Gamma-ray Burst 211025A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 25 Oct 21 05:11:35 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1081113,   Seg_Num: 0
GRB_RA:          162.377d {+10h 49m 30s} (J2000),
                 162.679d {+10h 50m 43s} (current),
                 161.683d {+10h 46m 44s} (1950)
GRB_DEC:         +31.557d {+31d 33' 26"} (J2000),
                 +31.441d {+31d 26' 29"} (current),
                 +31.822d {+31d 49' 20"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1346 [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:        19512 TJD;   298 DOY;   21/10/25
GRB_TIME:        18620.03 SOD {05:10:20.03} UT
GRB_PHI:         -154.23 [deg]
GRB_THETA:         9.75 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    8.05 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  -2  +0  +0 -45  +0 
SUN_POSTN:       209.84d {+13h 59m 21s}  -12.17d {-12d 10' 15"}
SUN_DIST:         62.80 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       81.46d {+05h 25m 50s}  +25.10d {+25d 05' 60"}
MOON_DIST:        70.17 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      196.08, 63.15 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      151.29, 22.18 [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 = 87.85,13.59 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 25 Oct 21 05:12:47 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1081113,   Seg_Num: 0
GRB_RA:          162.3810d {+10h 49m 31.44s} (J2000),
                 162.6828d {+10h 50m 43.87s} (current),
                 161.6876d {+10h 46m 45.01s} (1950)
GRB_DEC:         +31.5131d {+31d 30' 47.1"} (J2000),
                 +31.3973d {+31d 23' 50.1"} (current),
                 +31.7779d {+31d 46' 40.5"} (1950)
GRB_ERROR:       4.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       5.36e-09 [erg/cm2/sec]
GRB_SIGNIF:      12.52 [sigma]
IMG_START_DATE:  19512 TJD;   298 DOY;   21/10/25
IMG_START_TIME:  18743.29 SOD {05:12:23.29} UT,   123.3 [sec] since BAT Trigger Time
TAM[0-3]:        327.68 237.13 261.72 243.49
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       209.84d {+13h 59m 21s}  -12.17d {-12d 10' 16"}
SUN_DIST:         62.77 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       81.47d {+05h 25m 53s}  +25.10d {+25d 06' 05"}
MOON_DIST:        70.18 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      196.18, 63.16 [deg] galactic lon,lat of the burst
ECL_COORDS:      151.31, 22.14 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 2.66 arcmin from the BAT position.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 25 Oct 21 05:12:57 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1081113,   Seg_Num: 0
GRB_RA:          162.3810d {+10h 49m 31.4s} (J2000),
                 162.6828d {+10h 50m 43.8s} (current),
                 161.6876d {+10h 46m 45.0s} (1950)
GRB_DEC:         +31.5131d {+31d 30' 47.1"} (J2000),
                 +31.3973d {+31d 23' 50.1"} (current),
                 +31.7779d {+31d 46' 40.5"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       157 [cnts]
IMG_START_DATE:  19512 TJD;   298 DOY;   21/10/25
IMG_START_TIME:  18743.29 SOD {05:12:23.29} UT,   123.3 [sec] since BAT Trigger Time
CENTROID_X:      244.14,  raw= 244  [pixels]
CENTROID_Y:      234.22,  raw= 234  [pixels]
ROLL:            126.12 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -150.58
GRB_POS_XRT_Z:   -149.11
IMAGE_URL:       sw01081113000msxps_rw.img
SUN_POSTN:       209.84d {+13h 59m 21s}  -12.17d {-12d 10' 16"}
SUN_DIST:         62.77 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       81.47d {+05h 25m 53s}  +25.10d {+25d 06' 06"}
MOON_DIST:        70.18 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      196.18, 63.16 [deg] galactic lon,lat of the burst
ECL_COORDS:      151.31, 22.14 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 25 Oct 21 05:13:00 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1081113,   Seg_Num: 0
GRB_RA:          162.3810d {+10h 49m 31.4s} (J2000),
                 162.6828d {+10h 50m 43.8s} (current),
                 161.6876d {+10h 46m 45.0s} (1950)
GRB_DEC:         +31.5131d {+31d 30' 47.1"} (J2000),
                 +31.3973d {+31d 23' 50.1"} (current),
                 +31.7779d {+31d 46' 40.5"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       157 [cnts]
IMG_START_DATE:  19512 TJD;   298 DOY;   21/10/25
IMG_START_TIME:  18743.29 SOD {05:12:23.29} UT,   123.3 [sec] since BAT Trigger Time
CENTROID_X:      244.14,  raw= 244  [pixels]
CENTROID_Y:      234.22,  raw= 234  [pixels]
ROLL:            126.12 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -150.58
GRB_POS_XRT_Z:   -149.11
IMAGE_URL:       sw01081113000msxps_rw.img
SUN_POSTN:       209.84d {+13h 59m 21s}  -12.17d {-12d 10' 16"}
SUN_DIST:         62.77 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       81.47d {+05h 25m 53s}  +25.10d {+25d 06' 06"}
MOON_DIST:        70.18 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      196.18, 63.16 [deg] galactic lon,lat of the burst
