Gamma-ray Burst 231230A

(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 30 Dec 23 01:29:49 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1205319,   Seg_Num: 0
GRB_RA:          245.197d {+16h 20m 47s} (J2000),
                 245.310d {+16h 21m 14s} (current),
                 244.964d {+16h 19m 51s} (1950)
GRB_DEC:         +58.120d {+58d 07' 11"} (J2000),
                 +58.064d {+58d 03' 50"} (current),
                 +58.237d {+58d 14' 13"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       7675 [cnts]    Image_Peak=235 [image_cnts]
TRIGGER_DUR:     3.072 [sec] 
TRIGGER_INDEX:   487     E_range: 50-350 keV
BKG_INTEN:       56709 [cnts]
BKG_TIME:        5303.36 SOD {01:28:23.36} UT
BKG_DUR:         32 [sec]
GRB_DATE:        20308 TJD;   364 DOY;   23/12/30
GRB_TIME:        5348.73 SOD {01:29:08.73} UT
GRB_PHI:         -152.59 [deg]
GRB_THETA:        45.76 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     25.98 [sigma]
IMAGE_SIGNIF:    9.14 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +3  +0  +0  +0  -6  +0 
SUN_POSTN:       278.78d {+18h 35m 08s}  -23.19d {-23d 11' 22"}
SUN_DIST:         85.90 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.67d {+09h 06m 40s}  +21.40d {+21d 24' 01"}
MOON_DIST:        81.25 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.44, 42.41 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      204.74, 75.88 [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 = 109.72,-20.36 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(2.0<100sec) coincident with the FERMI_GBM event (trignum=725592555).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 30 Dec 23 01:29:39 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      48
TRIGGER_NUM:     725592555
GRB_RA:          260.900d {+17h 23m 36s} (J2000),
                 260.914d {+17h 23m 39s} (current),
                 260.872d {+17h 23m 29s} (1950)
GRB_DEC:         +65.817d {+65d 49' 00"} (J2000),
                 +65.796d {+65d 47' 44"} (current),
                 +65.861d {+65d 51' 39"} (1950)
GRB_ERROR:       9.88 [deg radius, statistical plus systematic]
GRB_INTEN:       258 [cnts/sec]
DATA_SIGNIF:     6.10 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        20308 TJD;   364 DOY;   23/12/30
GRB_TIME:        5350.05 SOD {01:29:10.05} UT
GRB_PHI:         165.00 [deg]
GRB_THETA:       160.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.47
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      89%  GRB
2nd_MOST_LIKELY:   5%  Cyg X-1
DETECTORS:       1,0,0, 0,0,0, 0,0,0, 0,1,1, 0,0,
SUN_POSTN:       278.78d {+18h 35m 08s}  -23.19d {-23d 11' 22"}
SUN_DIST:         90.03 [deg]   Sun_angle= 1.2 [hr] (West of Sun)
MOON_POSTN:      136.66d {+09h 06m 39s}  +21.40d {+21d 24' 03"}
MOON_DIST:        83.22 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       95.82, 33.53 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      187.26, 86.26 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231230062/quicklook/glg_lc_medres34_bn231230062.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 3.82,-3.88 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 30 Dec 23 01:29:57 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     725592555
GRB_RA:          232.460d {+15h 29m 50s} (J2000),
                 232.630d {+15h 30m 31s} (current),
                 232.105d {+15h 28m 25s} (1950)
GRB_DEC:         +52.290d {+52d 17' 24"} (J2000),
                 +52.209d {+52d 12' 32"} (current),
                 +52.460d {+52d 27' 37"} (1950)
GRB_ERROR:       4.43 [deg radius, statistical only]
DATA_SIGNIF:     7.50 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        20308 TJD;   364 DOY;   23/12/30
GRB_TIME:        5350.05 SOD {01:29:10.05} UT
GRB_PHI:         119.00 [deg]
GRB_THETA:       152.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       278.78d {+18h 35m 08s}  -23.19d {-23d 11' 22"}
SUN_DIST:         85.47 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:      136.67d {+09h 06m 40s}  +21.40d {+21d 24' 00"}
MOON_DIST:        76.76 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       84.38, 51.28 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      199.27, 66.75 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231230062/quicklook/glg_lc_medres34_bn231230062.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_725592555.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=1205319).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 30 Dec 23 01:38:38 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     725592555
