Gamma-ray Burst 130427B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:20:59 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     554635,   Seg_Num: 0
GRB_RA:          314.891d {+20h 59m 34s} (J2000),
                 315.083d {+21h 00m 20s} (current),
                 314.168d {+20h 56m 40s} (1950)
GRB_DEC:         -22.530d {-22d 31' 49"} (J2000),
                 -22.478d {-22d 28' 40"} (current),
                 -22.726d {-22d 43' 32"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       4411 [cnts]    Image_Peak=153 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   139     E_range: 15-50 keV
BKG_INTEN:       29280 [cnts]
BKG_TIME:        48029.51 SOD {13:20:29.51} UT
BKG_DUR:         8 [sec]
GRB_DATE:        16409 TJD;   117 DOY;   13/04/27
GRB_TIME:        48041.79 SOD {13:20:41.79} UT
GRB_PHI:         -70.91 [deg]
GRB_THETA:        37.52 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.16 [sigma]
IMAGE_SIGNIF:    8.70 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +1  -1  +0  +0  -6  +0 
SUN_POSTN:        35.09d {+02h 20m 22s}  +13.99d {+13d 59' 39"}
SUN_DIST:         86.38 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.26d {+15h 57m 03s}  -19.21d {-19d 12' 25"}
MOON_DIST:        70.15 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.39,-37.64 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      310.89, -5.24 [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 = 240.84,20.36 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:22:32 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     554635,   Seg_Num: 0
GRB_RA:          314.8962d {+20h 59m 35.08s} (J2000),
                 315.0886d {+21h 00m 21.26s} (current),
                 314.1729d {+20h 56m 41.49s} (1950)
GRB_DEC:         -22.5460d {-22d 32' 45.5"} (J2000),
                 -22.4936d {-22d 29' 36.8"} (current),
                 -22.7413d {-22d 44' 28.5"} (1950)
GRB_ERROR:       5.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.15e-09 [erg/cm2/sec]
GRB_SIGNIF:      7.21 [sigma]
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48119.16 SOD {13:21:59.16} UT,   77.4 [sec] since BAT Trigger Time
TAM[0-3]:        327.63 237.21 261.53 243.63
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:        35.09d {+02h 20m 22s}  +13.99d {+13d 59' 40"}
SUN_DIST:         86.38 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.28d {+15h 57m 07s}  -19.21d {-19d 12' 32"}
MOON_DIST:        70.14 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.37,-37.65 [deg] galactic lon,lat of the burst
ECL_COORDS:      310.89, -5.25 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.98 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:22:47 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     554635,   Seg_Num: 0
GRB_RA:          314.8962d {+20h 59m 35.0s} (J2000),
                 315.0886d {+21h 00m 21.2s} (current),
                 314.1729d {+20h 56m 41.4s} (1950)
GRB_DEC:         -22.5460d {-22d 32' 45.5"} (J2000),
                 -22.4936d {-22d 29' 36.8"} (current),
                 -22.7413d {-22d 44' 28.5"} (1950)
GRB_ERROR:       5.4 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       52 [cnts]
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48119.16 SOD {13:21:59.16} UT,   77.4 [sec] since BAT Trigger Time
CENTROID_X:      281.52,  raw= 282  [pixels]
CENTROID_Y:      265.95,  raw= 266  [pixels]
ROLL:            73.32 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -75.54
GRB_POS_XRT_Z:   -52.27
IMAGE_URL:       sw00554635000msxps_rw.img
SUN_POSTN:        35.09d {+02h 20m 22s}  +13.99d {+13d 59' 41"}
SUN_DIST:         86.38 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.28d {+15h 57m 08s}  -19.21d {-19d 12' 33"}
MOON_DIST:        70.13 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.37,-37.65 [deg] galactic lon,lat of the burst
ECL_COORDS:      310.89, -5.25 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:22:51 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     554635,   Seg_Num: 0
GRB_RA:          314.8962d {+20h 59m 35.0s} (J2000),
                 315.0886d {+21h 00m 21.2s} (current),
                 314.1729d {+20h 56m 41.4s} (1950)
GRB_DEC:         -22.5460d {-22d 32' 45.5"} (J2000),
                 -22.4936d {-22d 29' 36.8"} (current),
                 -22.7413d {-22d 44' 28.5"} (1950)
GRB_ERROR:       5.4 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       52 [cnts]
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48119.16 SOD {13:21:59.16} UT,   77.4 [sec] since BAT Trigger Time
CENTROID_X:      281.52,  raw= 282  [pixels]
CENTROID_Y:      265.95,  raw= 266  [pixels]
ROLL:            73.32 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -75.54
GRB_POS_XRT_Z:   -52.27
IMAGE_URL:       sw00554635000msxps_rw.img
SUN_POSTN:        35.09d {+02h 20m 22s}  +13.99d {+13d 59' 41"}
SUN_DIST:         86.38 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.28d {+15h 57m 08s}  -19.21d {-19d 12' 33"}
