Gamma-ray Burst 230911C

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 11 Sep 23 08:48:29 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     1191188,   Seg_Num: 0
  GRB_RA:          226.782d {+15h 07m 08s} (J2000),
                   227.171d {+15h 08m 41s} (current),
                   225.965d {+15h 03m 52s} (1950)
  GRB_DEC:         -41.334d {-41d 20' 01"} (J2000),
                   -41.424d {-41d 25' 25"} (current),
                   -41.142d {-41d 08' 30"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       14137 [cnts]    Image_Peak=315 [image_cnts]
  TRIGGER_DUR:     5.504 [sec] 
  TRIGGER_INDEX:   476     E_range: 25-100 keV
  BKG_INTEN:       111808 [cnts]
  BKG_TIME:        31576.01 SOD {08:46:16.01} UT
  BKG_DUR:         48 [sec]
  GRB_DATE:        20198 TJD;   254 DOY;   23/09/11
  GRB_TIME:        31645.51 SOD {08:47:25.51} UT
  GRB_PHI:         -53.31 [deg]
  GRB_THETA:        12.86 [deg]
  SOLN_STATUS:     0x83
  RATE_SIGNIF:     12.08 [sigma]
  IMAGE_SIGNIF:    6.76 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +2  +2  -3  +0  +0 -35  +0 
  SUN_POSTN:       169.31d {+11h 17m 15s}   +4.60d {+04d 35' 47"}
  SUN_DIST:         69.84 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
  MOON_POSTN:      131.91d {+08h 47m 39s}  +23.14d {+23d 08' 32"}
  MOON_DIST:       108.86 [deg]
  MOON_ILLUM:      12 [%]
  GAL_COORDS:      328.60, 14.68 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      236.09,-22.85 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Coordinates.  
  COMMENTS:        This is a rate trigger.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        Since the IMAGE_SIGNIF is less than 7 sigma, this is a questionable detection.  
  COMMENTS:        This trigger occurred at longitude,latitude = 149.52,-20.20 [deg].  
  

