GRB 110915A
GCN Circular 12335
Subject
GRB 110915A: Swift detection of a burst
Date
2011-09-15T13:29:30Z (14 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
S. T. Holland (CRESST/USRA/GSFC), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
S. Campana (INAF-OAB), J. R. Cummings (NASA/UMBC),
P. D'Avanzo (INAF-OAB), P. A. Evans (U Leicester), C. Gronwall (PSU),
E. A. Hoversten (PSU), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC),
A. Melandri (INAF-OAB), P. T. O'Brien (U Leicester),
P. Romano (INAF-IASFPA), B. Sbarufatti (INAF-OAB/IASFPA),
M. H. Siegel (PSU), C. A. Swenson (PSU) and G. Tagliaferri (INAF-OAB)
report on behalf of the Swift Team:
At 13:20:44 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110915A (trigger=503219). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 310.851, -0.709 which is
RA(J2000) = 20h 43m 24s
Dec(J2000) = -00d 42' 33"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows multiple peaks
with a total duration of about 95 sec. The peak count rate
was ~4000 counts/sec (15-350 keV), at ~68 sec after the trigger.
The XRT began observing the field at 13:22:00.5 UT, 76.1 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 310.8242, -0.7231 which is equivalent to:
RA(J2000) = 20h 43m 17.80s
Dec(J2000) = -00d 43' 23.1"
with an uncertainty of 4.7 arcseconds (radius, 90% containment). This
location is 108 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.
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 84 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
0.06.
Burst Advocate for this burst is S. T. Holland (Stephen.T.Holland 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 12336
Subject
GRB 110915A: Prompt enhanced Swift-XRT position
Date
2011-09-15T14:10:25Z (14 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 110915A, we find an
enhanced XRT position of the afterglow: RA, Dec: 310.8242, -0.7241
which is equivalent to:
RA (J2000) = 20 43 17.81
Dec (J2000) = -00 43 26.7
with an uncertainty of 3.4 arc sec (radius, 90% confidence). Analysis
of the promptly available data is online at
http://www.swift.ac.uk/sper/503219.
Position enhancement is 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 12337
Subject
GRB 110915A: MASTER-Net early limit
Date
2011-09-15T16:30:29Z (14 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V.Yurkov, Yu.Sergienko, E.Sinyakov, D.Varda, I.Kudelina
Blagoveschensk Educational State University, Blagoveschensk
K.Ivanov, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Gres,
O.Chuvalaev,E.Konstantinov,
Irkutsk State University
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina,
N.Shatskiy, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M.
Kornilov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Sankovich
Sternberg Astronomical Institute, Moscow State University
A. Tlatov, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov
Ural State University, Kourovka
MASTER robotic telescope (MASTER-Net: http://observ.pereplet.ru) located
at Blagoveschensk (Amur-site) was pointed to the GRB110915A 15 sec after
notice time and 31 sec after GRB time at 2011-09-15 13:21:15 UT.
On our first (10s exposure) MASTER II telescope set we haven`t found
optical transient within SWIFT error-box (Holland et al., GCN Circ
12335). Unfortunatelly the main telescopes was not in focus.
On our first (5s exposure) MASTER VWF (Very Wide Field Camera - FOV=420
square degrees) set we haven`t found optical transient within
SWIFT error-box (Holland et al., GCN Circ 12335).
Date T_start-T_trig ExpTime Limit Coadd Instrum
(UT) (s) (s) (unfilt)
13:21:15 31 10 12 No MASTER II
13:21:17 33 5 12 No MASTER VWF
13:21:17 33 60 14 12 MASTER VWF
The message may be cited.
GCN Circular 12338
Subject
GRB 110915A: MITSuME Akeno Optical upper limits
Date
2011-09-15T16:32:13Z (14 years ago)
From
Yoichi Yatsu at Tokyo Tech. <yatsu@hp.phys.titech.ac.jp>
K. Kawakami, K. Tokoyoda, Y. Yatsu, Y. Aoki, M. Hayashi, S. Song,
R. Usui, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME
collaboration:
We observed GRB 110915A (S. T. Holland et al, GCN12335)
with the optical three color (g, Rc, and Ic) CCD camera attached
to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.
