Gamma-ray Burst 230815A

(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:     Tue 15 Aug 23 11:10:40 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1185505,   Seg_Num: 0
GRB_RA:          184.7250d {+12h 18m 53.9s} (J2000),
                 185.0456d {+12h 20m 10.9s} (current),
                 184.0505d {+12h 16m 12.1s} (1950)
GRB_DEC:         -58.0550d {-58d 03' 17.9"} (J2000),
                 -58.1860d {-58d 11' 09.6"} (current),
                 -57.7774d {-57d 46' 38.6"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       75 [cnts]
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  39124.01 SOD {10:52:04.01} UT,   84492.9 [sec] since BAT Trigger Time
CENTROID_X:      325.73,  raw= 326  [pixels]
CENTROID_Y:      321.54,  raw= 322  [pixels]
ROLL:            320.59 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   55.27
GRB_POS_XRT_Z:   43.22
IMAGE_URL:       sw01185505000msxps_rw.img
SUN_POSTN:       144.75d {+09h 38m 59s}  +14.05d {+14d 02' 52"}
SUN_DIST:         79.41 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      136.12d {+09h 04m 28s}  +21.79d {+21d 47' 19"}
MOON_DIST:        89.65 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      298.62,  4.54 [deg] galactic lon,lat of the burst
ECL_COORDS:      215.60,-49.57 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 11:10:42 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1185505,   Seg_Num: 0
GRB_RA:          184.7250d {+12h 18m 53.9s} (J2000),
                 185.0456d {+12h 20m 10.9s} (current),
                 184.0505d {+12h 16m 12.1s} (1950)
GRB_DEC:         -58.0550d {-58d 03' 17.9"} (J2000),
                 -58.1860d {-58d 11' 09.6"} (current),
                 -57.7774d {-57d 46' 38.6"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       75 [cnts]
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  39124.01 SOD {10:52:04.01} UT,   84492.9 [sec] since BAT Trigger Time
CENTROID_X:      325.73,  raw= 326  [pixels]
CENTROID_Y:      321.54,  raw= 322  [pixels]
ROLL:            320.59 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   55.27
GRB_POS_XRT_Z:   43.22
IMAGE_URL:       sw01185505000msxps_rw.img
SUN_POSTN:       144.75d {+09h 38m 59s}  +14.05d {+14d 02' 52"}
SUN_DIST:         79.41 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      136.12d {+09h 04m 28s}  +21.79d {+21d 47' 19"}
MOON_DIST:        89.65 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      298.62,  4.54 [deg] galactic lon,lat of the burst
ECL_COORDS:      215.60,-49.57 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 11:11:01 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1185505,   Seg_Num: 0
GRB_RA:          184.772d {+12h 19m 05s} (J2000),
                 185.093d {+12h 20m 22s} (current),
                 184.097d {+12h 16m 23s} (1950)
GRB_DEC:         -58.065d {-58d 03' 53"} (J2000),
                 -58.196d {-58d 11' 45"} (current),
                 -57.788d {-57d 47' 14"} (1950)
GRB_DATE:        20171 TJD;   227 DOY;   23/08/15
GRB_TIME:        38995.94 SOD {10:49:55.94} UT
TRIGGER_INDEX:   155
GRB_PHI:          -2.70 [deg]
GRB_THETA:        54.43 [deg]
DELTA_TIME:      -56.00 [sec]
TRIGGER_DUR:      [sec],  copy from BAT_POS unavailable
SOLN_STATUS:     0x0
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    0.00 [sigma]
LC_URL:          sw01185505000msb.lc
SUN_POSTN:       144.75d {+09h 38m 59s}  +14.05d {+14d 02' 52"}
SUN_DIST:         79.43 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      136.12d {+09h 04m 29s}  +21.79d {+21d 47' 16"}
MOON_DIST:        89.67 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      298.65,  4.54 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      215.64,-49.56 [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.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 11:11:11 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1185505,   Seg_Num: 0
POINT_RA:        184.732d {+12h 18m 56s} (J2000)
POINT_DEC:       -58.037d {-58d 02' 13"} (J2000)
