Gamma-ray Burst 211023B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:06:09 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1080859,   Seg_Num: 0
GRB_RA:          170.302d {+11h 21m 12s} (J2000),
                 170.598d {+11h 22m 23s} (current),
                 169.622d {+11h 18m 29s} (1950)
GRB_DEC:         +39.137d {+39d 08' 14"} (J2000),
                 +39.017d {+39d 01' 02"} (current),
                 +39.411d {+39d 24' 40"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       2950 [cnts]    Image_Peak=189 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   137     E_range: 15-50 keV
BKG_INTEN:       18049 [cnts]
BKG_TIME:        75940.04 SOD {21:05:40.04} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19510 TJD;   296 DOY;   21/10/23
GRB_TIME:        75952.14 SOD {21:05:52.14} UT
GRB_PHI:         -162.51 [deg]
GRB_THETA:        41.90 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.44 [sigma]
IMAGE_SIGNIF:    9.67 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +1  +0  +0  +0 -46  +0 
SUN_POSTN:       208.56d {+13h 54m 15s}  -11.71d {-11d 42' 30"}
SUN_DIST:         61.83 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.57d {+04h 18m 16s}  +21.88d {+21d 53' 03"}
MOON_DIST:        87.96 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.62, 67.71 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      154.12, 31.81 [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 = 161.35,-6.74 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:07:36 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.277d {+11h 21m 07s} (J2000)
POINT_DEC:       +39.153d {+39d 09' 11"} (J2000)
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76047.36 SOD {21:07:27.36} UT,   95.2 [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:     Sat 23 Oct 21 21:09:36 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1080859,   Seg_Num: 0
GRB_RA:          170.302d {+11h 21m 12s} (J2000),
                 170.598d {+11h 22m 23s} (current),
                 169.622d {+11h 18m 29s} (1950)
GRB_DEC:         +39.137d {+39d 08' 14"} (J2000),
                 +39.017d {+39d 01' 02"} (current),
                 +39.411d {+39d 24' 40"} (1950)
GRB_DATE:        19510 TJD;   296 DOY;   21/10/23
GRB_TIME:        75952.14 SOD {21:05:52.14} UT
TRIGGER_INDEX:   137
GRB_PHI:         -162.51 [deg]
GRB_THETA:        41.90 [deg]
DELTA_TIME:      70.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.44 [sigma]
IMAGE_SIGNIF:    9.67 [sigma]
LC_URL:          sw01080859000msb.lc
SUN_POSTN:       208.56d {+13h 54m 15s}  -11.71d {-11d 42' 33"}
SUN_DIST:         61.83 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.60d {+04h 18m 23s}  +21.89d {+21d 53' 30"}
MOON_DIST:        87.94 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.62, 67.71 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      154.12, 31.81 [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 = 161.35,-6.74 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:10:19 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.277d {+11h 21m 07s} (J2000)
POINT_DEC:       +39.153d {+39d 09' 10"} (J2000)
POINT_ROLL:      136.638d
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76049.63 SOD {21:07:29.63} UT,   97.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.679
N_STARS:         21
X_OFFSET:        611 [pixels]
Y_OFFSET:        441 [pixels]
X_MAX:           1570 [pixels]
Y_MAX:           1400 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01080859000msufc0097.fits
SUN_POSTN:       208.56d {+13h 54m 15s}  -11.71d {-11d 42' 34"}
SUN_DIST:         61.86 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.60d {+04h 18m 24s}  +21.89d {+21d 53' 35"}
MOON_DIST:        87.91 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.60, 67.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.09, 31.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:10:37 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.277d {+11h 21m 07s} (J2000)
POINT_DEC:       +39.153d {+39d 09' 10"} (J2000)
POINT_ROLL:      136.638d
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76049.63 SOD {21:07:29.63} UT,   97.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.679
N_STARS:         21
X_OFFSET:        611 [pixels]
Y_OFFSET:        441 [pixels]
X_MAX:           1570 [pixels]
Y_MAX:           1400 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01080859000msufc0097.fits
SUN_POSTN:       208.56d {+13h 54m 15s}  -11.71d {-11d 42' 34"}
SUN_DIST:         61.86 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.60d {+04h 18m 25s}  +21.89d {+21d 53' 38"}
