optical counterpart
Date
2010-07-28T11:42:40Z (15 years ago)
From
Kim Page at U.of Leicester <kpa@star.le.ac.uk>
D. C. Morris (GWU/GSFC), A. P. Beardmore (U Leicester),
V. D'Elia (ASDC), P. A. Evans (U Leicester), J. M. Gelbord (PSU),
C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),
H. A. Krimm (CRESST/GSFC/USRA), O. M. Littlejohns (U Leicester),
C. B. Markwardt (CRESST/GSFC/UMD), J. P. Osborne (U Leicester),
C. Pagani (U Leicester), K. L. Page (U Leicester),
A. Rowlinson (U Leicester), B. Sbarufatti (INAF-OAB/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 10:31:55 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 100728B (trigger=430172). Swift slewed immediately to the
burst. The BAT on-board calculated location is RA, Dec 44.053, +0.280
which is
RA(J2000) = 02h 56m 13s
Dec(J2000) = +00d 16' 46"
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 plus some possible precursor
activity. The peak count rate was ~2000 counts/sec (15-350 keV),
at ~0 sec after the trigger.
The XRT began observing the field at 10:33:32.9 UT, 97.0 seconds after
the BAT trigger. No source was detected in the first 2.5 seconds image.
The XRT observed the field for approximately 80 seconds in WT mode.
The prompt spectrum from the WT data shows evidence of a source.
Due to an observing constraint no additional PC data were taken to allow
XRT to centroid on the afterglow and derive a position.
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 100 seconds after the BAT trigger. There is a candidate afterglow
in the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 02:56:13.46 = 44.05607
DEC(J2000) = +00:16:51.9 = 0.28109
with a 90%-confidence error radius of about 0.75 arc sec. This position is
11.7 arc sec. from the center of the BAT error circle. The estimated
magnitude is 17.30 with a 1-sigma error of about 0.14. No correction has
been made for the expected extinction corresponding to E(B-V) of 0.07.
Burst Advocate for this burst is D. C. Morris (david.c.morris 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 11010
Subject
GRB 100728B: KAIT optical afterglow detection (correction)
Date
2010-07-28T11:45:27Z (15 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley, A. N. Morgan, and C. R. Klein (UC Berkeley) report:
The burst observed in our previous circular was in fact 100728B (Swift
trigger #430172), and not 100728A (#430151, Cannizzo et al., GCN 11004).
We apologize for any confusion this may have caused.
GCN Circular 11011
Subject
GRB 100728B: Skynet/PROMPT Detections (correction)
Date
2010-07-28T12:00:18Z (15 years ago)
From
Kevin Ivarsen at UNC/PROMPT <kmi@physics.unc.edu>
K. Ivarsen, J. Haislip, D. Reichart, A. LaCluyze, J. Moore, A. Foster, R.
Egger, A. Oza, M. Schubel, A. Trotter, J. A. Crain, and M. Nysewander
The observations reported in GCN #11008 (Swift trigger #430172) should
refer to GRB 100728B rather than GRB 100728A.
We observed the optical transient at the following position:
RA = 02:56:13.51
Dec = +00:16:52.16
We apologize for any inconvenience this may have caused.
GCN Circular 11012
Subject
GRB 100728B: optical detection
Date
2010-07-28T12:13:28Z (15 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
L. Elenin (ISON), I. Molotov (ISON), A. Pozanenko (IKI) report on behalf of
larger GRB follow-up collaboration:
We observed the field of the Swift GRB 100728B (Page et al. GCN 11009) with
0.45-m astrograph f/2.8 �f ISON-NM observatory (32d 54' 11.64'', 105d 31'
42. 34'' ) starting July 28 (UT) 10:56:08, i.e. 24 minutes after burst
onset. A few unfiltered 300s exposures were taken before down. In a first
exposures we clearly detect the afterglow at the position (J2000) RA= 02 56
13.48 Dec= +00 16 51.4 which coincides with early afterglow detection
(Perley et al. GCN 11007; Page et al. GCN 11009).