ECL_COORDS:      151.31, 22.14 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 25 Oct 21 05:14:12 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1081113,   Seg_Num: 0
GRB_RA:          162.377d {+10h 49m 30s} (J2000),
                 162.679d {+10h 50m 43s} (current),
                 161.683d {+10h 46m 44s} (1950)
GRB_DEC:         +31.557d {+31d 33' 26"} (J2000),
                 +31.441d {+31d 26' 29"} (current),
                 +31.822d {+31d 49' 20"} (1950)
GRB_DATE:        19512 TJD;   298 DOY;   21/10/25
GRB_TIME:        18620.03 SOD {05:10:20.03} UT
TRIGGER_INDEX:   20000
GRB_PHI:         -154.23 [deg]
GRB_THETA:         9.75 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     64.000 [sec] 
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    8.05 [sigma]
LC_URL:          sw01081113000msb.lc
SUN_POSTN:       209.84d {+13h 59m 22s}  -12.17d {-12d 10' 17"}
SUN_DIST:         62.80 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       81.48d {+05h 25m 56s}  +25.10d {+25d 06' 11"}
MOON_DIST:        70.15 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      196.08, 63.15 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      151.29, 22.18 [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 = 87.85,13.59 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 25 Oct 21 05:15:45 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1081113,   Seg_Num: 0
POINT_RA:        162.371d {+10h 49m 29s} (J2000)
POINT_DEC:       +31.571d {+31d 34' 17"} (J2000)
POINT_ROLL:      126.124d
IMG_START_DATE:  19512 TJD;   298 DOY;   21/10/25
IMG_START_TIME:  18751.45 SOD {05:12:31.45} UT,   131.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.502
N_STARS:         14
X_OFFSET:        584 [pixels]
Y_OFFSET:        552 [pixels]
X_MAX:           1543 [pixels]
Y_MAX:           1511 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    10
SL_URL:          sw01081113000msufc0131.fits
SUN_POSTN:       209.84d {+13h 59m 22s}  -12.17d {-12d 10' 19"}
SUN_DIST:         62.81 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       81.50d {+05h 25m 59s}  +25.10d {+25d 06' 17"}
MOON_DIST:        70.13 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      196.05, 63.15 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      151.28, 22.19 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 25 Oct 21 05:15:59 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1081113,   Seg_Num: 0
POINT_RA:        162.371d {+10h 49m 29s} (J2000)
POINT_DEC:       +31.571d {+31d 34' 17"} (J2000)
POINT_ROLL:      126.124d
IMG_START_DATE:  19512 TJD;   298 DOY;   21/10/25
IMG_START_TIME:  18751.45 SOD {05:12:31.45} UT,   131.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.502
N_STARS:         14
X_OFFSET:        584 [pixels]
Y_OFFSET:        552 [pixels]
X_MAX:           1543 [pixels]
Y_MAX:           1511 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    10
SL_URL:          sw01081113000msufc0131.fits
SUN_POSTN:       209.84d {+13h 59m 22s}  -12.17d {-12d 10' 19"}
SUN_DIST:         62.81 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       81.50d {+05h 26m 00s}  +25.11d {+25d 06' 18"}
MOON_DIST:        70.13 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      196.05, 63.15 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      151.28, 22.19 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_srclist.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 25 Oct 21 05:17:40 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1081113,   Seg_Num: 0
POINT_RA:        162.371d {+10h 49m 29s} (J2000)
POINT_DEC:       +31.571d {+31d 34' 17"} (J2000)
ROLL:            126.124d
IMG_START_DATE:  19512 TJD;   298 DOY;   21/10/25
IMG_START_TIME:  18751.45 SOD {05:12:31.45} UT,   131.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     656831579
X_OFFSET:        1201 [pixels]
Y_OFFSET:        984 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1361
Y_GRB_POS:       1144
BINNING_INDEX:   1
IM_URL:          sw01081113000msuni0159.fits
SUN_POSTN:       209.84d {+13h 59m 22s}  -12.17d {-12d 10' 20"}
SUN_DIST:         62.82 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       81.51d {+05h 26m 03s}  +25.11d {+25d 06' 26"}
MOON_DIST:        70.11 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      196.05, 63.15 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      151.28, 22.19 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 25 Oct 21 05:17:48 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1081113,   Seg_Num: 0
POINT_RA:        162.371d {+10h 49m 29s} (J2000)
POINT_DEC:       +31.571d {+31d 34' 17"} (J2000)
ROLL:            126.124d
IMG_START_DATE:  19512 TJD;   298 DOY;   21/10/25
IMG_START_TIME:  18751.45 SOD {05:12:31.45} UT,   131.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     656831579
X_OFFSET:        1201 [pixels]
Y_OFFSET:        984 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1361
Y_GRB_POS:       1144
BINNING_INDEX:   1
