Gamma-ray Burst 130420B

(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 20 Apr 13 12:56:47 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     553996,   Seg_Num: 0
GRB_RA:          183.120d {+12h 12m 29s} (J2000),
                 183.284d {+12h 13m 08s} (current),
                 182.498d {+12h 10m 00s} (1950)
GRB_DEC:         +54.386d {+54d 23' 11"} (J2000),
                 +54.312d {+54d 18' 45"} (current),
                 +54.664d {+54d 39' 52"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1787 [cnts]    Image_Peak=124 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   124     E_range: 25-100 keV
BKG_INTEN:       20512 [cnts]
BKG_TIME:        46573.53 SOD {12:56:13.53} UT
BKG_DUR:         8 [sec]
GRB_DATE:        16402 TJD;   110 DOY;   13/04/20
GRB_TIME:        46591.07 SOD {12:56:31.07} UT
GRB_PHI:         162.99 [deg]
GRB_THETA:         8.62 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     12.64 [sigma]
IMAGE_SIGNIF:    7.39 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +2  -3  +0  +0 +35  +0 
SUN_POSTN:        28.49d {+01h 53m 58s}  +11.68d {+11d 41' 02"}
SUN_DIST:        110.63 [deg]   Sun_angle= -10.3 [hr] (East of Sun)
MOON_POSTN:      144.02d {+09h 36m 06s}   +8.76d {+08d 45' 41"}
MOON_DIST:        55.24 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:      134.97, 61.82 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      153.15, 49.33 [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 = 221.15,0.68 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(1.0<100sec) coincident with the FERMI_GBM event (trignum=388155395).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 20 Apr 13 12:57:06 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      44
TRIGGER_NUM:     388155395
GRB_RA:          176.417d {+11h 45m 40s} (J2000),
                 176.594d {+11h 46m 23s} (current),
                 175.747d {+11h 42m 59s} (1950)
GRB_DEC:         +56.533d {+56d 31' 60"} (J2000),
                 +56.459d {+56d 27' 34"} (current),
                 +56.811d {+56d 48' 40"} (1950)
GRB_ERROR:       28.93 [deg radius, statistical plus systematic]
GRB_INTEN:       105 [cnts/sec]
DATA_SIGNIF:     5.20 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        16402 TJD;   110 DOY;   13/04/20
GRB_TIME:        46592.99 SOD {12:56:32.99} UT
GRB_PHI:         252.00 [deg]
GRB_THETA:        45.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      1.07
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      66%  GRB
2nd_MOST_LIKELY:  32%  Distant Particles
DETECTORS:       0,0,0, 0,0,0, 1,1,0, 0,0,0, 0,0,
SUN_POSTN:        28.49d {+01h 53m 58s}  +11.68d {+11d 41' 03"}
SUN_DIST:        106.89 [deg]   Sun_angle= -9.9 [hr] (East of Sun)
MOON_POSTN:      144.03d {+09h 36m 07s}   +8.76d {+08d 45' 38"}
MOON_DIST:        54.04 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:      140.23, 58.33 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      146.56, 48.73 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 80.05,-23.97 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=553996).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 20 Apr 13 12:57:12 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      56
TRIGGER_NUM:     388155395
GRB_RA:          184.210d {+12h 16m 50s} (J2000),
                 184.373d {+12h 17m 30s} (current),
                 183.594d {+12h 14m 23s} (1950)
GRB_DEC:         +52.660d {+52d 39' 36"} (J2000),
                 +52.586d {+52d 35' 10"} (current),
                 +52.938d {+52d 56' 16"} (1950)
GRB_ERROR:       7.92 [deg radius, statistical only]
DATA_SIGNIF:     7.00 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        16402 TJD;   110 DOY;   13/04/20
GRB_TIME:        46592.99 SOD {12:56:32.99} UT
GRB_PHI:         245.00 [deg]
