Gamma-ray Burst 250603A

(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 03 Jun 25 01:10:37 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1320335,   Seg_Num: 0
GRB_RA:          129.918d {+08h 39m 40s} (J2000),
                 130.155d {+08h 40m 37s} (current),
                 129.452d {+08h 37m 49s} (1950)
GRB_DEC:         -39.268d {-39d 16' 05"} (J2000),
                 -39.359d {-39d 21' 33"} (current),
                 -39.091d {-39d 05' 25"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       2568 [cnts]    Image_Peak=149 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   146     E_range: 25-100 keV
BKG_INTEN:       15705 [cnts]
BKG_TIME:        4204.28 SOD {01:10:04.28} UT
BKG_DUR:         8 [sec]
GRB_DATE:        20829 TJD;   154 DOY;   25/06/03
GRB_TIME:        4223.09 SOD {01:10:23.09} UT
GRB_PHI:          -9.92 [deg]
GRB_THETA:        31.35 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.61 [sigma]
IMAGE_SIGNIF:    7.82 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  -2  +0  +1 -13  +0 
SUN_POSTN:        71.29d {+04h 45m 10s}  +22.32d {+22d 19' 16"}
SUN_DIST:         82.59 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      163.57d {+10h 54m 16s}   +8.23d {+08d 13' 37"}
MOON_DIST:        56.77 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      149.47,-54.78 [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 = 192.43,-16.64 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 03 Jun 25 01:12:10 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.923d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.272d {-39d 16' 18"} (J2000)
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  4324.76 SOD {01:12:04.76} UT,   101.7 [sec] since BAT Trigger Time
COUNTS:          11    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 03 Jun 25 01:14:51 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1320335,   Seg_Num: 0
GRB_RA:          129.918d {+08h 39m 40s} (J2000),
                 130.155d {+08h 40m 37s} (current),
                 129.452d {+08h 37m 49s} (1950)
GRB_DEC:         -39.268d {-39d 16' 05"} (J2000),
                 -39.359d {-39d 21' 33"} (current),
                 -39.091d {-39d 05' 25"} (1950)
GRB_DATE:        20829 TJD;   154 DOY;   25/06/03
GRB_TIME:        4223.09 SOD {01:10:23.09} UT
TRIGGER_INDEX:   146
GRB_PHI:          -9.92 [deg]
GRB_THETA:        31.35 [deg]
DELTA_TIME:      39.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.61 [sigma]
IMAGE_SIGNIF:    7.82 [sigma]
LC_URL:          sw01320335000msb.lc
SUN_POSTN:        71.29d {+04h 45m 11s}  +22.32d {+22d 19' 18"}
SUN_DIST:         82.59 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      163.60d {+10h 54m 24s}   +8.21d {+08d 12' 36"}
MOON_DIST:        56.77 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      149.47,-54.78 [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 = 192.43,-16.64 [deg].

GCN Circular #40613
T. M. Parsotan (GSFC), R. Brivio (INAF-OAB), R. Gupta (NASA GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL) and C. Salvaggio (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team:
At 01:10:23 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250603A (trigger=1320335). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 129.918, -39.268 which is
```
   RA(J2000) = 08h 39m 40s
   Dec(J2000) = -39d 16' 05"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 18 sec with a possible short spike at T0+16 sec. The peak count rate was ~1,300 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 01:12:04.7 UT, 101.7 seconds after the BAT trigger. No source was detected in the 2.5-s promptly available image. We are waiting for the full dataset to detect and localise the XRT counterpart.
Although the initial 2.5s of XRT data do not show a clear X-ray afterglow, the high significance of the BAT image (7.82 sigma) gives us confidence that this is an astrophysical source. Further analysis awaits the full downlinked dataset.
We note the presence of Fermi-GBM event at ~T+10 minutes (GBM trigger: 770606412) with a position consistent (to its 25Â° error radius) with this source location.
