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GRB 110411A

GCN Circular 11918

Subject
GRB 110411A: Swift detection of a burst
Date
2011-04-11T19:44:17Z (14 years ago)
From
Jamie A. Kennea at PSU/Swift-XRT <kennea@astro.psu.edu>
D. Grupe (PSU), S. Campana (INAF-OAB), J. R. Cummings (NASA/UMBC),
J. M. Gelbord (PSU), J. A. Kennea (PSU), C. B. Markwardt (NASA/GSFC),
B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU),
E. Sonbas (GSFC/USRA/Adiyaman Univ.), R. L. C. Starling (U Leicester),
C. A. Swenson (PSU) and T. N. Ukwatta (MSU) report on behalf of the
Swift Team:

At 19:34:11 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110411A (trigger=451165).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is RA, Dec 291.437, +67.732 which is 
   RA(J2000) = 19h 25m 45s
   Dec(J2000) = +67d 43' 55"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a double-peaked
structure with a duration of about 120 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 19:36:18.2 UT, 126.4 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 291.43966,
67.71117 which is equivalent to:
   RA(J2000)  = 19h 25m 45.52s
   Dec(J2000) = +67d 42' 40.2"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 75 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 (6.92 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 5.4
(+3.77/-2.83) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 1.26e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 135 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
0.10. 

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 11919

Subject
GRB 110411A: MASTER optical observations
Date
2011-04-11T21:16:53Z (14 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
O. Gres, K.Ivanov, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Chuvalaev
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

V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina
Blagoveschensk Educational State University, Blagoveschensk

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Tunka(Siberia) was pointed to the  GRB110411A 19 sec s after 
notice time and 44 sec after GRB time at 2011-04-11 19:34:55.3 UT in two 
polarizations.
On our first (10s exposure) set we haven`t found optical  transient 
within SWIFT error-box (ra=19 25 45 dec=+67 43 48 r=0.050000).
The 5-sigma upper limit has been about 17.5 mag
Observations and data reduction is continued.
The message may be cited.

GCN Circular 11920

Subject
GRB 110411A: Enhanced Swift-XRT position
Date
2011-04-11T23:56:36Z (14 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2358 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 110411A, 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 = 291.44219, +67.71167 which is equivalent
to:

RA (J2000): 19h 25m 46.13s
Dec (J2000): +67d 42' 42.0"

with an uncertainty of 1.8 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 11921

Subject
GRB 110411A, Swift-BAT refined analysis
Date
2011-04-12T00:05:34Z (14 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <james.r.cummings@nasa.gov>
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), D. Grupe (PSU), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):

Using the data set from T-61 to T+242 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 110411A (trigger #451165)
(Grupe, et al., GCN Circ. 11918).  The BAT ground-calculated position is
RA, Dec = 291.427, 67.706 deg which is
     RA(J2000)  =  19h 25m 42.5s
     Dec(J2000) = +67d 42' 21.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 71%.

The burst had multiple peaks with gradual rise and fall. The two largest peaks
were centered around T+5 sec and T+60 sec.  T90 (15-350 keV) is 80.3 +- 5.2 sec
(estimated error including systematics).

The time-averaged spectrum from T-11.9 to T+86.3 sec is best fit by a power
law with an exponential cutoff.  This fit gives a photon index 1.51 +- 0.31,
and Epeak of 41.0 +- 8.1 keV (chi squared 49.70 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 3.3 +- 0.2 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T+4.73 sec in the 15-150 keV band is
1.3 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 2.05 +- 0.07 (chi squared 59.73 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/451165/BA/

GCN Circular 11923

Subject
GRB 110411A : Xinglong TNT OT candidate
Date
2011-04-12T09:03:58Z (14 years ago)
From
L.P. Xin at NAOC <xlp@bao.ac.cn>
L.P. Xin, Z. X. Ling, Y.L. Qiu, J.Y. Wei, J. Wang, 
J.S. Deng, C. Wu, X. H. Han on behalf of EAFON report:

We began to observe GRB110411A ( Grope et al., GCN 11918) 
with Xinglong TNT telescope at  19:35:32 (UT), 81 sec after 
the burst. A series of White and R-band images were obtained. 
With the combination of all R-band images of 37*60 sec 
exposure time, we detected an new source nearby the 
errorbox  of X-ray counterpart ( Goad et al., GCN 11920 ).

The coordinates of new source are:

Ra:    19:25:45.65 
Dec:   67:42:39.1
Epoch: J2000

The uncertainty of the coordinates is about 1 arc. 

The brightness of this source is estimated to be about 
21 +/- 0.2 mag in the R band, at the mean time of 38 min 
after the burst, comparing to an USNO B1.0 R2 reference star, 
of which the coordinates are 
19:25:52.432 +67:43:44.07 J2000 R2=16.18mag.

