Gamma-ray Burst 230427A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 27 Apr 23 10:32:26 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1165948,   Seg_Num: 0
GRB_RA:          153.324d {+10h 13m 18s} (J2000),
                 153.687d {+10h 14m 45s} (current),
                 152.541d {+10h 10m 10s} (1950)
GRB_DEC:         +48.180d {+48d 10' 47"} (J2000),
                 +48.064d {+48d 03' 49"} (current),
                 +48.428d {+48d 25' 40"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3233 [cnts]    Image_Peak=155 [image_cnts]
TRIGGER_DUR:     2.048 [sec] 
TRIGGER_INDEX:   253     E_range: 15-50 keV
BKG_INTEN:       31137 [cnts]
BKG_TIME:        37880.81 SOD {10:31:20.81} UT
BKG_DUR:         24 [sec]
GRB_DATE:        20061 TJD;   117 DOY;   23/04/27
GRB_TIME:        37911.98 SOD {10:31:51.98} UT
GRB_PHI:         -77.19 [deg]
GRB_THETA:        13.59 [deg]
SOLN_STATUS:     0x83
RATE_SIGNIF:     11.04 [sigma]
IMAGE_SIGNIF:    6.80 [sigma]
MERIT_PARAMS:     +1  +0  +0  +1  +1  -3  +0  +0 +13  +0 
SUN_POSTN:        34.58d {+02h 18m 20s}  +13.82d {+13d 49' 23"}
SUN_DIST:         97.93 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.58d {+08h 22m 19s}  +24.87d {+24d 52' 12"}
MOON_DIST:        32.04 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.64, 52.89 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      136.21, 34.38 [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:        Since the IMAGE_SIGNIF is less than 7 sigma, this is a questionable detection.  
COMMENTS:        This trigger occurred at longitude,latitude = 124.10,-17.16 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 27 Apr 23 10:33:31 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.346d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 49"} (J2000)
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38005.93 SOD {10:33:25.93} UT,   93.9 [sec] since BAT Trigger Time
COUNTS:          2    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:     Thu 27 Apr 23 10:36:18 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.346d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 47"} (J2000)
POINT_ROLL:      300.798d
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38010.47 SOD {10:33:30.47} UT,   98.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.776
N_STARS:         25
X_OFFSET:        641 [pixels]
Y_OFFSET:        520 [pixels]
X_MAX:           1600 [pixels]
Y_MAX:           1479 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01165948000msufc0098.fits
SUN_POSTN:        34.59d {+02h 18m 21s}  +13.82d {+13d 49' 26"}
SUN_DIST:         97.95 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.62d {+08h 22m 28s}  +24.86d {+24d 51' 46"}
MOON_DIST:        32.03 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.66, 52.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      136.24, 34.37 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 27 Apr 23 10:36:29 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.346d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 47"} (J2000)
POINT_ROLL:      300.798d
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38010.47 SOD {10:33:30.47} UT,   98.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.776
N_STARS:         25
X_OFFSET:        641 [pixels]
Y_OFFSET:        520 [pixels]
X_MAX:           1600 [pixels]
Y_MAX:           1479 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01165948000msufc0098.fits
SUN_POSTN:        34.59d {+02h 18m 21s}  +13.82d {+13d 49' 26"}
SUN_DIST:         97.95 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.62d {+08h 22m 28s}  +24.86d {+24d 51' 45"}
MOON_DIST:        32.03 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.66, 52.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      136.24, 34.37 [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:     Thu 27 Apr 23 10:37:43 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.346d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 47"} (J2000)
ROLL:            300.798d
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38010.47 SOD {10:33:30.47} UT,   98.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     704284441
X_OFFSET:        960 [pixels]
Y_OFFSET:        839 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1120
Y_GRB_POS:       999
BINNING_INDEX:   1
IM_URL:          sw01165948000msuni0130.fits
SUN_POSTN:        34.59d {+02h 18m 21s}  +13.82d {+13d 49' 27"}
SUN_DIST:         97.95 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.63d {+08h 22m 31s}  +24.86d {+24d 51' 37"}
MOON_DIST:        32.02 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.66, 52.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      136.24, 34.37 [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:     Thu 27 Apr 23 10:37:57 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.346d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 47"} (J2000)
ROLL:            300.798d
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38010.47 SOD {10:33:30.47} UT,   98.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     704284441
X_OFFSET:        960 [pixels]
Y_OFFSET:        839 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1120
Y_GRB_POS:       999
BINNING_INDEX:   1
IM_URL:          sw01165948000msuni0130.fits
