Gamma-ray Burst 120311B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 11 Mar 12 15:08:41 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     517489,   Seg_Num: 0
GRB_RA:          258.501d {+17h 14m 00s} (J2000),
                 258.673d {+17h 14m 42s} (current),
                 257.798d {+17h 11m 11s} (1950)
GRB_DEC:         -13.060d {-13d 03' 34"} (J2000),
                 -13.073d {-13d 04' 22"} (current),
                 -13.003d {-13d 00' 08"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       5253 [cnts]    Image_Peak=192 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   146     E_range: 25-100 keV
BKG_INTEN:       32312 [cnts]
BKG_TIME:        54472.01 SOD {15:07:52.01} UT
BKG_DUR:         8 [sec]
GRB_DATE:        15997 TJD;    71 DOY;   12/03/11
GRB_TIME:        54490.83 SOD {15:08:10.83} UT
GRB_PHI:          22.42 [deg]
GRB_THETA:        30.90 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     16.18 [sigma]
IMAGE_SIGNIF:    7.22 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  -3  +0  +1  +4  +0 
SUN_POSTN:       352.14d {+23h 28m 34s}   -3.39d {-03d 23' 26"}
SUN_DIST:         92.61 [deg]   Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN:      212.53d {+14h 10m 08s}  -16.12d {-16d 06' 57"}
MOON_DIST:        44.67 [deg]
MOON_ILLUM:      86 [%]
GAL_COORDS:        9.52, 14.75 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      258.63,  9.93 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is a rate trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 313.65,1.94 [deg].

red DSS finding chart ps-file
GCN Circular #13038
F. E. Marshall (NASA/GSFC), S. D. Barthelmy (GSFC), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), P. D'Avanzo (INAF-OAB), C. Guidorzi (U Ferrara), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU), E. Sonbas (NASA/GSFC/Adiyaman Univ.) and B.-B. Zhang (PSU) report on behalf of the Swift Team:
At 15:08:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120311B (trigger=517489). Swift did not slew immediately because of the Earth limb observing constraint. The BAT on-board calculated location is RA, Dec 258.501, -13.060 which is
```
   RA(J2000)  =  17h 14m 00s
   Dec(J2000) = -13d 03' 34"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows two peaks structure with a duration of about 20 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~10 sec after the trigger.
Due to an observing constraint, Swift will not slew until T0+49.0 minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is F. E. Marshall (marshall 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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 11 Mar 12 15:12:28 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     517489,   Seg_Num: 0
GRB_RA:          258.501d {+17h 14m 00s} (J2000),
                 258.673d {+17h 14m 42s} (current),
                 257.798d {+17h 11m 11s} (1950)
GRB_DEC:         -13.060d {-13d 03' 34"} (J2000),
                 -13.073d {-13d 04' 22"} (current),
                 -13.003d {-13d 00' 08"} (1950)
GRB_DATE:        15997 TJD;    71 DOY;   12/03/11
GRB_TIME:        54490.83 SOD {15:08:10.83} UT
TRIGGER_INDEX:   146
GRB_PHI:          22.42 [deg]
GRB_THETA:        30.90 [deg]
DELTA_TIME:      39.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     16.18 [sigma]
IMAGE_SIGNIF:    7.22 [sigma]
LC_URL:          sw00517489000msb.lc
SUN_POSTN:       352.15d {+23h 28m 35s}   -3.39d {-03d 23' 22"}
SUN_DIST:         92.61 [deg]   Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN:      212.57d {+14h 10m 17s}  -16.13d {-16d 07' 34"}
MOON_DIST:        44.63 [deg]
MOON_ILLUM:      86 [%]
GAL_COORDS:        9.52, 14.75 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      258.63,  9.93 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
COMMENTS:           
COMMENTS:        The next comments were copied from the BAT_POS Notice:  
COMMENTS:        This is a rate trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 313.65,1.94 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 11 Mar 12 15:59:58 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     517489,   Seg_Num: 0
POINT_RA:        258.504d {+17h 14m 01s} (J2000)
POINT_DEC:       -13.049d {-13d 02' 56"} (J2000)
IMG_START_DATE:  15997 TJD;    71 DOY;   12/03/11
IMG_START_TIME:  57558.53 SOD {15:59:18.53} UT,   3067.7 [sec] since BAT Trigger Time
COUNTS:          1    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        0    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 11 Mar 12 16:04:01 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     517489,   Seg_Num: 0
POINT_RA:        258.504d {+17h 14m 01s} (J2000)
POINT_DEC:       -13.049d {-13d 02' 56"} (J2000)
ROLL:            94.102d
IMG_START_DATE:  15997 TJD;    71 DOY;   12/03/11
IMG_START_TIME:  57562.81 SOD {15:59:22.81} UT,   3072.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     353174370
X_OFFSET:        838 [pixels]
Y_OFFSET:        952 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       998
Y_GRB_POS:       1112
BINNING_INDEX:   1
