Gamma-ray Burst 110903A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Sat 03 Sep 11 02:41:19 UT
NOTICE_TYPE:    INTEGRAL Wakeup
TRIGGER_NUM:    6335,   Sub_Num: 0
GRB_RA:         197.0374d {+13h 08m 09s} (J2000),
                197.1552d {+13h 08m 37s} (current),
                196.5314d {+13h 06m 08s} (1950)
GRB_DEC:        +58.9956d {+58d 59' 44"} (J2000),
                +58.9335d {+58d 56' 01"} (current),
                +59.2621d {+59d 15' 44"} (1950)
GRB_ERROR:      2.62 [arcmin, radius, statistical only]
GRB_INTEN:      21.60 [sigma]
GRB_TIME:       9595.12 SOD {02:39:55.12} UT
GRB_DATE:       15807 TJD;   246 DOY;   11/09/03
SC_RA:          206.38 [deg] (J2000)
SC_DEC:          50.56 [deg] (J2000)
SUN_POSTN:      161.79d {+10h 47m 09s}   +7.72d {+07d 42' 56"}
SUN_DIST:        57.86 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:     225.93d {+15h 03m 43s}  -20.10d {-20d 06' 11"}
MOON_DIST:       82.51 [deg]
GAL_COORDS:     118.87, 58.00 [deg] galactic lon,lat of the burst
ECL_COORDS:     157.65, 57.83 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:           
COMMENTS:        NOTE: This INTEGRAL event is temporally(21.0<100sec) coincident with the FERMI_GBM event (trignum=336710376).  
COMMENTS:       Possibly real GRB event

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 03 Sep 11 02:39:51 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      50
TRIGGER_NUM:     336710376
GRB_RA:          195.700d {+13h 02m 48s} (J2000),
                 195.815d {+13h 03m 15s} (current),
                 195.208d {+13h 00m 50s} (1950)
GRB_DEC:         +63.250d {+63d 15' 00"} (J2000),
                 +63.187d {+63d 11' 15"} (current),
                 +63.518d {+63d 31' 06"} (1950)
GRB_ERROR:       8.75 [deg radius, statistical plus systematic]
GRB_INTEN:       280 [cnts/sec]
DATA_SIGNIF:     11.70 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        15807 TJD;   246 DOY;   11/09/03
GRB_TIME:        9574.42 SOD {02:39:34.42} UT
GRB_PHI:         317.00 [deg]
GRB_THETA:        45.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.26
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic Transient
DETECTORS:       1,0,0, 1,1,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       161.79d {+10h 47m 09s}   +7.72d {+07d 42' 58"}
SUN_DIST:         60.64 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      225.91d {+15h 03m 39s}  -20.10d {-20d 06' 00"}
MOON_DIST:        86.57 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      120.77, 53.83 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      150.67, 60.20 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 263.40,-5.80 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 03 Sep 11 02:40:01 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      60
TRIGGER_NUM:     336710376
GRB_RA:          208.100d {+13h 52m 24s} (J2000),
                 208.182d {+13h 52m 44s} (current),
                 207.747d {+13h 50m 59s} (1950)
GRB_DEC:         +65.517d {+65d 30' 60"} (J2000),
                 +65.459d {+65d 27' 34"} (current),
                 +65.763d {+65d 45' 45"} (1950)
GRB_ERROR:       6.48 [deg radius, statistical plus systematic]
GRB_INTEN:       415 [cnts/sec]
DATA_SIGNIF:     17.00 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        15807 TJD;   246 DOY;   11/09/03
GRB_TIME:        9574.42 SOD {02:39:34.42} UT
GRB_PHI:         313.00 [deg]
GRB_THETA:        40.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.26
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic Transient
DETECTORS:       1,0,0, 1,1,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       161.79d {+10h 47m 09s}   +7.72d {+07d 42' 57"}
SUN_DIST:         66.05 [deg]   Sun_angle= -3.1 [hr] (East of Sun)
MOON_POSTN:      225.92d {+15h 03m 40s}  -20.10d {-20d 06' 01"}
MOON_DIST:        86.62 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      113.08, 50.43 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      153.42, 65.87 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 263.40,-5.80 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 03 Sep 11 02:44:46 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      59
TRIGGER_NUM:     336710376
GRB_RA:          200.140d {+13h 20m 34s} (J2000),
                 200.257d {+13h 21m 02s} (current),
                 199.636d {+13h 18m 33s} (1950)