• red DSS finding chart ps-file
  
  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 11 Sep 23 08:49:30 UT
  NOTICE_TYPE:     Swift-XRT Nack-Position
  TRIGGER_NUM:     1191188,   Seg_Num: 0
  POINT_RA:        226.806d {+15h 07m 13s} (J2000)
  POINT_DEC:       -41.350d {-41d 21' 00"} (J2000)
  IMG_START_DATE:  20198 TJD;   254 DOY;   23/09/11
  IMG_START_TIME:  31764.49 SOD {08:49:24.49} UT,   119.0 [sec] since BAT Trigger Time
  COUNTS:          22    Min_needed= 20
  STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
  PH2_ITER:        4    Max_iter_allowed= 4
  ERROR_CODE:      2
  COMMENTS:        SWIFT-XRT Nack Position.  
  COMMENTS:        Algorithm did not converge; too many iterations.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 11 Sep 23 08:52:32 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     1191188,   Seg_Num: 0
  POINT_RA:        226.807d {+15h 07m 14s} (J2000)
  POINT_DEC:       -41.350d {-41d 21' 01"} (J2000)
  POINT_ROLL:      296.209d
  IMG_START_DATE:  20198 TJD;   254 DOY;   23/09/11
  IMG_START_TIME:  31767.85 SOD {08:49:27.85} UT,   122.3 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        3.716
  N_STARS:         190
  X_OFFSET:        656 [pixels]
  Y_OFFSET:        521 [pixels]
  X_MAX:           1615 [pixels]
  Y_MAX:           1480 [pixels]
  DET_THRESH:      16
  PHOTO_THRESH:    9
  SL_URL:          sw01191188000msufc0122.fits
  SUN_POSTN:       169.31d {+11h 17m 15s}   +4.60d {+04d 35' 43"}
  SUN_DIST:         69.86 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
  MOON_POSTN:      131.95d {+08h 47m 47s}  +23.13d {+23d 07' 58"}
  MOON_DIST:       108.85 [deg]
  MOON_ILLUM:      12 [%]
  GAL_COORDS:      328.61, 14.65 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      236.11,-22.86 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 11 Sep 23 08:52:53 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     1191188,   Seg_Num: 0
  POINT_RA:        226.807d {+15h 07m 14s} (J2000)
  POINT_DEC:       -41.350d {-41d 21' 01"} (J2000)
  POINT_ROLL:      296.209d
  IMG_START_DATE:  20198 TJD;   254 DOY;   23/09/11
  IMG_START_TIME:  31767.85 SOD {08:49:27.85} UT,   122.3 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        3.716
  N_STARS:         190
  X_OFFSET:        656 [pixels]
  Y_OFFSET:        521 [pixels]
  X_MAX:           1615 [pixels]
  Y_MAX:           1480 [pixels]
  DET_THRESH:      16
  PHOTO_THRESH:    9
  SL_URL:          sw01191188000msufc0122.fits
  SUN_POSTN:       169.31d {+11h 17m 15s}   +4.60d {+04d 35' 43"}
  SUN_DIST:         69.86 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
  MOON_POSTN:      131.95d {+08h 47m 48s}  +23.13d {+23d 07' 55"}
  MOON_DIST:       108.85 [deg]
  MOON_ILLUM:      12 [%]
  GAL_COORDS:      328.61, 14.65 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      236.11,-22.86 [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 11 Sep 23 08:54:16 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     1191188,   Seg_Num: 0
  POINT_RA:        226.807d {+15h 07m 14s} (J2000)
  POINT_DEC:       -41.350d {-41d 21' 01"} (J2000)
  ROLL:            296.209d
  IMG_START_DATE:  20198 TJD;   254 DOY;   23/09/11
  IMG_START_TIME:  31767.85 SOD {08:49:27.85} UT,   122.3 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     716114999
  X_OFFSET:        975 [pixels]
  Y_OFFSET:        840 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       1135
  Y_GRB_POS:       1000
  BINNING_INDEX:   1
  IM_URL:          sw01191188000msuni0154.fits
  SUN_POSTN:       169.31d {+11h 17m 15s}   +4.59d {+04d 35' 41"}
  SUN_DIST:         69.86 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
  MOON_POSTN:      131.96d {+08h 47m 51s}  +23.13d {+23d 07' 43"}
  MOON_DIST:       108.84 [deg]
  MOON_ILLUM:      12 [%]
  GAL_COORDS:      328.61, 14.65 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      236.11,-22.86 [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:     Mon 11 Sep 23 08:54:31 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     1191188,   Seg_Num: 0
  POINT_RA:        226.807d {+15h 07m 14s} (J2000)