SUN_POSTN:        34.59d {+02h 18m 21s}  +13.82d {+13d 49' 27"}
SUN_DIST:         97.95 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.63d {+08h 22m 31s}  +24.86d {+24d 51' 35"}
MOON_DIST:        32.02 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.66, 52.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      136.24, 34.37 [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:     Thu 27 Apr 23 10:37:45 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1165948,   Seg_Num: 0
GRB_RA:          153.3106d {+10h 13m 14.54s} (J2000),
                 153.6741d {+10h 14m 41.77s} (current),
                 152.5277d {+10h 10m 06.64s} (1950)
GRB_DEC:         +48.2043d {+48d 12' 15.4"} (J2000),
                 +48.0881d {+48d 05' 17.2"} (current),
                 +48.4522d {+48d 27' 07.8"} (1950)
GRB_ERROR:       4.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38014.00 SOD {10:33:34.00} UT,   102.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        34.59d {+02h 18m 21s}  +13.82d {+13d 49' 27"}
SUN_DIST:         97.90 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.63d {+08h 22m 31s}  +24.86d {+24d 51' 36"}
MOON_DIST:        32.03 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.61, 52.87 [deg] galactic lon,lat of the burst
ECL_COORDS:      136.19, 34.40 [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:     Thu 27 Apr 23 10:39:26 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     1165948,   Seg_Num: 0
GRB_RA:          153.3127d {+10h 13m 15.04s} (J2000),
                 153.6762d {+10h 14m 42.27s} (current),
                 152.5298d {+10h 10m 07.15s} (1950)
GRB_DEC:         +48.2040d {+48d 12' 14.4"} (J2000),
                 +48.0878d {+48d 05' 16.1"} (current),
                 +48.4519d {+48d 27' 06.8"} (1950)
GRB_ERROR:       0.7 [arcsec radius, statistical only]
GRB_MAG:         20.30 +/- 0.20 [mag]
FILTER:          10, White
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38007.00 SOD {10:33:27.00} UT,   95.0 [sec] since BAT Trigger Time
SUN_POSTN:        34.59d {+02h 18m 21s}  +13.82d {+13d 49' 29"}
SUN_DIST:         97.90 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.64d {+08h 22m 34s}  +24.86d {+24d 51' 25"}
MOON_DIST:        32.03 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.61, 52.88 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      136.19, 34.40 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 27 Apr 23 10:43:02 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.348d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 46"} (J2000)
POINT_ROLL:      300.800d
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38168.42 SOD {10:36:08.42} UT,   256.4 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.448
N_STARS:         33
X_OFFSET:        401 [pixels]
Y_OFFSET:        280 [pixels]
X_MAX:           1840 [pixels]
Y_MAX:           1719 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    3
SL_URL:          sw01165948000msufc0256.fits
SUN_POSTN:        34.59d {+02h 18m 22s}  +13.83d {+13d 49' 31"}
SUN_DIST:         97.94 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.67d {+08h 22m 42s}  +24.85d {+24d 51' 00"}
MOON_DIST:        32.01 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.66, 52.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      136.24, 34.37 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 27 Apr 23 10:43:19 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.348d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 46"} (J2000)
POINT_ROLL:      300.800d
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38168.42 SOD {10:36:08.42} UT,   256.4 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.448
N_STARS:         33
X_OFFSET:        401 [pixels]
Y_OFFSET:        280 [pixels]
X_MAX:           1840 [pixels]
Y_MAX:           1719 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    3
SL_URL:          sw01165948000msufc0256.fits
SUN_POSTN:        34.59d {+02h 18m 22s}  +13.83d {+13d 49' 32"}
SUN_DIST:         97.94 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.68d {+08h 22m 43s}  +24.85d {+24d 50' 58"}
MOON_DIST:        32.01 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.66, 52.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      136.24, 34.37 [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:     Thu 27 Apr 23 10:44:08 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.348d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 46"} (J2000)
ROLL:            300.800d
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38168.42 SOD {10:36:08.42} UT,   256.4 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     704284599
X_OFFSET:        960 [pixels]
Y_OFFSET:        839 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1120
Y_GRB_POS:       999
BINNING_INDEX:   1
IM_URL:          sw01165948000msuni0288.fits
SUN_POSTN:        34.59d {+02h 18m 22s}  +13.83d {+13d 49' 32"}
SUN_DIST:         97.94 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.68d {+08h 22m 44s}  +24.85d {+24d 50' 53"}
MOON_DIST:        32.00 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.66, 52.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      136.24, 34.37 [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:     Thu 27 Apr 23 10:44:15 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.348d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 46"} (J2000)
