Gamma-ray Burst 100420A

(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 20 Apr 10 05:24:02 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     419932,   Seg_Num: 0
GRB_RA:          296.127d {+19h 44m 31s} (J2000),
                 296.184d {+19h 44m 44s} (current),
                 295.854d {+19h 43m 25s} (1950)
GRB_DEC:         +55.793d {+55d 47' 33"} (J2000),
                 +55.818d {+55d 49' 04"} (current),
                 +55.671d {+55d 40' 14"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1522 [image_cnts]
TRIGGER_DUR:     64.000 [sec] 
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        15306 TJD;   110 DOY;   10/04/20
GRB_TIME:        19362.27 SOD {05:22:42.27} UT
GRB_PHI:         140.55 [deg]
GRB_THETA:        15.78 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.37 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  -3  +0  +0 -14  +0 
SUN_POSTN:        27.94d {+01h 51m 46s}  +11.48d {+11d 28' 58"}
SUN_DIST:         81.50 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.03d {+06h 44m 07s}  +23.46d {+23d 27' 40"}
MOON_DIST:        99.68 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.39, 15.20 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      331.55, 73.65 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
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 = 341.25,7.06 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Apr 10 05:25:07 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     419932,   Seg_Num: 0
POINT_RA:        296.124d {+19h 44m 30s} (J2000)
POINT_DEC:       +55.794d {+55d 47' 38"} (J2000)
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  19492.79 SOD {05:24:52.79} UT,   130.5 [sec] since BAT Trigger Time
COUNTS:          13    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    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:     Tue 20 Apr 10 05:26:50 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     419932,   Seg_Num: 0
GRB_RA:          296.127d {+19h 44m 31s} (J2000),
                 296.184d {+19h 44m 44s} (current),
                 295.854d {+19h 43m 25s} (1950)
GRB_DEC:         +55.793d {+55d 47' 33"} (J2000),
                 +55.818d {+55d 49' 04"} (current),
                 +55.671d {+55d 40' 14"} (1950)
GRB_DATE:        15306 TJD;   110 DOY;   10/04/20
GRB_TIME:        19362.27 SOD {05:22:42.27} UT
TRIGGER_INDEX:   20000
GRB_PHI:         140.55 [deg]
GRB_THETA:        15.78 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     64.000 [sec] 
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.37 [sigma]
LC_URL:          sw00419932000msb.lc
SUN_POSTN:        27.94d {+01h 51m 47s}  +11.48d {+11d 29' 01"}
SUN_DIST:         81.50 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.06d {+06h 44m 14s}  +23.46d {+23d 27' 24"}
MOON_DIST:        99.69 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.39, 15.20 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      331.55, 73.65 [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 an image 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 = 341.25,7.06 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Apr 10 05:28:19 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     419932,   Seg_Num: 0
POINT_RA:        296.124d {+19h 44m 30s} (J2000)
POINT_DEC:       +55.794d {+55d 47' 37"} (J2000)
POINT_ROLL:      81.989d
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  19496.46 SOD {05:24:56.46} UT,   134.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.090
N_STARS:         190
X_OFFSET:        478 [pixels]
Y_OFFSET:        557 [pixels]
X_MAX:           1437 [pixels]
Y_MAX:           1516 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00419932000msufc0134.fits
SUN_POSTN:        27.95d {+01h 51m 47s}  +11.48d {+11d 29' 02"}
SUN_DIST:         81.50 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.07d {+06h 44m 18s}  +23.45d {+23d 27' 15"}
MOON_DIST:        99.69 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.39, 15.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      331.55, 73.65 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Apr 10 05:29:04 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     419932,   Seg_Num: 0
GRB_RA:          296.1264d {+19h 44m 30.33s} (J2000),
                 296.1827d {+19h 44m 43.84s} (current),
                 295.8528d {+19h 43m 24.68s} (1950)
GRB_DEC:         +55.7688d {+55d 46' 07.6"} (J2000),
                 +55.7941d {+55d 47' 38.6"} (current),
                 +55.6468d {+55d 38' 48.4"} (1950)
GRB_ERROR:       4.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  19510.00 SOD {05:25:10.00} UT,   147.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        27.95d {+01h 51m 47s}  +11.48d {+11d 29' 03"}
SUN_DIST:         81.51 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.08d {+06h 44m 20s}  +23.45d {+23d 27' 11"}
MOON_DIST:        99.72 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.37, 15.19 [deg] galactic lon,lat of the burst
ECL_COORDS:      331.50, 73.63 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Apr 10 05:28:59 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     419932,   Seg_Num: 0
POINT_RA:        296.124d {+19h 44m 30s} (J2000)
POINT_DEC:       +55.794d {+55d 47' 37"} (J2000)