The follow-up observation was started at 14:29:30, ~69 min after the
BAT trigger.
We did not find any new point source within the enhanced XRT error
circle (P.A. Evans et al., GCNC 12336) in two bands.
Photometric results and are listed below. We used GSC2.3 catalog for
flux calibration.
T0+[s] MID-UT T-EXP[sec] g' Rc Ic
---------------------------------------------------------------------------------
+4126 14:34:59 1440 --- >17.6 >17.6
---------------------------------------------------------------------------------
T0+ : Elapsed time after the burst [sec]
T-EXP: Total Exposure time [sec]
GCN Circular 12339
Subject
GRB 110915A: GMG optical upper limit
Date
2011-09-15T17:05:38Z (14 years ago)
From
Dong Xu at Weizmann Inst <dong.dark@gmail.com>
X.-H. Zhao (YNAO), D. Xu (WIS), J.-R. Mao & J.-M. Bai (YNAO) report on
a larger collaboration:
We observed the XRT field (Evans, GCN 12336) of GRB 110915A (Holland
et al., GCN 12335) with the 2.4m GMG telescope in Yunnan, China
equipped with YFOSC. Observations started at 13:58:09 UT, 15th Sep.
2011 (i.e., 0.6236 hr after the burst), and 1x20 min R-band and 1x20
min V-band images were obtained under the cloudy weather.
No optical source was present within the XRT error circle in GCN
#12336, which sets a 3\sigma upper limit of R~21.6 mag, calibrated
with the USNO B1 catalog.
GCN Circular 12340
Subject
GRB 110915A: Enhanced Swift-XRT position
Date
2011-09-15T19:22:20Z (14 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 2062 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 110915A, 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 = 310.82447, -0.72312 which is equivalent
to:
RA (J2000): 20h 43m 17.87s
Dec (J2000): -00d 43' 23.2"
with an uncertainty of 1.6 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 12342
Subject
GRB 110915A: 1.23m CAHA I-band observations
Date
2011-09-15T22:54:19Z (14 years ago)
From
Javier Gorosabel at IAA-CSIC <jgu@iaa.es>
R. Sanchez-Ramirez (IAA-CSIC), N. Morales (IAA-CSIC), J. Gorosabel (IAA-CSIC), J.L. Ortiz (IAA-CSIC), P. Kubanek (U. Valencia & IAA-CSIC), A. de Ugarte Postigo (DARK/NBI), A.J. Castro-Tirado (IAA-CSIC), report on behalf of a larger collaboration:
"We imaged the field of the Swift GRB 110915A (Holland et al., GCN Circ 12335) with the 1.23m Calar Alto telescope. The observations were carried out in the I-band on Sep 15.7984-15.8500 UT (starting 5.81 hours after the GRB) with a total exposure time of 25 X 180 = 4500s. No object brighter than I=21.5 is detected in the XRT error circle (Evans et al., GCN Circ 12340)."
GCN Circular 12343
Subject
GRB 110915A: NOT observations
Date
2011-09-16T00:26:36Z (14 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
D. Malesani (DARK, NBI), P. Jakobsson (U. Iceland), A. de Ugarte Postigo
(DARK, NBI), J. Lykke (NOT), D. Xu (WIS), and N. R. Tanvir (U.
Leicester) report on behalf of a larger collaboration:
Using ALFOSC on the Nordic Optical Telescope (NOT) we have obtained
R-band (3 x 600 s) and z-band (18 x 300 s) imaging of the GRB 110915A
field (Holland et al., GCN 12335) starting on 2011 September 15.87 UT
(around 7.5 hr after the burst).
We do not detect any object within the refined XRT error circle (Evans
et al., GCN 12340). The limiting magnitudes are R(Vega) = 24.3 and z(AB)
= 23.5, calibrated against the USNO-B1 and SDSS catalogs, respectively.