ROLL:            300.800d
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38168.42 SOD {10:36:08.42} UT,   256.4 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     704284599
X_OFFSET:        960 [pixels]
Y_OFFSET:        839 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1120
Y_GRB_POS:       999
BINNING_INDEX:   1
IM_URL:          sw01165948000msuni0288.fits
SUN_POSTN:        34.59d {+02h 18m 22s}  +13.83d {+13d 49' 32"}
SUN_DIST:         97.94 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.69d {+08h 22m 44s}  +24.85d {+24d 50' 52"}
MOON_DIST:        32.00 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.66, 52.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      136.24, 34.37 [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:     Thu 27 Apr 23 10:49:03 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.348d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 46"} (J2000)
POINT_ROLL:      300.799d
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38772.11 SOD {10:46:12.11} UT,   860.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.824
N_STARS:         52
X_OFFSET:        401 [pixels]
Y_OFFSET:        280 [pixels]
X_MAX:           1840 [pixels]
Y_MAX:           1719 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    6
SL_URL:          sw01165948000msufc0860.fits
SUN_POSTN:        34.59d {+02h 18m 23s}  +13.83d {+13d 49' 36"}
SUN_DIST:         97.94 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.73d {+08h 22m 55s}  +24.84d {+24d 50' 19"}
MOON_DIST:        31.99 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.66, 52.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      136.24, 34.37 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 27 Apr 23 10:49:15 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.348d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 46"} (J2000)
POINT_ROLL:      300.799d
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38772.11 SOD {10:46:12.11} UT,   860.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.824
N_STARS:         52
X_OFFSET:        401 [pixels]
Y_OFFSET:        280 [pixels]
X_MAX:           1840 [pixels]
Y_MAX:           1719 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    6
SL_URL:          sw01165948000msufc0860.fits
SUN_POSTN:        34.59d {+02h 18m 23s}  +13.83d {+13d 49' 36"}
SUN_DIST:         97.94 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.73d {+08h 22m 55s}  +24.84d {+24d 50' 18"}
MOON_DIST:        31.99 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.66, 52.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      136.24, 34.37 [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:     Thu 27 Apr 23 10:50:23 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.348d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 46"} (J2000)
ROLL:            300.799d
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38772.11 SOD {10:46:12.11} UT,   860.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     704285203
X_OFFSET:        960 [pixels]
Y_OFFSET:        839 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1120
Y_GRB_POS:       999
BINNING_INDEX:   1
IM_URL:          sw01165948000msuni0892.fits
SUN_POSTN:        34.60d {+02h 18m 23s}  +13.83d {+13d 49' 37"}
SUN_DIST:         97.94 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.74d {+08h 22m 57s}  +24.84d {+24d 50' 10"}
MOON_DIST:        31.98 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.66, 52.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      136.24, 34.37 [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:     Thu 27 Apr 23 10:50:31 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1165948,   Seg_Num: 0
POINT_RA:        153.348d {+10h 13m 23s} (J2000)
POINT_DEC:       +48.163d {+48d 09' 46"} (J2000)
ROLL:            300.799d
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38772.11 SOD {10:46:12.11} UT,   860.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     704285203
X_OFFSET:        960 [pixels]
Y_OFFSET:        839 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1120
Y_GRB_POS:       999
BINNING_INDEX:   1
IM_URL:          sw01165948000msuni0892.fits
SUN_POSTN:        34.60d {+02h 18m 23s}  +13.83d {+13d 49' 37"}
SUN_DIST:         97.94 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.74d {+08h 22m 58s}  +24.84d {+24d 50' 09"}
MOON_DIST:        31.98 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.66, 52.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      136.24, 34.37 [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 #33687
E. Troja (UToV), P. A. Evans (U Leicester), R. A. J. Eyles-Ferris (U Leicester), C. Gronwall (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU) and K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift Observatory Team:
At 10:31:52 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 230427A (trigger=1165948). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 153.324, +48.180 which is
```
   RA(J2000) = 10h 13m 18s
   Dec(J2000) = +48d 10' 48"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). No BAT light-curve is available at this time.