A preliminary photometry of unfiltered exposures against USNO-B1.0 field
stars (R-filter) at 29.3 minutes after burst is 19m.
GCN Circular 11013
Subject
GRB 100728B: GROND Detection of the NIR Afterglow
Date
2010-07-28T13:28:07Z (15 years ago)
From
Robert Filgas at MPI <filgas@mpe.mpg.de>
F. Olivares, R. Filgas and J. Greiner (all MPE Garching) report on behalf of
the GROND team:
We observed the field of GRB 100728B (Swift trigger 430172; Morris et al.,
GCN #11009) simultaneously in 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 10:34 UT, 2 minutes after the GRB trigger. They
were performed during astronomical twilight at an average airmass of 1.2.
We detect a single point source at position reported by Perley et al. (GCN
#11007), Morris et al. (GCN #11009), Ivarsen et al. (GCN #11011) and
Elenin et al. (GCN #11012).
Based on the first 4 min of total exposures in JHK, we estimate
preliminary magnitudes (all in AB system) of
J = 16.4 +- 0.1 mag,
H = 16.2 +- 0.1 mag and
K = 16.0 +- 0.1 mag
Given magnitudes are calibrated against 2MASS field stars and are not
corrected for the expected Galactic foreground extinction corresponding to
a reddening of E_(B-V)=0.07 mag in the direction of the burst (Schlegel et
al. 1998).
GCN Circular 11015
Subject
GRB 100728B: Fermi GBM observation
Date
2010-07-28T13:47:40Z (15 years ago)
From
Andreas von Kienlin at MPE <azk@mpe.mpg.de>
A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team:
"At 10:31:54.97 UT on 28 July 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100728B (trigger 302005916 / 100728439),
which was also detected by the Swift-BAT (Morris et al. 2008, GCN 11009)
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 57.1 degrees.
The GBM light curve shows a single pulse
with a duration (T90) of about 11.8 +/- 2.4 s (50-300 keV).
The time-averaged spectrum from T0-1.024 s to T0+5.632 s is
well fit by a power law function with an exponential
high energy cutoff. The power law index is -0.9 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 131 +/- 15 keV
(chi squared 1043 for 599 d.o.f.).
The event fluence (8-1000 keV) in this time interval is
(2.4 +/- 0.1)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+1.22 s in the 8-1000 keV band
is 6.2 +/- 0.2 ph/s/cm^2.
A Band function fits the spectrum equally well (chi squared 1037
for 598 d.o.f.) with Epeak= 104 +/- 14 keV, alpha = -0.8 +/- 0.2
and beta = -2.2 +/-0.2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 11017
Subject
GRB 100728B: Enhanced Swift-XRT position
Date
2010-07-28T14:29:45Z (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 820 s of XRT Photon Counting mode data and 2 UVOT
images, 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 = 44.05620, 0.28120 which is equivalent to:
RA (J2000): 02 56 13.48
Dec (J2000): +00 16 52.5
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 is an official product of the Swift-XRT team.
GCN Circular 11022
Subject
GRB 100728B: Swift-XRT Refined Analysis
Date
2010-07-28T20:26:38Z (15 years ago)
From
Claudio Pagani at U of Leicester <cp232@star.le.ac.uk>
C. Pagani (U. Leicester) and D. C. Morris (GWU/GSFC) report on behalf of
the Swift-XRT team:
We have analysed 6.8 ks of XRT data for GRB 100728B (Morris et al. GCN
Circ. 11009), from 81 s to 17.4 ks after the BAT trigger. The data
comprise 86 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 11017).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.109 (+0.029, -0.030).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.20 (+/-0.20). The
best-fitting absorption column is 1.2 (+0.4, -0.5) x 10^21 cm^-2, in
excess of the Galactic value of 6.2 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 3.5 x 10^-11 (5.0 x 10^-11) erg
cm^-2 count^-1.