We proposed that the new source be the optical 
counterpart of GRB 110411A.

This message may be cited.

GCN Circular 11924

Subject
GRB 110411A: MASTER prompt and follow-up optical limits
Date
2011-04-12T11:00:43Z (14 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
O. Gres, K.Ivanov, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Chuvalaev
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

V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina
Blagoveschensk Educational State University, Blagoveschensk

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in 
Tunka(Siberia) was pointed to the  GRB110411A (Grupe et al., GCN 11918) 19 
sec s after notice time and 44 sec after GRB time at 2011-04-11 19:34:55.3 UT in two polarizations.
A series of Polarization, White and R-band images were obtained.
We have not found OT at Xinglong TNT OT candidate position (Xin et al., GCN Circ 11923). 
The results from two tubes are:
(GRB Time = 2011-04-11 19:34:11 UT)

Date time 	    Exp.time    Limit	Filt.(W-white)
    UT                   (s)   (5-sigma)
2011-04-11 19:34:55	10	17.4	W
2011-04-11 19:34:55	10	18.0	W
2011-04-11 19:35:23	10	14.8	P/
2011-04-11 19:35:23	10	15.4	P\
2011-04-11 19:35:50	20	15.5	P/
2011-04-11 19:35:51	20	16.0	P\
2011-04-11 19:36:29	30	16.0	P/
2011-04-11 19:36:29	30	16.5	P\
2011-04-11 19:37:17	40	16.0	P/
2011-04-11 19:37:18	40	16.7	P/
2011-04-11 19:38:14	50	16.3	P\
2011-04-11 19:38:14	50	16.9	P/
2011-04-11 19:39:22	60	16.5	P\
2011-04-11 19:39:22	60	17.0	P/
2011-04-11 19:40:39	80	16.6	P\
2011-04-11 19:40:39	80	17.2	P/
2011-04-11 19:42:14	3790	19.4	P\
2011-04-11 19:42:14	100	17.0	P/
2011-04-11 19:42:15	3970	18.9	P\
2011-04-11 19:42:15	100	17.7	P/
2011-04-11 19:44:10	120	17.4	P\
2011-04-11 19:44:11	120	17.4	P/
2011-04-11 19:46:26	150	17.8	P\
2011-04-11 19:46:26	150	17.7	P/
2011-04-11 19:49:11	180	18.1	P\
2011-04-11 19:49:12	180	17.9	P/
2011-04-11 19:52:30	180	18.0	P\
2011-04-11 19:52:30	180	17.9	P/
2011-04-11 19:55:46	180	18.1	P\
2011-04-11 19:55:46	180	18.0	P/
2011-04-11 19:59:02	180	18.1	P\
2011-04-11 19:59:02	180	18.1	P/
2011-04-11 20:02:17	180	18.1	P\
2011-04-11 20:02:18	180	18.1	P/
2011-04-11 20:05:33	180	18.1	P\
2011-04-11 20:05:34	180	18.1	P/
2011-04-11 20:08:49	180	18.0	P\
2011-04-11 20:08:49	180	18.0	P/
2011-04-11 20:12:06	180	18.0	P\
2011-04-11 20:12:06	180	18.0	P/
2011-04-11 20:15:23	180	18.1	P\
2011-04-11 20:15:24	180	18.0	P/
2011-04-11 20:18:40	180	18.1	P\
2011-04-11 20:18:41	180	18.0	P/
2011-04-11 20:21:57	180	18.1	P\
2011-04-11 20:21:58	180	18.0	P/
2011-04-11 20:25:14	180	18.0	P\
2011-04-11 20:25:14	180	18.0	P/
2011-04-11 20:28:38	180	18.1	P\
2011-04-11 20:28:40	180	18.0	P/
2011-04-11 20:31:56	180	18.1	P\
2011-04-11 20:31:57	180	18.0	P/
2011-04-11 20:35:13	180	18.0	P\
2011-04-11 20:35:13	180	17.9	P/
2011-04-11 20:38:32	180	18.1	P\
2011-04-11 20:38:32	180	17.9	P/
2011-04-11 20:41:48	180	17.8	P\
2011-04-11 20:41:48	180	17.9	P/
2011-04-11 20:45:04	180	17.8	P\
2011-04-11 20:45:04	180	17.9	P/
2011-04-11 20:48:20	180	17.8	P\
2011-04-11 20:48:20	180	17.7	P/
2011-04-11 20:51:45	180	17.7	P\
2011-04-11 20:51:46	180	17.7	P/
2011-04-11 20:59:09	180	19.0	W
2011-04-11 20:59:09	900	19.4	W
2011-04-11 20:59:09	180	18.8	R
2011-04-11 20:59:09	900	19.2	R
2011-04-11 21:02:42	180	18.7	W
2011-04-11 21:02:43	180	18.8	R
2011-04-11 21:06:52	180	18.5	W
2011-04-11 21:06:52	180	18.5	R
2011-04-11 21:10:28	180	18.2	W
2011-04-11 21:10:28	180	18.3	R
2011-04-11 21:14:04	180	18.0	W
2011-04-11 21:14:04	180	18.0	R

The message may be cited.