The XRT began observing the field at 10:33:25.9 UT, 94.0 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 153.31199, 48.20404 which is equivalent to:
```
   RA(J2000)  = 10h 13m 14.88s
   Dec(J2000) = +48d 12' 14.6"
```
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 91 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 https://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (8.35 x 10^19 cm^-2, Willingale et al. 2013), with an excess column of 3.5 (+2.81/-2.63) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 98 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	10:13:15.05 = 153.31270
  DEC(J2000) = +48:12:14.4  =  48.20400
```
with a 90%-confidence error radius of about 0.74 arc sec. This position is 1.4 arc sec. from the center of the XRT error circle. The estimated magnitude is 20.31 with a 1-sigma error of about 0.20. No correction has been made for the expected extinction corresponding to E(B-V) of 0.007.
Burst Advocate for this burst is E. Troja (nora.gsfc AT gmail.com). 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/)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 27 Apr 23 10:43:50 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1165948,   Seg_Num: 0
GRB_RA:          153.3121d {+10h 13m 14.90s} (J2000),
                 153.6756d {+10h 14m 42.13s} (current),
                 152.5292d {+10h 10m 07.00s} (1950)
GRB_DEC:         +48.2038d {+48d 12' 13.6"} (J2000),
                 +48.0876d {+48d 05' 15.4"} (current),
                 +48.4517d {+48d 27' 06.0"} (1950)
GRB_ERROR:       1.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20061 TJD;   117 DOY;   23/04/27
IMG_START_TIME:  38014.00 SOD {10:33:34.00} UT,   102.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        34.59d {+02h 18m 22s}  +13.83d {+13d 49' 32"}
SUN_DIST:         97.90 [deg]   Sun_angle= -7.9 [hr] (East of Sun)
MOON_POSTN:      125.68d {+08h 22m 44s}  +24.85d {+24d 50' 55"}
MOON_DIST:        32.01 [deg]
MOON_ILLUM:      46 [%]
GAL_COORDS:      167.61, 52.88 [deg] galactic lon,lat of the burst
ECL_COORDS:      136.19, 34.40 [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 Circular #33688
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 1112 s of XRT Photon Counting mode data and 2 UVOT images for GRB 230427A, 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 = 153.31316, +48.20393 which is equivalent to:
```
RA (J2000): 10h 13m 15.16s
Dec (J2000): +48d 12' 14.2"
```
with an uncertainty of 2.4 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 #33690
I. Takahashi, S. Hayatsu, N. Higuchi, M. Sasada, R. Hosokawa, S. Sato, M. Niwano, H. Seki, H. Takei, Y. Yatsu (Tokyo Tech), K. L. Murata (Kyoto U) and N. Kawai (Riken) report on behalf of the MITSuME collaboration:
We observed the field of GRB 230427A (Troja et al. GCN Circular #33687, Beardmore et al. GCN Circular #33688) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno.
The observation started at 2023-04-27 10:33:23 UT (91 seconds after the Swift/BAT trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the error region (Troja et al. GCN Circular #33687). We obtained the 5-sigma limits of the stacked images as follows.
```
T0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits
------------------------------------------------------------------------------------------------
263 | 2023-04-27 10:36:15 | 160.0 | g'>17.8, Rc>17.4, Ic>17.0
753 | 2023-04-27 10:44:25 | 540.0 | g'>18.7, Rc>18.7, Ic>18.2
2391 | 2023-04-27 11:11:43 | 2220.0 | g'>19.6, Rc>19.4, Ic>19.0
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
```
We used the PS1 catalog for flux calibration. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
GCN Circular #33692
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev (Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational State University)
MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB230427.44 (trigger No 1165948,10h 13m 17.76s , +48d 10m 48.0s, R=0.05) errorbox 24243 sec after notice time and 24285 sec after trigger time at 2023-04-27 17:16:37 UT, with upper limit up to 19.0 mag. Observations started at twilight. The observations began at zenith distance = 6 deg. The sun altitude is -12.4 deg.