MOON_DIST:        70.13 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.37,-37.65 [deg] galactic lon,lat of the burst
ECL_COORDS:      310.89, -5.25 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:24:42 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     554635,   Seg_Num: 0
GRB_RA:          314.891d {+20h 59m 34s} (J2000),
                 315.083d {+21h 00m 20s} (current),
                 314.168d {+20h 56m 40s} (1950)
GRB_DEC:         -22.530d {-22d 31' 49"} (J2000),
                 -22.478d {-22d 28' 40"} (current),
                 -22.726d {-22d 43' 32"} (1950)
GRB_DATE:        16409 TJD;   117 DOY;   13/04/27
GRB_TIME:        48041.79 SOD {13:20:41.79} UT
TRIGGER_INDEX:   139
GRB_PHI:         -70.91 [deg]
GRB_THETA:        37.52 [deg]
DELTA_TIME:      51.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.16 [sigma]
IMAGE_SIGNIF:    8.70 [sigma]
LC_URL:          sw00554635000msb.lc
SUN_POSTN:        35.09d {+02h 20m 23s}  +14.00d {+13d 59' 42"}
SUN_DIST:         86.38 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.30d {+15h 57m 13s}  -19.21d {-19d 12' 41"}
MOON_DIST:        70.11 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.39,-37.64 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      310.89, -5.24 [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 = 240.84,20.36 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:25:26 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     554635,   Seg_Num: 0
POINT_RA:        314.875d {+20h 59m 30s} (J2000)
POINT_DEC:       -22.529d {-22d 31' 45"} (J2000)
POINT_ROLL:      73.316d
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48129.26 SOD {13:22:09.26} UT,   87.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.878
N_STARS:         68
X_OFFSET:        660 [pixels]
Y_OFFSET:        630 [pixels]
X_MAX:           1619 [pixels]
Y_MAX:           1589 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00554635000msufc0087.fits
SUN_POSTN:        35.09d {+02h 20m 23s}  +14.00d {+13d 59' 43"}
SUN_DIST:         86.40 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.31d {+15h 57m 15s}  -19.21d {-19d 12' 44"}
MOON_DIST:        70.09 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.38,-37.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      310.88, -5.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:25:50 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     554635,   Seg_Num: 0
POINT_RA:        314.875d {+20h 59m 30s} (J2000)
POINT_DEC:       -22.529d {-22d 31' 45"} (J2000)
POINT_ROLL:      73.316d
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48129.26 SOD {13:22:09.26} UT,   87.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.878
N_STARS:         68
X_OFFSET:        660 [pixels]
Y_OFFSET:        630 [pixels]
X_MAX:           1619 [pixels]
Y_MAX:           1589 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00554635000msufc0087.fits
SUN_POSTN:        35.09d {+02h 20m 23s}  +14.00d {+13d 59' 43"}
SUN_DIST:         86.40 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.32d {+15h 57m 16s}  -19.21d {-19d 12' 46"}
MOON_DIST:        70.09 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.38,-37.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      310.88, -5.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:27:23 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     554635,   Seg_Num: 0
POINT_RA:        314.875d {+20h 59m 30s} (J2000)
POINT_DEC:       -22.529d {-22d 31' 45"} (J2000)
ROLL:            73.316d
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48129.26 SOD {13:22:09.26} UT,   87.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     388761739
X_OFFSET:        980 [pixels]
Y_OFFSET:        950 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1140
Y_GRB_POS:       1110
BINNING_INDEX:   1
IM_URL:          sw00554635000msuni0098.fits
SUN_POSTN:        35.10d {+02h 20m 23s}  +14.00d {+13d 59' 44"}
SUN_DIST:         86.40 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.33d {+15h 57m 20s}  -19.21d {-19d 12' 53"}
MOON_DIST:        70.07 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.38,-37.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      310.88, -5.23 [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).  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:27:39 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     554635,   Seg_Num: 0
POINT_RA:        314.875d {+20h 59m 30s} (J2000)
POINT_DEC:       -22.529d {-22d 31' 45"} (J2000)
ROLL:            73.316d
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48129.26 SOD {13:22:09.26} UT,   87.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     388761739
X_OFFSET:        980 [pixels]
Y_OFFSET:        950 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1140
Y_GRB_POS:       1110
BINNING_INDEX:   1
IM_URL:          sw00554635000msuni0098.fits
SUN_POSTN:        35.10d {+02h 20m 23s}  +14.00d {+13d 59' 45"}