GRB_DEC:         +55.080d {+55d 04' 48"} (J2000),
                 +55.019d {+55d 01' 08"} (current),
                 +55.342d {+55d 20' 30"} (1950)
GRB_ERROR:       8.31 [deg radius, statistical only]
DATA_SIGNIF:     18.70 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        15807 TJD;   246 DOY;   11/09/03
GRB_TIME:        9574.42 SOD {02:39:34.42} UT
GRB_PHI:         329.00 [deg]
GRB_THETA:        43.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4143 (Gnd S/W Version number)
SUN_POSTN:       161.79d {+10h 47m 09s}   +7.71d {+07d 42' 53"}
SUN_DIST:         56.30 [deg]   Sun_angle= -2.6 [hr] (East of Sun)
MOON_POSTN:      225.96d {+15h 03m 52s}  -20.11d {-20d 06' 36"}
MOON_DIST:        78.27 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      114.17, 61.55 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      164.87, 56.17 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 03 Sep 11 02:44:54 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      62
TRIGGER_NUM:     336710376
GRB_RA:          195.610d {+13h 02m 26s} (J2000),
                 195.736d {+13h 02m 57s} (current),
                 195.067d {+13h 00m 16s} (1950)
GRB_DEC:         +52.790d {+52d 47' 24"} (J2000),
                 +52.727d {+52d 43' 39"} (current),
                 +53.058d {+53d 03' 31"} (1950)
GRB_ERROR:       4.07 [deg radius, statistical only]
DATA_SIGNIF:     26.30 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        15807 TJD;   246 DOY;   11/09/03
GRB_TIME:        9574.42 SOD {02:39:34.42} UT
GRB_PHI:         332.00 [deg]
GRB_THETA:        46.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4143 (Gnd S/W Version number)
SUN_POSTN:       161.79d {+10h 47m 09s}   +7.71d {+07d 42' 53"}
SUN_DIST:         52.80 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      225.97d {+15h 03m 52s}  -20.11d {-20d 06' 37"}
MOON_DIST:        77.42 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      119.10, 64.26 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      163.96, 52.70 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 03 Sep 11 02:45:06 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      71
TRIGGER_NUM:     336710376
GRB_RA:          199.070d {+13h 16m 17s} (J2000),
                 199.192d {+13h 16m 46s} (current),
                 198.547d {+13h 14m 11s} (1950)
GRB_DEC:         +52.450d {+52d 27' 00"} (J2000),
                 +52.389d {+52d 23' 19"} (current),
                 +52.714d {+52d 42' 49"} (1950)
GRB_ERROR:       3.08 [deg radius, statistical only]
DATA_SIGNIF:     28.70 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        15807 TJD;   246 DOY;   11/09/03
GRB_TIME:        9574.42 SOD {02:39:34.42} UT
GRB_PHI:         333.00 [deg]
GRB_THETA:        44.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4143 (Gnd S/W Version number)
SUN_POSTN:       161.79d {+10h 47m 10s}   +7.71d {+07d 42' 53"}
SUN_DIST:         54.07 [deg]   Sun_angle= -2.5 [hr] (East of Sun)
MOON_POSTN:      225.97d {+15h 03m 52s}  -20.11d {-20d 06' 39"}
MOON_DIST:        76.16 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      114.20, 64.26 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      167.03, 53.77 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Sat 03 Sep 11 03:53:17 UT
NOTICE_TYPE:    INTEGRAL Offline
TRIGGER_NUM:    6335,   Sub_Num: 1
GRB_RA:         197.0613d {+13h 08m 15s} (J2000),
                197.1790d {+13h 08m 43s} (current),
                196.5554d {+13h 06m 13s} (1950)
GRB_DEC:        +58.9851d {+58d 59' 06"} (J2000),
                +58.9230d {+58d 55' 23"} (current),
                +59.2516d {+59d 15' 06"} (1950)
GRB_ERROR:      2.00 [arcmin, radius, statistical only]
GRB_INTEN:      21.60 [sigma]
GRB_TIME:       9595.12 SOD {02:39:55.12} UT
GRB_DATE:       15807 TJD;   246 DOY;   11/09/03
SC_RA:          206.38 [deg] (J2000)
SC_DEC:          50.56 [deg] (J2000)
SUN_POSTN:      161.83d {+10h 47m 20s}   +7.70d {+07d 41' 50"}
SUN_DIST:        57.86 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:     226.68d {+15h 06m 42s}  -20.25d {-20d 14' 53"}
MOON_DIST:       82.81 [deg]
GAL_COORDS:     118.85, 58.01 [deg] galactic lon,lat of the burst
ECL_COORDS:     157.68, 57.83 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:           
COMMENTS:        NOTE: This INTEGRAL event is temporally(21.0<100sec) coincident with the FERMI_GBM event (trignum=336710376).  