The galactic latitude b = 53 deg., longitude l = 168 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2213007
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   24376 |   MASTER-Kislovodsk |   C |   180 | 18.3 |        
   24376 |   MASTER-Kislovodsk |   C |   180 | 18.8 |        
   24576 |   MASTER-Kislovodsk |   C |   180 | 18.6 |        
   24576 |   MASTER-Kislovodsk |   C |   180 | 19.0 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #33693
Mohammad Odeh of Al-Khatim Observatory (AKO) operated by the International Astronomical Center, in Abu Dhabi, UAE.
As a follow-up for the GRB 230427A detected by Swift (GCN 33687), we observed the field of the GRB with our 0.35m f/7.7 robotic telescope. The observation was done on 27 April 2023 from 16:06:55 to 16:13:01 (UT), 5.7 hours after the GRB trigger. We obtained multiple 180-sec exposures in Ic filter. We did not detect any afterglow within XRT localization. This is consistent with the report of (Takahashi et al., GCN 33690) and (Lipunov et al., GCN 33692).
The following upper limit was calculated using Atlas catalogue as a reference:
-----------------------------------------------------------------------------
JD (mid), T_mid-T0(hrs), Exposure (sec), Filter, Lim_mag
-----------------------------------------------------------------------------
2460062.174630, 5.7, 3 x 180 (stacked), Ic, > 19.0
-----------------------------------------------------------------------------
These magnitudes are not corrected for galactic extinction.
GCN Circular #33695
Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar (UMA) and I. M. Carrasco-Garcia (SMA) and I. H. Park (SKKU), on behalf of a larger collaboration, report:
Following the detection of GRB 230427A by Swift (Troja et al. GCNC 33687), the BOOTES-5/JGT 0.6m robotic telescope at observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically observed the GRB location starting on Apr. 27, 10:35:34 UT (~ 282 s after trigger). A series of images in clear filter were gathered. A new optical transient was found within the enhanced Swift/XRT position (Beardmore et al. GCNC 33688) for which we measure a magnitude of 20.6 +- 0.2 on the co-added 10 s x 54 image, which is consistent with the detection of Swfit/UVOT (Troja et al. GCNC 33687).
We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for their excellent support.
GCN Circular #33696
D. Turpin (CEA Paris-Saclay), C. Adami (LAM), B. Schneider (MIT), S. Basa (LAM), E. Le Floc'h, D. Turpin, D. G=C3=B6tz (CEA Paris-Saclay), S. D. Vergani (GEPI, Obs. de Paris), report on behalf of a larger collaboration:
We observed the field of GRB 230427A (Troja et al., GCN 33687) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. 18 exposures were obtained in the r-band (16x300s + 2x60s) from 2023 27 April 20:36:47 UT to 2023 27 April 22:59:06 UT (mid time ~11.27h after trigger). In the combined =20 frame, we do not detect any source at the UVOT position reported by Troja et al., GCN 33687 and the enhanced XRT position (Beardmore et al., GCN 33688) down to the following 3-sigma limit:
r > 22.3 mag (AB)
The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitude is not corrected for Galactic extinction.
We acknowledge the excellent support from Observatoire de Haute-Provence, in particular Jean Balcaen.
GCN Circular #33697
J. Mao, H.-C. Feng, and J.-M. Bai (YNAO) report:
We observed the field of GRB 230427A (Troja et al. GCN 33687) by the GMG telescope in Yunnan observatories. The observation began from UT 14:52:28 April 27, 2023, about 4.3 hours from the trigger. We could not observe the optical afterglow down to a magnitude limit of R~20.6.
GCN Circular #33698
U.Quadri and=C2=A0 L.Strabla (Bassano Bresciano Astronomical Observatory), in a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan),=20 Y. Niino (Tokyo University, Institute of Astronomy),=20 K. Kalinowski (Aarhus University, Department of Physics and Astronomy), B. De Simone (Universita' degli Studi Di Salerno) report:=20
We imaged the field of GRB 230427A detected by SWIFT(trigger 1165948) with the robotic telescope of (IAU station 565) Bassano Bresciano=20 Observatory, Italy. Member of:=20 AAVSO - American Association of Variable Star Observers. UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili. GAC - Gruppo Astrofili Cremonesi.
