Gamma-ray Burst 120327A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Mar 12 03:06:10 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     518731,   Seg_Num: 0
GRB_RA:          246.828d {+16h 27m 19s} (J2000),
                 247.021d {+16h 28m 05s} (current),
                 246.044d {+16h 24m 11s} (1950)
GRB_DEC:         -29.415d {-29d 24' 54"} (J2000),
                 -29.442d {-29d 26' 30"} (current),
                 -29.304d {-29d 18' 13"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       6922 [cnts]    Image_Peak=250 [image_cnts]
TRIGGER_DUR:     2.048 [sec] 
TRIGGER_INDEX:   271     E_range: 50-350 keV
BKG_INTEN:       69757 [cnts]
BKG_TIME:        10479.96 SOD {02:54:39.96} UT
BKG_DUR:         24 [sec]
GRB_DATE:        16013 TJD;    87 DOY;   12/03/27
GRB_TIME:        10516.63 SOD {02:55:16.63} UT
GRB_PHI:          76.19 [deg]
GRB_THETA:        17.09 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     8.54 [sigma]
IMAGE_SIGNIF:    8.58 [sigma]
MERIT_PARAMS:     +1  +0  +0  +1  +3  -1  +0  +1 +45  +0 
SUN_POSTN:         6.29d {+00h 25m 11s}   +2.72d {+02d 43' 14"}
SUN_DIST:        116.66 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:       53.65d {+03h 34m 37s}  +20.15d {+20d 08' 59"}
MOON_DIST:       164.74 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      349.34, 13.42 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      249.77, -7.59 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger integration interval;  
COMMENTS:        probably due to it occurring during a Malindi downlink session.  
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 = 11.89,3.73 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Mar 12 03:07:00 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     518731,   Seg_Num: 0
GRB_RA:          246.8644d {+16h 27m 27.45s} (J2000),
                 247.0565d {+16h 28m 13.56s} (current),
                 246.0803d {+16h 24m 19.26s} (1950)
GRB_DEC:         -29.4156d {-29d 24' 56.1"} (J2000),
                 -29.4423d {-29d 26' 32.1"} (current),
                 -29.3045d {-29d 18' 16.0"} (1950)
GRB_ERROR:       4.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       5.41e-09 [erg/cm2/sec]
GRB_SIGNIF:      12.56 [sigma]
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  10592.21 SOD {02:56:32.21} UT,   75.6 [sec] since BAT Trigger Time
TAM[0-3]:        327.69 237.22 261.53 243.75
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:         6.29d {+00h 25m 11s}   +2.72d {+02d 43' 15"}
SUN_DIST:        116.63 [deg]   Sun_angle= 7.9 [hr] (West of Sun)
MOON_POSTN:       53.66d {+03h 34m 38s}  +20.15d {+20d 09' 03"}
MOON_DIST:       164.72 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      349.36, 13.40 [deg] galactic lon,lat of the burst
ECL_COORDS:      249.80, -7.58 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.88 arcmin from the BAT position.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Mar 12 03:07:07 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     518731,   Seg_Num: 0
GRB_RA:          246.8644d {+16h 27m 27.4s} (J2000),
                 247.0565d {+16h 28m 13.5s} (current),
                 246.0803d {+16h 24m 19.2s} (1950)
GRB_DEC:         -29.4156d {-29d 24' 56.1"} (J2000),
                 -29.4423d {-29d 26' 32.1"} (current),
                 -29.3045d {-29d 18' 16.0"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       158 [cnts]
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  10592.21 SOD {02:56:32.21} UT,   75.6 [sec] since BAT Trigger Time
CENTROID_X:      287.80,  raw= 288  [pixels]
CENTROID_Y:      305.63,  raw= 306  [pixels]
ROLL:            102.94 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   17.99
GRB_POS_XRT_Z:   -37.46
IMAGE_URL:       sw00518731000msxps_rw.img
SUN_POSTN:         6.29d {+00h 25m 11s}   +2.72d {+02d 43' 15"}
SUN_DIST:        116.63 [deg]   Sun_angle= 7.9 [hr] (West of Sun)
MOON_POSTN:       53.66d {+03h 34m 39s}  +20.15d {+20d 09' 03"}
MOON_DIST:       164.72 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      349.36, 13.40 [deg] galactic lon,lat of the burst
ECL_COORDS:      249.80, -7.58 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Mar 12 03:07:22 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     518731,   Seg_Num: 0
GRB_RA:          246.8644d {+16h 27m 27.4s} (J2000),
                 247.0565d {+16h 28m 13.5s} (current),
                 246.0803d {+16h 24m 19.2s} (1950)
GRB_DEC:         -29.4156d {-29d 24' 56.1"} (J2000),
                 -29.4423d {-29d 26' 32.1"} (current),
                 -29.3045d {-29d 18' 16.0"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       158 [cnts]