POINT_ROLL:      81.989d
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  19496.46 SOD {05:24:56.46} UT,   134.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.090
N_STARS:         190
X_OFFSET:        478 [pixels]
Y_OFFSET:        557 [pixels]
X_MAX:           1437 [pixels]
Y_MAX:           1516 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00419932000msufc0134.fits
SUN_POSTN:        27.95d {+01h 51m 47s}  +11.48d {+11d 29' 03"}
SUN_DIST:         81.50 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.08d {+06h 44m 20s}  +23.45d {+23d 27' 11"}
MOON_DIST:        99.69 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.39, 15.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      331.55, 73.65 [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:     Tue 20 Apr 10 05:29:29 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     419932,   Seg_Num: 0
POINT_RA:        296.124d {+19h 44m 30s} (J2000)
POINT_DEC:       +55.794d {+55d 47' 37"} (J2000)
ROLL:            81.989d
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  19496.46 SOD {05:24:56.46} UT,   134.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     293433902
X_OFFSET:        797 [pixels]
Y_OFFSET:        876 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       957
Y_GRB_POS:       1036
BINNING_INDEX:   1
IM_URL:          sw00419932000msuni0140.fits
SUN_POSTN:        27.95d {+01h 51m 47s}  +11.48d {+11d 29' 03"}
SUN_DIST:         81.50 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.09d {+06h 44m 21s}  +23.45d {+23d 27' 08"}
MOON_DIST:        99.69 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.39, 15.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      331.55, 73.65 [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 20 Apr 10 05:29:55 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     419932,   Seg_Num: 0
POINT_RA:        296.124d {+19h 44m 30s} (J2000)
POINT_DEC:       +55.794d {+55d 47' 37"} (J2000)
ROLL:            81.989d
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  19496.46 SOD {05:24:56.46} UT,   134.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     293433902
X_OFFSET:        797 [pixels]
Y_OFFSET:        876 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       957
Y_GRB_POS:       1036
BINNING_INDEX:   1
IM_URL:          sw00419932000msuni0140.fits
SUN_POSTN:        27.95d {+01h 51m 47s}  +11.48d {+11d 29' 03"}
SUN_DIST:         81.50 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.09d {+06h 44m 22s}  +23.45d {+23d 27' 06"}
MOON_DIST:        99.69 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.39, 15.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      331.55, 73.65 [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 20 Apr 10 05:28:19 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     419932,   Seg_Num: 0
POINT_RA:        296.124d {+19h 44m 30s} (J2000)
POINT_DEC:       +55.794d {+55d 47' 37"} (J2000)
POINT_ROLL:      81.989d
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  19496.46 SOD {05:24:56.46} UT,   134.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.090
N_STARS:         190
X_OFFSET:        478 [pixels]
Y_OFFSET:        557 [pixels]
X_MAX:           1437 [pixels]
Y_MAX:           1516 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00419932000msufc0134.fits
SUN_POSTN:        27.95d {+01h 51m 47s}  +11.48d {+11d 29' 02"}
SUN_DIST:         81.50 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.07d {+06h 44m 18s}  +23.45d {+23d 27' 15"}
MOON_DIST:        99.69 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.39, 15.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      331.55, 73.65 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN Circular #10628
W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), C. Guidorzi (U Ferrara), E. A. Hoversten (PSU), O. M. Littlejohns (U Leicester), R. Margutti (INAF-OAB), C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), A. Rowlinson (U Leicester), M. H. Siegel (PSU) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team:
At 05:22:42 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100420A (trigger=419932). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 296.127, +55.793 which is
```
   RA(J2000) = 19h 44m 31s
   Dec(J2000) = +55d 47' 33"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual for an image trigger, there is nothing of note in the BAT light curve.
The XRT began observing the field at 05:24:52.8 UT, 130.5 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 296.12646, 55.76885 which is equivalent to:
```
   RA(J2000)  = 19h 44m 30.35s
   Dec(J2000) = +55d 46' 07.9"
```
with an uncertainty of 4.0 arcseconds (radius, 90% containment). This location is 86 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 consistent with the Galactic value of 1.19e+21 cm^-2 (Kalberla et al. 2005).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 134 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 none of the XRT error circle. The coverage of the XRT error circle by the 8'x8' region for the list of sources generated on-board is uncertain because the large number of sources filled the available telemetry. No correction has been made for the expected extinction corresponding to E(B-V) of 0.11.