Given the location of the BAT detection at 1.42Â° from the Galactic plane, persistent flux over 10 minutes would suggest a Galactic transient. If so, we would name it Swift J0839.7-3916 .
Burst Advocate for this burst is T. M. Parsotan (tyler.parsotan AT 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/)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 03 Jun 25 02:35:46 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.922d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.273d {-39d 16' 23"} (J2000)
POINT_ROLL:      307.176d
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  4327.87 SOD {01:12:07.87} UT,   104.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.632
N_STARS:         166
X_OFFSET:        517 [pixels]
Y_OFFSET:        553 [pixels]
X_MAX:           1476 [pixels]
Y_MAX:           1512 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01320335000msufc0104.fits
SUN_POSTN:        71.35d {+04h 45m 24s}  +22.33d {+22d 19' 42"}
SUN_DIST:         82.56 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.22d {+10h 56m 53s}   +7.89d {+07d 53' 25"}
MOON_DIST:        56.81 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.48,-54.78 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 03 Jun 25 02:35:59 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.922d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.273d {-39d 16' 23"} (J2000)
POINT_ROLL:      307.176d
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  4327.87 SOD {01:12:07.87} UT,   104.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.632
N_STARS:         166
X_OFFSET:        517 [pixels]
Y_OFFSET:        553 [pixels]
X_MAX:           1476 [pixels]
Y_MAX:           1512 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01320335000msufc0104.fits
SUN_POSTN:        71.35d {+04h 45m 24s}  +22.33d {+22d 19' 42"}
SUN_DIST:         82.56 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.22d {+10h 56m 54s}   +7.89d {+07d 53' 21"}
MOON_DIST:        56.81 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.48,-54.78 [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 03 Jun 25 02:36:13 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.922d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.273d {-39d 16' 23"} (J2000)
ROLL:            307.176d
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  4327.87 SOD {01:12:07.87} UT,   104.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     770605963
X_OFFSET:        836 [pixels]
Y_OFFSET:        872 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       996
Y_GRB_POS:       1032
BINNING_INDEX:   1
IM_URL:          sw01320335000msuni0140.fits
SUN_POSTN:        71.35d {+04h 45m 24s}  +22.33d {+22d 19' 42"}
SUN_DIST:         82.56 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.22d {+10h 56m 54s}   +7.89d {+07d 53' 18"}
MOON_DIST:        56.81 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.48,-54.78 [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 03 Jun 25 02:35:51 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1320335,   Seg_Num: 0
GRB_RA:          129.9374d {+08h 39m 44.97s} (J2000),
                 130.1743d {+08h 40m 41.83s} (current),
                 129.4716d {+08h 37m 53.18s} (1950)
GRB_DEC:         -39.2932d {-39d 17' 35.5"} (J2000),
                 -39.3843d {-39d 23' 03.3"} (current),
                 -39.1153d {-39d 06' 55.2"} (1950)
GRB_ERROR:       3.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  4335.00 SOD {01:12:15.00} UT,   111.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        71.35d {+04h 45m 24s}  +22.33d {+22d 19' 42"}
SUN_DIST:         82.58 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.22d {+10h 56m 53s}   +7.89d {+07d 53' 23"}
MOON_DIST:        56.82 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.36,  1.42 [deg] galactic lon,lat of the burst
ECL_COORDS:      149.51,-54.79 [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 03 Jun 25 02:36:22 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.922d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.273d {-39d 16' 23"} (J2000)
ROLL:            307.176d
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  4327.87 SOD {01:12:07.87} UT,   104.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     770605963
X_OFFSET:        836 [pixels]
Y_OFFSET:        872 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       996
Y_GRB_POS:       1032