GRB_THETA:        48.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4143 (Gnd S/W Version number)
SUN_POSTN:        28.49d {+01h 53m 58s}  +11.68d {+11d 41' 03"}
SUN_DIST:        112.47 [deg]   Sun_angle= -10.4 [hr] (East of Sun)
MOON_POSTN:      144.03d {+09h 36m 07s}   +8.76d {+08d 45' 37"}
MOON_DIST:        54.65 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:      134.80, 63.66 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      155.52, 48.34 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=553996).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Apr 13 12:58:01 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     553996,   Seg_Num: 0
POINT_RA:        183.115d {+12h 12m 28s} (J2000)
POINT_DEC:       +54.389d {+54d 23' 20"} (J2000)
IMG_START_DATE:  16402 TJD;   110 DOY;   13/04/20
IMG_START_TIME:  46645.62 SOD {12:57:25.62} UT,   54.6 [sec] since BAT Trigger Time
COUNTS:          18    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        2    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:     Sat 20 Apr 13 12:58:34 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     553996,   Seg_Num: 0
POINT_RA:        183.115d {+12h 12m 28s} (J2000)
POINT_DEC:       +54.389d {+54d 23' 21"} (J2000)
POINT_ROLL:      333.368d
IMG_START_DATE:  16402 TJD;   110 DOY;   13/04/20
IMG_START_TIME:  46648.08 SOD {12:57:28.08} UT,   57.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.081
N_STARS:         10
X_OFFSET:        445 [pixels]
Y_OFFSET:        558 [pixels]
X_MAX:           1404 [pixels]
Y_MAX:           1517 [pixels]
DET_THRESH:      4
PHOTO_THRESH:    2
SL_URL:          sw00553996000msufc0057.fits
SUN_POSTN:        28.49d {+01h 53m 58s}  +11.68d {+11d 41' 04"}
SUN_DIST:        110.63 [deg]   Sun_angle= -10.3 [hr] (East of Sun)
MOON_POSTN:      144.04d {+09h 36m 10s}   +8.76d {+08d 45' 24"}
MOON_DIST:        55.24 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:      134.98, 61.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      153.15, 49.33 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Apr 13 12:59:00 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     553996,   Seg_Num: 0
POINT_RA:        183.115d {+12h 12m 28s} (J2000)
POINT_DEC:       +54.389d {+54d 23' 21"} (J2000)
POINT_ROLL:      333.368d
IMG_START_DATE:  16402 TJD;   110 DOY;   13/04/20
IMG_START_TIME:  46648.08 SOD {12:57:28.08} UT,   57.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.081
N_STARS:         10
X_OFFSET:        445 [pixels]
Y_OFFSET:        558 [pixels]
X_MAX:           1404 [pixels]
Y_MAX:           1517 [pixels]
DET_THRESH:      4
PHOTO_THRESH:    2
SL_URL:          sw00553996000msufc0057.fits
SUN_POSTN:        28.49d {+01h 53m 58s}  +11.68d {+11d 41' 04"}
SUN_DIST:        110.63 [deg]   Sun_angle= -10.3 [hr] (East of Sun)
MOON_POSTN:      144.04d {+09h 36m 10s}   +8.76d {+08d 45' 20"}
MOON_DIST:        55.24 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:      134.98, 61.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      153.15, 49.33 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_srclist.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Apr 13 12:59:38 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     553996,   Seg_Num: 0
POINT_RA:        183.115d {+12h 12m 28s} (J2000)
POINT_DEC:       +54.389d {+54d 23' 21"} (J2000)
ROLL:            333.368d
IMG_START_DATE:  16402 TJD;   110 DOY;   13/04/20
IMG_START_TIME:  46648.08 SOD {12:57:28.08} UT,   57.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     388155458
X_OFFSET:        764 [pixels]
Y_OFFSET:        877 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       924
Y_GRB_POS:       1037
BINNING_INDEX:   1
IM_URL:          sw00553996000msuni0068.fits
SUN_POSTN:        28.49d {+01h 53m 59s}  +11.68d {+11d 41' 05"}