SUN_DIST:         86.40 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.34d {+15h 57m 20s}  -19.22d {-19d 12' 54"}
MOON_DIST:        70.07 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.38,-37.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      310.88, -5.23 [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.  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:29:58 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     554635,   Seg_Num: 0
GRB_RA:          314.8984d {+20h 59m 35.61s} (J2000),
                 315.0908d {+21h 00m 21.79s} (current),
                 314.1751d {+20h 56m 42.02s} (1950)
GRB_DEC:         -22.5462d {-22d 32' 46.3"} (J2000),
                 -22.4938d {-22d 29' 37.5"} (current),
                 -22.7415d {-22d 44' 29.2"} (1950)
GRB_ERROR:       1.1 [arcsec radius, statistical only]
GRB_MAG:         17.19 +/- 0.40 [mag]
FILTER:          10, White
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48128.00 SOD {13:22:08.00} UT,   86.2 [sec] since BAT Trigger Time
SUN_POSTN:        35.10d {+02h 20m 23s}  +14.00d {+13d 59' 46"}
SUN_DIST:         86.39 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.36d {+15h 57m 26s}  -19.22d {-19d 13' 04"}
MOON_DIST:        70.06 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.37,-37.65 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      310.89, -5.25 [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 7.2 arcsec from the XRT position.  
COMMENTS:        Result based on srclist data.  
COMMENTS:        Notice generated automatically.

GCN Circular #14460
A. Maselli (INAF-IASFPA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (NASA/GSFC/ORAU), V. Mangano (INAF-IASFPA), C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC), C. J. Mountford (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 13:20:41 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130427B (trigger=554635). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 314.891, -22.530 which is
```
 
   RA(J2000)  =  20h 59m 34s 
   Dec(J2000) = -22d 31' 49" 
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows 3 peaks with a total duration of about 40 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 13:21:59.1 UT, 77.4 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 314.89766, -22.54548 which is equivalent to:
```
   RA(J2000)  = 20h 59m 35.44s 
   Dec(J2000) = -22d 32' 43.7" 
```
with an uncertainty of 4.4 arcseconds (radius, 90% containment). This location is 59 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. We cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 4.41 x 10^20 cm^-2 (Kalberla et al. 2005).
The initial flux in the 2.5 s image was 1.15e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 87 seconds after the BAT trigger. There is a candidate afterglow in the list of sources generated on-board at
```
  RA(J2000)  =  20:59:35.64 = 314.89848 
  DEC(J2000) = -22:32:46.5  = -22.54626 
```
with a 90%-confidence error radius of about 1.10 arc sec. This position is 7.6 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.19. No correction has been made for the expected extinction corresponding to E(B-V) of 0.07.
Burst Advocate for this burst is A. Maselli (maselli AT ifc.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:     Sat 27 Apr 13 13:37:54 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     554635,   Seg_Num: 0
GRB_RA:          314.8976d {+20h 59m 35.42s} (J2000),
                 315.0900d {+21h 00m 21.60s} (current),
                 314.1743d {+20h 56m 41.83s} (1950)
GRB_DEC:         -22.5454d {-22d 32' 43.4"} (J2000),
                 -22.4930d {-22d 29' 34.6"} (current),
                 -22.7407d {-22d 44' 26.3"} (1950)
GRB_ERROR:       4.4 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48247.00 SOD {13:24:07.00} UT,   205.2 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        35.10d {+02h 20m 25s}  +14.00d {+13d 59' 53"}
SUN_DIST:         86.39 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.45d {+15h 57m 47s}  -19.23d {-19d 13' 38"}
MOON_DIST:        69.98 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.37,-37.65 [deg] galactic lon,lat of the burst
ECL_COORDS:      310.89, -5.25 [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:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN Circular #14461
C. Guidorzi (U. Ferrara), J. Japeli, A. Gomboc (U. Ljubljana), A. Melandri (INAF-OAB) on behalf of a large collaboration report:
The 2-m Faulkes Telescope North automatically began observing GRB 130427B (Maselli et al. GCN Circ. 14460) at 4.6 minutes from the Swift/BAT trigger time. The automatic LT-TRAP procedure identified a bright uncatalogued object at the following position consistent with that reported by Maselli et al.:
```
RA=   20:59:35.62
Dec= -22:32:46.9
```
(J2000.0). Its magnitude is estimated to be 15.5 in the R band.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:43:02 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     554635,   Seg_Num: 0