IM_URL:          sw00517489000msuni3079.fits
SUN_POSTN:       352.18d {+23h 28m 43s}   -3.38d {-03d 22' 31"}
SUN_DIST:         92.64 [deg]   Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN:      213.10d {+14h 12m 24s}  -16.27d {-16d 15' 57"}
MOON_DIST:        44.12 [deg]
MOON_ILLUM:      86 [%]
GAL_COORDS:        9.53, 14.75 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      258.63,  9.94 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 11 Mar 12 16:04:24 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     517489,   Seg_Num: 0
POINT_RA:        258.504d {+17h 14m 01s} (J2000)
POINT_DEC:       -13.049d {-13d 02' 56"} (J2000)
ROLL:            94.102d
IMG_START_DATE:  15997 TJD;    71 DOY;   12/03/11
IMG_START_TIME:  57562.81 SOD {15:59:22.81} UT,   3072.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     353174370
X_OFFSET:        838 [pixels]
Y_OFFSET:        952 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       998
Y_GRB_POS:       1112
BINNING_INDEX:   1
IM_URL:          sw00517489000msuni3079.fits
SUN_POSTN:       352.18d {+23h 28m 43s}   -3.38d {-03d 22' 31"}
SUN_DIST:         92.64 [deg]   Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN:      213.10d {+14h 12m 25s}  -16.27d {-16d 16' 01"}
MOON_DIST:        44.12 [deg]
MOON_ILLUM:      86 [%]
GAL_COORDS:        9.53, 14.75 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      258.63,  9.94 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 11 Mar 12 16:08:00 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     517489,   Seg_Num: 0
GRB_RA:          258.5614d {+17h 14m 14.73s} (J2000),
                 258.7331d {+17h 14m 55.93s} (current),
                 257.8578d {+17h 11m 25.88s} (1950)
GRB_DEC:         -13.0519d {-13d 03' 06.8"} (J2000),
                 -13.0653d {-13d 03' 54.9"} (current),
                 -12.9950d {-12d 59' 42.0"} (1950)
GRB_ERROR:       4.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  15997 TJD;    71 DOY;   12/03/11
IMG_START_TIME:  57589.00 SOD {15:59:49.00} UT,   3098.2 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       352.18d {+23h 28m 44s}   -3.37d {-03d 22' 27"}
SUN_DIST:         92.59 [deg]   Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN:      213.14d {+14h 12m 34s}  -16.28d {-16d 16' 36"}
MOON_DIST:        44.14 [deg]
MOON_ILLUM:      85 [%]
GAL_COORDS:        9.56, 14.70 [deg] galactic lon,lat of the burst
ECL_COORDS:      258.69,  9.94 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 1.1% < P(seren) < 2.8%.

GCN Circular #13040
J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU), G. Tagliaferri (INAF-OAB), S. Campana (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
The XRT began observing the field of GRB 120311B at 15:59:18.5 UT, 3067.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 258.56101, -13.05235 which is equivalent to:
```
   RA(J2000)  = 17h 14m 14.64s
   Dec(J2000) = -13d 03' 08.5"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 212 arcseconds from the BAT onboard position. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. This position is more than 2-sigma away from the BAT position, and so possibly unrelated to the trigger.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.64 x 10^21 cm^-2 (Kalberla et al. 2005).
GCN Circular #13041
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), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC) (i.e. the Swift-BAT team):
Using the data set from T-120 to T+258 sec from recent telemetry downlinks, we report further analysis of BAT GRB 120311B (trigger #517489) (Marshall, et al., GCN Circ. 13038). The BAT ground-calculated position is RA, Dec = 258.551, -13.068 deg, which is
```
   RA(J2000)  =  17h 14m 12.2s 
   Dec(J2000) = -13d 04' 05.0" 
```
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 62%.
The mask-weighted light curve shows two nearly separated peaks, the first starting at ~T-15 sec, peaking at ~T_0, and the minimum between the two peaks is at ~T+5 sec. The second peak peaks at ~T+10 sec, and returns to baseline at ~T+22 sec. T90 (15-350 keV) is 28.2 +- 5.5 sec (estimated error including systematics).
The time-averaged spectrum from T-13.88 to T+21.63 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.96 +- 0.14. The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+9.04 sec in the 15-150 keV band is 1.5 +- 0.2 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/517489/BA/
GCN Circular #13042
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 4834 s of XRT Photon Counting mode data and 10 UVOT images for GRB 120311B, 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 = 258.56208, -13.05144 which is equivalent to:
```
RA (J2000): 17h 14m 14.90s
Dec (J2000): -13d 03' 05.2"
```
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 #13044
P. D'Avanzo (INAF-OAB) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift-XRT team:
We have analysed 10 ks of XRT data for GRB 120311B (Marshall et al. GCN Circ. 13038), from 3.1 ks to 22.9 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN. Circ 13042).