  POINT_DEC:       -41.350d {-41d 21' 01"} (J2000)
  ROLL:            296.209d
  IMG_START_DATE:  20198 TJD;   254 DOY;   23/09/11
  IMG_START_TIME:  31767.85 SOD {08:49:27.85} UT,   122.3 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     716114999
  X_OFFSET:        975 [pixels]
  Y_OFFSET:        840 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       1135
  Y_GRB_POS:       1000
  BINNING_INDEX:   1
  IM_URL:          sw01191188000msuni0154.fits
  SUN_POSTN:       169.31d {+11h 17m 15s}   +4.59d {+04d 35' 41"}
  SUN_DIST:         69.86 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
  MOON_POSTN:      131.96d {+08h 47m 51s}  +23.13d {+23d 07' 41"}
  MOON_DIST:       108.83 [deg]
  MOON_ILLUM:      12 [%]
  GAL_COORDS:      328.61, 14.65 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      236.11,-22.86 [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:     Mon 11 Sep 23 08:55:09 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     8388223,   Seg_Num: 0
  GRB_RA:          226.782d {+15h 07m 08s} (J2000),
                   227.171d {+15h 08m 41s} (current),
                   225.965d {+15h 03m 52s} (1950)
  GRB_DEC:         -41.334d {-41d 20' 01"} (J2000),
                   -41.424d {-41d 25' 25"} (current),
                   -41.142d {-41d 08' 30"} (1950)
  GRB_DATE:        20198 TJD;   254 DOY;   23/09/11
  GRB_TIME:        31645.51 SOD {08:47:25.51} UT
  TRIGGER_INDEX:   476
  GRB_PHI:         -53.31 [deg]
  GRB_THETA:        12.86 [deg]
  DELTA_TIME:      0.00 [sec]
  TRIGGER_DUR:     5.504 [sec] 
  SOLN_STATUS:     0x83
  RATE_SIGNIF:     0.00 [sigma]
  IMAGE_SIGNIF:    0.00 [sigma]
  LC_URL:          sw01191188000msb.lc
  SUN_POSTN:       169.31d {+11h 17m 15s}   +4.59d {+04d 35' 41"}
  SUN_DIST:         69.84 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
  MOON_POSTN:      131.97d {+08h 47m 53s}  +23.13d {+23d 07' 36"}
  MOON_DIST:       108.81 [deg]
  MOON_ILLUM:      12 [%]
  GAL_COORDS:      328.60, 14.68 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      236.09,-22.85 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Lightcurve.  
  COMMENTS:           
  COMMENTS:        WARNING: No BAT_Position TDRSS message was received for this trigger_number!  
  COMMENTS:           
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        Since the IMAGE_SIGNIF is less than 7 sigma, this is a questionable detection.  
  COMMENTS:        This trigger occurred at longitude,latitude = 149.52,-20.20 [deg].  
  COMMENTS:        The 3rd packet (of 3) was missing in the lightcurve data stream.
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 11 Sep 23 08:56:38 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     1191188,   Seg_Num: 0
  POINT_RA:        226.806d {+15h 07m 14s} (J2000)
  POINT_DEC:       -41.351d {-41d 21' 04"} (J2000)
  POINT_ROLL:      296.210d
  IMG_START_DATE:  20198 TJD;   254 DOY;   23/09/11
  IMG_START_TIME:  31925.84 SOD {08:52:05.84} UT,   280.3 [sec] since BAT Trigger Time
  FILTER:          7, U
  BKG_MEAN:        1.087
  N_STARS:         190
  X_OFFSET:        416 [pixels]
  Y_OFFSET:        281 [pixels]
  X_MAX:           1855 [pixels]
  Y_MAX:           1720 [pixels]
  DET_THRESH:      9
  PHOTO_THRESH:    4
  SL_URL:          sw01191188000msufc0280.fits
  SUN_POSTN:       169.32d {+11h 17m 16s}   +4.59d {+04d 35' 39"}
  SUN_DIST:         69.86 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
  MOON_POSTN:      131.98d {+08h 47m 56s}  +23.12d {+23d 07' 23"}
  MOON_DIST:       108.82 [deg]
  MOON_ILLUM:      12 [%]
  GAL_COORDS:      328.61, 14.65 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      236.11,-22.86 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 11 Sep 23 08:56:55 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     1191188,   Seg_Num: 0
  POINT_RA:        226.806d {+15h 07m 14s} (J2000)
  POINT_DEC:       -41.351d {-41d 21' 04"} (J2000)
  POINT_ROLL:      296.210d
  IMG_START_DATE:  20198 TJD;   254 DOY;   23/09/11
  IMG_START_TIME:  31925.84 SOD {08:52:05.84} UT,   280.3 [sec] since BAT Trigger Time
  FILTER:          7, U