POINT_RA:        314.872d {+20h 59m 29s} (J2000)
POINT_DEC:       -22.531d {-22d 31' 50"} (J2000)
POINT_ROLL:      73.318d
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48341.90 SOD {13:25:41.90} UT,   300.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.270
N_STARS:         32
X_OFFSET:        660 [pixels]
Y_OFFSET:        630 [pixels]
X_MAX:           1619 [pixels]
Y_MAX:           1589 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    4
SL_URL:          sw00554635000msufc0300.fits
SUN_POSTN:        35.11d {+02h 20m 25s}  +14.00d {+13d 59' 57"}
SUN_DIST:         86.41 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.50d {+15h 58m 00s}  -19.23d {-19d 14' 00"}
MOON_DIST:        69.91 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.38,-37.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      310.87, -5.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:43:30 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     554635,   Seg_Num: 0
POINT_RA:        314.872d {+20h 59m 29s} (J2000)
POINT_DEC:       -22.531d {-22d 31' 50"} (J2000)
POINT_ROLL:      73.318d
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48341.90 SOD {13:25:41.90} UT,   300.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.270
N_STARS:         32
X_OFFSET:        660 [pixels]
Y_OFFSET:        630 [pixels]
X_MAX:           1619 [pixels]
Y_MAX:           1589 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    4
SL_URL:          sw00554635000msufc0300.fits
SUN_POSTN:        35.11d {+02h 20m 25s}  +14.00d {+13d 59' 57"}
SUN_DIST:         86.41 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.51d {+15h 58m 02s}  -19.23d {-19d 14' 02"}
MOON_DIST:        69.91 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.38,-37.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      310.87, -5.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:43:55 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     554635,   Seg_Num: 0
GRB_RA:          314.8987d {+20h 59m 35.68s} (J2000),
                 315.0911d {+21h 00m 21.86s} (current),
                 314.1754d {+20h 56m 42.09s} (1950)
GRB_DEC:         -22.5466d {-22d 32' 47.7"} (J2000),
                 -22.4942d {-22d 29' 39.0"} (current),
                 -22.7419d {-22d 44' 30.7"} (1950)
GRB_ERROR:       2.4 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48247.00 SOD {13:24:07.00} UT,   205.2 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        35.11d {+02h 20m 26s}  +14.00d {+13d 59' 57"}
SUN_DIST:         86.39 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.51d {+15h 58m 03s}  -19.23d {-19d 14' 04"}
MOON_DIST:        69.92 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.37,-37.65 [deg] galactic lon,lat of the burst
ECL_COORDS:      310.89, -5.25 [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 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:45:51 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     554635,   Seg_Num: 0
POINT_RA:        314.872d {+20h 59m 29s} (J2000)
POINT_DEC:       -22.531d {-22d 31' 50"} (J2000)
ROLL:            73.318d
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48341.90 SOD {13:25:41.90} UT,   300.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     388761952
X_OFFSET:        980 [pixels]
Y_OFFSET:        950 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1140
Y_GRB_POS:       1110
BINNING_INDEX:   1
IM_URL:          sw00554635000msuni0311.fits
SUN_POSTN:        35.11d {+02h 20m 26s}  +14.00d {+13d 59' 59"}
SUN_DIST:         86.42 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.53d {+15h 58m 08s}  -19.24d {-19d 14' 12"}
MOON_DIST:        69.88 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.38,-37.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      310.87, -5.23 [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).  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:46:14 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     554635,   Seg_Num: 0
POINT_RA:        314.872d {+20h 59m 29s} (J2000)
POINT_DEC:       -22.531d {-22d 31' 50"} (J2000)
ROLL:            73.318d
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48341.90 SOD {13:25:41.90} UT,   300.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     388761952
X_OFFSET:        980 [pixels]
Y_OFFSET:        950 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1140
Y_GRB_POS:       1110
BINNING_INDEX:   1
IM_URL:          sw00554635000msuni0311.fits
SUN_POSTN:        35.11d {+02h 20m 26s}  +14.00d {+13d 59' 59"}
SUN_DIST:         86.42 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.54d {+15h 58m 09s}  -19.24d {-19d 14' 14"}
MOON_DIST:        69.88 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.38,-37.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      310.87, -5.23 [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.  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:46:40 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     554635,   Seg_Num: 0