If the light curve continues to decay with a power-law decay index of
1.109, the count rate at T+24 hours will be 5.0 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x
10^-13 (2.5 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/00430172.
This circular is an official product of the Swift-XRT team.
GCN Circular 11023
Subject
GRB 100728B, Swift-BAT refined analysis
Date
2010-07-28T21:31:46Z (15 years ago)
From
Hans Krimm at NASA-GSFC <hans.krimm@nasa.gov>
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. C. Morris (GWU/GSFC),
D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+350 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 100728B (trigger #430172)
(Morris, et al., GCN Circ. 11009). The BAT ground-calculated position is
RA, Dec = 44.051, 0.296 deg which is
RA(J2000) = 02h 56m 12.2s
Dec(J2000) = +00d 17' 45.9"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 11%.
The mask-weighted light curve shows a single peak of duration 10 seconds,
starting at T-2 sec and continuing at a low level to about T+20 sec. An
observing constraint moved the burst out of the BAT field of view at T+350
sec, but there is no sign of extended emission from this burst.
T90 (15-350 keV) is 12.1 +- 2.4 sec (estimated error including systematics).
The time-averaged spectrum from T-1.7 to T+13.2 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.55 +- 0.14. The fluence in the 15-150 keV band is 1.7 +- 0.1 x 10-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.18 sec in the 15-150 keV band
is 3.5 +- 0.5 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/430172/BA/
GCN Circular 11024
Subject
GRB 100728B: Continued KAIT observations
Date
2010-07-29T05:56:35Z (15 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley, W. Li, and A. V. Filippenko (UC Berkeley) report on behalf
of the KAIT GRB follow-up team:
The Katzman Automatic Imaging Telescope (KAIT) began observations of GRB
100728B (Morris et al., GCN 11009) at 30 sec after the trigger time (10
sec after the GCN notice), and continued to track the afterglow in a
combination of V, I, and unfiltered exposures until shut down by morning
twilight. The afterglow remains detected throughout this period.
An series of 2-second frames taken between 30-64 sec clearly shows a
rapid rise from an initial mag of ~16.5 (calibrated to USNO B1.0) to a
peak of 16.1 mag at ~50 seconds. The afterglow decays as an unbroken
power-law with decay index alpha=0.97 after that time through the end of
our observations at 5700 s.
A subset of the unfiltered photometry is presented below:
tstart(s) exp(s) mag unc
149 20 17.02 +/- 0.02
249 20 17.61 +/- 0.03
446 20 18.21 +/- 0.05
643 20 18.51 +/- 0.07
846 20 18.90 +/- 0.07
1141 60 19.15 +/- 0.07
1440 60 19.40 +/- 0.07
1668 60 19.76 +/- 0.10
2264 100 19.81 +/- 0.10
3326 100 19.86 +/- 0.08
4186 140 20.33 +/- 0.10
5115 140 20.58 +/- 0.14
5544 200 20.88 +/- 0.19
All times are referenced to the BAT trigger at 10:31:55 UT. Magnitudes
are calibrated relative to USNO B1.0 standards in the field.
Further analysis is in progress. We note that the I-band magnitude in
our previous circular (GCN 11007) was calibrated to USNO R-band
standards and should not be relied upon for detailed analysis. In
addition, the time from burst specified in that circular is relative to
the BAT position notice time, rather than the trigger time as specified.
(The UT time given is correct as stated.)
GCN Circular 11025
Subject
GRB 100728B: Lick Observations
Date
2010-07-29T05:59:34Z (15 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley, C. R. Klein, and A. N. Morgan (UC Berkeley) report:
We began observations of the afterglow of GRB 100728B (Morris et al.,
GCN 11009; Perley et al., GCN 11007) with the Nickel 40-inch telescope
at Lick Observatory starting at 10:38:32 UT, 397 sec after the Swift
trigger. A series of frames in R-band (as well as one V-band and one
U-band exposure) was acquired. The resulting light curve shows a
gradual, unbroken power-law decay with a decay index consistent with
that seen in the KAIT observations (Perley et al., GCN 11024).