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  10592.21 SOD {02:56:32.21} UT,   75.6 [sec] since BAT Trigger Time
CENTROID_X:      287.80,  raw= 288  [pixels]
CENTROID_Y:      305.63,  raw= 306  [pixels]
ROLL:            102.94 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   17.99
GRB_POS_XRT_Z:   -37.46
IMAGE_URL:       sw00518731000msxps_rw.img
SUN_POSTN:         6.29d {+00h 25m 11s}   +2.72d {+02d 43' 16"}
SUN_DIST:        116.63 [deg]   Sun_angle= 7.9 [hr] (West of Sun)
MOON_POSTN:       53.66d {+03h 34m 39s}  +20.15d {+20d 09' 04"}
MOON_DIST:       164.72 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      349.36, 13.40 [deg] galactic lon,lat of the burst
ECL_COORDS:      249.80, -7.58 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Mar 12 03:08:03 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     518731,   Seg_Num: 0
GRB_RA:          246.828d {+16h 27m 19s} (J2000),
                 247.021d {+16h 28m 05s} (current),
                 246.044d {+16h 24m 11s} (1950)
GRB_DEC:         -29.415d {-29d 24' 54"} (J2000),
                 -29.442d {-29d 26' 30"} (current),
                 -29.304d {-29d 18' 13"} (1950)
GRB_DATE:        16013 TJD;    87 DOY;   12/03/27
GRB_TIME:        10516.63 SOD {02:55:16.63} UT
TRIGGER_INDEX:   271
GRB_PHI:          76.19 [deg]
GRB_THETA:        17.09 [deg]
DELTA_TIME:      12.00 [sec]
TRIGGER_DUR:     2.048 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     8.54 [sigma]
IMAGE_SIGNIF:    8.58 [sigma]
LC_URL:          sw00518731000msb.lc
SUN_POSTN:         6.30d {+00h 25m 11s}   +2.72d {+02d 43' 16"}
SUN_DIST:        116.66 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:       53.67d {+03h 34m 41s}  +20.15d {+20d 09' 07"}
MOON_DIST:       164.75 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      349.34, 13.42 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      249.77, -7.59 [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 = 11.89,3.73 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Mar 12 03:11:41 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     518731,   Seg_Num: 0
POINT_RA:        246.853d {+16h 27m 25s} (J2000)
POINT_DEC:       -29.418d {-29d 25' 05"} (J2000)
POINT_ROLL:      102.941d
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  10657.57 SOD {02:57:37.57} UT,   140.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.694
N_STARS:         190
X_OFFSET:        0 [pixels]
Y_OFFSET:        0 [pixels]
X_MAX:           2047 [pixels]
Y_MAX:           2047 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00518731000msufc0140.fits
SUN_POSTN:         6.30d {+00h 25m 11s}   +2.72d {+02d 43' 20"}
SUN_DIST:        116.64 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:       53.70d {+03h 34m 48s}  +20.16d {+20d 09' 24"}
MOON_DIST:       164.76 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      349.35, 13.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      249.79, -7.59 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Mar 12 03:13:17 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     518731,   Seg_Num: 0
POINT_RA:        246.853d {+16h 27m 25s} (J2000)
POINT_DEC:       -29.418d {-29d 25' 05"} (J2000)
ROLL:            102.941d
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  10657.57 SOD {02:57:37.57} UT,   140.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     354509865
X_OFFSET:        835 [pixels]
Y_OFFSET:        814 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       995
Y_GRB_POS:       974
BINNING_INDEX:   1
IM_URL:          sw00518731000msuni0149.fits
SUN_POSTN:         6.30d {+00h 25m 12s}   +2.72d {+02d 43' 21"}
SUN_DIST:        116.64 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:       53.71d {+03h 34m 51s}  +20.16d {+20d 09' 31"}
MOON_DIST:       164.77 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      349.35, 13.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      249.79, -7.59 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Mar 12 03:12:58 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     518731,   Seg_Num: 0
POINT_RA:        246.853d {+16h 27m 25s} (J2000)
POINT_DEC:       -29.418d {-29d 25' 05"} (J2000)
ROLL:            102.941d
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  10657.57 SOD {02:57:37.57} UT,   140.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     354509865
X_OFFSET:        835 [pixels]
Y_OFFSET:        814 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       995
Y_GRB_POS:       974
BINNING_INDEX:   1
IM_URL:          sw00518731000msuni0149.fits
SUN_POSTN:         6.30d {+00h 25m 12s}   +2.72d {+02d 43' 21"}
SUN_DIST:        116.64 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:       53.71d {+03h 34m 51s}  +20.16d {+20d 09' 29"}