GRB_RA:          240.700d {+16h 02m 48s} (J2000),
                 240.850d {+16h 03m 24s} (current),
                 240.389d {+16h 01m 33s} (1950)
GRB_DEC:         +53.560d {+53d 33' 36"} (J2000),
                 +53.495d {+53d 29' 41"} (current),
                 +53.697d {+53d 41' 49"} (1950)
GRB_ERROR:       5.20 [deg radius, statistical only]
GRB_DATE:        20308 TJD;   364 DOY;   23/12/30
GRB_TIME:        5350.05 SOD {01:29:10.05} UT
GRB_PHI:         121.00 [deg]
GRB_THETA:       157.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       278.79d {+18h 35m 09s}  -23.19d {-23d 11' 21"}
SUN_DIST:         83.41 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:      136.74d {+09h 06m 58s}  +21.38d {+21d 22' 36"}
MOON_DIST:        80.91 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       83.43, 46.19 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      208.11, 70.76 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231230062/quicklook/glg_lc_medres34_bn231230062.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231230062/quicklook/glg_locplot_all_bn231230062.png
COMMENTS:        Fermi-GBM Final Position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
COMMENTS:        This notice was generated completely by automated pipeline processing.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=1205319).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 30 Dec 23 01:33:11 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1205319,   Seg_Num: 0
GRB_RA:          245.197d {+16h 20m 47s} (J2000),
                 245.310d {+16h 21m 14s} (current),
                 244.964d {+16h 19m 51s} (1950)
GRB_DEC:         +58.120d {+58d 07' 11"} (J2000),
                 +58.064d {+58d 03' 50"} (current),
                 +58.237d {+58d 14' 13"} (1950)
GRB_DATE:        20308 TJD;   364 DOY;   23/12/30
GRB_TIME:        5348.73 SOD {01:29:08.73} UT
TRIGGER_INDEX:   487
GRB_PHI:         -152.59 [deg]
GRB_THETA:        45.76 [deg]
DELTA_TIME:      -57.00 [sec]
TRIGGER_DUR:     3.072 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     25.98 [sigma]
IMAGE_SIGNIF:    9.14 [sigma]
LC_URL:          sw01205319000msb.lc
SUN_POSTN:       278.78d {+18h 35m 08s}  -23.19d {-23d 11' 22"}
SUN_DIST:         85.91 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.69d {+09h 06m 47s}  +21.39d {+21d 23' 29"}
MOON_DIST:        81.24 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.44, 42.41 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      204.74, 75.88 [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 = 109.72,-20.36 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 30 Dec 23 01:35:47 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1205319,   Seg_Num: 0
POINT_RA:        245.119d {+16h 20m 29s} (J2000)
POINT_DEC:       +58.132d {+58d 07' 56"} (J2000)
POINT_ROLL:      149.307d
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  5494.08 SOD {01:31:34.08} UT,   145.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.068
N_STARS:         36
X_OFFSET:        567 [pixels]
Y_OFFSET:        252 [pixels]
X_MAX:           1526 [pixels]
Y_MAX:           1211 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    12
SL_URL:          sw01205319000msufc0145.fits
SUN_POSTN:       278.79d {+18h 35m 09s}  -23.19d {-23d 11' 21"}
SUN_DIST:         85.94 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.72d {+09h 06m 52s}  +21.38d {+21d 23' 03"}
MOON_DIST:        81.19 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.48, 42.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      204.58, 75.86 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 30 Dec 23 01:36:03 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1205319,   Seg_Num: 0
POINT_RA:        245.119d {+16h 20m 29s} (J2000)
POINT_DEC:       +58.132d {+58d 07' 56"} (J2000)
POINT_ROLL:      149.307d
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  5494.08 SOD {01:31:34.08} UT,   145.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.068
N_STARS:         36
X_OFFSET:        567 [pixels]
Y_OFFSET:        252 [pixels]
X_MAX:           1526 [pixels]
Y_MAX:           1211 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    12
SL_URL:          sw01205319000msufc0145.fits
SUN_POSTN:       278.79d {+18h 35m 09s}  -23.19d {-23d 11' 21"}
SUN_DIST:         85.94 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.72d {+09h 06m 53s}  +21.38d {+21d 23' 01"}