BINNING_INDEX:   1
IM_URL:          sw01320335000msuni0140.fits
SUN_POSTN:        71.35d {+04h 45m 24s}  +22.33d {+22d 19' 42"}
SUN_DIST:         82.56 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.23d {+10h 56m 54s}   +7.89d {+07d 53' 16"}
MOON_DIST:        56.82 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.48,-54.78 [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 03 Jun 25 02:37:57 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.922d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.273d {-39d 16' 23"} (J2000)
ROLL:            307.176d
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  4540.69 SOD {01:15:40.69} UT,   317.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     770606176
X_OFFSET:        836 [pixels]
Y_OFFSET:        872 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       996
Y_GRB_POS:       1032
BINNING_INDEX:   1
IM_URL:          sw01320335000msuni0353.fits
SUN_POSTN:        71.35d {+04h 45m 25s}  +22.33d {+22d 19' 43"}
SUN_DIST:         82.56 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.24d {+10h 56m 57s}   +7.88d {+07d 52' 53"}
MOON_DIST:        56.82 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.48,-54.78 [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 03 Jun 25 02:37:37 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.922d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.273d {-39d 16' 23"} (J2000)
POINT_ROLL:      307.176d
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  4540.69 SOD {01:15:40.69} UT,   317.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.197
N_STARS:         190
X_OFFSET:        277 [pixels]
Y_OFFSET:        313 [pixels]
X_MAX:           1716 [pixels]
Y_MAX:           1752 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw01320335000msufc0317.fits
SUN_POSTN:        71.35d {+04h 45m 25s}  +22.33d {+22d 19' 43"}
SUN_DIST:         82.56 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.24d {+10h 56m 57s}   +7.88d {+07d 52' 58"}
MOON_DIST:        56.82 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.48,-54.78 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 03 Jun 25 02:38:15 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.922d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.273d {-39d 16' 23"} (J2000)
ROLL:            307.176d
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  4540.69 SOD {01:15:40.69} UT,   317.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     770606176
X_OFFSET:        836 [pixels]
Y_OFFSET:        872 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       996
Y_GRB_POS:       1032
BINNING_INDEX:   1
IM_URL:          sw01320335000msuni0353.fits
SUN_POSTN:        71.35d {+04h 45m 25s}  +22.33d {+22d 19' 43"}
SUN_DIST:         82.56 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.24d {+10h 56m 58s}   +7.88d {+07d 52' 49"}
MOON_DIST:        56.82 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.48,-54.78 [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 03 Jun 25 02:37:59 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1320335,   Seg_Num: 0
GRB_RA:          129.9371d {+08h 39m 44.90s} (J2000),
                 130.1740d {+08h 40m 41.76s} (current),
                 129.4713d {+08h 37m 53.11s} (1950)
GRB_DEC:         -39.2928d {-39d 17' 34.0"} (J2000),
                 -39.3839d {-39d 23' 01.9"} (current),
                 -39.1149d {-39d 06' 53.8"} (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:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  4335.00 SOD {01:12:15.00} UT,   111.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        71.35d {+04h 45m 25s}  +22.33d {+22d 19' 43"}
SUN_DIST:         82.58 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.24d {+10h 56m 57s}   +7.88d {+07d 52' 53"}
MOON_DIST:        56.82 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.36,  1.42 [deg] galactic lon,lat of the burst
ECL_COORDS:      149.51,-54.79 [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 03 Jun 25 02:37:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.922d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.273d {-39d 16' 23"} (J2000)
POINT_ROLL:      307.176d
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  4540.69 SOD {01:15:40.69} UT,   317.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.197
N_STARS:         190
X_OFFSET:        277 [pixels]
Y_OFFSET:        313 [pixels]