POINT_RA:        314.872d {+20h 59m 29s} (J2000)
POINT_DEC:       -22.531d {-22d 31' 50"} (J2000)
ROLL:            73.318d
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48919.68 SOD {13:35:19.68} UT,   877.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     388762530
X_OFFSET:        979 [pixels]
Y_OFFSET:        949 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1139
Y_GRB_POS:       1109
BINNING_INDEX:   1
IM_URL:          sw00554635000msuni0888.fits
SUN_POSTN:        35.11d {+02h 20m 26s}  +14.00d {+13d 59' 60"}
SUN_DIST:         86.42 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.54d {+15h 58m 10s}  -19.24d {-19d 14' 15"}
MOON_DIST:        69.88 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.38,-37.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      310.87, -5.23 [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:     Sat 27 Apr 13 13:46:57 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     554635,   Seg_Num: 0
POINT_RA:        314.872d {+20h 59m 29s} (J2000)
POINT_DEC:       -22.531d {-22d 31' 50"} (J2000)
ROLL:            73.318d
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48919.68 SOD {13:35:19.68} UT,   877.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     388762530
X_OFFSET:        979 [pixels]
Y_OFFSET:        949 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1139
Y_GRB_POS:       1109
BINNING_INDEX:   1
IM_URL:          sw00554635000msuni0888.fits
SUN_POSTN:        35.11d {+02h 20m 26s}  +14.00d {+13d 59' 60"}
SUN_DIST:         86.42 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.54d {+15h 58m 11s}  -19.24d {-19d 14' 17"}
MOON_DIST:        69.87 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.38,-37.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      310.87, -5.23 [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:     Sat 27 Apr 13 13:46:06 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     554635,   Seg_Num: 0
POINT_RA:        314.872d {+20h 59m 29s} (J2000)
POINT_DEC:       -22.531d {-22d 31' 50"} (J2000)
POINT_ROLL:      73.318d
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48919.68 SOD {13:35:19.68} UT,   877.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.061
N_STARS:         110
X_OFFSET:        420 [pixels]
Y_OFFSET:        390 [pixels]
X_MAX:           1859 [pixels]
Y_MAX:           1829 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    12
SL_URL:          sw00554635000msufc0877.fits
SUN_POSTN:        35.11d {+02h 20m 26s}  +14.00d {+13d 59' 59"}
SUN_DIST:         86.42 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.53d {+15h 58m 08s}  -19.24d {-19d 14' 13"}
MOON_DIST:        69.88 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.38,-37.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      310.87, -5.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Apr 13 13:46:17 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     554635,   Seg_Num: 0
POINT_RA:        314.872d {+20h 59m 29s} (J2000)
POINT_DEC:       -22.531d {-22d 31' 50"} (J2000)
POINT_ROLL:      73.318d
IMG_START_DATE:  16409 TJD;   117 DOY;   13/04/27
IMG_START_TIME:  48919.68 SOD {13:35:19.68} UT,   877.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.061
N_STARS:         110
X_OFFSET:        420 [pixels]
Y_OFFSET:        390 [pixels]
X_MAX:           1859 [pixels]
Y_MAX:           1829 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    12
SL_URL:          sw00554635000msufc0877.fits
SUN_POSTN:        35.11d {+02h 20m 26s}  +14.00d {+13d 59' 59"}
SUN_DIST:         86.42 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:      239.54d {+15h 58m 09s}  -19.24d {-19d 14' 14"}
MOON_DIST:        69.88 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:       24.38,-37.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      310.87, -5.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN Circular #14467
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 1221 s of XRT Photon Counting mode data and 2 UVOT images for GRB 130427B, 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 = 314.89849, -22.54670 which is equivalent to:
```
RA (J2000): 20h 59m 35.64s
Dec (J2000): -22d 32' 48.1"
```
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 #14469
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), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), A. Maselli (INAF-IASFPA), D. M. Palmer (LANL), T. Sakamoto (AGU), 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-60 to T+243 sec from recent telemetry downlinks, we report further analysis of BAT GRB 130427B (trigger #554635) (Maelli, et al., GCN Circ. 14460). The BAT ground-calculated position is RA, Dec = 314.900, -22.548 deg, which is
```
   RA(J2000)  =  20h 59m 36.0s 
   Dec(J2000) = -22d 32' 51.6" 
```
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 22%.