Burst Advocate for this burst is W. H. Baumgartner (wayne AT milkyway.gsfc.nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Apr 10 05:44:23 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     419932,   Seg_Num: 0
POINT_RA:        296.127d {+19h 44m 31s} (J2000)
POINT_DEC:       +55.793d {+55d 47' 34"} (J2000)
POINT_ROLL:      81.991d
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  20235.24 SOD {05:37:15.24} UT,   873.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.819
N_STARS:         190
X_OFFSET:        238 [pixels]
Y_OFFSET:        317 [pixels]
X_MAX:           1677 [pixels]
Y_MAX:           1756 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00419932000msufc0872.fits
SUN_POSTN:        27.96d {+01h 51m 49s}  +11.49d {+11d 29' 16"}
SUN_DIST:         81.50 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.24d {+06h 44m 58s}  +23.43d {+23d 25' 42"}
MOON_DIST:        99.74 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.39, 15.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      331.55, 73.65 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Apr 10 05:45:03 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     419932,   Seg_Num: 0
POINT_RA:        296.127d {+19h 44m 31s} (J2000)
POINT_DEC:       +55.793d {+55d 47' 34"} (J2000)
POINT_ROLL:      81.991d
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  20235.24 SOD {05:37:15.24} UT,   873.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.819
N_STARS:         190
X_OFFSET:        238 [pixels]
Y_OFFSET:        317 [pixels]
X_MAX:           1677 [pixels]
Y_MAX:           1756 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00419932000msufc0872.fits
SUN_POSTN:        27.96d {+01h 51m 50s}  +11.49d {+11d 29' 16"}
SUN_DIST:         81.50 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.25d {+06h 44m 59s}  +23.43d {+23d 25' 39"}
MOON_DIST:        99.74 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.39, 15.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      331.55, 73.65 [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:     Tue 20 Apr 10 05:44:23 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     419932,   Seg_Num: 0
POINT_RA:        296.127d {+19h 44m 31s} (J2000)
POINT_DEC:       +55.793d {+55d 47' 34"} (J2000)
POINT_ROLL:      81.991d
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  20235.24 SOD {05:37:15.24} UT,   873.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.819
N_STARS:         190
X_OFFSET:        238 [pixels]
Y_OFFSET:        317 [pixels]
X_MAX:           1677 [pixels]
Y_MAX:           1756 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00419932000msufc0872.fits
SUN_POSTN:        27.96d {+01h 51m 49s}  +11.49d {+11d 29' 16"}
SUN_DIST:         81.50 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.24d {+06h 44m 58s}  +23.43d {+23d 25' 42"}
MOON_DIST:        99.74 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.39, 15.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      331.55, 73.65 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Apr 10 05:45:40 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     419932,   Seg_Num: 0
GRB_RA:          296.1270d {+19h 44m 30.48s} (J2000),
                 296.1833d {+19h 44m 43.98s} (current),
                 295.8534d {+19h 43m 24.82s} (1950)
GRB_DEC:         +55.7695d {+55d 46' 10.2"} (J2000),
                 +55.7948d {+55d 47' 41.1"} (current),
                 +55.6475d {+55d 38' 50.9"} (1950)
GRB_ERROR:       2.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  19510.00 SOD {05:25:10.00} UT,   147.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        27.96d {+01h 51m 50s}  +11.49d {+11d 29' 17"}
SUN_DIST:         81.51 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.25d {+06h 45m 01s}  +23.43d {+23d 25' 35"}
MOON_DIST:        99.76 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.37, 15.19 [deg] galactic lon,lat of the burst
ECL_COORDS:      331.50, 73.63 [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 20 Apr 10 05:46:05 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     419932,   Seg_Num: 0
POINT_RA:        296.127d {+19h 44m 31s} (J2000)
POINT_DEC:       +55.793d {+55d 47' 34"} (J2000)
ROLL:            81.991d
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  20235.24 SOD {05:37:15.24} UT,   873.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     293434640
X_OFFSET:        797 [pixels]
Y_OFFSET:        876 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       957
Y_GRB_POS:       1036
BINNING_INDEX:   1
IM_URL:          sw00419932000msuni0878.fits
SUN_POSTN:        27.96d {+01h 51m 50s}  +11.49d {+11d 29' 17"}
SUN_DIST:         81.51 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.26d {+06h 45m 02s}  +23.43d {+23d 25' 33"}
MOON_DIST:        99.74 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.39, 15.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      331.55, 73.65 [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 20 Apr 10 05:46:38 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     419932,   Seg_Num: 0
POINT_RA:        296.127d {+19h 44m 31s} (J2000)
POINT_DEC:       +55.793d {+55d 47' 34"} (J2000)
ROLL:            81.991d
IMG_START_DATE:  15306 TJD;   110 DOY;   10/04/20
IMG_START_TIME:  20235.24 SOD {05:37:15.24} UT,   873.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     293434640
X_OFFSET:        797 [pixels]
Y_OFFSET:        876 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       957
Y_GRB_POS:       1036
BINNING_INDEX:   1
IM_URL:          sw00419932000msuni0878.fits
SUN_POSTN:        27.96d {+01h 51m 50s}  +11.49d {+11d 29' 18"}
SUN_DIST:         81.51 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:      101.26d {+06h 45m 03s}  +23.42d {+23d 25' 29"}
MOON_DIST:        99.75 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:       88.39, 15.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      331.55, 73.65 [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 #10629
L. Xiao (Louisiana State), W. Rujopakarn (Steward), B. E. Schaefer (Louisiana State), T. Guver (U Arizona) and S. B. Pandey (U Mich), report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 100420A (Swift trigger 419932; W. H. Baumgartner et al., GCN 10628), producing images beginning 8.8 s after the GCN notice time. An automated response took the first image at 05:24:07.8 UT, 79.8 s after the burst, and during the gamma-ray emission. We took 10 5-sec, 10 20-sec and 10 60-sec exposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging is on going.
Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma Swift/BAT error circle or the XRT error circle, for both single images and coadding into sets of 10. Individual images have limiting magnitudes ranging from 15.3-16.8; we set the following specific limits.
```
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
05:24:07.8 05:25:14.9 67 16.7 79.8 Y
05:25:28.5 05:30:11.0 282 17.3 160.5 Y
05:30:20.3 05:41:42.0 681 17.6 452.3 Y
```
GCN Circular #10636
Adria C. Updike, Dieter H. Hartmann (Clemson University), and Chris De Pree (Agnes Scott College) report:
We observed the field of GRB 100420A (Baumgartner et al., GCN 10628) using the 0.9m SARA telescope located at KPNO beginning 3 hours and 4 minutes after the BAT trigger. We obtained 22 minutes of observations in the R band followed by 20 minutes in the I band at high airmass. At the location of the XRT error circle, we detect no new sources down to a limiting magnitude of R > 19.0, I > 18.5 (as compared to the USNO B1.0 catalog). No further observations are planned.
GCN Circular #10638
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 1862 s of XRT Photon Counting mode data and 1 UVOT images for GRB 100420A, 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 = 296.12761, +55.76926 which is equivalent to:
```
RA (J2000): 19h 44m 30.63s
Dec (J2000): +55d 46' 09.3"
```
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 was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #10639
A. Rowlinson (U Leicester) and W. H. Baumgartner (GSFC/UMBC) report on behalf of the Swift-XRT team:
We have analysed 6.9 ks of XRT data for GRB 100420A (Baumgartner et al. GCN Circ. 10628), from 115 s to 13.6 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 Beardmore et al. (GCN. Circ 10638).
The light curve can be modelled with a power-law decay with a decay index of alpha=2.69 (+0.47, -0.39), followed by a break at T+721 s to an alpha of 1.22 (+0.34, -4.02).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.83 (+0.22, -0.20). The best-fitting absorption column is consistent with the Galactic value of 1.2 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.2 x 10^-11 (5.3 x 10^-11) erg cm^-2 count^-1.
If the light curve continues to decay with a power-law decay index of 1.22, the count rate at T+24 hours will be 2.3 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.7 x 10^-15 (1.2 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/00419932.
This circular is an official product of the Swift-XRT team.
GCN Circular #10640
M. M. Chester (PSU) and W. H. Baumgartner (GSFC/UMBC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 100420A 134 s after the BAT trigger (Baumgartner et al., GCN Circ. 10628). No optical afterglow consistent with the enhanced XRT position (Beardmore et al., GCN Circ. 10638) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           134          284          147         >20.8
u_FC               292          542          246         >20.0
white              134        13589         1503         >22.7
v                  624        30201         1434         >20.5
b                  548        19368         1911         >22.2
u                  292        18659         2409         >21.7
w1                 674        17744         1435         >21.6
m2                 648        30928         1260         >21.5
w2                 598        29287         1434         >21.4
```
The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.11 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #10642
D. Kuroda, K. Yanagisawa, Y. Shimizu, S. Nagayama, H. Toda (OAO, NAOJ), M. Yoshida (Hiroshima) and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 100420A (Baumgartner et al. GCN 10628) 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 2010-04-20 18:03:04 UT (~12.7h after the burst). We did not find any new point source in the Enhanced XRT error circle (Beardmore et al., GCNC 10638) 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
------------------------------------------------------
0.53748   18:16:41   1320.0      >18.7  >18.6  >18.3
------------------------------------------------------
```
T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]
GCN Circular #10660
J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team):
Using the data set from T-205 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100420A (trigger #419932) (Baumgartner, et al., GCN Circ. 10628). The BAT ground-calculated position is RA, Dec = 296.090, 55.755 deg, which is
```
   RA(J2000)  =  19h 44m 21.5s 
   Dec(J2000) = +55d 45' 18.7" 
```
with an uncertainty of 4.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 92%.