MOON_DIST:        81.19 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.48, 42.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      204.58, 75.86 [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 30 Dec 23 01:36:45 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1205319,   Seg_Num: 0
GRB_RA:          245.2166d {+16h 20m 51.98s} (J2000),
                 245.3292d {+16h 21m 18.99s} (current),
                 244.9831d {+16h 19m 55.93s} (1950)
GRB_DEC:         +58.1225d {+58d 07' 21.0"} (J2000),
                 +58.0666d {+58d 03' 59.8"} (current),
                 +58.2397d {+58d 14' 22.9"} (1950)
GRB_ERROR:       3.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  5565.00 SOD {01:32:45.00} UT,   216.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       278.79d {+18h 35m 09s}  -23.19d {-23d 11' 21"}
SUN_DIST:         85.90 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.73d {+09h 06m 54s}  +21.38d {+21d 22' 54"}
MOON_DIST:        81.24 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.44, 42.40 [deg] galactic lon,lat of the burst
ECL_COORDS:      204.76, 75.89 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 30 Dec 23 01:38:03 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1205319,   Seg_Num: 0
POINT_RA:        245.119d {+16h 20m 29s} (J2000)
POINT_DEC:       +58.132d {+58d 07' 56"} (J2000)
ROLL:            149.307d
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  5494.08 SOD {01:31:34.08} UT,   145.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     725592726
X_OFFSET:        886 [pixels]
Y_OFFSET:        571 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1046
Y_GRB_POS:       731
BINNING_INDEX:   1
IM_URL:          sw01205319000msuni0178.fits
SUN_POSTN:       278.79d {+18h 35m 09s}  -23.19d {-23d 11' 21"}
SUN_DIST:         85.94 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.74d {+09h 06m 57s}  +21.38d {+21d 22' 41"}
MOON_DIST:        81.19 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.48, 42.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      204.58, 75.86 [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:     Sat 30 Dec 23 01:38:17 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1205319,   Seg_Num: 0
POINT_RA:        245.119d {+16h 20m 29s} (J2000)
POINT_DEC:       +58.132d {+58d 07' 56"} (J2000)
ROLL:            149.307d
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  5494.08 SOD {01:31:34.08} UT,   145.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     725592726
X_OFFSET:        886 [pixels]
Y_OFFSET:        571 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1046
Y_GRB_POS:       731
BINNING_INDEX:   1
IM_URL:          sw01205319000msuni0178.fits
SUN_POSTN:       278.79d {+18h 35m 09s}  -23.19d {-23d 11' 21"}
SUN_DIST:         85.94 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.74d {+09h 06m 57s}  +21.38d {+21d 22' 39"}
MOON_DIST:        81.19 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.48, 42.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      204.58, 75.86 [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 Circular #35434
The Fermi GBM team reports the detection of a likely LONG GRB
At 01:29:10 UT on 30 Dec 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231230A (trigger 725592555.052228 / 231230062).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 240.7, Dec = 53.6 (J2000 degrees, equivalent to J2000 16h 02m, 53d 36'), with a statistical uncertainty of 5.2 degrees.
The angle from the Fermi LAT boresight is 157.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231230062/quicklook/glg_skymap_all_bn231230062.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231230062/quicklook/glg_healpix_all_bn231230062.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231230062/quicklook/glg_lc_medres34_bn231230062.gif
GCN Circular #35435
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-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB231230.06 (trigger No 1205319,16h 20m 47.28s , +58d 07m 12.0s, R=0.05) errorbox 12 sec after notice time and 68 sec after trigger time at 2023-12-30 01:30:17 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 54 deg. The sun altitude is -39.8 deg.
MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB231230.06 errorbox 16 sec after notice time and 72 sec after trigger time at 2023-12-30 01:30:20 UT, with upper limit up to 17.2 mag. The observations began at zenith distance = 51 deg. The sun altitude is -34.0 deg.