Using our R-band limit and preliminary X-ray fluxes, we obtain a
corresponding upper limit on beta_OX of around 0.1, rendering the burst
dark according to the definition proposed by Jakobsson et al. (2004,
ApJ, 617, L21). This burst may therefore be at high redshift, or suffer
from significant dust extinction. The presence of significant excess
absorption in the X-ray afterglow spectrum
(http://www.swift.ac.uk/xrt_spectra/00503219/) makes the second option
more likely.
GCN Circular 12344
Subject
GRB 110915A: MITSuME Okayama and Ishigakijima Optical upper limits
Date
2011-09-16T00:58:08Z (14 years ago)
From
Daisuke Kuroda at OAO/NAOJ <dikuroda@oao.nao.ac.jp>
D. Kuroda, (OAO, NAOJ), H. Hanayama (IAO, NAOJ), K. Yanagisawa,
Y. Shimizu, H. Toda (OAO, NAOJ), T. Miyaji J. Watanabe, (IAO, 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 110915A (Holland et al., GCNC 12335)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory
and the Murikabushi 1m telescope of Ishigakijima Astronomical
Observatory.
We did not find any new point source within the enhanced XRT error
circle (Evans, GCNC 12336) in all the three bands.
Three sigma upper limits of the OT are listed below. We used
SDSS catalog for flux calibration.
Ishigakijima Astronomical Observatory:
The observation started on 2011-09-15 13:28:55 UT (~8.2 min after
the burst).
T0+[day] MID-UT T-EXP[sec] g' Rc Ic
------------------------------------------------------
0.07421 15:07:35 9360.0 >22.0 >21.8 >20.7
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
Okayama Astrophysical Observatory:
The observation started on 2011-09-15 14:58:17 UT (~1.6 h after
the burst).
T0+[day] MID-UT T-EXP[sec] g' Rc Ic
------------------------------------------------------
0.08645 15:25:12 3060.0 >19.8 >20.2 >19.34
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
GCN Circular 12345
Subject
GRB110915A MITSuME Okayama J-band upper-limit
Date
2011-09-16T04:24:57Z (14 years ago)
From
Daisuke Kuroda at OAO/NAOJ <dikuroda@oao.nao.ac.jp>
Kenshi Yanagisawa, Daisuke Kuroda, Yasuhiro Shimizu, Kiichi Okita
(OAO/NAOJ), Michitoshi Yoshida (Hiroshima-U), Kouji Ohta(Kyoto-U)
and Nobuyuki Kawai(Tokyo Tech.) report on behalf of the MITSuME
collaboration.
We observed the field of GRB110915A (Holland et al, GCN12355) in J-band
with a wide-field near infrared imager at Okayama Astrophysical
Observatory (Japan). The imager has effective aperture of 0.91 m.
Observations started from 15:19 UT on 15th September, just 2 hours after
the BAT trigger, to 16:02 UT. The total exposure of 35 min was
successfully obtained.
In our co-add image, we did not find any new point source within the
enhanced XRT error circle (P.A. Evans et al., GCNC 12340) down to
limiting magnitude of J=17.3 (Vega, S/N=3) . The photometric
calibration was made against 2MASS field stars.
T0+[s] MID-UT T-EXP[sec] J
---------------------------------------------------
+8130 15:35 2110 >17.3
---------------------------------------------------
T0+ : Elapsed time after the burt [sec]
T-EXP: Total Exposure time [sec]
GCN Circular 12346
Subject
GRB 110915A: Deep Gemini-South i/z-band imaging
Date
2011-09-16T04:40:32Z (14 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley (Caltech), A. Cucchiara (UC Santa Cruz), and N. R. Tanvir
(Leicester) report on behalf of a larger collaboration:
We imaged the field of GRB 110915A (Holland et al., GCN 12335) with
GMOS-S on Gemini-South starting at 00:36 UT on 2011-09-16. We acquired
6x240 seconds in i-band, and 7x240 seconds in z-band. Conditions were
clear with generally good seeing (0.7").
We find no significant sources within the XRT error circle in either
filter. We calculate the following 3-sigma limits:
i > 26.0 mag (t_mid = 11.49 hr)
z > 24.9 mag (t_mid = 12.03 hr)
Given the bright X-ray afterglow and and other optical limits reported
to date, these results indicate that GRB 110915A is a very dark burst,
as also noted by Malesani et al (GCN 12343). Infrared and radio
follow-up is encouraged.