The observations started 8.72 hour after the GRB trigger, at the end of twilight, with our Newton telescope D=3D250 mm F/D=3D4.8.
Weather conditions were good.
We co-added 2 series of 25 exposures of 60 sec each.
Start T0+=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 End T0+=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0 Rlim 8.72 hour=C2=A0=C2=A0=C2=A0=C2=A0 9.63 hour=C2=A0=C2=A0=C2=A0=C2=A0 19.5
We did not found any optical counterpart in the error box of the XRTcandida= te. Troja et al., GCN 33687
Magnitudes were estimated with the USNO-B1.0 cat. and=20 are not corrected for galactic dust extinction.
Reference: http://www.osservatoriobassano.org/GRB.asp
The message may be cited.
GCN Circular #33699
T. Roychowdhury(IITB), V. Swain (IITB), A. Suresh (IITB), H. Kumar(IITB), D. Raman(IITB), Kaysang (IAO), V. Bhalerao(IITB), G. C. Anupama(IIA), S. Barway(IIA) report on behalf of the GIT team:
We observed GRB 230427A detected by Swift-BAT (Troja et al., GCN 33687) with 0.7m GROWTH-India Telescope (GIT). The observations started at 14:20:43 UT on 2023-04-27, 3.8 hours after the Swift-BAT trigger. We obtained 10 images of 300-sec exposures in the r' filter and 5 images of 300-sec exposures in the i', z' and g' filters. We did not detect any new source in our stacked image within the 2.4 arcsec circle, around R.A.=3D 10= h 13m 15.16s, DEC.=3D+48d 12' 14.2". The obtained upper limits follow as:
=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94 =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94
JD (mid) | T_mid-T0(hrs) | Exposure (sec) | Filter | Lim_mag (5-sigma) |
=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94 =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94
2460062.1148169 | 4.22 | 10 x 300 (stacked) | r' | > 21.70 |
2460062.1433660 | 4.91 | 5 x 300 (stacked) | i' | > 20.76 |
2460062.1604599 | 5.31 | 5 x 300 (stacked) | z' | > 19.42 |
2460062.1775733 | 5.73 | 5 x 300 (stacked) | g' | > 21.35 |
=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94= =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80= =94 =E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94=E2= =80=94=E2=80=94=E2=80=94=E2=80=94=E2=80=94
Our results are consistent with the upper limit reported by AKO (M. Odeh, GCN #33693), BOOTES-5/JGT (Y.-D. Hu et al., GCN #33695), OHP/T193 (D. Turpin et al., GCN #33696), GMG (J. Mao et al., GCN #33697) and Bassano Bresciano Observatory (U.Quadri et al., GCN #33698). The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT, Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
GCN Circular #33703
A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), J. D. Gropp (PSU) report on behalf of the Swift-XRT team:
We have analysed 4.5 ks of XRT data for GRB 230427A, from 80 s to 75.0 ks after the BAT trigger. The data comprise 7 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode.
The light curve can be modelled with a power-law decay with a decay index of alpha=1.21 (+0.12, -0.11).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.94 (+0.30, -0.26). The best-fitting absorption column is 4.0 (+6.6, -3.2) x 10^20 cm^-2, consistent with the Galactic value of 8.4 x 10^19 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (3.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     4.0 (+6.6, -3.2) x 10^20 cm^-2
Galactic foreground: 8.4 x 10^19 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.94 (+0.30, -0.26)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01165948.
This circular is an official product of the Swift-XRT team.
GCN Circular #33704
J. F. Agui Fernandez (IAA-CSIC), A. de Ugarte Postigo (OCA), C. C. Thoene (ASU-CAS), Fabricio Perez, Alvaro Tejero and A. L. Cabrera Lavers (GTC, IAC) report:
We observed the afterglow of GRB 230427A at ~ 11.3 hours after burst (Page et al. GCN 33687; Takahashi et al. GCN 33690; Hu et al. GCN=C2=A0 33695; Tohuvavohu et al. 33703) with OSIRIS+ at the 10.4m GTC telescope, at the Roque de los Muchachos Observatory (La Palma, Spain). Observations consisted of 3x1200 s spectroscopy with grism R1000B, covering the spectral range between 3700 and 7800 AA under good observing conditions.