MOON_DIST:       164.76 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      349.35, 13.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      249.79, -7.59 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Mar 12 03:20:43 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     518731,   Seg_Num: 0
POINT_RA:        246.853d {+16h 27m 25s} (J2000)
POINT_DEC:       -29.418d {-29d 25' 05"} (J2000)
ROLL:            102.941d
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  11390.03 SOD {03:09:50.03} UT,   873.4 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     354510598
X_OFFSET:        834 [pixels]
Y_OFFSET:        813 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       994
Y_GRB_POS:       973
BINNING_INDEX:   1
IM_URL:          sw00518731000msuni0882.fits
SUN_POSTN:         6.30d {+00h 25m 13s}   +2.72d {+02d 43' 29"}
SUN_DIST:        116.65 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:       53.78d {+03h 35m 07s}  +20.17d {+20d 10' 03"}
MOON_DIST:       164.82 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      349.35, 13.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      249.79, -7.59 [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:     Tue 27 Mar 12 03:20:54 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     518731,   Seg_Num: 0
POINT_RA:        246.853d {+16h 27m 25s} (J2000)
POINT_DEC:       -29.418d {-29d 25' 05"} (J2000)
ROLL:            102.941d
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  11390.03 SOD {03:09:50.03} UT,   873.4 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     354510598
X_OFFSET:        834 [pixels]
Y_OFFSET:        813 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       994
Y_GRB_POS:       973
BINNING_INDEX:   1
IM_URL:          sw00518731000msuni0882.fits
SUN_POSTN:         6.30d {+00h 25m 13s}   +2.72d {+02d 43' 29"}
SUN_DIST:        116.65 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:       53.78d {+03h 35m 07s}  +20.17d {+20d 10' 04"}
MOON_DIST:       164.82 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      349.35, 13.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      249.79, -7.59 [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:     Tue 27 Mar 12 03:12:19 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     518731,   Seg_Num: 0
POINT_RA:        246.853d {+16h 27m 25s} (J2000)
POINT_DEC:       -29.418d {-29d 25' 05"} (J2000)
POINT_ROLL:      102.941d
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  10657.57 SOD {02:57:37.57} UT,   140.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.694
N_STARS:         190
X_OFFSET:        0 [pixels]
Y_OFFSET:        0 [pixels]
X_MAX:           2047 [pixels]
Y_MAX:           2047 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00518731000msufc0140.fits
SUN_POSTN:         6.30d {+00h 25m 12s}   +2.72d {+02d 43' 20"}
SUN_DIST:        116.64 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:       53.71d {+03h 34m 49s}  +20.16d {+20d 09' 26"}
MOON_DIST:       164.76 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      349.35, 13.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      249.79, -7.59 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN Circular #13123
B. Sbarufatti (INAF-OAB/PSU), S. D. Barthelmy (GSFC), N. Gehrels (NASA/GSFC), E. A. Hoversten (PSU), N. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC) and T. N. Ukwatta (MSU) report on behalf of the Swift Team:
At 02:55:16 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120327A (trigger=518731). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 246.828, -29.415, which is
```
   RA(J2000)  =  16h 27m 19s
   Dec(J2000) = -29d 24' 54"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows 3 main peaks with a total duration of about 60 sec. The peak count rate was ~6500 counts/sec (15-350 keV), at ~38 sec after the trigger.
The XRT began observing the field at 02:56:32.2 UT, 75.6 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 246.86308, -29.41514 which is equivalent to:
```
   RA(J2000)  = 16h 27m 27.14s
   Dec(J2000) = -29d 24' 54.5"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 110 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 (1.40 x 10^21 cm^-2, Kalberla et al. 2005), with an excess column of 1.9 (+1.51/-1.37) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 5.41e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 140 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	16:27:27.47 = 246.86445
  DEC(J2000) = -29:24:53.8  = -29.41494
```
with a 90%-confidence error radius of about 0.64 arc sec. This position is 3.6 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.92 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.34.