MOON_DIST:        87.91 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.60, 67.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.09, 31.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:11:42 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.277d {+11h 21m 07s} (J2000)
POINT_DEC:       +39.153d {+39d 09' 10"} (J2000)
ROLL:            136.638d
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76049.63 SOD {21:07:29.63} UT,   97.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     656716077
X_OFFSET:        930 [pixels]
Y_OFFSET:        760 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1090
Y_GRB_POS:       920
BINNING_INDEX:   1
IM_URL:          sw01080859000msuni0125.fits
SUN_POSTN:       208.57d {+13h 54m 16s}  -11.71d {-11d 42' 35"}
SUN_DIST:         61.86 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.61d {+04h 18m 27s}  +21.90d {+21d 53' 46"}
MOON_DIST:        87.90 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.60, 67.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.09, 31.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:11:54 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.277d {+11h 21m 07s} (J2000)
POINT_DEC:       +39.153d {+39d 09' 10"} (J2000)
ROLL:            136.638d
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76049.63 SOD {21:07:29.63} UT,   97.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     656716077
X_OFFSET:        930 [pixels]
Y_OFFSET:        760 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1090
Y_GRB_POS:       920
BINNING_INDEX:   1
IM_URL:          sw01080859000msuni0125.fits
SUN_POSTN:       208.57d {+13h 54m 16s}  -11.71d {-11d 42' 35"}
SUN_DIST:         61.86 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.62d {+04h 18m 28s}  +21.90d {+21d 53' 47"}
MOON_DIST:        87.90 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.60, 67.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.09, 31.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:13:43 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     1080859,   Seg_Num: 0
GRB_RA:          170.3096d {+11h 21m 14.30s} (J2000),
                 170.6054d {+11h 22m 25.29s} (current),
                 169.6294d {+11h 18m 31.06s} (1950)
GRB_DEC:         +39.1357d {+39d 08' 08.5"} (J2000),
                 +39.0160d {+39d 00' 57.4"} (current),
                 +39.4098d {+39d 24' 35.4"} (1950)
GRB_ERROR:       0.8 [arcsec radius, statistical only]
GRB_MAG:         19.31 +/- 0.16 [mag]
FILTER:          10, White
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76046.00 SOD {21:07:26.00} UT,   93.9 [sec] since BAT Trigger Time
SUN_POSTN:       208.57d {+13h 54m 16s}  -11.71d {-11d 42' 37"}
SUN_DIST:         61.83 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.63d {+04h 18m 31s}  +21.90d {+21d 54' 01"}
MOON_DIST:        87.91 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.61, 67.72 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      154.13, 31.81 [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 Circular #30960
S. Dichiara (NASA/GSFC/UMCP), J.D. Gropp (PSU), J. A. Kennea (PSU), H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (U Tampa), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), D. M. Palmer (LANL), B. Sbarufatti (PSU), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 21:05:52 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 211023B (trigger=1080859). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 170.302, +39.137 which is
```
   RA(J2000) = 11h 21m 12s
   Dec(J2000) = +39d 08' 14"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 2 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 21:07:27.3 UT, 95.3 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 170.31048, 39.13595 which is equivalent to:
```
   RA(J2000)  = 11h 21m 14.52s
   Dec(J2000) = +39d 08' 09.4"
```
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 23 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 (2.30 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.5 (+2.51/-2.21) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 97 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	11:21:14.31 = 170.30963
  DEC(J2000) = +39:08:08.8  =  39.13578
```
with a 90%-confidence error radius of about 0.79 arc sec. This position is 3.2 arc sec. from the center of the XRT error circle. The estimated magnitude is 19.32 with a 1-sigma error of about 0.16. No correction has been made for the expected extinction corresponding to E(B-V) of 0.024.
We note that this is Swift's 1500th GRB.