POINT_ROLL:      320.587d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  39151.09 SOD {10:52:31.09} UT,   84520.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.000
N_STARS:         0
X_OFFSET:        837 [pixels]
Y_OFFSET:        983 [pixels]
X_MAX:           837 [pixels]
Y_MAX:           983 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    12
SL_URL:          sw01185505000msufc862120.fits
SUN_POSTN:       144.75d {+09h 38m 59s}  +14.05d {+14d 02' 52"}
SUN_DIST:         79.40 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      136.12d {+09h 04m 29s}  +21.79d {+21d 47' 14"}
MOON_DIST:        89.63 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      298.63,  4.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.59,-49.55 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 11:10:30 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1185505,   Seg_Num: 0
GRB_RA:          184.7250d {+12h 18m 53.99s} (J2000),
                 185.0456d {+12h 20m 10.95s} (current),
                 184.0505d {+12h 16m 12.12s} (1950)
GRB_DEC:         -58.0550d {-58d 03' 17.9"} (J2000),
                 -58.1860d {-58d 11' 09.6"} (current),
                 -57.7774d {-57d 46' 38.6"} (1950)
GRB_ERROR:       5.1 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       2.07e-09 [erg/cm2/sec]
GRB_SIGNIF:      8.66 [sigma]
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  39124.01 SOD {10:52:04.01} UT,   84492.9 [sec] since BAT Trigger Time
TAM[0-3]:        327.62 237.15 261.68 243.71
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       144.75d {+09h 38m 59s}  +14.05d {+14d 02' 52"}
SUN_DIST:         79.41 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      136.12d {+09h 04m 28s}  +21.79d {+21d 47' 20"}
MOON_DIST:        89.65 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      298.62,  4.54 [deg] galactic lon,lat of the burst
ECL_COORDS:      215.60,-49.57 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:           
COMMENTS:        WARNING: No BAT_Position TDRSS message was received for this trigger_number!  
COMMENTS:

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 11:12:36 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1185505,   Seg_Num: 0
POINT_RA:        184.732d {+12h 18m 56s} (J2000)
POINT_DEC:       -58.037d {-58d 02' 13"} (J2000)
ROLL:            320.587d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  39151.09 SOD {10:52:31.09} UT,   84520.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     713789582
X_OFFSET:        677 [pixels]
Y_OFFSET:        823 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       837
Y_GRB_POS:       983
BINNING_INDEX:   1
IM_URL:          sw01185505000msuni862152.fits
SUN_POSTN:       144.75d {+09h 38m 59s}  +14.05d {+14d 02' 51"}
SUN_DIST:         79.40 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      136.13d {+09h 04m 32s}  +21.78d {+21d 47' 01"}
MOON_DIST:        89.62 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      298.63,  4.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.59,-49.55 [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:     Tue 15 Aug 23 11:12:46 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1185505,   Seg_Num: 0
POINT_RA:        184.732d {+12h 18m 56s} (J2000)
POINT_DEC:       -58.037d {-58d 02' 13"} (J2000)
ROLL:            320.587d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  39151.09 SOD {10:52:31.09} UT,   84520.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     713789582
X_OFFSET:        677 [pixels]
Y_OFFSET:        823 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       837
Y_GRB_POS:       983
BINNING_INDEX:   1
IM_URL:          sw01185505000msuni862152.fits
SUN_POSTN:       144.75d {+09h 38m 59s}  +14.05d {+14d 02' 50"}
SUN_DIST:         79.40 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      136.13d {+09h 04m 32s}  +21.78d {+21d 46' 60"}
MOON_DIST:        89.62 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      298.63,  4.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.59,-49.55 [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:        All 4 attachments are included.