X_MAX:           1716 [pixels]
Y_MAX:           1752 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw01320335000msufc0317.fits
SUN_POSTN:        71.35d {+04h 45m 25s}  +22.33d {+22d 19' 43"}
SUN_DIST:         82.56 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.24d {+10h 56m 57s}   +7.88d {+07d 52' 55"}
MOON_DIST:        56.82 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.48,-54.78 [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 03 Jun 25 02:39:06 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.922d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.273d {-39d 16' 23"} (J2000)
POINT_ROLL:      307.176d
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  5095.65 SOD {01:24:55.65} UT,   872.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.010
N_STARS:         190
X_OFFSET:        277 [pixels]
Y_OFFSET:        313 [pixels]
X_MAX:           1716 [pixels]
Y_MAX:           1752 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw01320335000msufc0872.fits
SUN_POSTN:        71.35d {+04h 45m 25s}  +22.33d {+22d 19' 43"}
SUN_DIST:         82.56 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.25d {+10h 56m 59s}   +7.88d {+07d 52' 37"}
MOON_DIST:        56.82 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.48,-54.78 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 03 Jun 25 02:39:21 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.922d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.273d {-39d 16' 23"} (J2000)
POINT_ROLL:      307.176d
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  5095.65 SOD {01:24:55.65} UT,   872.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.010
N_STARS:         190
X_OFFSET:        277 [pixels]
Y_OFFSET:        313 [pixels]
X_MAX:           1716 [pixels]
Y_MAX:           1752 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw01320335000msufc0872.fits
SUN_POSTN:        71.35d {+04h 45m 25s}  +22.33d {+22d 19' 43"}
SUN_DIST:         82.56 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.25d {+10h 57m 00s}   +7.88d {+07d 52' 34"}
MOON_DIST:        56.82 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.48,-54.78 [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 03 Jun 25 02:39:44 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.922d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.273d {-39d 16' 23"} (J2000)
ROLL:            307.176d
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  5095.65 SOD {01:24:55.65} UT,   872.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     770606731
X_OFFSET:        836 [pixels]
Y_OFFSET:        872 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       996
Y_GRB_POS:       1032
BINNING_INDEX:   1
IM_URL:          sw01320335000msuni0908.fits
SUN_POSTN:        71.35d {+04h 45m 25s}  +22.33d {+22d 19' 43"}
SUN_DIST:         82.56 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.25d {+10h 57m 00s}   +7.87d {+07d 52' 28"}
MOON_DIST:        56.82 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.48,-54.78 [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 03 Jun 25 02:39:28 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1320335,   Seg_Num: 0
POINT_RA:        129.922d {+08h 39m 41s} (J2000)
POINT_DEC:       -39.273d {-39d 16' 23"} (J2000)
ROLL:            307.176d
IMG_START_DATE:  20829 TJD;   154 DOY;   25/06/03
IMG_START_TIME:  5095.65 SOD {01:24:55.65} UT,   872.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     770606731
X_OFFSET:        836 [pixels]
Y_OFFSET:        872 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       996
Y_GRB_POS:       1032
BINNING_INDEX:   1
IM_URL:          sw01320335000msuni0908.fits
SUN_POSTN:        71.35d {+04h 45m 25s}  +22.33d {+22d 19' 43"}
SUN_DIST:         82.56 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      164.25d {+10h 57m 00s}   +7.88d {+07d 52' 32"}
MOON_DIST:        56.82 [deg]
MOON_ILLUM:      50 [%]
GAL_COORDS:      259.33,  1.42 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      149.48,-54.78 [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 Circular #40614
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB250603.05 (trigger No 1320335,08h 39m 40.32s , -39d 16m 04.8s, R=0.05) errorbox 19 sec after notice time and 41 sec after trigger time at 2025-06-03 01:11:04 UT, with upper limit up to 19.2 mag. The observations began at zenith distance = 57 deg. The sun altitude is -44.5 deg.