Burst Advocate for this burst is B. Sbarufatti (boris.sbarufatti AT brera.inaf.it). 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:     Tue 27 Mar 12 03:20:14 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     518731,   Seg_Num: 0
GRB_RA:          246.8646d {+16h 27m 27.50s} (J2000),
                 247.0567d {+16h 28m 13.61s} (current),
                 246.0805d {+16h 24m 19.31s} (1950)
GRB_DEC:         -29.4152d {-29d 24' 54.7"} (J2000),
                 -29.4419d {-29d 26' 30.6"} (current),
                 -29.3041d {-29d 18' 14.6"} (1950)
GRB_ERROR:       2.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  10769.00 SOD {02:59:29.00} UT,   252.4 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:         6.30d {+00h 25m 13s}   +2.72d {+02d 43' 28"}
SUN_DIST:        116.64 [deg]   Sun_angle= 7.9 [hr] (West of Sun)
MOON_POSTN:       53.77d {+03h 35m 06s}  +20.17d {+20d 10' 01"}
MOON_DIST:       164.81 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      349.36, 13.40 [deg] galactic lon,lat of the burst
ECL_COORDS:      249.80, -7.58 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
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:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Mar 12 03:15:06 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     518731,   Seg_Num: 0
GRB_RA:          246.8644d {+16h 27m 27.45s} (J2000),
                 247.0565d {+16h 28m 13.56s} (current),
                 246.0803d {+16h 24m 19.26s} (1950)
GRB_DEC:         -29.4149d {-29d 24' 53.6"} (J2000),
                 -29.4416d {-29d 26' 29.6"} (current),
                 -29.3038d {-29d 18' 13.5"} (1950)
GRB_ERROR:       0.6 [arcsec radius, statistical only]
GRB_MAG:         17.92 +/- 0.14 [mag]
FILTER:          7, U
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  10657.00 SOD {02:57:37.00} UT,   140.4 [sec] since BAT Trigger Time
SUN_POSTN:         6.30d {+00h 25m 12s}   +2.72d {+02d 43' 23"}
SUN_DIST:        116.63 [deg]   Sun_angle= 7.9 [hr] (West of Sun)
MOON_POSTN:       53.73d {+03h 34m 55s}  +20.16d {+20d 09' 39"}
MOON_DIST:       164.77 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      349.36, 13.40 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      249.80, -7.58 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The UVOT position is 2.2 arcsec from the XRT position.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Mar 12 03:19:17 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     518731,   Seg_Num: 0
POINT_RA:        246.853d {+16h 27m 25s} (J2000)
POINT_DEC:       -29.418d {-29d 25' 05"} (J2000)
POINT_ROLL:      102.941d
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  11390.03 SOD {03:09:50.03} UT,   873.4 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.468
N_STARS:         190
X_OFFSET:        275 [pixels]
Y_OFFSET:        254 [pixels]
X_MAX:           1714 [pixels]
Y_MAX:           1693 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00518731000msufc0873.fits
SUN_POSTN:         6.30d {+00h 25m 13s}   +2.72d {+02d 43' 27"}
SUN_DIST:        116.65 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:       53.77d {+03h 35m 04s}  +20.17d {+20d 09' 57"}
MOON_DIST:       164.81 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      349.35, 13.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      249.79, -7.59 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Mar 12 03:19:43 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     518731,   Seg_Num: 0
POINT_RA:        246.853d {+16h 27m 25s} (J2000)
POINT_DEC:       -29.418d {-29d 25' 05"} (J2000)
POINT_ROLL:      102.941d
IMG_START_DATE:  16013 TJD;    87 DOY;   12/03/27
IMG_START_TIME:  11390.03 SOD {03:09:50.03} UT,   873.4 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.468
N_STARS:         190
X_OFFSET:        275 [pixels]
Y_OFFSET:        254 [pixels]
X_MAX:           1714 [pixels]
Y_MAX:           1693 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00518731000msufc0873.fits
SUN_POSTN:         6.30d {+00h 25m 13s}   +2.72d {+02d 43' 28"}
SUN_DIST:        116.65 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:       53.77d {+03h 35m 05s}  +20.17d {+20d 09' 59"}
MOON_DIST:       164.81 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      349.35, 13.40 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      249.79, -7.59 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN Circular #13124
Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR), Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:
We imaged the field of GRB 120327A detected by SWIFT (trigger 518731) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile.
The observations started 32.40min after the GRB trigger. The elevation of the field increased from 21 degrees above horizon and weather conditions were good. Observations cannot begin earlier because of the presence of the ESO 3.6 meter telescope that hid the field of view!
We detect a new fading source in the error box given by SWIFT We detected the candidate couterpart mentioned by Sbarufatti et al. (GCNC 13123).
OT is still at R=17.5 at 45 min after GRB.
Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction.
This message may be cited.
GCN Circular #13125
R.J. Smith, Francisco Virgili (Liverpool JMU) report on behalf of the LJMU GRB group:
The 2-m Liverpool Telescope automatically observed Swift GRB 120327A (Sbarufatti et al., GCN Circ. 13123) on March 27, from 03:22:59.1 UT, corresponding to 27.7 minutes after the BAT trigger time. Within the XRT error circle we clearly detect an fading optical source at
16:27:27.46 , -29:24:54.00 J2000
with an uncertainty of 0.6 arcsec, confirming the observations of Klotz et al (GCN 13124). We estimate the magnitude of the afterglow as follows:
```
Mid time from    Exp     Filter    Magnitude
GRB (min)        (s)
---------------------------------------------
34.9             10    R        16.1 +/- 0.3
64.5             60    R        17.0 +/- 0.3
---------------------------------------------
```
Magnitudes are calibrated against nearby USNOB-1 stars.
Observations are continuing.
GCN Circular #13127
A. LaCluyze, J. Haislip, K. Ivarsen, D. Reichart, J. Moore, H. T. Cromartie, R. Egger, A. Foster, N. Frank, M. Nysewander, A. Oza, E. Speckhard, A.Trotter, and J. A. Crain report:
Skynet observed the field of GRB120327A (Sbarufatti et al., GCN 13123) with the PROMPT telescopes located at CTIO in Chile beginning ~11 minutes after the burst in BVRI. =A0Observations were delayed due to horizon limits. We detect a bright, fading afterglow at the location reported by Klotz et al. (GCN 13124) in all filters. =A0A preliminary light curve, calibrated to nearby USNO B1.0 stars, =A0can be found at:
http://skynet.unc.edu/grb/grb120327a.png
Further observations are ongoing.