From the acquisition image we detect a source at the GRB location and we measure a magnitude of r ~ 24.2 compared to PanSTARRS field stars. We detect a faint trace at GRB location above ~3950A which set a limit for the redshift of z < 3.3.
GCN Circular #33705
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy in a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy), B. De Simone (Universita' degli Studi Di Salerno) report:
We image the field of GRB 230427A detected by SWIFT(trigger 1165948) with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy. Member of: AAVSO - American Association of Variable Star Observers. UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili. AstroCampania Associazione
The observations started at 19:04 UT of 2023/04/27, after 8,30 hours after the GRB trigger, at the end of twilight with principal telescope SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME I took 32 image of 120 sec each. All images are unfiltered, calibrated with masterdark and masterflat,stacked with Tycho Tracker software We have not detected any clearly visible sources, up to 20th magnitude with lightly hazy skies and lunar disturbance
```
Start T0+                End T0+       Rlim
19:04:53 UT            20:22:52 UT      20
```
We did not found any optical counterpart in the error box of the XRTcandidate. Troja et al., GCN 33687
Magnitudes were estimated with the Gaia DR2 cat. and are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular #33706
S.Q. Jiang, S.Y. Fu, X. Liu, T.H. Lu, D. Xu (NAOC), Z.P. Zhu (NAOC, HUST), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 230427A detected by Swift (Troja et al., GCN 33687) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 14:50:24 UT on 2023-04-27, i.e., 4.3 hr after the Swift/BAT trigger, and 30x60 s unfiltered frames were obtained.
No optical source is detected in our stacked image at the UVOT position (Troja et al., GCN 33687), down to a 3-sigma limiting magnitude m(r) > 21.1 mag (AB) at 4.7 hr post-burst, calibrated with the nearby PanSTAR field in the Sloan r-filter. The magnitude is not corrected for Galactic extinction.
GCN Circular #33707
FROM: Benjamin Schneider at MIT
C. Adami, M. Garnichey, F. Michel (LAM), B. Schneider (MIT), S. Basa (LAM), S. D. Vergani (GEPI, Obs. de Paris), D. Turpin, D. G=C3=B6tz, E. Le Floc'h (CEA Paris-Saclay), report on behalf of a larger collaboration:
We re-observed the field of GRB 230427A (Troja et al., GCN 33687) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped=20 with the MISTRAL spectro-imager. This time, we targeted in spectroscopy=20 the galaxy close to the GRB line of sight: WISEA J101316.01+481158.7, at=20 r'SDSS(PSF) =3D 19.6 (AB). Two exposures of 900s were obtained in the blue= =20 configuration (4200A-8000A) from 2023 28 April 00:25:02 UT to 2023 28 April= =20 00:55:59 UT. The wavelength calibration was performed using the MISTRAL=20 calibration lamp, exposed just after the science observation. Data were=20 reduced using the ASPIRED package (https://github.com/cylammarco/ASPIRED)= configured for MISTRAL data.
In the combined frame, we clearly detect the [NII]@6548A, Halpha, [NII]@6583A, and [SII]@6718A. Halpha is the dominant line of the spectrum. Based on these lines, we inferred a redshift of z =3D 0.1524 +/- 0.0005, in good agreement with the SDSS photometric redshift of z =3D 0.13 +/- 0.03.
The GRB is at an offset of ~18 arcsec from the WISEA J101316.01+481158.7 center. At the redshift of this galaxy, the burst would have a projected offset of ~48 kpc and a probability of chance coincidence of ~0.16, which is not commonly observed for the long GRB population. For this reason ,=20 this object is probably not the host galaxy of GRB 230427A.
We acknowledge the excellent support from Observatoire de Haute-Provence, in particular Jean Balcaen.
GCN Circular #33708
S.Y. Fu, S.Q. Jiang, X. Liu, T.H. Lu, D Xu (NAOC), Z.P. Zhu (NAOC, HUST), S.W. Luo, M.M. Yang, Z. K. Feng (GYZO, NAOC) report:
We observed the field of GRB 230427A detected by Swift (Troja et al., GCN 33687) with the GOT-0.5m telescope located at Gaoyazi, Xinjiang, China. Observations started at 16:34:35 UT on 2023-04-27, i.e., 6.05 hr after the Swift/BAT trigger, 5 x 90 s and 10 x 120 s images were obtained in the Sloan r filter.