IM_URL:          sw01081113000msuni0159.fits
SUN_POSTN:       209.84d {+13h 59m 22s}  -12.17d {-12d 10' 21"}
SUN_DIST:         62.82 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       81.52d {+05h 26m 04s}  +25.11d {+25d 06' 26"}
MOON_DIST:        70.11 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      196.05, 63.15 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      151.28, 22.19 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 25 Oct 21 05:22:55 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1081113,   Seg_Num: 0
POINT_RA:        162.369d {+10h 49m 29s} (J2000)
POINT_DEC:       +31.570d {+31d 34' 13"} (J2000)
POINT_ROLL:      126.121d
IMG_START_DATE:  19512 TJD;   298 DOY;   21/10/25
IMG_START_TIME:  18909.52 SOD {05:15:09.52} UT,   289.5 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.763
N_STARS:         1
X_OFFSET:        881 [pixels]
Y_OFFSET:        664 [pixels]
X_MAX:           1840 [pixels]
Y_MAX:           1623 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01081113000msufc0289.fits
SUN_POSTN:       209.85d {+13h 59m 23s}  -12.17d {-12d 10' 25"}
SUN_DIST:         62.82 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       81.56d {+05h 26m 15s}  +25.11d {+25d 06' 48"}
MOON_DIST:        70.07 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      196.05, 63.14 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      151.27, 22.19 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 25 Oct 21 05:24:21 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1081113,   Seg_Num: 0
POINT_RA:        162.369d {+10h 49m 29s} (J2000)
POINT_DEC:       +31.570d {+31d 34' 13"} (J2000)
ROLL:            126.121d
IMG_START_DATE:  19512 TJD;   298 DOY;   21/10/25
IMG_START_TIME:  18909.52 SOD {05:15:09.52} UT,   289.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     656831737
X_OFFSET:        1201 [pixels]
Y_OFFSET:        984 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1361
Y_GRB_POS:       1144
BINNING_INDEX:   1
IM_URL:          sw01081113000msuni0317.fits
SUN_POSTN:       209.85d {+13h 59m 23s}  -12.17d {-12d 10' 26"}
SUN_DIST:         62.82 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       81.57d {+05h 26m 18s}  +25.11d {+25d 06' 54"}
MOON_DIST:        70.06 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      196.05, 63.14 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      151.27, 22.19 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 25 Oct 21 05:24:28 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1081113,   Seg_Num: 0
POINT_RA:        162.369d {+10h 49m 29s} (J2000)
POINT_DEC:       +31.570d {+31d 34' 13"} (J2000)
ROLL:            126.121d
IMG_START_DATE:  19512 TJD;   298 DOY;   21/10/25
IMG_START_TIME:  18909.52 SOD {05:15:09.52} UT,   289.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     656831737
X_OFFSET:        1201 [pixels]
Y_OFFSET:        984 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1361
Y_GRB_POS:       1144
BINNING_INDEX:   1
IM_URL:          sw01081113000msuni0317.fits
SUN_POSTN:       209.85d {+13h 59m 23s}  -12.17d {-12d 10' 26"}
SUN_DIST:         62.82 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:       81.57d {+05h 26m 18s}  +25.12d {+25d 06' 54"}
MOON_DIST:        70.06 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      196.05, 63.14 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      151.27, 22.19 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN Circular #30986
J.D. Gropp (PSU), D. M. Palmer (LANL), B. Sbarufatti (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 05:10:20 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 211025A (trigger=1081113). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 162.377, +31.557 which is
```
   RA(J2000) = 10h 49m 30s
   Dec(J2000) = +31d 33' 26"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual for an image trigger, the immediately available BAT lightcurve is unclear, but there does appear to be a peak between T+30 and T+64, with a peak count rate of ~300 counts/s (15-350 kev) at ~38 s after the nominal trigger time.
The XRT began observing the field at 05:12:23.2 UT, 123.3 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 162.38427, 31.51343 which is equivalent to:
```
   RA(J2000)  = 10h 49m 32.22s
   Dec(J2000) = +31d 30' 48.3"
```
with an uncertainty of 4.1 arcseconds (radius, 90% containment). This location is 158 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. We cannot determine whether the source is fading at the present time. No spectrum from the promptly downlinked event data is yet available to determine the column density.
The initial flux in the 2.5 s image was 5.36e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 131 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image processing FAILED because of no aspect solution. Results from the list of sources generated on-board are not available at this time. No correction has been made for the expected extinction corresponding to E(B-V) of 0.027.
Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu). 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 Circular #30987
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 2418 s of XRT Photon Counting mode data and 5 UVOT images for GRB 211025A, 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 = 162.38304, +31.51233 which is equivalent to:
```
RA (J2000): 10h 49m 31.93s
Dec (J2000): +31d 30' 44.4"
```
with an uncertainty of 2.1 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 #30991
S. R. Oates (U.Birmingham) and J. D. Gropp (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 211025A 131 s after the BAT trigger (Gropp et al., GCN Circ. 30986). A source consistent with the XRT position (Evans et al. GCN Circ. 30987) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
RA  (J2000) =  10:49:31.93 = 162.38304 (deg.)
 Dec (J2000) = +31:30:44.3  =  31.51231 (deg.)
```
with an estimated uncertainty of 0.9 arc sec. (radius, 90% confidence).
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_FC           131          281          147       > 20.2
white              131          943          220       19.90 +/- 0.25
white             5965         6164          197       > 20.4
v                 4940         6509          329       > 19.0
b                 5760         5960          197       > 19.8 
uvw1               669          688           19       > 17.5
uvw1              5350         5550          197       > 19.5
uvm2              5145         5345          197       > 19.4
uvw2              4735         6370          393       > 20.0  
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.027 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #30996
J.P. Osborne (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and J.D. Gropp report on behalf of the Swift-XRT team:
We have analysed 4.0 ks of XRT data for GRB 211025A (Gropp et al. GCN Circ. 30986), from 115 s to 28.0 ks after the BAT trigger. The data comprise 203 s in Windowed Timing (WT) mode (the first 6 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 Evans et al. (GCN Circ. 30987).
The late-time light curve (from T0+4.7 ks) can be modelled with a power-law decay with a decay index of alpha=1.3 (+0.6, -0.4).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.91 (+/-0.06). The best-fitting absorption column is 7.1 (+/-1.4) x 10^20 cm^-2, in excess of the Galactic value of 2.4 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.33 (+0.22, -0.12) and a best-fitting absorption column consistent with the Galactic value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 2.8 x 10^-11 (3.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     2.4 (+3.5, -0.0) x 10^20 cm^-2
Galactic foreground: 2.4 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2.33 (+0.22, -0.12)
```
If the light curve continues to decay with a power-law decay index of 1.3, the count rate at T+24 hours will be 2.1 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.8 x 10^-14 (6.4 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/01081113.
This circular is an official product of the Swift-XRT team.
GCN Circular #30997
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J.D. Gropp (PSU), H. A. Krimm (NSF),S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), D. M. Palmer (LANL),T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+844 sec from the recent telemetry downlink, we report further analysis of BAT GRB 211025A (trigger #1081113) (Gropp, et al., GCN Circ. 30986). The BAT ground-calculated position is RA, Dec = 162.407, 31.506 deg which is
```
  RA(J2000)  =  10h 49m 37.8s 
  Dec(J2000) = +31d 30' 20.8" 
```
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%.
The mask-weighted light curve shows a single broad pulse beginning at T+0, peaking around T+50 sec and declining to background by T+150 sec. T90 (15-350 keV) is 103.5 +- 27.6 sec (estimated error including systematics).
The time-averaged spectrum from T+12.32 to T+128.5 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.96 +- 0.28. The fluence in the 15-150 keV band is 7.7 +- 1.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+51.66 sec in the 15-150 keV band is 0.5 +- 0.1 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/1081113/BA/
GCN Circular #31001
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina, A.Chasovnikov, V.Topolev, V.Grinshpun, D.Kuvshinov, D. Cheryasov (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),
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 GRB 211025A ( J.D. Gropp et al., GCN 30986) errorbox 63953 sec after notice time and 64035 sec after trigger time at 2021-10-25 22:57:35 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 76 deg. The sun altitude is -49.5 deg.
The galactic latitude b = 64 deg., longitude l = 197 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1764428
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   64126 |   MASTER-Kislovodsk |   C |   180 | 17.5 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #31009
R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (College of Marin) report on behalf of a larger collaboration:
We observed Swift GRB 211025A (Gropp, et al., GCN 30986) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on October 25, from 11:27 to 11:49 UT (corresponding to 6.28 to 6.82 hours from the GRB trigger time) with the Bessel R and I filters.
We performed a series of 4x160s exposures in R and I bands. We detect a source consistent with the Swift UVOT detection coordinates (Oates, et al., GCN 30991) in R-band, but not in I-band. The following magnitudes and upper limits are calculated using the USNO-B.1 catalog as reference:
```
R=20.51+/-0.27
I>18.04
```
These magnitudes are not corrected for galactic extinction.
R.S. is funded by NSF AST grant #1831682

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Jochen Greiner, last update: 26-Oct-2021 [Disclaimer]