GCN Circular #13128
S. Covino, D. Fugazza, A. Rossi on behalf of the REM team report:
We imaged the field of GRB120327A (Sbarufatti et al., GCN 13123) with the recently re-aluminized REM telescope located at La Silla.
The optical counterpart also reported in GCN 13124 (Klotz et al.), GCN 13125 (Smith et al.) and GCN 13126 (LaCluyze et al.) is well detected both in the optical and in the NIR.
The source is detected from about 10 min from the GRB time and observations are still in progress. At 10min after the burst the source was approximately at H=12.69 +- 0.03, calibrated to 2MASS field stars.
GCN Circular #13129
V. Sudilovsky (MPE Garching), A. Nicuesa Guelbenzu (Tautenburg Observatory) and J. Greiner (MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 120327A (Swift trigger 518731; Sbarufatti et al., GCN #13123) simultaneously in g'r'i'z'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 03:34 UT, 39 minutes min after the GRB trigger, and are continuing. They were performed at an average seeing of 1.6" and at an average airmass of 2.3.
We found a single point source consistent with both the UVOT (Sbarufatti et al, GCN #13123) and Liverpool telescope (Smith et al., GCN #13125) afterglow position.
Based on the second of two 2.4 min of exposures in g'r'i'z' and 4 min in JHK, we estimate preliminary magnitudes (all in AB) at an observations midpoint 03:44 UT of
```
g' = 18.6 +- 0.1 mag,
r' = 17.5 +- 0.1 mag,
i' = 17.2 +- 0.1 mag,
z' = 17.0 +- 0.1 mag,
J  = 16.3 +- 0.1 mag, and
H  = 15.9 +- 0.1 mag
```
Given magnitudes are calibrated against GROND zeropoints as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.34 mag in the direction of the burst (Schlegel et al. 1998). If this value is correct for the line-of-sight to this GRB, then the substantially reduced g-band flux suggests a redshift around 3.
GCN Circular #13130
J. Gorosabel, A. J. Castro-Tirado (IAA-CSIC, Granada), C. Walker, J. Court, R. Duffy, T. Edwards, M. Herath, J. Kirk, S. Patel, S. Prajs, B. Tunbridge, D. Williams, R. Wood, P. Wright, T. Munoz-Darias, C. Knigge, M. Coriat (University of Southampton) and R. Gimeno (IAC, Tenerife), report:
"We observed the optical counterpart of GRB 120327A (Sbarufatti et al., GCNC 13123) with the 82cm IAC80 telescope at the Observatorio del Teide, Tenerife, Spain. The observations were carried out in the I-band on 04:06 - 05:33 UT (starting 1.12 hours post burst) with a total exposure time of 14x300s. A preliminary photometry, against the USNO B1.0 catalogue, shows a clear decay from R~18 to R~19.2".
GCN Circular #13132
Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR), Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:
We continue observations of GRB 120327A (trigger 518731) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile.
An optical decay alpha=1.3 (+/- 0.3) is deduced from the following observations:
No filter:
```
start  end     Rmag  dmag filter
(sec)  (sec)
1944.2 2234.6  16.96 0.17 CR
2387.2 3159.2  17.31 0.19 CR
3169.5 3938.0  17.81 0.09 CR
4156.0 4916.2  18.03 0.17 CR
4926.5 6102.7  18.84 0.13 CR
```
R filter:
```
start   end     Rmag  dmag filter
(sec)   (sec)
2767.6  3539.5  17.65 0.09 R
3948.0  4716.3  18.34 0.32 R
5116.5  7072.8  18.56 0.17 R
7472.9 10018.6  18.84 0.09 R
```
Photometry is relative to the star NOMAD1 0605-0398765: (ra,dec) J2000 = (246.8438328,-29.4187269) R=14.930. Magnitudes are not corrected for galactic dust extinction.
This message may be cited.
GCN Circular #13133
D. A. Perley (Caltech) and N. R. Tanvir (U. Leicester) report on behalf of a larger collaboration:
On March 27 starting at 06:01 UT (186 minutes after the BAT trigger) we began spectroscopic observations of the optical afterglow of GRB 120327A (Sbarufatti et al., GCN 13123) using GMOS-South on the Gemini-South 8-m telescope. We acquired four exposures of 800s each using the B600 grating, with wavelength coverage between 3865-6680 Angstroms.
In the reduced spectrum we identify a strong damped Lyman-alpha system at z=2.81 as well as numerous narrow absorption lines corresponding to (among others) CIV, CII, OI, SiII at the same redshift, as well as possible Lyman-beta. We therefore identify this as the redshift of the GRB.
We thank German Gimeno and the Gemini staff for prompt execution of the observations.