  BKG_MEAN:        1.087
  N_STARS:         190
  X_OFFSET:        416 [pixels]
  Y_OFFSET:        281 [pixels]
  X_MAX:           1855 [pixels]
  Y_MAX:           1720 [pixels]
  DET_THRESH:      9
  PHOTO_THRESH:    4
  SL_URL:          sw01191188000msufc0280.fits
  SUN_POSTN:       169.32d {+11h 17m 16s}   +4.59d {+04d 35' 39"}
  SUN_DIST:         69.86 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
  MOON_POSTN:      131.98d {+08h 47m 56s}  +23.12d {+23d 07' 21"}
  MOON_DIST:       108.82 [deg]
  MOON_ILLUM:      12 [%]
  GAL_COORDS:      328.61, 14.65 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      236.11,-22.86 [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 11 Sep 23 08:58:03 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     1191188,   Seg_Num: 0
  POINT_RA:        226.806d {+15h 07m 14s} (J2000)
  POINT_DEC:       -41.351d {-41d 21' 04"} (J2000)
  ROLL:            296.210d
  IMG_START_DATE:  20198 TJD;   254 DOY;   23/09/11
  IMG_START_TIME:  31925.84 SOD {08:52:05.84} UT,   280.3 [sec] since BAT Trigger Time
  FILTER:          7, U
  EXPOSURE_ID:     716115157
  X_OFFSET:        975 [pixels]
  Y_OFFSET:        840 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       1135
  Y_GRB_POS:       1000
  BINNING_INDEX:   1
  IM_URL:          sw01191188000msuni0312.fits
  SUN_POSTN:       169.32d {+11h 17m 16s}   +4.59d {+04d 35' 38"}
  SUN_DIST:         69.86 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
  MOON_POSTN:      131.99d {+08h 47m 58s}  +23.12d {+23d 07' 11"}
  MOON_DIST:       108.81 [deg]
  MOON_ILLUM:      12 [%]
  GAL_COORDS:      328.61, 14.65 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      236.11,-22.86 [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:     Mon 11 Sep 23 08:58:11 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     1191188,   Seg_Num: 0
  POINT_RA:        226.806d {+15h 07m 14s} (J2000)
  POINT_DEC:       -41.351d {-41d 21' 04"} (J2000)
  ROLL:            296.210d
  IMG_START_DATE:  20198 TJD;   254 DOY;   23/09/11
  IMG_START_TIME:  31925.84 SOD {08:52:05.84} UT,   280.3 [sec] since BAT Trigger Time
  FILTER:          7, U
  EXPOSURE_ID:     716115157
  X_OFFSET:        975 [pixels]
  Y_OFFSET:        840 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       1135
  Y_GRB_POS:       1000
  BINNING_INDEX:   1
  IM_URL:          sw01191188000msuni0312.fits
  SUN_POSTN:       169.32d {+11h 17m 16s}   +4.59d {+04d 35' 38"}
  SUN_DIST:         69.86 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
  MOON_POSTN:      131.99d {+08h 47m 59s}  +23.12d {+23d 07' 10"}
  MOON_DIST:       108.81 [deg]
  MOON_ILLUM:      12 [%]
  GAL_COORDS:      328.61, 14.65 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      236.11,-22.86 [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:     Mon 11 Sep 23 09:04:36 UT
  NOTICE_TYPE:     Swift-XRT Position
  TRIGGER_NUM:     1191188,   Seg_Num: 0
  GRB_RA:          226.7970d {+15h 07m 11.27s} (J2000),
                   227.1855d {+15h 08m 44.53s} (current),
                   225.9798d {+15h 03m 55.15s} (1950)
  GRB_DEC:         -41.3291d {-41d 19' 44.7"} (J2000),
                   -41.4191d {-41d 25' 08.6"} (current),
                   -41.1371d {-41d 08' 13.4"} (1950)
  GRB_ERROR:       4.2 [arcsec radius, statistical plus systematic, 90% containment]
  GRB_INTEN:       1.00e-10 [erg/cm2/sec]
  GRB_SIGNIF:      10.00 [sigma]
  IMG_START_DATE:  20198 TJD;   254 DOY;   23/09/11
  IMG_START_TIME:  31784.00 SOD {08:49:44.00} UT,   138.5 [sec] since BAT Trigger Time
  TAM[0-3]:        100.00 100.00 100.00 100.00
  AMPLIFIER:       1
  WAVEFORM:        31
  SUN_POSTN:       169.32d {+11h 17m 17s}   +4.59d {+04d 35' 32"}
  SUN_DIST:         69.84 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
  MOON_POSTN:      132.05d {+08h 48m 12s}  +23.10d {+23d 06' 16"}
  MOON_DIST:       108.74 [deg]
  MOON_ILLUM:      12 [%]
  GAL_COORDS:      328.61, 14.68 [deg] galactic lon,lat of the burst
  ECL_COORDS:      236.10,-22.84 [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 1.1% < P(seren) < 2.8%.  
  