GCN Circular 11925

Subject
GRB 110411A: Swift/UVOT Upper Limits
Date
2011-04-12T11:59:12Z (14 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N.P.M. Kuin (MSSL/UCL) and D. Grupe (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 110411A
135 s after the BAT trigger (Grupe et al., GCN Circ. 11918).
No optical afterglow consistent with the XRT (Goad et al., GCN Circ.
11920) or the Xinglong (Xin et al., GCN Circ. 11923) positions
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           135          285          147         >21.3
u_FC               347          597          246         >20.4
white              135         7753          883         >22.2
v                  677         8164          607         >19.9
b                  603         7548          586         >21.1
u                  347         7343          637         >20.4
w1                 726         7139          391         >20.2
m2                 701         8326          508         >20.1
w2                 653         7959          607         >20.9

The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.10 in the direction of the burst
(Schlegel et al. 1998).

GCN Circular 11927

Subject
GRB 110411A: Swift-XRT refined Analysis
Date
2011-04-12T16:26:11Z (14 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 11 ks of XRT data for GRB 110411A (Grupe  et al. GCN
Circ. 11918), from 117 s to 37.2 ks after the  BAT trigger. The data
comprise 64 s in Windowed Timing (WT) mode (the first 8 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 Goad et al.
(GCN. Circ 11920).

The light curve can be modeled with a series of power-law decays. The
initial decay index is alpha=6.0 (+/-0.6). At T+230 s  the decay
flattens to an alpha of 0.58 (+0.11, -0.12) before breaking again at
T+4446 s to a final decay with index alpha=1.39 (+0.27, -0.24).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.93 (+0.23, -0.21). The
best-fitting absorption column is  1.02 (+0.14, -0.12) x 10^22 cm^-2,
in excess of the Galactic value of 6.9 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 4.0 x 10^-11 (2.3 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.02 (+0.14, -0.12) x 10^22 cm^-2
Galactic foreground: 6.9 x 10^20 cm^-2
Excess significance: 13.5 sigma
Photon index:	     2.93 (+0.23, -0.21)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00451165.

With an excess absorption column density of 9.5 x 10^21 cm^-2 following
the relation in Grupe et al. (2007, AJ, 133, 2216) the estimated 
 maximum redshift of the afterglow is z < 1.0.

This circular is an official product of the Swift-XRT team.

GCN Circular 11928

Subject
GRB 110411A: optical limits from OSN
Date
2011-04-12T18:26:34Z (14 years ago)
From
Martin Jelinek at Inst.Astrophys.Andalucia,Granada <mates@iaa.es>
A. Sota, J. Gorosabel and M. Jelinek (IAA-CSIC), 
report on behalf of a larger collaboration.

"We have observed the XRT error circle (Goad et al. GCNC
11920) of GRB 110411A (Grupe et al. GCNC 11918) with the 1.5m
telescope of Observatorio de Sierra Nevada, Granada, Spain.
The observations were carried out on April 12.06606-12.12741
UT (6.01-7.49 hours post trigger) in the R and I bands with an
exposure time of 8x300s in each band. No object is detected
within the XRT error circle down to R < 23.5 and I < 22.4,
calibrated against USNO B1.0".

GCN Circular 11930

Subject
GRB 110411A: PAIRITEL NIR Upper Limits
Date
2011-04-12T22:35:19Z (14 years ago)
From
Adam Morgan at U.C. Berkeley <qmorgan@gmail.com>
A. N. Morgan, A. Cucchiara, and J. S. Bloom (UC Berkeley) report:

We observed the field of GRB 110411A (Grupe et al., GCN 11918) with the 1.3m
PAIRITEL located at Mt. Hopkins, Arizona. Observations began at 2011-04-12
09:53:13 UT, ~14.3 hours after the Swift Trigger.  In  mosaics (effective
exposure time of 1.22 hours) taken simultaneously in the J, H, and Ks
filters, we do not detect any source at the optical afterglow candidate
location (Xin et al., GCN 11923).

The preliminary photometry yields:

post burst
t_mid (hr) exp.(hr) filt  U. Limit (3 sig)
15.37      1.22     J     > 18.7
15.37      1.22     H     > 18.0
15.37      1.22     H     > 16.6

All magnitudes are given in the Vega system, calibrated to 2MASS. No
correction for Galactic extinction has been made to the above reported
values.

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