The galactic latitude b = 42 deg., longitude l = 88 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2346177
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

      73 |      MASTER-Tavrida |   C |    10 | 16.1 |        
      77 |   MASTER-Kislovodsk |  P- |    10 | 16.0 |        
      97 |   MASTER-Kislovodsk |  P- |    50 | 16.7 |  Coadd 
      77 |   MASTER-Kislovodsk |  P| |    10 | 15.8 |        
      96 |      MASTER-Tavrida |   C |    20 | 17.7 |        
     100 |   MASTER-Kislovodsk |  P- |    20 | 16.3 |        
     100 |   MASTER-Kislovodsk |  P| |    20 | 16.0 |        
     122 |      MASTER-Tavrida |   C |    20 | 17.7 |        
     128 |   MASTER-Kislovodsk |  P- |    20 | 16.2 |        
     128 |   MASTER-Kislovodsk |  P| |    20 | 16.0 |        
     155 |      MASTER-Tavrida |   C |    30 | 17.7 |        
     161 |   MASTER-Kislovodsk |  P- |    30 | 16.6 |        
     206 |   MASTER-Kislovodsk |  P- |   120 | 17.3 |  Coadd 
     161 |   MASTER-Kislovodsk |  P| |    30 | 16.5 |        
     196 |      MASTER-Tavrida |   C |    40 | 17.9 |        
     206 |   MASTER-Kislovodsk |  P- |    40 | 16.5 |        
     206 |   MASTER-Kislovodsk |  P| |    40 | 16.6 |        
     242 |      MASTER-Tavrida |   C |    40 | 17.9 |        
     259 |   MASTER-Kislovodsk |  P- |    50 | 16.6 |        
     259 |   MASTER-Kislovodsk |  P| |    50 | 16.5 |        
     294 |      MASTER-Tavrida |   C |    50 | 17.8 |        
     322 |   MASTER-Kislovodsk |  P- |    60 | 16.8 |        
     322 |   MASTER-Kislovodsk |  P| |    60 | 16.6 |        
     361 |      MASTER-Tavrida |   C |    70 | 18.3 |        
     444 |      MASTER-Tavrida |   C |    80 | 18.5 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 30 Dec 23 01:44:17 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1205319,   Seg_Num: 0
POINT_RA:        245.118d {+16h 20m 28s} (J2000)
POINT_DEC:       +58.131d {+58d 07' 51"} (J2000)
POINT_ROLL:      149.306d
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  5652.76 SOD {01:34:12.76} UT,   304.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        2.593
N_STARS:         46
X_OFFSET:        327 [pixels]
Y_OFFSET:        12 [pixels]
X_MAX:           1766 [pixels]
Y_MAX:           1451 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw01205319000msufc0304.fits
SUN_POSTN:       278.79d {+18h 35m 10s}  -23.19d {-23d 11' 20"}
SUN_DIST:         85.94 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.79d {+09h 07m 09s}  +21.36d {+21d 21' 40"}
MOON_DIST:        81.18 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.47, 42.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      204.58, 75.86 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN Circular #35436
M. J. Moss (GSFC), C. Gronwall (PSU), J.D. Gropp (PSU), H. A. Krimm (NSF), A. Y. Lien (U Tampa), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 01:29:08 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 231230A (trigger=1205319). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 245.197, +58.120 which is
```
   RA(J2000) = 16h 20m 47s
   Dec(J2000) = +58d 07' 11"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 30 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 01:32:45.0 UT, 216.3 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 245.21706, 58.12324 which is equivalent to:
```
   RA(J2000)  = 16h 20m 52.09s
   Dec(J2000) = +58d 07' 23.7"
```
with an uncertainty of 3.5 arcseconds (radius, 90% containment). This location is 39 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 (1.31 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.3 (+4.82/-3.83) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 145 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. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.015.