GCN Circular #34434
N. J. Klingler (GSFC/UMBC/CRESSTII), C. Gronwall (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL) and T. M. Parsotan (GSFC/UMBC/CRESSTII) report on behalf of the Neil Gehrels Swift Observatory Team:
At 10:49:55 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 230815A (trigger=1185505). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 184.772, -58.065 which is
```
   RA(J2000) = 12h 19m 05s
   Dec(J2000) = -58d 03' 53"
```
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 ~6000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 10:52:04.0 UT, 128.1 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 184.72347, -58.05386 which is equivalent to:
```
   RA(J2000)  = 12h 18m 53.63s
   Dec(J2000) = -58d 03' 13.9"
```
with an uncertainty of 3.5 arcseconds (radius, 90% containment). 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 (4.94 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 7.8 (+3.75/-3.24) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 2.07e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 155 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. Because of the density of catalogued stars, further analysis is required to report an upper limit for any afterglow in the sub-image. Data from the list of sources generated on-board are not available at this time. No correction has been made for the large, but uncertain, extinction expected.
Burst Advocate for this burst is N. J. Klingler (noelklin AT umbc.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 #34437
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 927 s of XRT Photon Counting mode data and 1 UVOT images for GRB 230815A, 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 = 184.72225, -58.05290 which is equivalent to:
```
RA (J2000): 12h 18m 53.34s
Dec (J2000): -58d 03' 10.4"
```
with an uncertainty of 2.2 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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 18:51:32 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1185505,   Seg_Num: 1
POINT_RA:        184.729d {+12h 18m 55s} (J2000)
POINT_DEC:       -58.043d {-58d 02' 33"} (J2000)
POINT_ROLL:      330.829d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  67571.86 SOD {18:46:11.86} UT,   26540.8 [sec] since BAT Trigger Time
FILTER:          9, B
BKG_MEAN:        3.752
N_STARS:         190
X_OFFSET:        390 [pixels]
Y_OFFSET:        538 [pixels]
X_MAX:           1349 [pixels]
Y_MAX:           1497 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01185505001msufc890540.fits
SUN_POSTN:       145.04d {+09h 40m 11s}  +13.95d {+13d 56' 52"}
SUN_DIST:         79.21 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      139.98d {+09h 19m 55s}  +20.56d {+20d 33' 53"}
MOON_DIST:        87.12 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      298.63,  4.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.59,-49.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO on an old GRB -- this is not a newly detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 18:51:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1185505,   Seg_Num: 1
POINT_RA:        184.729d {+12h 18m 55s} (J2000)
POINT_DEC:       -58.043d {-58d 02' 33"} (J2000)
POINT_ROLL:      330.829d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  67571.86 SOD {18:46:11.86} UT,   26540.8 [sec] since BAT Trigger Time
FILTER:          9, B
BKG_MEAN:        3.752
N_STARS:         190
X_OFFSET:        390 [pixels]
Y_OFFSET:        538 [pixels]
X_MAX:           1349 [pixels]
Y_MAX:           1497 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01185505001msufc890540.fits
SUN_POSTN:       145.05d {+09h 40m 11s}  +13.95d {+13d 56' 52"}
SUN_DIST:         79.21 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      139.98d {+09h 19m 55s}  +20.56d {+20d 33' 50"}
MOON_DIST:        87.12 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      298.63,  4.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.59,-49.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO on an old GRB -- this is not a newly detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 18:53:20 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1185505,   Seg_Num: 1
POINT_RA:        184.729d {+12h 18m 55s} (J2000)
POINT_DEC:       -58.043d {-58d 02' 33"} (J2000)
ROLL:            330.829d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  67571.86 SOD {18:46:11.86} UT,   26540.8 [sec] since BAT Trigger Time
FILTER:          9, B
EXPOSURE_ID:     713818003
X_OFFSET:        709 [pixels]
Y_OFFSET:        857 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       869
Y_GRB_POS:       1017
BINNING_INDEX:   1
IM_URL:          sw01185505001msuni890572.fits
SUN_POSTN:       145.05d {+09h 40m 11s}  +13.95d {+13d 56' 50"}
SUN_DIST:         79.21 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      139.99d {+09h 19m 58s}  +20.56d {+20d 33' 35"}
MOON_DIST:        87.11 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      298.63,  4.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.59,-49.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO on an old GRB -- this is not a newly detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 18:53:27 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1185505,   Seg_Num: 1
POINT_RA:        184.729d {+12h 18m 55s} (J2000)
POINT_DEC:       -58.043d {-58d 02' 33"} (J2000)
ROLL:            330.829d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  67571.86 SOD {18:46:11.86} UT,   26540.8 [sec] since BAT Trigger Time
FILTER:          9, B
EXPOSURE_ID:     713818003
X_OFFSET:        709 [pixels]
Y_OFFSET:        857 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       869
Y_GRB_POS:       1017
BINNING_INDEX:   1
IM_URL:          sw01185505001msuni890572.fits
SUN_POSTN:       145.05d {+09h 40m 11s}  +13.95d {+13d 56' 50"}
SUN_DIST:         79.21 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      139.99d {+09h 19m 59s}  +20.56d {+20d 33' 34"}
MOON_DIST:        87.11 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      298.63,  4.56 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.59,-49.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO on an old GRB -- this is not a newly detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.  