• GCN Circular #34655
  E. Sonbas (Adiyaman Univ.), R. Brivio (INAF-OAB), S. Dichiara (PSU), M. Ferro (INAF-OAB), J.D. Gropp (PSU), A. Y. Lien (U Tampa), A. Melandri (INAF-OAR), K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sakamoto (AGU), C. Salvaggio (INAF-OAB) and T. Sbarrato (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team:
  At 08:47:25 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 230911C (trigger=1191188). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 226.782, -41.334 which is

     RA(J2000) = 15h 07m 08s
     Dec(J2000) = -41d 20' 01"
  

  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 10 sec. The peak count rate was ~700 counts/sec (15-350 keV), at ~3 sec after the trigger.
  The XRT began observing the field at 08:49:24.4 UT, 119.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 226.79804, -41.32973 which is equivalent to:

     RA(J2000)  = 15h 07m 11.53s
     Dec(J2000) = -41d 19' 47.0"
  

  with an uncertainty of 4.2 arcseconds (radius, 90% containment). This location is 46 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.
  A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (9.36 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 4 (+3.90/-3.22) x 10^21 cm^-2 (90% confidence).
  Processed UVOT data were not available at low latency, with the images affected by the attitude issues reported in GCN Circ. 34633.
  Burst Advocate for this burst is E. Sonbas (edasonbas AT yahoo.com). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 11 Sep 23 09:17:37 UT
  NOTICE_TYPE:     Swift-XRT Position UPDATE
  TRIGGER_NUM:     1191188,   Seg_Num: 0
  GRB_RA:          226.7980d {+15h 07m 11.52s} (J2000),
                   227.1865d {+15h 08m 44.77s} (current),
                   225.9808d {+15h 03m 55.39s} (1950)
  GRB_DEC:         -41.3297d {-41d 19' 46.9"} (J2000),
                   -41.4197d {-41d 25' 10.8"} (current),
                   -41.1377d {-41d 08' 15.5"} (1950)
  GRB_ERROR:       4.2 [arcsec radius, statistical plus systematic, 90% containment]
  GRB_INTEN:       1.00e-10 [erg/cm2/sec]
  GRB_SIGNIF:      10.00 [sigma]
  IMG_START_DATE:  20198 TJD;   254 DOY;   23/09/11
  IMG_START_TIME:  31784.00 SOD {08:49:44.00} UT,   138.5 [sec] since BAT Trigger Time
  TAM[0-3]:        100.00 100.00 100.00 100.00
  AMPLIFIER:       1
  WAVEFORM:        31
  SUN_POSTN:       169.33d {+11h 17m 19s}   +4.59d {+04d 35' 19"}
  SUN_DIST:         69.83 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
  MOON_POSTN:      132.16d {+08h 48m 39s}  +23.07d {+23d 04' 25"}
  MOON_DIST:       108.65 [deg]
  MOON_ILLUM:      12 [%]
  GAL_COORDS:      328.61, 14.67 [deg] galactic lon,lat of the burst
  ECL_COORDS:      236.10,-22.84 [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:        The probability that this is a serendipitous source in the  
  COMMENTS:        SPER window is 1.1% < P(seren) < 2.8%.  
  