GCN Circular #13134
T. Kruehler, J. P. U Fynbo, B. Milvang-Jensen (all DARK), N. Tanvir (U. Leicester) and P. Jakobsson (U. Iceland) report on behalf of a larger collaboration.
We observed the optical/NIR afterglow (e.g., Sbarufatti et al., GCN# 13123, Klotz et al., GCN#13124, Smith et al., GCN#13125) of the Swift GRB 120327A (Sbarufatti et al., GCN# 13123) with the VLT/UT2 equipped with the X-shooter spectrograph. Observations started around 05:03 UT on 2012-03-27, which is roughly 2.13 hrs after the trigger. Four exposures in a nodding pattern with an integration time of 600 s each were obtained. The spectrum covers an approximate wavelength range between 3100 and 23000 AA. The slit width was set to 1" in the ultra-violet/blue arm, and 0.9" in the visual and near-infrared arm, resulting in a resolving power range of approximately 4500-7500.
Preliminary reduction of the spectrum shows a well detected continuum with several absorption features, that we identify with Ly-limit and Ly-alpha as well as absorption lines of CII/CII*, SiII/SiII*, AlI, FeII and MgII at a redshift of 2.813. This is confirms previous reports based on spectroscopy (Perley & Tanvir, GCN #13133) and photometry (Sudilovsky et al. GCN #13129).
We are grateful for the excellent support from the Paranal Observatory staff, in particular Dimitri Gadotti. We acknowledge private communication with the GROND team, in particular Vlad Sudilovsky.
GCN Circular #13135
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 1105 s of XRT Photon Counting mode data and 2 UVOT images for GRB 120327A, 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 = 246.86448, -29.41491 which is equivalent to:
```
RA (J2000): 16h 27m 27.47s
Dec (J2000): -29d 24' 53.7"
```
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 #13137
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), B. Sbarufatti (INAF-OAB/PSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from recent telemetry downlinks, we report further analysis of BAT GRB 120327A (trigger #518731) (Sbarufatti, et al., GCN Circ. 12123). The BAT ground-calculated position is RA, Dec = 246.854, -29.415 deg, which is
```
   RA(J2000)  =  16h 27m 25.0s 
   Dec(J2000) = -29d 24' 55.5" 
```
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 76%.
The mask-weighted light curve shows 3 main peaks (two weak peaks, then the main peak). The first starts at ~T-25 sec, peaks at ~T+2 sec; and the second peaks at ~T+18 sec. The main peak starts at ~T+30 sec, peaks at ~T+37 sec, and returns to baseline at ~T+180 sec. T90 (15-350 keV) is 62.9 +- 7.5 sec (estimated error including systematics).
The time-averaged spectrum from T-15.79 to T+74.58 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.52 +- 0.06. The fluence in the 15-150 keV band is 3.6 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+37.09 sec in the 15-150 keV band is 3.9 +- 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/518731/BA/
GCN Circular #13138
N. P. M. Kuin (MSSL-UCL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 120327A 141 s after the BAT trigger (Sbarufatti et al., GCN Circ. 13123). A source consistent with the enhanced XRT position (Osborne et al. GCN Circ. 13135) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
   RA  (J2000) =  16:27:27.48  = 246.864500 (deg.)
   Dec (J2000) = -29:24:53.74  = -29.414928 (deg.)
```
with an estimated uncertainty of 0.48 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

v                  448          468           20         15.68 +/- 0.10
b                  396          416           20         16.97 +/- 0.11
u                  141          391          246         18.02 +/- 0.08
w1                 497         1295           97        >19.0
m2                 622         1271           78        >19.2
w2                 424         1222           97        >19.6
```
The absence of detection in uvw1, uvm2, and uvw2 is consistent with the reported redshift of 2.81 (Perley & Tanvir, GCN Circ 13133, and Krueler et al, GCN Circ. 13134).
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.34 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #13140
Myungshin Im, Jae-Woo Kim, and Duho Kim (CEOU/Seoul National Univ.)
We observed GRB 120327A (Sbarufatti et al., GCN 13123) in g,r,i,z,Y filters using CQUEAN camera on the 2.1m Otto-Struve telescope at McDonald Observatory, Texas, US.
The observation started at 2012-03-27 11:00:08 UT, or about 8 hours after the BAT alert. In all of the g,r,i,z,Y-band images taken with 300 sec exposure each, we identify the afterglow (r ~ 20 AB mag) which was reported earlier by several groups (Klotz et al. GCN 13124, Smith et al. GCN 13125, Soulier et al. GCN 13126, LaCluyze et al. GCN 13127, Covino et al. GCN 13128,Sudilovsky et al. GCN 13129, Grosabel et al. GCN 13130).
Further observations are planned.
GCN Circular #13141
M.C. Stroh (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. Maselli (INAF-IASFPA), J.A. Kennea (PSU) and B. Sbarufatti report on behalf of the Swift-XRT team:
We have analysed 7.3 ks of XRT data for GRB 120327A (Sbarufatti et al. GCN Circ. 13123), from 66 s to 0 s after the BAT trigger. The data comprise 267 s in Windowed Timing (WT) mode (the first 7 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 Osborne et al. (GCN. Circ 13135).