Burst Advocate for this burst is S. Dichiara (dichiara AT umd.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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:18:00 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.276d {+11h 21m 06s} (J2000)
POINT_DEC:       +39.151d {+39d 09' 05"} (J2000)
POINT_ROLL:      136.635d
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76262.44 SOD {21:11:02.44} UT,   310.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.908
N_STARS:         32
X_OFFSET:        371 [pixels]
Y_OFFSET:        201 [pixels]
X_MAX:           1810 [pixels]
Y_MAX:           1640 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw01080859000msufc0310.fits
SUN_POSTN:       208.57d {+13h 54m 17s}  -11.71d {-11d 42' 41"}
SUN_DIST:         61.86 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.67d {+04h 18m 40s}  +21.91d {+21d 54' 34"}
MOON_DIST:        87.85 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.60, 67.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.09, 31.81 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:19:21 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.276d {+11h 21m 06s} (J2000)
POINT_DEC:       +39.151d {+39d 09' 05"} (J2000)
ROLL:            136.635d
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76262.44 SOD {21:11:02.44} UT,   310.3 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     656716290
X_OFFSET:        930 [pixels]
Y_OFFSET:        760 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1090
Y_GRB_POS:       920
BINNING_INDEX:   1
IM_URL:          sw01080859000msuni0338.fits
SUN_POSTN:       208.57d {+13h 54m 17s}  -11.71d {-11d 42' 42"}
SUN_DIST:         61.86 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.68d {+04h 18m 43s}  +21.91d {+21d 54' 45"}
MOON_DIST:        87.84 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.60, 67.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.09, 31.81 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:18:13 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.276d {+11h 21m 06s} (J2000)
POINT_DEC:       +39.151d {+39d 09' 05"} (J2000)
POINT_ROLL:      136.635d
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76262.44 SOD {21:11:02.44} UT,   310.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.908
N_STARS:         32
X_OFFSET:        371 [pixels]
Y_OFFSET:        201 [pixels]
X_MAX:           1810 [pixels]
Y_MAX:           1640 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw01080859000msufc0310.fits
SUN_POSTN:       208.57d {+13h 54m 17s}  -11.71d {-11d 42' 41"}
SUN_DIST:         61.86 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.67d {+04h 18m 41s}  +21.91d {+21d 54' 36"}
MOON_DIST:        87.85 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.60, 67.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.09, 31.81 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:19:30 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.276d {+11h 21m 06s} (J2000)
POINT_DEC:       +39.151d {+39d 09' 05"} (J2000)
ROLL:            136.635d
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76262.44 SOD {21:11:02.44} UT,   310.3 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     656716290
X_OFFSET:        930 [pixels]
Y_OFFSET:        760 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1090
Y_GRB_POS:       920
BINNING_INDEX:   1
IM_URL:          sw01080859000msuni0338.fits
SUN_POSTN:       208.57d {+13h 54m 17s}  -11.71d {-11d 42' 42"}
SUN_DIST:         61.86 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.68d {+04h 18m 43s}  +21.91d {+21d 54' 46"}
MOON_DIST:        87.84 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.60, 67.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.09, 31.81 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:23:10 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.276d {+11h 21m 06s} (J2000)
POINT_DEC:       +39.151d {+39d 09' 04"} (J2000)
POINT_ROLL:      136.635d
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76815.93 SOD {21:20:15.93} UT,   863.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.405
N_STARS:         67
X_OFFSET:        371 [pixels]
Y_OFFSET:        201 [pixels]
X_MAX:           1810 [pixels]
Y_MAX:           1640 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw01080859000msufc0863.fits
SUN_POSTN:       208.57d {+13h 54m 17s}  -11.71d {-11d 42' 45"}
SUN_DIST:         61.87 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.71d {+04h 18m 51s}  +21.92d {+21d 55' 14"}
MOON_DIST:        87.81 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.61, 67.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.09, 31.81 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:23:23 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.276d {+11h 21m 06s} (J2000)
POINT_DEC:       +39.151d {+39d 09' 04"} (J2000)
POINT_ROLL:      136.635d
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76815.93 SOD {21:20:15.93} UT,   863.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.405
N_STARS:         67
X_OFFSET:        371 [pixels]
Y_OFFSET:        201 [pixels]
X_MAX:           1810 [pixels]
Y_MAX:           1640 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw01080859000msufc0863.fits
SUN_POSTN:       208.57d {+13h 54m 17s}  -11.71d {-11d 42' 45"}
SUN_DIST:         61.87 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.71d {+04h 18m 51s}  +21.92d {+21d 55' 15"}
MOON_DIST:        87.81 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.61, 67.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.09, 31.81 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:24:52 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.276d {+11h 21m 06s} (J2000)
POINT_DEC:       +39.151d {+39d 09' 04"} (J2000)
ROLL:            136.635d
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76815.93 SOD {21:20:15.93} UT,   863.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     656716843
X_OFFSET:        930 [pixels]
Y_OFFSET:        760 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1090
Y_GRB_POS:       920
BINNING_INDEX:   1
IM_URL:          sw01080859000msuni0891.fits
SUN_POSTN:       208.57d {+13h 54m 18s}  -11.71d {-11d 42' 46"}
SUN_DIST:         61.87 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.73d {+04h 18m 54s}  +21.92d {+21d 55' 27"}
MOON_DIST:        87.80 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.61, 67.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.09, 31.81 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 23 Oct 21 21:25:05 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1080859,   Seg_Num: 0
POINT_RA:        170.276d {+11h 21m 06s} (J2000)
POINT_DEC:       +39.151d {+39d 09' 04"} (J2000)
ROLL:            136.635d
IMG_START_DATE:  19510 TJD;   296 DOY;   21/10/23
IMG_START_TIME:  76815.93 SOD {21:20:15.93} UT,   863.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     656716843
X_OFFSET:        930 [pixels]
Y_OFFSET:        760 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1090
Y_GRB_POS:       920
BINNING_INDEX:   1
IM_URL:          sw01080859000msuni0891.fits
SUN_POSTN:       208.57d {+13h 54m 18s}  -11.71d {-11d 42' 47"}
SUN_DIST:         61.87 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:       64.73d {+04h 18m 55s}  +21.92d {+21d 55' 28"}
MOON_DIST:        87.80 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:      174.61, 67.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.09, 31.81 [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 #30964
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, 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, O.Ershova (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko (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 211023B ( S. Dichiara et al., GCN 30960) errorbox 631 sec after notice time and 655 sec after trigger time at 2021-10-23 21:16:47 UT, with upper limit up to 15.2 mag. The observations began at zenith distance = 89 deg. The sun altitude is -58.3 deg.