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 #34439
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev (Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 230815A ( N. J. Klingler et al., GCN 34434) errorbox 27081 sec after notice time and 28191 sec after trigger time at 2023-08-15 18:41:55 UT, with upper limit up to 17.4 mag. The observations began at zenith distance = 58 deg. The sun altitude is -32.4 deg.
The galactic latitude b = 4 deg., longitude l = 299 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2254590
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   28282 |         MASTER-SAAO |   C |   180 | 16.8 |        
   29125 |         MASTER-SAAO |   C |   180 | 17.4 |        
   29335 |         MASTER-SAAO |   C |   180 | 17.3 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #34440
B. Mailyan (Florida tech), A. von Kienlin (MPE) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 10:49:54.66 UT on 15 August 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230815A (trigger 713789399/230815451). which was also detected by Swift BAT (N. J. Klingler et al. 2023, GCN 34434). The Fermi GBM on-ground location is consistent with the Swift BAT position.
The angle from the Fermi LAT boresight is 159 degrees.
The GBM light curve consists of a single emission episode with a duration (T90) of about 5.2 s (50-300 keV). The time-averaged spectrum from T0+0.002 to T0+3.264 s is best fit by a Band function with Epeak = 235 +/- 25 keV, alpha = -0.6 +/- 0.1, and beta = -2.22 +/- 0.09.
The event fluence (10-1000 keV) in this time interval is (1.20 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.1 s in the 10-1000 keV band is 27 +/- 2 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular #34441
E. Fernandez-Garcia, Y.-D. Hu, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy and A. J. Castro-Tirado (IAA-CSIC, Granada), P. J. Meintjes and H. J. van Heerden (UFS, SouthAfrica), 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 230815A by Swift (Klingler et al. GCNC 34434) and Fermi (Mayland et al. GCNC 34440), the BOOTES-6/DPRT 0.6m robotic telescope at Boyden Observatory in Maselspoort (South Africa) automatically observed the GRB location starting on Aug. 15, 19:21 UT (~ 8.5 h after trigger). No new optical source is detected on the co-added image (5 x 60 s, clear filter) within the enhanced Swift/XRT error region (Beardmore et al. GCNC 34437) down to 19.5 mag.