No optical source is detected in our stacked image at the UVOT position (Troja et al,. GCN 33687), down to a 3-sigma limiting magnitude r > 20.4 (AB) at 6.32 hr post-burst, calibrated with nearby PanSTARRS stars. The magnitude is not corrected for Galactic extinction.
GCN Circular #33710
N. J. Klingler (GSFC/UMBC/CRESTII) and E. Troja (UToV) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 230427A 98 s after the BAT trigger (Troja et al., GCN Circ. 33687). A source consistent with the XRT position (Evans et al. 2023, GCN Circ. 33688) is detected in the initial UVOT exposures.
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               98          248          147         20.19 +/- 0.15
v                  586         4999          255        >19.3
b                  512         1158           58        >19.6
u                  256          854          265        >20.5
w1                 810         5404          231        >20.0
m2                5004         5204          197        >19.6
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.007 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #33711
I. Reva (FAP), A. S. Moskvitin (SAO RAS), O. A. Maslennikova (SAO RAS), R. Ya. Inasaridze (AbAO), A. Volnova (IKI), A. Pozanenko (IKI), N. Pankov (HSE), S. Belkin (IKI) report on behalf of GRB IKI FuN:
We observed the field of Swift GRB 230427A (Troja et al., GCN 33687) in R-filter on 2023-04-27 starting (UT) 15:09:59 with with Zeiss-1000 telescope of TSHAO observatory, (UT) 17:21:56 with Zeiss-1000 telescope of SAO RAS, (UT) 21:56:16 with AS-32 telescope of Abastumani observatory. We do not detect the optical counterpart of GRB 230427A (Troja et al., GCN 33687; Hu et al., GCN 33695; Agui Fernandez et al., GCN 33704; Klingler et al., GCN 33710). Preliminary photometry of stacked images is following
```
Date       UT start  t-T0     Exp.  Filter OT   Err.  UL(3sigma) Obs.
                    (mid, days)  (s)

2023-04-27 15:09:59 0.22388  37*120 R      n/d  n/d   21.8     TSAHO
2023-04-27 17:21:56 0.30117   4*300 R      n/d  n/d   21.4     SAO RAS
2023-04-27 21:56:16 0.51140 104*60  R      n/d  n/d   21.0     AbAO
```
The photometry is based on nearby USNO-B1.0 stars.
```
USNO-B1.0    R2
1381-0248742 15.71
1381-0240666 16.93
1381-0240629 16.83
```
GCN Circular #33712
Z.P. Zhu (NAOC, HUST), D. B. Malesani (Radboud Univ. and DAWN/NBI), X. Liu, D. Xu (NAOC), report on behalf of a larger collaboration:
We observed the field of GRB 230427A detected by Swift (Troja et al., GCN 33687) using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 23:06:58 UT on 2023-04-27, i.e., ~12.6 hr after the Swift/BAT trigger, and 3x300 s Sloan r-filter images and 5x200 s Sloan z-filter images were obtained, respectively.
No new source is detected in our stacked images at the Swift/UVOT position (Troja et al., GCN 33687), and preliminary photometric results are as follows:
```
T_mid-T0 (hr)    Filter   Upper_Limit (3-sigma)
    12.7                r          >23.5
    13.0                z          >22.5
```
calibrated with the nearby Pan-STARRS field and not corrected for Galactic extinction.
GCN Circular #33722
M. Stamatikos (OSU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU), (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 230427A (trigger #1165948) (Troja et al., GCN Circ. 33687). The BAT ground-calculated position is RA, Dec = 153.339, 48.231 deg which is
```
   RA(J2000)  =  10h 13m 21.5s
   Dec(J2000) = +48d 13' 52.3"
```
with an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 86%.
The BAT light curve showed a complex structure with a duration of about 20 sec. T90 (15-350 keV) is 4.00 +- 1.41 sec (estimated error including systematics).
The time-averaged spectrum from T-0.17 to T+3.83 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.36 +- 0.47. The fluence in the 15-150 keV band is 9.5 +- 2.9 x 10^-08 erg/cm2. The 1-sec peak photon flux measured from T-0.17 sec in the 15-150 keV band is 0.7 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1165948/BA/

Back to JG's homepage

Jochen Greiner, last update: 04-May-2023 [Disclaimer]