The light curve can be modelled with a power-law decay with a decay index of alpha=0.69 (+/-0.11).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.01 (+0.22, -0.21). The best-fitting absorption column is 3.6 (+0.9, -0.8) x 10^21 cm^-2, in excess of the Galactic value of 1.6 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.2 x 10^-11 (7.0 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.6 (+0.9, -0.8) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^21 cm^-2
Excess significance: 3.9 sigma
Photon index:	     2.01 (+0.22, -0.21)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00517489.
This circular is an official product of the Swift-XRT team.
GCN Circular #13045
C. Guidorzi (U. Ferrara), A. Melandri (INAF-OAB), F. Virgili (LJMU), J. Japeli (U. Ljubljana) on behalf of a larger collaboration report:
"The 2-m Faulkes Telescope North robotically followed up GRB 120311B (Swift trigger 517489, Marshall et al., GCN Circ 13038) 200 sec after the GRB trigger time. Within the enhanced XRT error circle (Osborne et al., GCN Circ. 13042) we do not detect any object in R and i' filters down to the following limits:
```
Mid time from       Exposure        Filter       Magnitude
GRB (hr)            (s)
----------------------------------------------------------
0.29                240             R > 20.5
0.39                220             i' > 20.3
----------------------------------------------------------
```
Values are calibrated against nearby USNOB-1 field stars.
GCN Circular #13046
D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, 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 120311B (Marshall et al., GCNC 13038) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.
The observation started on 2012-03-11 16:48:04 UT (~1.7 h after the burst) We did not find any new point source within the enhanced XRT circle (Osborne et al., GCNC 13042) in all the three bands.
Three sigma upper limits of the OT are listed below. We used SDSS catalog for flux calibration.
```
T0+[day]   MID-UT   T-EXP[sec]    g'     Rc     Ic
------------------------------------------------------
0.09146    17:19:52    4380.0   >18.7  >18.8  >18.3
0.15451    18:50:40    4740.0   >19.6  >19.6  >18.9
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #13047
A. A. Breeveld (MSSL-UCL) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 120311B 3072 s after the BAT trigger (Marshall et al., GCN Circ. 13038). No optical afterglow consistent with the XRT position (Osborne et al., GCN Circ. 13042) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC          3072         3222          147         >21.4
white             3072        16503         2114         >22.8
v                 3228        21300         2013         >20.3
b                 4048        15591         1233         >20.7
u                 3843         5479          393         >19.7
w1                3638        22969         1136         >20.9
m2                3433        22206         1082         >20.8
w2                4460        17192         1754         >21.9
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.52 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #13050
Simone Leonini and Paolo Rosi (Montarrenti Observatory, Siena, Italy) report:
We observed the field of GRB 120311B (Swift trigger 517489, Marshall et al., GCN Circ 13038) with 0.53m RC telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code C88).
The first session of observations was started at 2012-03-12 03:59:24 UT and stopped at 2012-03-12 04:00:07 UT. The second session started at 04:11:47 UT and stopped at 04.12.26 UT (~13 hours after the trigger).
Four unfiltered images of 40s exposure was obtained. We do not detect any new point source in the coadded images (limit R~18.9, USNO-B1 catalogue) within the enhanced XRT error circle (Osborne et al., GCN Circ. 13042). Target was very low on the horizon.
[GCN OPS NOTE(12mar12): Distribution was delayed by ~3 hrs until an account could be created.]
GCN Circular #13059
Brajesh Kumar, Vijay Kumar Bhatt, S.B. Pandey (ARIES, Nainital, India, on behalf of larger Indian GRB collaboration).
GRB 120311B field (Marshall et al., GCN Circ 13038) was observed with the newly installed 1.3m Devasthal Fast Optical Telescope at Nainital. Several images in R_c pass-band (300 sec each) were taken in two sessions starting at UT 21:11:10, 11-03-2012.
In the initial co-added R_c frame (3x300sec), we did not detect any new optical source within the XRT error-box (Osborne et al., GCN Circ. 13042) down to a limiting magnitude of ~ 20.5 mag. The photometry was done in comparison to nearby USNO- B1 stars.
This massage may be cited.
GCN Report 371.1
GCN_Report 371.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_371_1.pdf by F.E. Marshall at NASA/GSFC titled: "Final Swift Observations of GRB 120311B"

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Jochen Greiner, last update: 13-Mar-2012 [Disclaimer]