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=2.95 (+0.10, -0.11). At T+217 s the decay flattens to an alpha of 0.62 (+0.09, -0.13) before breaking again at T+2540 s to a final decay with index alpha=1.42 (+0.13, -0.12).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.98 (+/-0.08). The best-fitting absorption column is 1.5 (+0.5, -0.4) x 10^22 cm^-2, at a redshift of 2.81, in addition to the Galactic value of 1.4 x 10^21 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 1.79 (+0.11, -0.10) and a best-fitting absorption column of 1.5 (+0.8, -0.7) x 10^22 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.4 x 10^-11 (5.8 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Galactic foreground: 1.4 x 10^21 cm^-2
Intrinsic column:    1.5 (+0.8, -0.7) x 10^22 cm^-2 at z=2.81
Photon index:	     1.79 (+0.11, -0.10)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00518731.
This circular is an official product of the Swift-XRT team.
GCN Circular #13144
S. Meehan, L. Hanlon, M. Topinka (UCD Dublin), P. Kubanek (FZU AV CR Prague), report on behalf of a large collaboration:
We imaged the field of GRB 120327A detected by SWIFT (trigger 518731) with the Watcher robotic telescope (D=40cm) located at Boyden Observatory, Bloemfontein, South Africa.
Our first good observation was 14.4 min after the GRB trigger, 3 min after receipt of the GCN notice. The source was close to the zenith with an airmass of 1.01.
We detect a fading source in the error box given by SWIFT, which coincides with candidate counterpart mentioned by Sbarufatti et al. (GCN 13123).
The optical transient was measured at 15.5 +/- 0.1 mag @ 14.4 minutes after the trigger in the clear filter.
Magnitudes were estimated using the nearby USNO-B1 stars as references and are not corrected for galactic dust extinction.
Analysis of the remaining images is on-going.
GCN Circular #13146
R. S=E1nchez-Ram=EDrez, J. Gorosabel, A. J. Castro-Tirado (IAA-CSIC Granada), M. A. Rivero and G. G=F3mez-Velarde (GTC La Palma), on behalf of a larger collaboration, report:
"Following the detection of the optical afterglow to GRB 120327A (Sbarufatti et al. GCNC 13123), we have taken three spectra (400s each) with the 10.4m GTC (+ OSIRIS) at the Spanish Observatorio del Roque de los Muchachos (La Palma). The spectra, covering the range 3800-7800 A were taken starting 2.33 hr post burst, and reveal a strong damped Ly-alpha system besides several absorption features, including SiIV, SiII, CIV, FeII, AlII (and others) at a common redshift of 2.813, consistent with the value reported by Perley and Tanvir (GCNC 13133) and Kruehler et al. (GCNC 13134)."
This message can be quoted.
GCN Circular #13152
Daniele Malesani (DARK/NBI), Johan P. U. Fynbo (DARK/NBI), Pall Jakobsson (Univ. Iceland), Jens Jessen-Hansen (NOT and Univ. Aarhus), Jyri Lehtinen (NOT and Univ. Helsinki), report:
We observed the optical afterglow of GRB 120327A (Sbarufatti et al., GCN 13123) with the NOT equipped with ALFOSC in imaging mode. Observations were carried out in the R band, for a total exposure time of 30 min, with a seeing of 1.2".
The optical afterglow is well detected in our images taken at a mean epoch of March 28.164 UT (1.05 days after the GRB), with a magnitude R = 21.8+-0.16 calibrated against nearby USNO-B1 stars (R1 magnitudes).
This value is in fair agreement with the extrapolation of the R-band data reported in the literature (LaCluyze et al., GCN 13127; Klotz et al., GCNs 13124, 13132; Sudilovsky et al., GCN 13129; Gorosabel et al., GCN 13130; Im et al., GCN 13140; Meehan et al., GCN 13144). The afterglow has faded following a single power-law decay with slope alpha = 1.3 between 12 min and 1 day after the GRB, though small-scale variability may be present (see also LaCluyze et al., GCN 13127).
GCN Circular #13156
D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (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 120327A (Sbarufatti et al., GCNC 13123) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory.
The observation started on 2012-03-27 19:19:59 UT (~16.4 h after the burst). We detected the previously reported afterglow (Klotz et al., GCNC 13124; Smith et al., GCNC 13125) in Rc and Ic bands.
Photometric results of the OT are listed below. We used GSC2.3 catalog for flux calibration.
```
#T0+[day]  MID-UT    T-EXP[sec]   g'    Rc  Rc_err   Ic  Ic_err
----------------------------------------------------------------------
0.70335    19:48:05   2640.0    >21.3  20.3  0.1    19.7  0.3
----------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #13164
A. Klotz (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. Coward (UWA), B. Gendre (ASDC/INAF-OAR), M. Boer (UNS-CNRS-OCA), A. Williams (PO-UWA), R. Martin (PO-UWA) report:
We imaged the field of GRB 120327A detected by SWIFT (trigger 518731) with the Zadko robotic telescope (D=100cm) located at Gingin observatory, Australia.