We thank the staff at Boyden Observatory for their excellent support.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 22:01:31 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1185505,   Seg_Num: 1
POINT_RA:        184.682d {+12h 18m 44s} (J2000)
POINT_DEC:       -58.024d {-58d 01' 24"} (J2000)
ROLL:            331.042d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  78815.62 SOD {21:53:35.62} UT,   37784.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     713829247
X_OFFSET:        565 [pixels]
Y_OFFSET:        1039 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       725
Y_GRB_POS:       1199
BINNING_INDEX:   1
IM_URL:          sw01185505001msuni901816.fits
SUN_POSTN:       145.17d {+09h 40m 40s}  +13.91d {+13d 54' 23"}
SUN_DIST:         79.10 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      141.55d {+09h 26m 12s}  +20.04d {+20d 02' 08"}
MOON_DIST:        86.05 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      298.60,  4.57 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.54,-49.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO on an old GRB -- this is not a newly detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 22:01:45 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1185505,   Seg_Num: 1
POINT_RA:        184.682d {+12h 18m 44s} (J2000)
POINT_DEC:       -58.024d {-58d 01' 24"} (J2000)
ROLL:            331.042d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  78815.62 SOD {21:53:35.62} UT,   37784.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     713829247
X_OFFSET:        565 [pixels]
Y_OFFSET:        1039 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       725
Y_GRB_POS:       1199
BINNING_INDEX:   1
IM_URL:          sw01185505001msuni901816.fits
SUN_POSTN:       145.17d {+09h 40m 40s}  +13.91d {+13d 54' 23"}
SUN_DIST:         79.10 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      141.55d {+09h 26m 13s}  +20.03d {+20d 02' 06"}
MOON_DIST:        86.05 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      298.60,  4.57 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.54,-49.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO on an old GRB -- this is not a newly detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 22:20:37 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1185505,   Seg_Num: 1
POINT_RA:        184.682d {+12h 18m 44s} (J2000)
POINT_DEC:       -58.023d {-58d 01' 23"} (J2000)
POINT_ROLL:      331.043d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  79639.11 SOD {22:07:19.11} UT,   38608.0 [sec] since BAT Trigger Time
FILTER:          9, B
BKG_MEAN:        3.760
N_STARS:         190
X_OFFSET:        246 [pixels]
Y_OFFSET:        720 [pixels]
X_MAX:           1205 [pixels]
Y_MAX:           1679 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01185505001msufc902608.fits
SUN_POSTN:       145.18d {+09h 40m 43s}  +13.90d {+13d 54' 08"}
SUN_DIST:         79.09 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      141.71d {+09h 26m 50s}  +19.98d {+19d 58' 54"}
MOON_DIST:        85.95 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      298.60,  4.57 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.54,-49.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO on an old GRB -- this is not a newly detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 22:20:50 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1185505,   Seg_Num: 1
POINT_RA:        184.682d {+12h 18m 44s} (J2000)
POINT_DEC:       -58.023d {-58d 01' 23"} (J2000)
POINT_ROLL:      331.043d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  79639.11 SOD {22:07:19.11} UT,   38608.0 [sec] since BAT Trigger Time
FILTER:          9, B
BKG_MEAN:        3.760
N_STARS:         190
X_OFFSET:        246 [pixels]
Y_OFFSET:        720 [pixels]
X_MAX:           1205 [pixels]
Y_MAX:           1679 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01185505001msufc902608.fits
SUN_POSTN:       145.18d {+09h 40m 43s}  +13.90d {+13d 54' 08"}
SUN_DIST:         79.09 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      141.71d {+09h 26m 51s}  +19.98d {+19d 58' 52"}
MOON_DIST:        85.95 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      298.60,  4.57 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.54,-49.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO on an old GRB -- this is not a newly detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 22:22:25 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1185505,   Seg_Num: 1
POINT_RA:        184.682d {+12h 18m 44s} (J2000)
POINT_DEC:       -58.023d {-58d 01' 23"} (J2000)
ROLL:            331.043d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  79639.11 SOD {22:07:19.11} UT,   38608.0 [sec] since BAT Trigger Time
FILTER:          9, B
EXPOSURE_ID:     713830070
X_OFFSET:        565 [pixels]
Y_OFFSET:        1039 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       725
Y_GRB_POS:       1199
BINNING_INDEX:   1
IM_URL:          sw01185505001msuni902640.fits
SUN_POSTN:       145.18d {+09h 40m 44s}  +13.90d {+13d 54' 07"}
SUN_DIST:         79.09 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      141.72d {+09h 26m 54s}  +19.98d {+19d 58' 36"}
MOON_DIST:        85.94 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      298.60,  4.57 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.54,-49.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO on an old GRB -- this is not a newly detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 15 Aug 23 22:22:39 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1185505,   Seg_Num: 1
POINT_RA:        184.682d {+12h 18m 44s} (J2000)
POINT_DEC:       -58.023d {-58d 01' 23"} (J2000)
ROLL:            331.043d
IMG_START_DATE:  20171 TJD;   227 DOY;   23/08/15
IMG_START_TIME:  79639.11 SOD {22:07:19.11} UT,   38608.0 [sec] since BAT Trigger Time
FILTER:          9, B
EXPOSURE_ID:     713830070
X_OFFSET:        565 [pixels]
Y_OFFSET:        1039 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       725
Y_GRB_POS:       1199
BINNING_INDEX:   1
IM_URL:          sw01185505001msuni902640.fits
SUN_POSTN:       145.18d {+09h 40m 44s}  +13.90d {+13d 54' 06"}
SUN_DIST:         79.09 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:      141.73d {+09h 26m 54s}  +19.98d {+19d 58' 33"}
MOON_DIST:        85.94 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      298.60,  4.57 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      215.54,-49.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO on an old GRB -- this is not a newly detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.  