The galactic latitude b = 68 deg., longitude l = 175 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1762968
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

     721 |   MASTER-Kislovodsk |  P- |   130 | 14.5 |        
     874 |   MASTER-Kislovodsk |  P- |   160 | 14.9 |        
    1252 |   MASTER-Kislovodsk |  P- |   180 | 15.2 |        
```
The observation and reduction will continue. The message may be cited.
GCN Circular #30966
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 3338 s of XRT Photon Counting mode data and 2 UVOT images for GRB 211023B, 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 = 170.30871, +39.13534 which is equivalent to:
```
RA (J2000): 11h 21m 14.09s
Dec (J2000): +39d 08' 07.2"
```
with an uncertainty of 2.7 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 #30967
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU) and S. Dichiara report on behalf of the Swift-XRT team:
We have analysed 6.3 ks of XRT data for GRB 211023B (Dichiara et al. GCN Circ. 30960), from 79 s to 24.8 ks after the BAT trigger. The data comprise 8 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 30966).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.03 (+0.12, -0.10).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.08 (+0.24, -0.22). The best-fitting absorption column is 9.8 (+6.0, -5.1) x 10^20 cm^-2, in excess of the Galactic value of 2.3 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.2 x 10^-11 (4.0 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     9.8 (+6.0, -5.1) x 10^20 cm^-2
Galactic foreground: 2.3 x 10^20 cm^-2
Excess significance: 2.4 sigma
Photon index:	     2.08 (+0.24, -0.22)
```
If the light curve continues to decay with a power-law decay index of 1.03, the count rate at T+24 hours will be 1.5 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.7 x 10^-14 (5.9 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/01080859.
This circular is an official product of the Swift-XRT team.
GCN Circular #30972
A. Pozanenko (IKI), I. Reva (FAP), M.Krugov (FAP), S. Belkin (IKI), V. Kim (FAP), N. Pankov (HSE) report on behalf of GRB-IKI-FuN:
We observed the field of possible short GRB 211023B detected by Swift (Dichiara et al., GCN 30960) with Zeiss-1000 telescope of Tien Shan Astronomical Observatory stating on Oct. 23 (UT) 21:17:06. We obtained series with 120 sec expositions in R-filter.
Within enhanced Swift-XRT position (Beardmore et al., GCN 30966) we do not detected any source (see upper limits below). In particular we do not detect possible optical afterglow (Dichiara et al., GCN 30960). Preliminary photometry of stacked images is following
```
Date       UT start t-T0    Filter  Exp.  OT    Err.  UL(3 sigma)
                     (mid, days)     (s)

2021-10-23 21:17:06 0.01127  R      5*120 n/d n/d     18.9
2021-10-23 21:17:06 0.02238  R     21*120 n/d n/d     19.5
```
The photometry is based on nearby USNO-B1.0 stars.
In addition we found a source in Legacy Survey (https://www.legacysurvey.org) which is coincident with UVOT detection (Dichiara et al., GCN 30960). This is a point-like object at ~0.67 arces distance from UVOT position and has a LS DR9 photometry g=24.32, r=24.36, z=23.31
GCN Circular #30973
Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Eleonora Troja (GSFC), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Enrico Ramirez-Ruiz (UCSC), Jes�s Gonz�lez (UNAM), Carlos Rom�n-Z��iga (UNAM), Harvey Moseley (GSFC), Rosa L. Becerra (UNAM), Simone Dichiara (UMD), and Oc�lotl L�pez (UNAM) report:
We observed the field of GRB 211023B (Dichiara et al., GCN 30960) with the Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on Sierra San Pedro M�rtir from 2021/10 24.49 to 2021/10 24.53 UTC (14.54 to 15.54 hours after the BAT trigger), obtaining a total of 0.73 hours exposure in the r and i bands and 0.30 hours exposure in the Z, Y, J, and H bands.
For a source within the UVOT error circle, in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following detections and upper limits (3-sigma):
```
  r	> 22.4
  i	> 22.1
  Z	> 20.6
  Y	> 20.3
  J	> 21.0
  H	> 20.7
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron�mico Nacional in San Pedro M�rtir.