SUN_DIST:        110.63 [deg]   Sun_angle= -10.3 [hr] (East of Sun)
MOON_POSTN:      144.05d {+09h 36m 12s}   +8.75d {+08d 45' 13"}
MOON_DIST:        55.24 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:      134.98, 61.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      153.15, 49.33 [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 20 Apr 13 12:59:45 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     553996,   Seg_Num: 0
POINT_RA:        183.115d {+12h 12m 28s} (J2000)
POINT_DEC:       +54.389d {+54d 23' 21"} (J2000)
ROLL:            333.368d
IMG_START_DATE:  16402 TJD;   110 DOY;   13/04/20
IMG_START_TIME:  46648.08 SOD {12:57:28.08} UT,   57.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     388155458
X_OFFSET:        764 [pixels]
Y_OFFSET:        877 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       924
Y_GRB_POS:       1037
BINNING_INDEX:   1
IM_URL:          sw00553996000msuni0068.fits
SUN_POSTN:        28.49d {+01h 53m 59s}  +11.68d {+11d 41' 05"}
SUN_DIST:        110.63 [deg]   Sun_angle= -10.3 [hr] (East of Sun)
MOON_POSTN:      144.05d {+09h 36m 12s}   +8.75d {+08d 45' 12"}
MOON_DIST:        55.24 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:      134.98, 61.82 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      153.15, 49.33 [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 20 Apr 13 13:00:40 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     553996,   Seg_Num: 0
GRB_RA:          183.120d {+12h 12m 29s} (J2000),
                 183.284d {+12h 13m 08s} (current),
                 182.498d {+12h 10m 00s} (1950)
GRB_DEC:         +54.386d {+54d 23' 11"} (J2000),
                 +54.312d {+54d 18' 45"} (current),
                 +54.664d {+54d 39' 52"} (1950)
GRB_DATE:        16402 TJD;   110 DOY;   13/04/20
GRB_TIME:        46591.07 SOD {12:56:31.07} UT
TRIGGER_INDEX:   124
GRB_PHI:         162.99 [deg]
GRB_THETA:         8.62 [deg]
DELTA_TIME:      6.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.64 [sigma]
IMAGE_SIGNIF:    7.39 [sigma]
LC_URL:          sw00553996000msb.lc
SUN_POSTN:        28.49d {+01h 53m 59s}  +11.68d {+11d 41' 06"}
SUN_DIST:        110.63 [deg]   Sun_angle= -10.3 [hr] (East of Sun)
MOON_POSTN:      144.06d {+09h 36m 14s}   +8.75d {+08d 45' 03"}
MOON_DIST:        55.23 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:      134.97, 61.82 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      153.15, 49.33 [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 = 221.15,0.68 [deg].

GCN Circular #14411
S. R. Oates (UCL-MSSL), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC), S. T. Holland (STScI), N. P. M. Kuin (UCL-MSSL), C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC), M. H. Siegel (PSU) and E. Sonbas (NASA/GSFC/Adiyaman Univ.) report on behalf of the Swift Team:
At 12:56:31 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130420B (trigger=553996). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 183.120, +54.386 which is
```
   RA(J2000) = 12h 12m 29s
   Dec(J2000) = +54d 23' 11"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 10 sec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 12:57:25.6 UT, 54.5 seconds after the BAT trigger. No source was detected in the 2.5-s promptly available image. About 8 seconds of data were obtained in WT mode before Swift slewed away from the field, indicating a bright X-ray source in the field, but no position is available from the WT data. No XRT position will be available until data from the second orbit are processed.
UVOT took a finding chart exposure of 8 seconds with the White filter starting 57 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag. Results from the list of sources generated on-board are not available at this time. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02.