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 #34444
P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), D.N. Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi (INAF-IASFPA) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 6.0 ks of XRT data for GRB 230815A, from 117 s to 45.2 ks after the BAT trigger. The data comprise 574 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+6.1 ks) can be modelled with a power-law decay with a decay index of alpha=1.94 (+0.25, -0.29).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.92 (+0.06, -0.05). The best-fitting absorption column is 7.4 (+0.5, -0.4) x 10^21 cm^-2, in excess of the Galactic value of 4.9 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.94 (+0.18, -0.17) and a best-fitting absorption column of 9.1 (+1.7, -1.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.9 x 10^-11 (8.5 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     9.1 (+1.7, -1.5) x 10^21 cm^-2
Galactic foreground: 4.9 x 10^21 cm^-2
Excess significance: 4.5 sigma
Photon index:	     1.94 (+0.18, -0.17)
```
If the light curve continues to decay with a power-law decay index of 1.94, the count rate at T+24 hours will be 2.5 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x 10^-13 (2.1 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01185505.
This circular is an official product of the Swift-XRT team.
GCN Circular #34446
A. A. Breeveld (UCL-MSSL) and N. J. Klingler (GSFC/UMBC/CRESSTII) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 230815A 155 s after the BAT trigger (Klingler et al., GCN Circ. 34434). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ. 34437) 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 summed exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           155          305        147           >20.1
white              513         1531        242           >20.3
v                  390         1582        136           >18.5
b                  489         1506        114           >19.3
u                  464         6300        293           >19.4
uvw1               439         1632        136           >18.6
uvm2               761         1606         97           >18.3
uvw2               365         1557        136           >18.8
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.73 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #34449
S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), 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-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 230815A (trigger #1185505) (Klingler, et al., GCN Circ. 34434). The BAT ground-calculated position is RA, Dec = 184.760, -58.067 deg which is
```
RA(J2000) = 12h 19m 02.4s
Dec(J2000) = -58d 03' 59.5"
```
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 11%.
The mask-weighted light curve shows a strong peak at trigger time with precursor emission At T-14 sec from trigger. T90 (15-350 keV) is 17.00 +- 7.62 sec (estimated error including systematics).
The time-averaged spectrum from T-14.78 to T+9.22 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.19 +- 0.10. The fluence in the 15-150 keV band is 5.2 +- 0.3 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+0.22 sec in the 15-150 keV band is 13.7 +- 1.1 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/1185505/BA/
GCN Circular #34452
C. D. Kilpatrick (Northwestern), C. R. Bom (CBPF), A. Santos (CBPF/Fermilab= ), S. Panda (LNA), Felipe Navarete (NOIRLab/SOAR) on behalf of a larger col= laboration, report:
Following the detection of GRB230815A (Klingler et al., GCN 34434, Mailyan = et al., GCN 34440), we triggered observations with the Goodman high-through= put imaging spectrograph on the SOAR 4.1m telescope at Cerro Pach=C3=B3n, C= hile. Targeting the site of the reported Swift/XRT counterpart (Beardmore = et al., GCN 34437), we obtained 6x180s exposures in SDSS i-band and 7x180s = in SDSS z-band at start times of 2023-08-15 23:17:36 and 2023-08-15 23:50:4= 8 UTC, respectively. We did not detect a counterpart in either stacked ima= ge, with the limiting magnitude in both frames significantly affected by po= or atmospheric transparency. Performing forced photometry at the site of t= he XRT counterpart (R.A.=3D12:18:53.34, Decl.=3D-58:03:10.4), we derive lim= its on an optical counterpart of:
```
MJD Filter Maglimit
60171.97055 i 20.5
60171.99361 z 17.9
```
Both magnitude limits are on the AB magnitude system calibrated from SkyMap= per DR2 standard stars (Onken et al. 2019) and are not corrected for the si= gnificant Galactic extinction along this sight line (A_i=3D1.25 mag, A_z=3D= 0.93 mag).