GCN Circular 12349
Subject
GRB 110915A: Deep Near-IR Limits from Magellan
Date
2011-09-16T12:27:01Z (14 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
E. Berger, R. Chornock, J. Strader (Harvard) and L. Spitler (Swinburne)
report:
"We imaged the field of GRB 110915A (GCN 12335) with the FourStar near-IR
imager mounted on the Magellan/Baade 6.5-m telescope starting on 2011 Sep
16.155 UT (14.4 hr after the burst). Observations were obtained in the J
and Ks filters in good seeing (0.6"). We do not detect any sources in
coincidence with the enhanced XRT position (GCN 12340) to a 3-sigma limit of
J>23.5 mag and Ks>23.0 mag (AB). The X-ray flux on the same timescale
(extrapolated from the existing XRT light curve) is F_X ~ 4e-12 cgs,
indicating an expected near-IR brightness of J~19 mag and K~18.5 mag. If
due to extinction, the required ~4.5 mag in J and Ks are suggestive of an
unusually large A_V."
GCN Circular 12351
Subject
GRB 110915A: Swift-XRT refined Analysis
Date
2011-09-16T13:30:40Z (14 years ago)
From
Boris Sbarufatti at INAF-OAB/IASFPA <boris.sbarufatti@brera.inaf.it>
B. Sbarufatti (INAF-OAB/IASFPA) and S. T. Holland (CRESST/USRA/GSFC)
report on behalf of the Swift-XRT team:
We have analysed 3.3 ks of XRT data for GRB 110915A (Holland et al.
GCN Circ. 12335), from 82 s to 7.7 ks after the BAT trigger. The data
comprise 1.6 ks in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Evans et al. (GCN. Circ 12336).
The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=5.6 (+0.6, -0.4). At T+120 s the decay
flattens to an alpha of 0.49 (+0.15, -1.09) before breaking again at
T+309 s to a final decay with index alpha=0.84 (+0.04, -0.03).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.98 (+/-0.05). The
best-fitting absorption column is 2.69 (+0.18, -0.17) x 10^21 cm^-2,
in excess of the Galactic value of 5.3 x 10^20 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 2.04 (+0.21, -0.20)
and a best-fitting absorption column of 2.6 (+/-0.7) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 4.0 x 10^-11 (6.3 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.6 (+/-0.7) x 10^21 cm^-2
Galactic foreground: 5.3 x 10^20 cm^-2
Excess significance: 6.5 sigma
Photon index: 2.04 (+0.21, -0.20)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00503219.
This circular is an official product of the Swift-XRT team.
GCN Circular 12352
Subject
GRB 110915A, Swift-BAT refined analysis
Date
2011-09-16T14:33:10Z (14 years ago)
From
Hans Krimm at NASA-GSFC <hans.krimm@nasa.gov>
T. N. Ukwatta (MSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), S. T.
Holland (CRESST/USRA/GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU),
J. Tueller (GSFC), (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 110915A (trigger #503219)
(Holland, et al., GCN Circ. 12335). The BAT ground-calculated position is
RA, Dec = 310.830, -0.713 deg which is
RA(J2000) = 20h 43m 19.2s
Dec(J2000) = -00d 42' 45.8"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 25%.
The light curve consists first of a group of multiple overlapping peaks lasting
from T0-5 sec to T0+45 sec. This is followed by a second cluster from T0+55
sec to T0+85 sec, containing the brightest peak at ~T0+70 sec. T90 (15-350 keV)
is 78.76 +- 1.25 sec (estimated error including systematics).