GCN Circular #30975
N. P. M. Kuin (UCL-MSSL) and S. Dichiara (NASA/GSFC/UMCP) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 211023B 98 s after the BAT trigger (Dichiara et al., GCN Circ. 30960). A source consistent with the XRT position (Beardmore et al. GCN Circ. 30966) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
    RA  (J2000) =  11:21:14.33 = 170.30971 (deg.)
    Dec (J2000) = +39:08:08.8  =  39.13579 (deg.)
```
with an estimated uncertainty of 0.53 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               98          247          147         19.44 +/- 0.11
v                  640         1753          136        >18.8
b                  566         1679          117        >19.9
u                  310          734          265         19.50 +/- 0.20
w1                 690         1803          117        >19.3
w2                 615         1039           39        >19.9
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.024 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #30976
Y.-D. Hu, V. Casanova, T.-R. Sun, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado, E. Fernandez-Garcia (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), S. Guziy (Univ. of Nikolaev) and D. R. Xiong, Y. F. Fan, J. M. Bai, C. J. Wang, Y. X. Xin, X. H. Zhao (Yunnan Observatories of CAS) on behalf of a larger collaboration, report:
Following the detection of GRB 211023B by Swift (S. Dichiara et al. GCNC 30960), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) automatically respond to this burst starting on Oct 23 at 21:06:20 UT (~28 sec after trigger). Due to technical problems, the useful images were obtained only after 21:18:39 UT (~13 min after trigger). The optical afterglow reported by Swift/UVOT (S. Dichiara et al. GCNC 30960, N. P. M. Kuin et al. GCNC 30975) is not detected in the co-added image (10s x 30, clear filter) down to 19.9 mag.
We then triggered the 1.5m OSN telescope in Sierra Nevada Observatory (Granada, Spain) on Oct. 24 03:20 UT (~6.2 hrs after trigger). A series of image were taken in R and I -bands (300s exposures each filter). The optical afterglow is not detected in the co-added image (300s x 12) down to 21.6 mag (R-band).
These non-detections are consistent with the reports by MASTER (Lipunov et al. GCNC 30964), TSHAO (Pozanenko et al. GCNC 30972) and RATIR (Watson et al. GCNC 30973).
We thank the staff at Lijiang observatory and OSN for their excellent support.
GCN Circular #30979
S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), S. Dichiara (NASA/GSFC/UMCP), H. A. Krimm (NSF), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), 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+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 211023B (trigger #1080859) (Dichiara, et al., GCN Circ. 30960). The BAT ground-calculated position is RA, Dec = 170.314, 39.133 deg which is
```
  RA(J2000)  =  11h 21m 15.3s 
  Dec(J2000) = +39d 07' 58.7" 
```
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 48%.
The mask-weighted light curves shows a single peak from approximately T+0 to T+1.5 seconds. T90 (15-350 keV) is 1.30 +- 0.26 sec (estimated error including systematics).
The time-averaged spectrum from T-0.01 to T+1.45 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.97 +- 0.24. The fluence in the 15-150 keV band is 1.7 +- 0.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.24 sec in the 15-150 keV band is 2.2 +- 0.3 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/1080859/BA/
GCN Circular #30992
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/DARK/NBI), C. C. Thoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC), A. Guijarro, and P. Martin-Fernandez (both CAHA) report:
We observed the optical afterglow of the potentially short Swift GRB 211023B (Dichiara et al., GCN #30960; Kuin & Dichiara, GCN #30975) with CAFOS mounted on the 2.2m Telescope at Calar Alto, Almeria, Spain. We obtained 30 x 90 s in the SDSS i' band under mediocre conditions.
At the position of the GRB afterglow discovered by Swift/UVOT (Kuin & Dichiara, GCN #30975), we detect a source. Against two Pan-STARRS comparison stars, we measure:
i' = 22.26 +\- 0.10 mag (AB) at 0.3091 d after the GRB.
We note this faint magnitude is in agreement with both earlier (Lipunov et al., GCN #30964; Pozanenko et al., GCN #30972; Yu et al., GCN #30976), simultaneous (Yu et al., GCN #30976), and later (Watson et al., GCN #30973) non-detections.
GCN Circular #31000
B. O'Connor (UMD, GWU),S.B. Cenko (UMD,NASA-GSFC), E. Troja (UMD, NASA-GSFC),A.Gottlieb (UMD,NASA-GSFC), S.Dichiara (PSU),A. Kutyrev (UMD,NASA-GSFC), S. Veilleux (UMD)
We observed the field of GRB 211023B (Dichiara et al., GCN 30960) using the Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery Telescope (LDT) at Happy Jack, AZ. Observations began on October 25, 2021 at 11:42:14 UT (~1.61 d after the GRB), and were performed in r-band for a total of 18x150 s exposures under poor conditions.