The mask-weighted light curve shows shows a very small peak at ~T-3 sec, the main peak starting at ~T-1 sec, peaking at ~T+2 sec, and ending at ~T+40 sec. T90 (15-350 keV) is 27.0 +- 7.3 sec (estimated error including systematics).
The time-averaged spectrum from T-1.29 to T+32.71 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.64 +- 0.15. The fluence in the 15-150 keV band is 1.5 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+0.71 sec in the 15-150 keV band is 3.0 +- 0.4 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/554635/BA/
GCN Circular #14477
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 130427B (Maselli et al., GCNC 14460) 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 2013-04-27 18:47:30 UT (~5.4 h after the burst). We did not find any new point source within the enhanced XRT circle (Osborne et al., GCNC 14467) in all the three 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     Ic
-----------------------------------------------------
0.22892    18:50:19    2160.0   >18.0  >18.3  >17.9
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #14479
V. Mangano (INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU), M.C. Stroh (PSU), B.P. Gompertz (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU) and A. Maselli report on behalf of the Swift-XRT team:
We have analysed 7.3 ks of XRT data for GRB 130427B (Maselli et al. GCN Circ. 14460), from 67 s to 24.2 ks after the BAT trigger. The data comprise 120 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 Osborne et al. (GCN. Circ 14467).
The late-time light curve (from T0+11.6 ks) can be modelled with a power-law decay with a decay index of alpha=1.9 (+0.6, -0.5).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.93 (+0.14, -0.13). The best-fitting absorption column is 8.3 (+2.8, -2.6) x 10^20 cm^-2, in excess of the Galactic value of 4.4 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 1.79 (+0.23, -0.11) and a best-fitting absorption column consistent with the Galactic value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     0 (+4.7, -0) x 10^20 cm^-2
Galactic foreground: 4.4 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.79 (+0.23, -0.11)
```
If the light curve continues to decay with a power-law decay index of 1.9, the count rate at T+24 hours will be 9.7 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.8 x 10^-14 (4.2 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00554635.
This circular is an official product of the Swift-XRT team.
GCN Circular #14493
H. Flores (GEPI/Obs. de Paris), S. Covino (INAF), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), J. Fynbo, T. Kruehler, D. Xu (DARK/NBI) and N. Tanvir (U. Leicester) report on behalf of the X-Shooter GRB collaboration:
We have observed the afterglow of the GRB 130427B (Maselli et al., GCN 14460) with the ESO VLT equipped with the X-shooter spectrograph. The observation started on 2013-04-28 at 9:45 UT. A total exposure of 2x600 s was obtained just before morning twilight, covering the spectral range from 300 to 2500 nm.
In the spectrum we detect a feature consistent with a damped Lyman-alpha line in the UVB arm at redshift of z=2.78 +/- 0.02. Given the low S/N of the spectrum, this redshift measurement should be considered tentative.
We thank the Paranal staff for enthusiastic support, in particular Andrea Mehner and Christophe Martayan.
GCN Circular #14496
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), Willia= m H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC)= , Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UN= AM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley= (GSFC) report:
We observed the field of GRB 130427B (Maselli, et al., GCN 14460) with th= e Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional = on Sierra San Pedro M=E1rtir from 2013/04 28.44 to 2013/04 28.48 UTC (21.26 = to 22.19 hours after the BAT trigger), obtaining a total of 0.71 hours exposure in the r' and i' bands and 0.29 hours exposure in the Z, Y, J, a= nd H bands.
For a source within the Swift-XRT error circle (Osborne, et al., GCN 14467), in comparison with USNO-B1 and 2MASS, we obtain the following upp= er limits (3-sigma):
```
  r' > 22.08
  i' > 22.06
  Z  > 21.28
  Y  > 20.77
  J  > 20.57
  H  > 19.84
```
These limits, in the AB system and not corrected for Galactic extinction in the direction of the GRB, were derived from PSF-fitting photometry, because of the presence of a 16.5 magnitude star only 5 arcseconds to the south of the SWIFT-XRT source position.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedr= o M=E1rtir.
GCN Circular #14499
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 130427B (Maselli et al., GCNC 14460) 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 2013-04-28 18:47:24 UT (~1.23 days after the burst). We did not find any new point source within the enhanced XRT circle (Osborne et al., GCNC 14467) 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
-----------------------------------------------------
1.25418    19:26:42    3540.0   >20.6  >20.7  >20.1
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```

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Jochen Greiner, last update: 29-Apr-2013 [Disclaimer]