COMMENTS:       refined_coordinates_after_offline_analysis

GCN Circular #12322
S.Mereghetti (IASF-Milano), D.Gotz (CEA-Saclay), J. Borkowski (CAMK, Torun), C.Ferrigno, E.Bozzo (ISDC, Versoix), on behalf of the IBAS Localization Team report:
a long gamma ray burst lasting about 400 s has been detected by IBAS in the IBIS/ISGRI data at 02:39:55 UT of September 3.
Its refined coordinates (J2000) are:
```
  RA: 197.0614 [degrees]
  DEC: 58.9852 [degrees]
```
with an uncertainty of 2 arcmin (90% c.l.).
The light curve consists of three main peaks starting approximately at t0, t0+200 s, and t0+300 s. The high count rate of the burst saturated the ISGRI telemetry.
A plot of the light curve will be posted at
http://ibas.iasf-milano.inaf.it/IBAS_Results.html
GCN Circular #12323
S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report:
The very long GRB 110903A (localized by INTEGRAL: Mereghetti et al., GCN 12322) triggered Konus-Wind at T0=09573.115s UT (02:39:33.115)
The light curve shows two equally hard peaks started at ~T0 and at ~T0+190s respectively, and a third, softer peak, started at ~T0+320s. A total duration of the burst is ~370 s. The emission is seen up to ~7 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB110903_T09573/
As observed by Konus-Wind the burst had a fluence of 4.2(-0.7,+2.2)x10-5 erg/cm2, and a 256-ms peak flux, measured from T0+196.352 s, of 1.8(-0.4,+0.6)x10-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum of the burst (measured from T0 to T0+368.896 s) is best fitted in the 20 keV - 10 MeV range by a power law with exponential cutoff model, for which alpha = -0.96 (-0.29, +0.37), and Ep = 301(-80, +185) keV, chi2 = 77.8/88 dof. Fitting this spectrum by the GRB (Band) function yields the following model parameters: the low-energy photon index alpha = -0.93 (-0.31, +0.41), the high energy photon index beta = -2.7 (<-1.9), the peak energy Ep = 287(-89, +191) keV, chi2 = 77.6/87 dof.
The spectrum near the maximum count rate (measured from T0+196.864 to T0+205.056 s) is best fitted in the 20 keV - 10 MeV range by the GRB (Band) model, for which: the low-energy photon index alpha = -0.69 (-0.20, +0.24), the high energy photon index beta = -2.7 (<-2.2), the peak energy Ep = 295(-57, +77) keV, chi2 = 95.3/87 dof.
All the quoted results are preliminary. All the quoted errors are at the 90% confidence level.
GCN Circular #12324
K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:
We have analysed 3.9 ks of XRT data for the INTEGRAL-detected burst: GRB 110903A (Mereghetti et al., GCN Circ. 12322), from 33.8 ks to 45.3 ks after the INTEGRAL trigger. This GRB was also detected by Konus-Wind (Golenetskii et al., GCN Circ. 12323). The data are entirely in Photon Counting (PC) mode. An X-ray source is detected within the INTEGRAL error circle. Using 2176 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 197.06570, +58.98150 which is equivalent to:
```
RA (J2000): 13h 08m 15.77s
Dec(J2000): +58d 58' 53.5"
```
with an uncertainty of 1.8 arcsec (radius, 90% confidence). This position is 15.5 arcsec from the INTEGRAL position. The light curve is consistent with a constant source of mean count rate 6.1e-02 ct/sec. A power-law fit gives an index of 0.9 (+/-1.9).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.8 (+0.4, -0.5). The best-fitting absorption column is 3.7 (+2.2, -1.5) x 10^21 cm^-2, in excess of the Galactic value of 1.3 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 4.8 x 10^-11 (7.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.7 (+2.2, -1.5) x 10^21 cm^-2
Galactic foreground: 1.3 x 10^20 cm^-2
Excess significance: 4.0 sigma
Photon index:	     1.8 (+0.4, -0.5)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020184.