We detect a source coincident with the position of the optical counterpart reported by UVOT (Kuin et al., GCN 30975) and CAHA (Kann et al., GCN 30992). We measure a brightness of r~23 AB mag, brighter than the archival object reported by Pozanenko et al. (GCN 30972). We do not detect any other source within 5" radius of the UVOT position with a 3-sigma upper limit r>24.0 mag.
Given the non-detection at ~15 hours (Watson et al., GCN 30973), our detection implies a shallow temporal decay index beta<0.6, assuming a power-law decline as F~t^-beta. While this may be due in part to the underlying source (Pozanenko et al., GCN 30972), we note that the same flattening is also observed in X-rays by Swift/XRT. Therefore, we strongly encourage continued follow-up of this source.
Magnitudes are calibrated against the SDSS catalog and are not corrected for Galactic extinction.
We thank the staff of the Lowell Discovery Telescope for assistance with these observations.
GCN Circular #31002
J. Rastinejad, K. Paterson, W. Fong, C. Kilpatrick, A. Rouco Escorial (Northwestern), Antonino Cucchiara (College of Marin) report on behalf of a larger collaboration:
We observed the location of GRB 211023B (Dichiara et al. GCNC 30960) over two nights with the Gemini Multi-Object Spectrograph (GMOS) mounted on Gemini-North under Program GN-2021B-Q-109. We obtained 11x60-sec and 20x60-sec imaging in i-band at a mid-time of 2021 October 25.63 UT (0.7484 days post-burst) and 2021October 24.62 UT (1.745 days post-burst), respectively, both at a median airmass of 1.9. At 1.745 days post-burst, we detect a source consistent with both the UVOT position and the previously reported Legacy Survey source (Kuin et al. GCN 30975, Pozanenko et al. GCN 30972). Calibrated to SDSS, we measure a brightness of i_AB = 23.1 +/- 0.1 mag at seeing < 0.8'' for this source.
This is consistent with previously reported upper limits (Watson et al., GCN 30973, Hu et al. GCN 30976, Pozanenko et al. GCN 30972) and indicates significant fading from the i-band measurement reported by Kann et al. (GCN 30995) at 0.3091 days post-burst. At present, the source appears marginally extended, and it is very likely that the underlying host galaxy is contributing significantly to our measured flux (based on the expected i-band magnitude of the host from interpolating Legacy Survey DR9 photometry; Dey et al., 2019).
Further observations are planned to monitor the variability of the source. We thank Jennifer Andrews and additional Gemini staff for the rapid planning and execution of these observations.
GCN Circular #31003
A. Pozanenko (IKI), S. Belkin (IKI), E. Klunko (ISTP), N. Pankov (HSE), report on behalf of GRB IKI FuN:
We observed the field of GRB 211023B (Dichiara et al., GCN 30960) with AZT-33IK telescope of Sayan observatory (Mondy) starting on 2021-10-23 (UT) 21:23:21. We obtained 60 images in R-filter. We confirm afterglow of the GRB 211023B (Dichiara et al., GCN 30960; Kuin et al. GCN 30975; Kann et al. GCN 30995; O'Connor et al., GCN 31000; Rastinejad et al., GCN 31002). Preliminary photometry of the afterglow in stacked images is following
```
Date       UT start   t-T0       Filter Exp.   OT    Err.  UL(3sigma)
                     (mid, days)        (s)

2021-10-23 21:23:21  0.15613    R     15*60   20.46  0.31  20.5
2021-10-23 21:23:21  0.03297    R     60*60   20.97  0.40  20.9
```
The photometry is based on the nearby USNO-B1.0 stars
```
RA DEC R2
11:21:12.41280 +39:08:38.1120 15.33
11:21:05.20872 +39:04:33.9600 14.18
```
We note the obtained magnitudes are in agreement with non-detections of the optical counterpart (Lipunov et al., GCN 30964; Pozanenko et al., GCN 30972; Watson et al., GCN 30973; Yu et al., GCN 30976).
GCN Circular #31016
B. Grossan (UCB, NU), T. Komesh (NU), Z. Maksut (NU), M. Krugov (FAI), E. Linder (UCB, NU), E. Abdikamalov (NU), G. F. Smoot (HKUST, UCB, NU), report on behalf of the Energetic Cosmos Laboratory:
The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) observed the field of GRB 211023B soon after receipt an automated GCN / BAT position alert, observing in Sloan g', r' and i' bands, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14).