Photometry from our first seven R-band exposures is as follows:
tstart(s) exp(s) filt mag unc
397 60 R = 17.38 +/- 0.06
830 300 R = 18.33 +/- 0.05
1162 300 R = 18.53 +/- 0.06
1497 200 R = 18.71 +/- 0.07
1888 160 R = 18.88 +/- 0.09
2062 120 R = 18.80 +/- 0.09
2197 120 R = 18.99 +/- 0.11
Calibration is relative to a single bright star at RA=44.041108,
dec=+0.242409 (SDSS DR6 magnitudes g=15.61, r=14.52, i=14.57; the
equivalent Cousins R magnitude is R=14.3 using the average of the two
SDSS Lupton transformations.) As this star may be weakly blended with a
faint neighbor and its USNO magnitude (R2=13.94) differs from this SDSS
value, caution is advised in interpreting the absolute calibration.
GCN Circular 11026
Subject
GRB 100728B: Swift/UVOT Observations
Date
2010-07-29T08:52:21Z (15 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates (MSSL-UCL) and D. C. Morris (GWU/GSFC) report on behalf of
the Swift/UVOT team:
The Swift/UVOT began observerving the field of GRB 100728B 101s
after the BAT trigger (Morris et al., GCN Circ. 11009). We detect the
optical afterglow in the white, v, b and u filters only.
The refined UVOT position is RA (J2000)= 163.48809, DEC
(J2000)=-45.47265,
which is equivalent to:
RA (J2000) = 02:56:13.467
Dec (J2000) = +00:16:52.18
with an estimated uncertainty of 0.52 arcsec (radius, 90% confidence).
This position is consistent with the XRT refined position (Evans et
al., GCN Circ 11017)
and with the optical afterglow positions reported by KAIT (Perley et
al., GCN Circ 11007, 11010 & 11024),
PROMPT (Ivarsen et al., GCN Circ 11008, 11011) & the SON-NM
observatory (Elenin et al., GCN Circ 11012).
The non-detection in the UV filters suggests a photometric redshift of
z~2.8.
Preliminary magnitudes and the 3 sigma upper limits are reported below
for
individual optical images and summed UV images.
Filter T_start(s) T_stop(s) Exposure Mag/3SigUL
###########################################################
white 101 251 147 17.43 +/- 0.08
white 4713 4913 197 20.62 +/- 0.22
v 3687 3887 197 20.19 +/- 0.56
b 4509 4709 197 20.47 +/- 0.33
u 4303 4503 197 19.90 +/- 0.28
uvw1 4098 6050 294 > 20.50
uvm2 3892 5529 393 > 20.52
uvw2 3482 5119 393 > 20.93
###########################################################
The above magnitudes are not corrected for the Galactic extinction
corresponding to a non-negligible reddening of E_{B-V} = 0.07 mag
(Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT photometric system
described in Poole et al. (2008, MNRAS, 383,627).
GCN Circular 11027
Subject
GRB 100728B - NOT optical observation
Date
2010-07-29T10:51:33Z (15 years ago)
From
Annalisa De Cia at U of Reykjavik,Science Inst. <annalisa@raunvis.hi.is>
A. De Cia (University of Iceland), D. Malesani (DARK/NBI), P.M.
Vreeswijk, S. Schulze and P. Jakobsson (University of Iceland)
report:
We observed the field of GRB 100728B (Morris et al., GCN 11009)
with the NOT equipped with StanCam, under poor seeing
conditions. Observations were carried out in the R filter for 40
minutes, with mean time 18.36 hours after the GRB trigger. The
seeing was 1.3".