Burst Advocate for this burst is S. R. Oates (samantha.oates AT ucl.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN Circular #14412
V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, D.Denisenko, A.Sankovich Sternberg Astronomical Institute, Moscow State University
K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University
V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory
Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA)
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB130420B (Oates et. al GCN 14411) 44 sec s after notice time and 63 sec after GRB time at 2013-04-20 12:57:34.948 UT in two polarizations. On our first (10s exposure) set we haven`t found optical transient within SWIFT error-box (ra=12 12 28 dec=+54 23 24 r=0.050000). The 5-sigma upper limit has been about 16.0 mag. The message may be cited.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Apr 13 14:01:26 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     553996,   Seg_Num: 0
POINT_RA:        183.058d {+12h 12m 14s} (J2000)
POINT_DEC:       +54.357d {+54d 21' 25"} (J2000)
POINT_ROLL:      333.321d
IMG_START_DATE:  16402 TJD;   110 DOY;   13/04/20
IMG_START_TIME:  50318.40 SOD {13:58:38.40} UT,   3727.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.540
N_STARS:         23
X_OFFSET:        714 [pixels]
Y_OFFSET:        814 [pixels]
X_MAX:           1673 [pixels]
Y_MAX:           1773 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00553996000msufc3727.fits
SUN_POSTN:        28.53d {+01h 54m 08s}  +11.70d {+11d 41' 57"}
SUN_DIST:        110.62 [deg]   Sun_angle= -10.3 [hr] (East of Sun)
MOON_POSTN:      144.57d {+09h 38m 17s}   +8.58d {+08d 35' 02"}
MOON_DIST:        55.11 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:      135.07, 61.84 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      153.14, 49.29 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Apr 13 14:01:44 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     553996,   Seg_Num: 0
POINT_RA:        183.058d {+12h 12m 14s} (J2000)
POINT_DEC:       +54.357d {+54d 21' 25"} (J2000)
POINT_ROLL:      333.321d
IMG_START_DATE:  16402 TJD;   110 DOY;   13/04/20
IMG_START_TIME:  50318.40 SOD {13:58:38.40} UT,   3727.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.540
N_STARS:         23
X_OFFSET:        714 [pixels]
Y_OFFSET:        814 [pixels]
X_MAX:           1673 [pixels]
Y_MAX:           1773 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00553996000msufc3727.fits
SUN_POSTN:        28.53d {+01h 54m 08s}  +11.70d {+11d 41' 58"}
SUN_DIST:        110.62 [deg]   Sun_angle= -10.3 [hr] (East of Sun)
MOON_POSTN:      144.57d {+09h 38m 17s}   +8.58d {+08d 34' 59"}
MOON_DIST:        55.11 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:      135.07, 61.84 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      153.14, 49.29 [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 20 Apr 13 14:03:29 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     553996,   Seg_Num: 0
POINT_RA:        183.058d {+12h 12m 14s} (J2000)
POINT_DEC:       +54.357d {+54d 21' 25"} (J2000)
ROLL:            333.321d
IMG_START_DATE:  16402 TJD;   110 DOY;   13/04/20
IMG_START_TIME:  50318.40 SOD {13:58:38.40} UT,   3727.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     388159128
X_OFFSET:        1033 [pixels]
Y_OFFSET:        1133 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1193
Y_GRB_POS:       1293
BINNING_INDEX:   1
IM_URL:          sw00553996000msuni3738.fits
SUN_POSTN:        28.54d {+01h 54m 08s}  +11.70d {+11d 41' 59"}
SUN_DIST:        110.62 [deg]   Sun_angle= -10.3 [hr] (East of Sun)
MOON_POSTN:      144.59d {+09h 38m 21s}   +8.58d {+08d 34' 42"}
MOON_DIST:        55.11 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:      135.07, 61.84 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      153.14, 49.29 [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 20 Apr 13 14:03:47 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     553996,   Seg_Num: 0
POINT_RA:        183.058d {+12h 12m 14s} (J2000)
POINT_DEC:       +54.357d {+54d 21' 25"} (J2000)
ROLL:            333.321d
IMG_START_DATE:  16402 TJD;   110 DOY;   13/04/20
IMG_START_TIME:  50318.40 SOD {13:58:38.40} UT,   3727.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     388159128
X_OFFSET:        1033 [pixels]
Y_OFFSET:        1133 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1193
Y_GRB_POS:       1293
BINNING_INDEX:   1
IM_URL:          sw00553996000msuni3738.fits
SUN_POSTN:        28.54d {+01h 54m 08s}  +11.70d {+11d 41' 59"}
SUN_DIST:        110.62 [deg]   Sun_angle= -10.3 [hr] (East of Sun)
MOON_POSTN:      144.59d {+09h 38m 22s}   +8.58d {+08d 34' 39"}
MOON_DIST:        55.11 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:      135.07, 61.84 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      153.14, 49.29 [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 Circular #14414
A. Melandri (INAF-OAB), C. Guidorzi (U. Ferrara) and C. G. Mundell (Liverpool) report on behalf of a larger collaboration:
The 2-m Faulkes Telescope North (FTN) automatically began observing GRB130420B (Oates et al., GCN 14411) on April 20, 12:59:50 UT corresponding to ~200 seconds after the burst event.