The time-averaged spectrum from -2.74 to 92.1 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 0.94 +- 0.23,
and Epeak of 124.8 +- 41.4 keV (chi squared 58.07 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 5.7 +- 0.2 x 1006 erg/cm2
and the 1-sec peak flux measured from T+68.04 sec in the 15-150 keV band is
3.3 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.41 +- 0.05 (chi squared 72.11 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/503219/BA/
GCN Circular 12353
Subject
GRB 110915A: GROND Upper limits
Date
2011-09-16T18:32:42Z (14 years ago)
From
Alexander Kann at TLS Tautenburg <kann@tls-tautenburg.de>
J. Elliott (MPE Garching), D. A. Kann (Tautenburg Obs.), and J. Greiner
(also MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 110915A (Swift trigger 503219; Holland et
al., GCN 12335) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2m MPI/ESO telescope at La Silla
Observatory (Chile).
Observations started at 23:26 UT on 15 September, 10.1 hours after the GRB
trigger. They were performed at an average seeing of 1.1 and at an average
airmass of 1.2.
We do not detect a source within the enhanced UVOT/Swift-XRT error circle
reported by Evans et al. (GCN 12340). For a total exposure time of 6003 s
in g'r'i'z' and 4800 s in JHK, we do not detect a source down to:
g' > 25.5,
r' > 25.4,
i' > 24.3,
z' > 23.8,
J > 21.2,
H > 20.0, and
K > 18.6
The given limits are derived based on calibrating the images against GROND
zeropoints (g'r'i'z' are AB mags) and 2MASS field stars (JHK are Vega
mags) and are not corrected for the Galactic foreground extinction
corresponding to a reddening of E(B-V) = 0.058 in the direction of the
burst (Schlegel et al. 1998).
These upper limits are in agreement with the i/z upper limits from Perley
et al. (GCN 12346) and the J/Ks upper limits from Berger et al. (GCN
12349).
[GCN OPS NOTE(16sep11): Per author's request, the date in the second paragraph
was corrected from "16 Sep" to "15 Sep", and Perley citation was changed
from "12345" to "12346".]
GCN Circular 12355
Subject
GRB 110915A: Swift/UVOT Upper Limits
Date
2011-09-17T20:18:06Z (14 years ago)
From
Erik Hoversten at Swift/Penn State <hoversten@astro.psu.edu>
E. A. Hoversten (PSU) and S. T. Holland (CRESST/USRA/GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 110915A
84 ks after the BAT trigger (Holland et al., GCN Circ. 12335). No
optical afterglow consistent with the enhanced XRT position (Evans et
al., GCN Circ. 12340) is detected in the initial UVOT exposures.
UVOT magnitude 3-sigma upper limits are reported in the following table:
Filter T_start T_stop Exp(s) Mag (3-sigma upper limit)
-------------------------------------------------------------
white 84 1884 429 > 21.46
v 616 5316 203 > 19.35
b 540 1858 136 > 20.10
u 284 1834 362 > 20.36
uvw1 665 1809 136 > 19.59
uvm2 641 1784 136 > 19.46
uvw2 592 1897 144 > 19.82
The quoted upper limits have not been corrected for the expected
Galactic extinction along the line of sight of E_(B-V) = 0.06
(Schlegel et al. 1998). All photometry is on the UVOT photometric
system described in Poole et al. (2008, MNRAS, 383, 627).
GCN Circular 12358
Subject
GRB 110915A: Konus-Wind and Swift/BAT joint spectral analysis
Date
2011-09-19T21:22:41Z (14 years ago)
From
Valentin Pal'shin at Ioffe Inst <val@mail.ioffe.ru>
V. Pal'shin, S. Golenetskii, R.Aptekar, E. Mazets, D. Frederiks, and
T. Cline on behalf of the Konus-Wind team,
T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC),
W. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
D. Palmer (LANL), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC), and T. Ukwatta (GWU)
report:
We performed the Konus-Wind and the Swift/BAT joint spectral analysis
of GRB 110915A (Swift/BAT trigger #503219: Holland et al., GCN Circ.
12335, Ukwatta et al. GCN Circ. 12352). Since the Konus-Wind observed
this GRB in the waiting mode, we only have 3 channel spectral data for
the Konus-Wind which cover the energy range from 20 keV to 1.2 MeV. The
joint spectral analysis of the Konus-Wind and the Swift/BAT data
allows us to derive the broad-band spectral parameters of this burst.