The observations started 41 hours after the GRB trigger. Weather conditions were excellent.
The optical transcient (Sbarufatti et al. GCNC 13123) is detected very close to the limiting magnitude of a co addition of images obtained with no filter.
```
start   end     Rmag  dmag filter
(day) (day)
1.73   1.75     22.0  0.3  CR
```
Magnitude was estimated with the nearby star NOMAD1 0605-0398765 (246.8438328 -29.4187269) using R=14.930.
GCN Circular #13169
D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (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 120327A (Sbarufatti et al., GCNC 13123) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory.
The observation started on 2012-03-28 17:27:54 UT (~1.61 days after the burst). We could not detect the previously reported afterglow (Klotz et al., GCNC 13124; Smith et al., GCNC 13125; Kuroda et al., GCNC 13156) in all the three bands.
Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration.
```
#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc    Ic
----------------------------------------------------------------------
1.62756    17:58:57   1500.0    >20.5  >20.2  >19.0
----------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #13180
P. Hancock, T. Murphy, B. Gaensler, M. Bell, D. Burlon (University of Sydney/CAASTRO), A. de Ugarte Postigo (Dark Cosmology / IAA)
We observed GRB120327A (GCN13123) with the Australia Telescope Compact Array for 40 mins centered on 17:55UT on March 31 2012 (T0+4.625days).
We find an unresolved radio source at ra=16:27:27.4, dec=-29:24:54.0 with a flux of 0.72+/-0.03 mJy. This position is consistent with the optical position of GCN13138.
Further observations are planned.
These observations were obtained as part of ATCA project C2689. We thank the observatory staff for their support and scheduling the observations. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.
GCN Circular #13188
B. E. Cobb (GWU), reports:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 120327A (GCN 13123, Sbarufatti et al.) over several epochs, starting ~1.8 hours post-burst. For each epoch, several dithered images were obtained with total summed exposure times of 15 min in V and I and 12 min in J and K.
The fading afterglow of GRB 120327A (e.g. GCN 13123, Sbarufatti et al.; GCN 13124, Klotz et al.; GCN 13125, Smith et al.) was detected with the following magnitudes (or 3-sigma limits):
```
mid-exposure
time         V mag              I mag           J mag          K mag
 1.8 hrs   18.92+/-0.03     17.73+/-0.04    16.46+/-0.07    14.83+/-0.09
 4.1 hrs   19.97+/-0.03     18.57+/-0.04    17.42+/-0.08    15.73+/-0.09
25.8 hrs       >21.9            >20.9            >19.0          >17.4
```
(Optical photometry is calibrated against Landolt standard stars and IR photometry is calibrated against 2MASS stars in the field.)
Between about 1.8 hrs and 4.1 hrs post-burst, the GRB afterglow fades with a decay rate of approximately alpha = 1 (where afterglow flux is proportional to t^-alpha).
1402.4026 from 18 Feb 14
V. D'Elia et al.: VLT/X-shooter spectroscopy of the GRB 120327A afterglow
We present a study of the environment of the Swift long gamma-ray burst GRB 120327A at z ~2.8 through optical spectroscopy of its afterglow. We analyzed medium-resolution, multi-epoch spectroscopic observations (~7000 - 12000, corresponding to ~ 15 - 23 km/s, S/N = 15- 30 and wavelength range 3000-25000AA) of the optical afterglow of GRB 120327A, taken with X-shooter at the VLT 2.13 and 27.65 hr after the GRB trigger. The first epoch spectrum shows that the ISM in the GRB host galaxy at z = 2.8145 is extremely rich in absorption features, with three components contributing to the line profiles. The hydrogen column density associated with GRB 120327A has log NH / cm^(-2) = 22.01 +/- 0.09, and the metallicity of the host galaxy is in the range [X/H] = -1.3 to -1.1. In addition to the ground state lines, we detect absorption features associated with excited states of CII, OI, SiII, FeII, and NiII, which we used to derive information on the distance between the host absorbing gas and the site of the GRB explosion. The variability of the FeI\lambda2396 excited line between the two epochs proves that these features are excited by the GRB UV flux. Moreover, the distance of component I is found to be dI=200+100-60 pc, while component II is located closer to the GRB, at dII=100+40-30 pc. These values are among the lowest found in GRBs. Component III does not show excited transitions, so it should be located farther away from the GRB. The presence of H2 molecules is firmly established, with a molecular fraction in the range f=4 X 10^(-7) - 10^(-4). This particularly low value can be attributed to the small dust content. This represents the third positive detection of molecules in a GRB environment.

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Jochen Greiner, last update: 18-Feb-2014 [Disclaimer]