Based on observations obtained at the Southern Astrophysical Research (SOAR= ) telescope, which is a joint project of the Minist=C3=A9rio da Ci=C3=AAnci= a, Tecnologia e Inova=C3=A7=C3=B5es do Brasil (MCTI/LNA), the US National S= cience Foundation=E2=80=99s NOIRLab, the University of North Carolina at Ch= apel Hill (UNC), and Michigan State University (MSU).
GCN Circular #34467
B. Schneider (MIT), A. Chrimes (Radboud), D. B. Malesani (Radboud and DAWN/NBI), A. J. Levan (Radboud), N. R. Tanvir (U. Leicester), A. de Ugarte Postigo (OCA/CNRS), report on behalf of the Stargate collaboration:
We observed the field of GRB 230815A (Klingler et al., GCN 34434; Mailyan et al. GCN 34440) with the ESO Very Large Telescope, equipped with the HAWK-I near-infrared camera. Observations consisted of two epochs of 20 min exposure in the H band at 23:19:53 UT on 2023-08-15 (~12.5 hr after trigger) and 23:15:46 UT on 2023-08-16 (~36.4 hr after trigger).
In both epochs, we clearly detected two sources consistent with the XRT error circle (Beardmore et al., GCN 34437). One of the sources has significantly faded (~2 mag) between the two epochs, evolving from AB mag = 20.11 +/- 0.02 to AB mag = 22.01 +/- 0.08. This corresponds to a power-law decay index of 1.65, similar to the X-ray decay rate, suggesting a small host contribution to the NIR flux. The proposed afterglow of the burst is detected at coordinates:
```
RA (J2000) = 12:18:53.24
DEC (J2000) = -58:03:09.45
```
with an uncertainty of 0.3".
We acknowledge the excellent support provided by the Paranal staff, in particular Joe Anderson.
GCN Circular #34518
J. K. Leung (USyd), G. E. Anderson (Curtin), S. D. Ryder (Macquarie), A. J. van der Horst (GWU), A. Gulati (USyd), L. Rhodes (Oxford), S. Chastain (UNM) on behalf of the PanRadio GRB collaboration
The Australia Telescope Compact Array (ATCA) observed long GRB 230815A (Klingler et al., GCN 34434; Mailyan et al., GCN 34440) as part of the ATCA "PanRadio GRB" follow-up Large Project C3542 (PI. Anderson) on 2023-08-17 UT and 2023-08-18 UT.
No radio sources were detected at the GRB location in the first observation conducted from 2023-08-17 02:00 UT for 10 hrs at 5.5, 9.0, 16.7 and 21.2 GHz. The 3-sigma upper limits were 75, 69, 324, 741 microJy/beam, respectively. Note the higher than usual rms was due to bad weather during the observation.
The second observation was conducted from 2023-08-18 22:00 UT for 6 hrs at 5.5, 9.0 and 44 GHz. In our preliminary analysis, we detect a radio counterpart with a flux density of 70+/-10 microJy at 9 GHz. The fitted position is:
```
RAJ2000  = 12:18:53.2
DECJ2000 = -58:03:09.0
```
with an uncertainty of ~0.3".
This is in broad agreement with previously reported Swift/XRT (Beardmore et al., GCN 34437) and VLT/HAWK-I (Schneider et al., GCN 34467) afterglow positions. There was also a marginal ~3 sigma detection at 5.5 GHz (rms=14 microJy/beam) and a non-detection at 44 GHz with a 3-sigma upper limit of 111 microJy/beam.
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.

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Jochen Greiner, last update: 22-Aug-2023 [Disclaimer]