The galactic latitude b = 2 deg., longitude l = 260 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2890204
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

      46 |         MASTER-OAFA |   C |    10 | 17.9 |        
      62 |         MASTER-OAFA |   C |    10 | 17.9 |        
      78 |         MASTER-OAFA |   C |    10 | 17.9 |        
      99 |         MASTER-OAFA |   C |    20 | 18.3 |        
     126 |         MASTER-OAFA |   C |    20 | 18.3 |        
     157 |         MASTER-OAFA |   C |    30 | 18.5 |        
     198 |         MASTER-OAFA |   C |    40 | 18.7 |        
     245 |         MASTER-OAFA |   C |    40 | 18.6 |        
     296 |         MASTER-OAFA |   C |    50 | 18.7 |        
     362 |         MASTER-OAFA |   C |    70 | 19.0 |        
     443 |         MASTER-OAFA |   C |    80 | 19.0 |        
     539 |         MASTER-OAFA |   C |   100 | 19.1 |        
     656 |         MASTER-OAFA |   C |   120 | 19.1 |        
     794 |         MASTER-OAFA |   C |   140 | 19.2 |        
     955 |         MASTER-OAFA |   C |   170 | 19.2 |        
    1138 |         MASTER-OAFA |   C |   180 | 19.2 |        
    1324 |         MASTER-OAFA |   C |   180 | 19.1 |        
    1511 |         MASTER-OAFA |   C |   180 | 19.1 |        
    1697 |         MASTER-OAFA |   C |   180 | 19.1 |        
    1884 |         MASTER-OAFA |   C |   180 | 19.1 |        
    2070 |         MASTER-OAFA |   C |   180 | 19.1 |        
    2257 |         MASTER-OAFA |   C |   180 | 19.1 |        
    2443 |         MASTER-OAFA |   C |   180 | 19.1 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #40615
K.L. Page and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
The XRT began observing the field of GRB 250603A (GCN Circ. 40613) at 01:12:04.7 UT, 101.7 seconds after the BAT trigger. Using promptly-collected data (although downlinked after a delay), we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 129.93750, -39.29289 which is equivalent to:
```
   RA(J2000)  = 08h 39m 45.00s
   Dec(J2000) = -39d 17' 34.4"
```
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 104 arcseconds from the BAT onboard position, within the BAT error circle.
Given the nature of the fading X-ray light-curve, we confirm this trigger as GRB 250603A, and not a new Galactic transient.
This circular is an official product of the Swift-XRT team.
GCN Circular #40616
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 1415 s of XRT Photon Counting mode data and 1 UVOT images for GRB 250603A, 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 = 129.93745, -39.29287 which is equivalent to:
```
RA (J2000): 08h 39m 44.99s
Dec (J2000): -39d 17' 34.3"
```
with an uncertainty of 2.3 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 #40618
S. Campana (INAF-OAB), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), D.N. Burrows (PSU), M.A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 7.3 ks of XRT data for GRB 250603A, from 92 s to 34.7 ks after the trigger. The data comprise 3 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=1.17 (+0.09, -0.08).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.48 (+0.32, -0.30). The best-fitting absorption column is 1.6 (+0.5, -0.4) x 10^22 cm^-2, in excess of the Galactic value of 6.9 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 7.6 x 10^-11 (1.1 x 10^-10) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.6 (+0.5, -0.4) x 10^22 cm^-2
Galactic foreground: 6.9 x 10^21 cm^-2
Excess significance: 3.3 sigma
Photon index:	     1.48 (+0.32, -0.30)
```
If the light curve continues to decay with a power-law decay index of 1.17, the count rate at T+24 hours will be 8.8 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.7 x 10^-14 (9.8 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/01320335.
This circular is an official product of the Swift-XRT team.
GCN Circular #40619
S. R. Oates (Lancaster U.) and T. M. Parsotan (GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 250603A 105 s after the BAT trigger (Parsotan et al., GCN Circ. 40613). No optical afterglow consistent with the enhanced XRT position (Beardmore et al., GCN Circ. 40616) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           105          255          147         >20.4
u_FC               318          567          246         >19.7
white              105         1531          382         >21.0
v                  647         5129          190         >19.0
b                  573         1516           97         >19.6
u                  318         1491          324         >19.8
w1                 697         1467           78         >18.7
m2                 672         1442           97         >18.5
w2                 623         5029          294         >19.2
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.89 in the direction of the burst (Schlegel et al. 1998).

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Jochen Greiner, last update: 03-Jun-2025 [Disclaimer]