• GCN Circular #34658
  P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
  Using 1217 s of XRT Photon Counting mode data and 2 UVOT images for GRB 230911C, 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 = 226.79850, -41.33017 which is equivalent to:

  RA (J2000): 15h 07m 11.64s
  Dec (J2000): -41d 19' 48.6"
  

  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 #34662
  D. O=E2=80=99Neill; A. Kumar; B. P. Gompertz; K. Ulaczyk; G. Ramsay; R. Sta= rling; K. Ackley; M. J. Dyer; J. Lyman; F. Jiminez-Ibarra; D. Steeghs; D. K= . Galloway; V. Dhillon; P. O'Brien; K. Noysena; R. Kotak; R. P. Breton; L. = K. Nuttall; E. Pall'e and D. Pollacco report on behalf of the GOTO collabor= ation:
  We report on observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) in response to GRB 230911C (Sonbas et al., GCN 34655). Three targeted observations were performed by GOTO-South, located at Siding Spring Observatory, between 08:52:42 UT and 09:14:52 UT on 2023-09-11 (5.28, 16.08 and 27.47 minutes after trigger). Each observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. We identify no candidate optical counterparts within the enhanced XRT localisation region (Evans et al., GCN 34658). The 5-sigma limiting magnitudes were 20.7, 20.4 and 21.0 mag, respectively.
  GOTO (https://goto-observatory.org) is a network of telescopes operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astro nomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC). We note that this is the first scientific contribution from GOTO-South.
• GCN Circular #34665
  A. A. Breeveld (UCL-MSSL) and E. Sonbas (Adiyaman Univ.) report on behalf of the Swift/UVOT team:
  The Swift/UVOT began settled observations of the field of GRB 230911C 122 s after the BAT trigger (Sonbas et al., GCN Circ. 34655). No optical afterglow consistent with the XRT position (Evans et al., GCN Circ. 34658) 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           122          272          147         >20.4
  white              122         4926          289         >21.0
  u_FC               280          530          246         >19.7
  u                  280         4572          708         >20.2
  b                  537         4778          235         >19.8
  w1                 661         4368          216         >19.0
  w2                 587          781           39         >18.2
  

  The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.101 in the direction of the burst (Schlegel et al. 1998).
• GCN Circular #34667
  R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration:
  We observed the Swift GRB 230911C (Sonbas et al., GCN 34655) field with the LCOGT 1-meter Sinistro instrument at the South African Astronomical Observatory site, on September 11, from 17:20 to 17:52 UT (corresponding to 8.55 to 9.08 hours from the GRB trigger time) with the SDSS r and i filters.
  We performed a series of 3x300s exposures in each band. We do not detect a source within the Swift-XRT enhanced error region (Evans et al., GCN 34658) in either band.
  The following upper limits are calculated using the USNO-B1.0 catalog as reference:

  r > 21.6
  i > 21.1
  

  These magnitudes are not corrected for galactic extinction.
• GCN Circular #34671
  V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (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. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API),
  L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
  A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
  V. Yurkov, A. Gabovich (Blagoveschensk Educational State University)
  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 GRB 230911C ( E. Sonbas et al., GCN 34655) errorbox 51970 sec after notice time and 52039 sec after trigger time at 2023-09-11 23:14:45 UT, with upper limit up to 17.3 mag. Observations started at twilight. The observations began at zenith distance = 37 deg. The sun altitude is -11.6 deg.
  The galactic latitude b = 14 deg., longitude l = 329 deg.
  Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2268945
  We obtain a following upper limits.

  Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
  _________|_____________________|_____|_______|______|________
  
     52130 |         MASTER-OAFA |   C |   180 | 16.3 |        
     52362 |         MASTER-OAFA |   C |   180 | 16.5 |        
     52795 |         MASTER-OAFA |   C |   180 | 17.3 |        
  