We started observations at 21:26:33 UT on 2021-10-23, 1241 s after the BAT trigger. Observations were made partly cloudy conditions starting at only about 18 deg. target altitude. No source consistent with the XRT (P. Evans et al., GCN Circ. 30966) or UVOT position (S. Dichiara; GCN Circ. 30960) was detected. Note that these observations provide essentially full-time coverage, simultaneous in all three bands. We report the following results:
```
start time    t-t0(s)  end time        UL g'    UL r'    ULi'       exposure_time (s)
------------    --------  ------------        ------    ------     ------      --------------------
21:26:33     1241   21:27:33        17.6    18.7      17.8           60
21:27:56     1324   22:47:56        18.5    19.5      18.7         300
```
start time is in UT. t-t0(s) gives the time since trigger, in seconds. UL g', r', i', gives the 5 sigma upper limit sensitivity in magnitudes in the respective filter, for images co-added to the given exposure time. The first row in the table corresponds to co-adds of an initial short exposure image sequence of 7.5 s for g' and i', and 0.3 s for r' (these sub-second exposures are read-noise suppressed by our EMCCD cameras, with high gain electron multiplication active; other images are taken in conventional CCD operation mode). The second row corresponds to co-adds from a continuing series of 15 s exposures for g' and i', and 3 s for r', uninterrupted for the 80 minutes. Calibration was done with the 2-5 bright Pan-STARRS catalog stars on our images.
We caution the reader that these are preliminary results, without color or other corrections. Please also note that times are approximate.
```
----------------------------------
NU = Nazarbayev University, Nur-Sultan, Kazakhstan
UCB = University of California, Berkeley, USA
HKUST = Hong Kong University of Science and Technology
FAI = Fesenkov Astrophysical Institute, Kazakhstan
```
The NUTTelA-TAO Team acknowledges the support of the staff of the Assy-Turgen Astrophysical Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical Institute, Almaty, Kazkhstan.
GCN Circular #31021
G. Schroeder, W. Fong, A. Rouco Escorial, (Northwestern), T. Laskar (Univ. Radboud), E. Berger (Harvard) report:
"We observed the position of GRB 211023B (Dichiara et al. GCN 30960) with the Karl G. Jansky Very Large Array (VLA) under program 21B-198 (PI: Fong) beginning on 2021 October 27.51 UT (3.63 days post-burst) at a mean frequency of 6 GHz.
Based on preliminary analysis, in 1 hour of observations we do not detect any radio emission at or near the position of the optical afterglow and host (Kuin et al. GCN 30975; Pozanenko et al. GCN 30972; Kann et al. GCN 30995; O'Connor et al., GCN 31000; Rastinejad et al., GCN 31002; Pozanenko et al., GCN 31003) to a 3-sigma limit of 13 microJy. We also do not detect any source within the XRT position (Beardmore et al. GCN 30966). Additional, detailed analysis is ongoing.
We thank the VLA staff for quickly approving and executing these observations."
GCN Circular #31031
R. Hosokawa, Y. Imai, K. L. Murata, M. Niwano, Y. Takamatsu, N. Ito, R. Noto, S. Sato, M. Takaku, R. Yamaguchi, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 211023B (S. Dichiara et al. GCN Circular #30960, V. Lipunov et al. GCN Circular #30964, A.P. Beardmore et al. GCN Circular #30966, A.P. Beardmore et al. GCN Circular #30967, A. Pozanenko et al. GCN Circular #30972, Alan M. Watson et al. GCN Circular #30973, N. P. M. Kuin et al. GCN Circular #30975, Y.-D. Hu et al. GCN Circular #30976, S. Laha et al. GCN Circular #30979, D. A. Kann et al. GCN Circular #30992, B. O'Connor et al. GCN Circular #31000, J. Rastinejad et al. GCN Circular #31002, A. Pozanenko et al. GCN Circular #31003, B. Grossan et al. GCN Circular #31016) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno. The observation with a series of 60 sec exposures started at 21-10-24 17:18:57 UT (20.2 hours after Swift trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the UVOT error region (S. Dichiara et al. GCN Circular #30960). We obtained the 5-sigma limits of the stacked images as follows.
```
T0+[days] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
2.9 2021-10-26 19:25:18 2160 g'>19.5, Rc>19.6, Ic>18.7
3.9 2021-10-27 19:10:47 4020 g'>19.5, Rc>20.1, Ic>19.4
4.9 2021-10-28 19:02:53 7020 g'>19.8, Rc>20.1, Ic>19.3
5.9 2021-10-29 18:56:59 6120 g'>20.3, Rc>20.5, Ic>19.9
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
```
We used 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 #31038
T. Sakamoto (AGU), G.S.H. Paek (SNU), Y. Urata (NCU), E. Troja (NASA/GSFC), M. Im (SNU), K. Aoki (NAOJ) report on behalf of Subaru GRB team:
We observed the field of GRB 211023B (Dichiara et al., GCN Circ. 30960) with Hyper Suprime-Cam (HSC) on the Subaru 8.2 m telescope starting from 13:36 on October 28 about 4.7 days after the trigger. Observations were performed in the r filter for a total of 4800 s (32 x 150 s) exposure.