At the position of the optical afterglow (Perley et al., GCN
11007; Morris et al., GCN 11009) we do not detect any clear
source, down to a limiting mag R > 22.2. By smoothing the image,
a weak source can be marginally detected with magnitude R = 22.5
+/- 0.5 mag, calibrated against SDSS stars converted to Vega.
We acknowledge the careful assistence of the NOT staff, in
particular Anders Thygesen.
GCN Circular 11028
Subject
GRB 100728B: Swift/UVOT Observations (correction)
Date
2010-07-30T15:10:48Z (15 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
The coordinates in circular 11026 should be
RA (J2000)= 0.28116, DEC (J2000)=44.05611,
which is equivalent to:
RA (J2000) = 02:56:13.467
Dec (J2000) = +00:16:52.18
The coordinates in the degree format in circular 11026 were
accidentally taken from a different GRB.
GCN Circular 11029
Subject
GRB 100728B: Swift/UVOT Observations (correction to GCN 11028)
Date
2010-07-30T15:27:55Z (15 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
Apologies, the coordinates in circular 11028 should be RA (J2000)=
44.05611, DEC (J2000)=0.28116
GCN Circular 11045
Subject
GRB 100728B: optical photometry of ISON-NM
Date
2010-08-03T21:25:21Z (15 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (SAI MASU), L. Elenin, I. Molotov (ISON), A. Pozanenko (IKI)
report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 100728B (Morris et al. GCN 11009)
with 0.45-m telescope �f ISON-NM observatory on July 28 (Elenin at al.,
GCN 11012).
The afterglow ( Perley et al. GCN 11007; Morris et al. GCN 11009; Ivarsen et
al. GCN 11011) is detectable on each of four images taken between July 28
(UT) 10:45:49 - 11:01:14.
A photometry of unfiltered images against SDSS field stars and R-mag
obtained with Lupton transformations is following
t-t0, filter, exposure, OT
(sec)
984 W 300 18.36+/-0.17
1294 W 300 18.93+/-0.22
1603 W 300 18.80+/-0.18
1909 W 300 19.00+/-0.30
Finding chart and SDSS calibration stars can be found at
http://grb.rssi.ru/GRB100728B/100728b-refstars.png
GCN Circular 11317
Subject
GRB 100728B: X-shooter redshift
Date
2010-10-07T12:41:13Z (15 years ago)
From
Hector Flores at Obs.de Paris,Meudon <hector.flores@obspm.fr>
H. Flores (GEPI/Obs. de Paris), J. P. U. Fynbo, A. de Ugarte
Postigo, B. Milvang-Jensen, D. Malesani (DARK/NBI), P. Goldoni
(APC/Univ. Paris 7 and SAp/CEA), C. C. Thoene (IAA-CSIC Granada), S.
Piranomonte (INAF/Roma), S. D. Vergani (GEPI/Obs. de Paris),
F. Onori (Univ. Roma 3)
report on behalf of the X-Shooter GRB collaboration:
We have observed the afterglow of the GRB 100728B (Morris et al., GCN
11009; Perley et al., GCN 11010) with the ESO VLT equipped with the
X-shooter spectrograph. The observation started on 2010-07-29 at 08:15
UT (22 hr after the GRB). A total exposure of 4x600 s was obtained,
covering the spectral range from 300 to 2500 nm. Due to technical
problems with the atmospheric dispersion corrector, the sensitivity of
the instrument was below the nominal value during this observation so
the signal-to-noise ratio of the spectrum is very low.
In the spectra we detect a broad absorption line consistent with a
damped Lyman-alpha line and absorption features consistent with the MgII
doublet at a common redshift of z=2.106. Given the low S/N of the
spectrum, this redshift measurement should be considered tentative.
We acknowledge the Paranal staff, in particular Alain Smette, for
valuable support with the observations, and Daniel Perley (Berkeley) for
providing us a finding chart with the afterglow.
[GCN OPS NOTE(07oct10): Per author's request, Onori was added to the
author list.]