This circular is an official product of the Swift-XRT team.
GCN Circular #12325
E. A. Hoversten (PSU) and K.L. Page (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 110903A 33.8 ks after the INTEGRAL trigger (Mereghetti et al., GCN Circ. 12322). No optical afterglow consistent with the enhanced XRT position (Page, GCN Circ. 12324) 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    38935   45300    1507        > 21.94
v        39664   40380     705        > 19.86
u        33776   44483    1589        > 20.73
```
The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight of E_(B-V) = 0.01 (Schlegel et al. 1998). All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627).
GCN Circular #12326
S. McBreen (UCD/MPE) and G. Fitzpatrick (UCD) report on behalf of the Fermi GBM Team:
"At 02:39:34.42 UT on 03 September 2011, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 110903A (trigger 336710376 / 110903111), which was also detected by INTEGRAL (Mereghetti et al. 2011, GCN 12322) and Konus-Wind (Golenetskii et al. 2011, GCN 12323). The GBM on-ground location is consistent with the INTEGRAL position. The angle from the Fermi LAT boresight is 44 degrees.
The GBM light curve shows/consists of 3 main emission phases with a duration (T90) of about 339.9 (+/-2.3)s (50-300 keV). The time-averaged spectrum from T0-0 s to T0+339 s is well fit by a power law function with an exponential high-energy cutoff. The power law index is -0.88 +/- 0.04 and the cutoff energy, parameterized as Epeak, is 281.3 +/- 21.1 keV.
The event fluence (10-1000 keV) in this time interval is (3.3E-05 +/- 0.1)E-05 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+7.7 s in the 10-1000 keV band is 5.24 +/- 0.22 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #12347
Y. Hanabata, T. Uehara, T. Takahashi, M. Mizuno, M. Ohno, Y. Fukazawa (Hiroshima U.), T. Yasuda, Y. Terada, M. Tashiro, W. Iwakiri, K. Takahara, M. Asahina, S. Kobayashi, A. Sakamoto (Saitama U.), S. Sugita (Nagoya U.), K. Yamaoka (Aoyama Gakuin U.), M. Kokubun, T. Takahashi (ISAS/JAXA), Y. E. Nakagawa (Waseda U.), N. Ohmori, M. Akiyama, M. Yamauchi (Univ. of Miyazaki), Y. Urata, P. Tsai, C-J. Chuang (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo), on behalf of the Suzaku WAM team, report:
The very long, bright GRB110903A (Mereghetti et al. GCN 12322) was detected by the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 02:39:34.298 UT (=T0).
The observed light curve shows a multi-peaked structure starting at T0-57 s, ending at T0+364 s with a duration (T90) of about 340 secnds. There is a possible precursor at T0-57 s with a duration of about 15 seconds. The fluence in 100 - 1000 keV was 2.18 (-0.47, +0.22) x 10^-5 erg/cm^2. The 1-s peak flux measured from T0+198 s was 2.45 (-0.20, +0.17) photons/cm^2/s in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0 to T0+364 s is well fitted by a power-law with exponential cutoff model:
```
 dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
 alpha : 1.19 (-0.44, +0.54), and
 Epeak : 281 (-78, +33) keV (chi^2/d.o.f. = 39.2/31).
```
All the quoted errors are at statistical 90% confidence level.
The light curves for this burst are available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html
GCN Report 365.1
GCN_Report 365.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_365_1.pdf by K.L. Page at U.Leicester titled: "Final Swift Observations of GRB 110903A"

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Jochen Greiner, last update: 16-Sep-2011 [Disclaimer]