At a position consistent with the UVOT localization (Kuin & Dichiara, GCN Circ. 30975) and the Legacy Survey object (Pozanenko et al. GCN 30972), we detect an optical source with magnitude r~23.6 AB. Since the source appears clearly extended in our images and its brightness is consistent with the Gemini-North observation (Rastinejad et al., GCN Circ. 31002), archival HSC g-band images of March 2016, and CFHT archival r-band images of September 2020, we conclude that the source detected by Subaru is dominated by the host galaxy contribution, in agreement with Rastinejad et al. (GCN Circ. 31002).
We would like to thank the Subaru director, Dr. Michitoshi Yoshida for approving our ToO, and Dr. Tsuyoshi Terai and Dr. Ichi Tanaka for supporting our observation.
GCN Circular #31107
A. Rossi, E. Palazzi, L. Amati, E. Pian (INAF-OAS), D. B. Malesani (Univ. Radboud and DAWN/NBI), S. Savaglio (UNICAL), P. D'Avanzo (INAF/OABr), and V. D'Elia (SSDC & INAF-OAR), M. De Pasquale (University of Messina),� report on behalf of the CIBO collaboration:
We report the results of the photometric and spectroscopic follow-up of the short GRB 211023B (Dichiara et al., GCN Circ. 30960) obtained with the Multi-Object Double Spectrographs (MODS) instrument mounted on the 2x8.4-m LBT telescope (Mt Graham, AZ, USA). Data were obtained at the mid time of 12:40 UT on 2021-11-06, ~13.6 days after the burst trigger.
At the position of the UVOT localization (Kuin & Dichiara, GCN 30975) and the Legacy Survey object (Pozanenko et al., GCN 30972), we detect the GRB host galaxy (Sakamato et al. GCN 31038, Rastinejad et al. GCN 31002). We measure the following AB magnitudes:
```
g = 24.02+-0.17
r = 23.99+-0.15
```
calibrated against Pan-STARRS field stars and not corrected for Galactic extinction.
Spectroscopy of the source was obtained for a total of 4550s, covering the wavelength range 3200-10000 AA.Continuum is faintly detected over the wavelength range 3200-10000 AA, and a single emission line is visible at ~6940 AA. The most likely interpretation is [O II] at z = 0.862. At this redshift, [O III] would unfortunately fall on top of a region affected by sky lines, so its non-detection is not very constraining. Other interpretations are less likely. We can disregard Lyalpha, since there is no drop in the continuum blueward of the line. We deem Halpha unlikely, as the corresponding redshift z = 0.057 would imply an extremely faint host galaxy (absolute magnitude ~ -13), and we don't see the expected [O III] and Hbeta lines. The interpretation of the observed feature as [O III] 5008 seems to be also unlikely as we would expect to detect hints of [O III] 4959 as well as Halpha which would fall in a wavelength region clean of skylines.
Assuming the redshift z=0.862, standard cosmology (Planck 2016) and Swift/BAT refined and on-line automated spectral analysis (Laha et al., GCN 30979, and http://gcn.gsfc.nasa.gov/notices_s/1080859/BA/ ) we estimate an isotropic-equivalent radiated energy Eiso (1-10000 keV) of about (0.9-1.2)x E^51 erg, which is typical of short GRBs. However, we note that: a) despite its short duration, the burst has a rather soft spectrum (simple power with index ~2) which is consistent with a spectral peak energy Ep close to (or even below) the BAT low-energy threshold and would imply a rest-frame peak energy Ep,i < ~30-40 keV, thus locating this GRB in the region of the Ep,i - Eiso plane populated by long GRBs. The preliminary automatic modelling with a cut-off power-law or a Band function is consistent with a larger Ep,i, which would make this burst more similar to other short GRBs, but with a very large uncertainty. b) the soft spectra and short duration put GRB 211023B closer to the region populated by long GRBs than to to the one populated by short events also in the HR-T90 diagram, even though it is still consistent with belonging to the tail of the distribution of short GRBs in this plane.
We acknowledge the excellent support from the LBTO and LBT-INAF staff, particularly O. Kuhn, S. Allanson, F. Cusano, S. Bisogni, and D. Paris, in obtaining these observations.
Redshift z= 0.862 +- 0.001 from host galaxy emission ([OII], [OIII])
W.-F. Fong et al. 2022, ApJ 940, 56

Back to JG's homepage

Jochen Greiner, last update: 17-Jan-2023 [Disclaimer]