The time interval of the spectral data for each instrument is chosen
from T0(BAT)-3.3 to T0(BAT)+82.1 s where T0(BAT) is the trigger time
of BAT at 13:20:44.40 UTC. The energy ranges which we used in the joint
spectral analysis are 20-1200 keV and 14-150 keV for the Konus-Wind and
the Swift/BAT respectively. The spectral data of two instruments are
fitted with the spectral model multiplied by the constant factor to take
into account the systematic effective area uncertainties in the response
matrices of each instrument.
The spectrum is well fitted with a power-law with exponential cutoff
model: dN/dE ~ E^{alpha}*exp(-(2+alpha)*E/Epeak). No systematic residual
from the best fit model is seen in the spectral data of each instrument.
The BAT constant factor is 0.76(-0.08,+0.09) (the KW constant factor is
fixed to 1). The best fit spectral parameters are: alpha = -1.08
(-0.14/+0.19) and Epeak = 183 (-48/+80) keV (chi2/dof = 62/58). The best
fit spectral parameters for the GRB (Band) model are: alpha =
-0.90(-0.21,+0.24), beta = -2.2(-0.8,+0.3), and Epeak = 132(-28,+57) keV
(chi2/dof = 58/57). The derived alpha and Epeak are in agreement with
those derived from analysis of the BAT data alone (Ukwatta et al. GCN
Circ. 12352). The energy fluence in the 15-1200 keV band calculated by a
power-law with exponential cutoff model for this 85.4 s interval is
1.35(-0.20,+0.25)x10^-5 erg/cm2.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB110915A/
All the quoted errors are at the 90% confidence level.
GCN Circular 12786
Subject
GRB 110915A, the review of the sky area in plate archives
Date
2011-12-30T17:58:18Z (13 years ago)
From
Valentyna Golovnya at Main Astro Obs,Kyiv <golov_v@ukr.ne>
V.V. Golovnya (Main Astro Obs, Kyiv)
report:
We have undertaken the review of the sky area in vicinity of
GRB 110915A (Evans et al., GCN Circ.12340) on astronegatives,
collected in Ukrainian NAS Main astronomical observatory plate
archive (1976-1996). All the plates with the possible object
appearance are digitized using Microtek ScanMaker 9800XL TMA
and Epson Expression 10000XL flatbed scanners and have been
placed into Golosiiv Plate Archive database DBGPA with open
access to them.
The list of plates is given in the table:
YYYYMMDD/TimeUT --Plates-- Exp. LimMag Star USNOA2
19810930/180433 GUA040C000001A 27.0 16.50 0825-18636133
19820827/205711 GUA040C002422 60.3 14.40 0825-18638528
19820827/205711 GUA040D002423 60.3 14.40 0825-18638528
19820827/223853 GUA040C002424 15.0 13.75 0825-18638504
19820909/165505 TAS040A000325 23.0 17.10 0825-18635715
19820918/160521 TAS040A000331 23.0 16.50 0825-18636133
19910709/231157 GUA040C001830A 22.5 15.50 0825-18638699
Plates:
GUA040C,�the plates archive identifier of DWA (D/F=400/2000,
GUA040D M=103"/mm) of the Ukrainian NAS Main Astro obs.
(Marsden's number - 83) the plate number [1].
TAS040A -the plates archive identifier of DAZ (D/F=400/3000,
M=68.8"/mm) of the Tashkent Astro obs.
(Marsden's number - 186) the plate number [1].
Exp. - Duration of the maximum exposure (minutes).
LimMag - Limited V mag, derived in the 15 minutes area around
the location given in GCN Circ.12340:
RA(J2000): 20h 43m 17.87s, Dec(J2000): -00d 43' 23.2"
Star USNOA2 - Comparison star.
The preview images of 7 areas together with
the 15x15 min.of arc area from SkyMap can be found in
http://gua.db.ukr-vo.org/img/grb/110915A/index.html
The images with full resolution are available via e-mail on
demand.
References:
1.L.Pakuliak DATABASE of GOLOSIIV PLATE ARCHIVE (DBGPA V2.0),
http://gua.db.ukr-vo.org