We detect no new, uncatalogued source in the BAT error circle down to the following limiting magnitudes:
```
Mid time from   Exp    Filter   Mag limit
trigger (min)   (sec)
---------------------------------------------------
28.62           540      R       > 20.5
32.75           520      I        > 20.0
---------------------------------------------------
```
The magnitudes are calibrated against nearby USNO-B1.0 stars.
GCN Circular #14420
C. B. Markwardt (GSFC), 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), S. R. Oates (UCL-MSSL), 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-61 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130420B (trigger #553996) (Oates et al., GCN 14411). The BAT ground-calculated position is RA, Dec = 183.095, 54.376 deg which is
```
    RA(J2000)  =  12h 12m 22.7s
    Dec(J2000) = +54d 22' 33.2"
```
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%.
The mask-weighted light curve shows a single gradual peak beginning at about T-5 seconds and detectable to T+12 seconds. T90 (15-350 keV) is 10.2 +- 5.4 sec (estimated error including systematics).
The time-averaged spectrum from T-1.0 to T+16.0 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.28 +- 0.52, and Epeak of 71.3 +- 14.0 keV (chi squared 42.36 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 6.0 +- 0.5 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T+0.91 sec in the 15-150 keV band is 1.4 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.45 +- 0.10 (chi squared 61.94 for 57 d.o.f.). All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/553996/BA/
GCN Circular #14421
K.L. Page, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team:
Using 1436 s of XRT Photon Counting mode data and 3 UVOT images, 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 = 183.12805, 54.39054 which is equivalent to:
```
RA (J2000):  12 12 30.73
Dec (J2000): +54 23 25.9
```
with an uncertainty of 2.0 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 is an official product of the Swift-XRT team.
GCN Circular #14423
X.-H. Zhao (YNAO and PSU), J. Mao (RIKEN and YNAO), J.-M. Bai (YNAO) report on behalf of a larger collaboration:
We observed the field of GRB 130420B (Page et al., GCN 14421; Oates et al., GCN +14411) with 2.4m Gao-Mei-Gu (GMG) telescope. Observations started at 13:21:14 UT on 2013-04-20 (i.e., 0.4 hrs after the burst). The +observations lasted for ~10min. The afterglow was not found at the XRT position, down to a upper limit of R>22.6.
We thank the GMG staff, especially Yu-Xin Xin, Gui-Hua He and Jian-Duo He for performing these observations.
GCN Circular #14425
M. De Pasquale, S. R. Oates (MSSL-UCL) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 130420B 57 s after the BAT trigger (Oates et al., GCN Circ. 14411). No optical afterglow consistent with the XRT position (Page et al., GCN circ. 14421) is detected in the initial and summed UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white               57         5841          460         >21.7
v                 4707         4907          197         >19.6
b                 4091         5727          393         >20.9
u                 3886         5521          393         >20.6
w1                5117         5317          197         >20.1
m2                4912         5111          197         >19.8
w2                4502         4702          197         >20.1
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #14426
Dong Xu (DARK/NBI), Chen Cao, Shaoming Hu, Dayong Ren (SDU) report:
We observed the field of GRB 130420B (Oates et al., GCN 14411) using the 1m telescope located in Weihai, Shandong Province, China. We obtained 12x300s I-band frames with a mean time of 2.973 hr after the BAT trigger.