  Filter C is a clear (unfiltred) band.
  The observation and reduction will continue. The message may be cited.
• GCN Circular #34673
  E. Fernandez-Garcia, Y.-D. Hu, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, S.-Y. Wu and A. J. Castro-Tirado (IAA-CSIC, Granada), P. J. Meintjes and H. J. van Heerden (UFS, South Africa), A. Martin-Carrillo and L. Hanlon (UCD, Ireland) and C. J. Perez del Pulgar (UMA, Malaga), on behalf of a larger collaboration, report:
  Following the detection of GRB 230911C by Swift (Sonbas et al. GCNC 34655), the BOOTES-6/DPRT 0.6m robotic telescope at Boyden Observatory in Maselspoort (South Africa) automatically observed the GRB location starting on Sep. 11, 17:26 UT (~ 8.7 h after trigger). No new optical source is detected on the co-added images (3 x 60 s, i-filter & 3 x 60 s, Z-filter) within the enhanced Swift/XRT error region (Evans et al. GCNC 34658) down to 19.2 mag and 18.5 mag respectively, which are consistent with reports from GOTO (O'Neill et al. GCNC 34662), UVOT (Breeveld et al. GCNC 34665), LCOGT (Strausbaugh et al. GCNC 34667) and MASTER (Lipunov et al. GCNC 34671).
  We thank the staff at Boyden Observatory for their excellent support.
• GCN Circular #34675
  T. Sakamoto (AGU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), E. Sonbas (Adiyaman Univ.), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
  Using the data set from T-61 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 230911C (trigger #1191188) (Sonbas et al., GCN Circ. 34655). The BAT ground-calculated position is RA, Dec = 226.796, -41.356 deg which is

     RA(J2000)  =  15h 07m 11.0s
     Dec(J2000) = -41d 21' 21.2"
  

  with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 95%.
  The mask-weighted light curve shows multiple weak overlapping pulses that start at ~T-9 s and end at ~T+10 s. T90 (15-350 keV) is 16.21 +- 2.89 sec (estimated error including systematics).
  The time-averaged spectrum from T-8.63 to T+9.58 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.26 +- 0.28. The fluence in the 15-150 keV band is 3.8 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+2.07 sec in the 15-150 keV band is 0.7 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
  The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1191188/BA/
• GCN Circular #34676
  A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team:
  We have analysed 7.2 ks of XRT data for GRB 230911C, from 103 s to 74.1 ks after the BAT trigger. The data comprise 106 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode.
  The late-time light curve (from T0+4.2 ks) can be modelled with a power-law decay with a decay index of alpha=0.48 (+0.22, -0.18).
  A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.86 (+0.26, -0.21). The best-fitting absorption column is 1.3 (+0.9, -0.3) x 10^21 cm^-2, consistent with the Galactic value of 9.4 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 3.6 x 10^-11 (4.4 x 10^-11) erg cm^-2 count^-1.
  A summary of the PC-mode spectrum is thus:

  Total column:	     1.3 (+0.9, -0.3) x 10^21 cm^-2
  Galactic foreground: 9.4 x 10^20 cm^-2
  Excess significance: <1.6 sigma
  Photon index:	     1.86 (+0.26, -0.21)
  

  The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01191188.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #34843
  S. Chastain (UNM), G. E. Anderson (Curtin), J. K. Leung (UofT/HUJI), S. D. Ryder (Macquarie), A. J. van der Horst (GWU), A. Gulati (USyd), and L. Rhodes (Oxford) on behalf of the ATCA PanRadio GRB collaboration
  The Australia Telescope Compact Array (ATCA) observed long GRB 230911C (E. Sonbas et al., GCN 34655) as part of the ATCA "PanRadio GRB" Large Project C3542 (PI: G. Anderson) on 2023-09-11 UT, 2023-09-13 UT, 2023-09-26 UT, and 2023-10-16 UT.
  We detect a possible radio afterglow at 9 GHz in the second epoch, which continues to brighten in the third, and fourth epoch. At 5.5 GHz this source is not detected in any of the observations. In the fourth epoch at 5.5 GHz, we find 3-sigma upper limit of 105 microJy/beam. In the fourth epoch at 9.0 GHz, the source detected in the previous observations is detected at 150 +/- 35 microJy/beam. The fitted position is:

  RAJ2000  = 15:07:13 +/- 8 arcseconds
  DECJ2000 = -41:19:51 +/- 1 arcsecond
  

  This is approximately 18 arcseconds away from the reported Swift/XRT enhanced position (P. A. Evans et al., GCN 34658).
  Further observations are planned.
  We thank the CSIRO Space and Astronomy staff for supporting these observations. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO.
  View this GCN Circular online at https://gcn.nasa.gov/circulars/34843.