The mask-weighted light curve shows a single peak starting around T-10 sec, peaking at ~T+10 sec, and ending at ~T+60 sec. T90 (15-350 keV) is 48 +- 36 sec (estimated error including systematics).
The time-averaged spectrum from T-30 to T+70 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.17 +- 0.22. The fluence in the 15-150 keV band is 5.7 +- 1.0 x 10^-7 erg/cm2. 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/419932/BA/
GCN Circular #10666
T. Sakamoto (UMBC/GSFC), D. Donato (ORAU/GSFC), N. Gehrels (GSFC), T. Okajima (JHU/GSFC), Y. Urata (NCU), C.A. Wallace (FGCU)
We observed the field of GRB 100420A detected by Swift (trigger #419932; Baumgartner et al., GCN Circ. 10628) with the 14-inch Goddard Robotic Telescope (GRT) located at the Goddard Geophysical and Astronomical Observatory (http://cddisa.gsfc.nasa.gov/ggao/).
Total 435 images of 5 sec (200 images), 30 sec (80 images), 60 sec (120 images) and 100 sec (35 images) exposures were taken in the R filter starting from April 20 05:26:53 (UT) about 4.2 minutes after the trigger and stopped on April 20 09:49:15 (UT). We do not detect the optical afterglow both in the individual images and the stucked image, which only combined good quality 400 images, inside the XRT position (Rowlinson et al., GCN #10639). The estimated three sigma upper limit of the combined image (total exposure of 10600 sec) is ~18.9 mag using the USNO-B1 catalog.
GCN Circular #10704
M. Andreev, A. Sergeev (Terskol Branch of Institute of Astronomy), A. Volnova (SAI MSU), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 100420A (Baumgartner et al., GCN 10628) with the Z-600 telescope of Mt.Terskol observatory in R-filter between (UT) Apr. 20 23:30 - Apr. 21 00:39 under good weather conditions with mean seeing of about 1.2 arcsec. We do not detect any source at the position of the enhanced XRT error circle (Beardmore et al., GCN 10638).
The 3 sigma upper limit of the stacked image based on several USNO-B1.0 field stars is following:
```
T0+      Filter,  Exposure,  mag.
(mid, d)           (s)

0.7789   R       20x180    >20.2
```
GCN Circular #10706
A.J. Levan (U. Warwick), A. Cucchiara (PSU), N.R. Tanvir (U. Leicester), D. Fox (PSU) report on behalf of a larger collaboration:
"We obtained two epochs of observations of GRB 100420A (Baumgartner et al. GCN 10628) using Gemini-North/NIRI. Our first epoch consisted of 540s of observations in each of YJH and K and began at April 20 13:24 UT, approximately 8.2 hours after the burst. Our second epoch was obtained at April 22 14:27 ~57 hours after the burst.
Within the refined XRT error circle we find a single object in our first epoch K-band observation. The object has a location of
```
RA(J2000) 19:44:30.57
Dec(J2000) 55:46:10.0
```
with an error of 0.3" in each axis. It has a magnitude of K~21 in our first epoch observation, but has faded below our 3-sigma detection limit of K~22 in the second epoch. We therefore identify this source as the infrared afterglow of GRB 100420A.
The source is not significantly detected in our J or H-band observations to preliminary limiting magnitudes of H>21.5, J>22.5 (3 sigma). However, because of the relative faintness of the K-band observations these limits are not constraining in terms of high-z and dust extinguished afterglow models"
GCN Circular #10707
Dale A. Frail (NRAO) and Poonam Chandra (RMC) report on behalf of a larger collaboration:
"We observed the localization of dark burst GRB 100420A (Baumgartner et al. GCN 10628) with the Expanded Very Large Array (EVLA) on May 1.50 UT at a center frequency of 8.46 GHz. We do not detect any radio source anywhere within the refined XRT error circle (Beardmore et al., GCN 10638) to a 3-sigma limit of 51 uJy.
The EVLA is still undergoing active commissioning and we caution that these results should be considered preliminary. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc."

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Jochen Greiner, last update: 20-Apr-2010 [Disclaimer]