No optical source is detected within the enhanced XRT error circle (Page et al., GCN 14421) in the stacked image, down to a limiting magnitude of I>21.2 mag.
GCN Circular #14430
K.L. Page (U. Leicester) and S. R. Oates (UCL-MSSL) report on behalf of the Swift-XRT team:
We have analysed 6.4 ks of XRT data for GRB 130420B (Oates et al. GCN Circ. 14411), from 39 s to 39.9 ks after the BAT trigger. The data comprise 18 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. Using 2638 s of PC mode data and 4 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 183.12838, +54.39054 which is equivalent to:
```
RA (J2000): 12h 12m 30.81s
Dec(J2000): +54d 23' 26.0"
```
with an uncertainty of 1.8 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.11 (+0.09, -0.14).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.0 (+/-0.4). The best-fitting absorption column is 6.8 (+9.6, -5.4) x 10^20 cm^-2, consistent with the Galactic value of 1.4 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     6.8 (+9.6, -5.4) x 10^20 cm^-2
Galactic foreground: 1.4 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2.0 (+/-0.4)
```
If the light curve continues to decay with a power-law decay index of 1.11, the count rate at T+24 hours will be 2.0 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.1 x 10^-14 (8.5 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/00553996.
This circular is an official product of the Swift-XRT team.
GCN Circular #14432
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 130420B (Oates et al., GCN 14411) with the 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 21.15 to 2013/04 21.29 UTC (14.54 = to 18.10 hours after the BAT trigger), obtaining a total of 1.32 hours exposure in the r' and i' bands and 0.55 hours exposure in the Z, Y, J, a= nd H bands.
For a source within the Swift-XRT error circle (Page et al., GCN 14430), = in comparison with SDSS DR8 and 2MASS, we obtain the following upper limits (3-sigma) in the AB magnitude system:
```
 r'> 23.19
 i'> 22.99
 Z > 21.87
 Y > 21.39
 J > 21.20
 H > 20.53
```
These magnitudes are not corrected for Galactic extinction in the directi= on of the GRB.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedr= o M=E1rtir.
GCN Circular #14435
Arne Rau (MPE) reports on behalf of the Fermi GBM Team:
"At 12:56:32.99 UT on 20 April 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 130420B (trigger 388155395 / 130420539), which was also detected by Swift/BAT (Oates et al., GCN 14411). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is about 50 degrees.
The GBM light curve shows a single pulse with a duration (T90) of about 16 s (50-300 keV). The time-averaged spectrum from T0-4 s to T0+4 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is 0.24 +/- 0.25 and the cutoff energy, parameterized as Epeak, is 91 +/- 9 keV.
The event fluence (10-1000 keV) in this time interval is (1.04 +/- 0.08)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.0 s in the 10-1000 keV band is 2.6 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #14444
B. A. Zauderer and E. Berger (Harvard) report on behalf of the CARMA Key Project "A Millimeter View of the Transient Universe" and a larger collaboration:
"We observed the position of GRB 130420B (Oates et al.; GCN 14411) beginning 2013 Apr 23.29 UT (dt = 2.75 d) with the Very Large Array (VLA) and beginning 2013 Apr 22.91 (dt = 2.37 d) with the Combined Array for Research at Millimeter Astronomy (CARMA). We do not find any significant radio emission at the position of the enhanced Swift-XRT position (Page et al.; GCN 14421) at a mean frequency of 5.8 GHz (VLA) to a 3-sigma limit of 32 uJy, at 21.8 GHz (VLA) to a 3-sigma limit of 47 uJy, or at 85 GHz (CARMA) to a 3-sigma limit of 0.78 mJy.
We thank the VLA and CARMA observatories for their support of these observations."
GCN Report 430.1
GCN_Report 430.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_430_1.pdf by S.R. Oates at UCL-MSSL titled: "Swift Observations of GRB 130420B"

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Jochen Greiner, last update: 25-Apr-2013 [Disclaimer]