Burst Advocate for this burst is M. J. Moss (mikejmoss3 AT gmail.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:     Sat 30 Dec 23 01:44:24 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1205319,   Seg_Num: 0
POINT_RA:        245.118d {+16h 20m 28s} (J2000)
POINT_DEC:       +58.131d {+58d 07' 51"} (J2000)
POINT_ROLL:      149.306d
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  5652.76 SOD {01:34:12.76} UT,   304.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        2.593
N_STARS:         46
X_OFFSET:        327 [pixels]
Y_OFFSET:        12 [pixels]
X_MAX:           1766 [pixels]
Y_MAX:           1451 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw01205319000msufc0304.fits
SUN_POSTN:       278.79d {+18h 35m 10s}  -23.19d {-23d 11' 20"}
SUN_DIST:         85.94 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.79d {+09h 07m 10s}  +21.36d {+21d 21' 39"}
MOON_DIST:        81.18 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.47, 42.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      204.58, 75.86 [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:     Sat 30 Dec 23 01:44:44 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1205319,   Seg_Num: 0
GRB_RA:          245.2141d {+16h 20m 51.38s} (J2000),
                 245.3266d {+16h 21m 18.39s} (current),
                 244.9806d {+16h 19m 55.34s} (1950)
GRB_DEC:         +58.1252d {+58d 07' 30.7"} (J2000),
                 +58.0693d {+58d 04' 09.5"} (current),
                 +58.2424d {+58d 14' 32.7"} (1950)
GRB_ERROR:       1.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  5565.00 SOD {01:32:45.00} UT,   216.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       278.79d {+18h 35m 11s}  -23.19d {-23d 11' 20"}
SUN_DIST:         85.91 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.79d {+09h 07m 10s}  +21.36d {+21d 21' 36"}
MOON_DIST:        81.23 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.45, 42.40 [deg] galactic lon,lat of the burst
ECL_COORDS:      204.75, 75.89 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 30 Dec 23 01:45:41 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1205319,   Seg_Num: 0
POINT_RA:        245.118d {+16h 20m 28s} (J2000)
POINT_DEC:       +58.131d {+58d 07' 51"} (J2000)
ROLL:            149.306d
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  5652.76 SOD {01:34:12.76} UT,   304.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     725592885
X_OFFSET:        886 [pixels]
Y_OFFSET:        571 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1046
Y_GRB_POS:       731
BINNING_INDEX:   1
IM_URL:          sw01205319000msuni0337.fits
SUN_POSTN:       278.79d {+18h 35m 11s}  -23.19d {-23d 11' 20"}
SUN_DIST:         85.94 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.80d {+09h 07m 12s}  +21.36d {+21d 21' 27"}
MOON_DIST:        81.18 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.47, 42.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      204.58, 75.86 [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:     Sat 30 Dec 23 01:45:51 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1205319,   Seg_Num: 0
POINT_RA:        245.118d {+16h 20m 28s} (J2000)
POINT_DEC:       +58.131d {+58d 07' 51"} (J2000)
ROLL:            149.306d
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  5652.76 SOD {01:34:12.76} UT,   304.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     725592885
X_OFFSET:        886 [pixels]
Y_OFFSET:        571 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1046
Y_GRB_POS:       731
BINNING_INDEX:   1
IM_URL:          sw01205319000msuni0337.fits
SUN_POSTN:       278.79d {+18h 35m 11s}  -23.19d {-23d 11' 20"}
SUN_DIST:         85.94 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.80d {+09h 07m 13s}  +21.36d {+21d 21' 25"}
MOON_DIST:        81.18 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.47, 42.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      204.58, 75.86 [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:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 30 Dec 23 01:51:17 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1205319,   Seg_Num: 0
POINT_RA:        245.117d {+16h 20m 28s} (J2000)
POINT_DEC:       +58.131d {+58d 07' 52"} (J2000)
POINT_ROLL:      149.306d
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  6209.83 SOD {01:43:29.83} UT,   861.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.736
N_STARS:         73
X_OFFSET:        327 [pixels]
Y_OFFSET:        12 [pixels]
X_MAX:           1766 [pixels]
Y_MAX:           1451 [pixels]
DET_THRESH:      22
PHOTO_THRESH:    13
SL_URL:          sw01205319000msufc0861.fits
SUN_POSTN:       278.80d {+18h 35m 12s}  -23.19d {-23d 11' 19"}
SUN_DIST:         85.94 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.85d {+09h 07m 24s}  +21.34d {+21d 20' 32"}
MOON_DIST:        81.17 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.48, 42.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      204.58, 75.86 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 30 Dec 23 01:51:26 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1205319,   Seg_Num: 0
POINT_RA:        245.117d {+16h 20m 28s} (J2000)
POINT_DEC:       +58.131d {+58d 07' 52"} (J2000)
POINT_ROLL:      149.306d
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  6209.83 SOD {01:43:29.83} UT,   861.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.736
N_STARS:         73
X_OFFSET:        327 [pixels]
Y_OFFSET:        12 [pixels]
X_MAX:           1766 [pixels]
Y_MAX:           1451 [pixels]
DET_THRESH:      22
PHOTO_THRESH:    13
SL_URL:          sw01205319000msufc0861.fits
SUN_POSTN:       278.80d {+18h 35m 12s}  -23.19d {-23d 11' 19"}
SUN_DIST:         85.94 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.85d {+09h 07m 24s}  +21.34d {+21d 20' 31"}
MOON_DIST:        81.17 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.48, 42.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      204.58, 75.86 [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 30 Dec 23 01:52:47 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1205319,   Seg_Num: 0
POINT_RA:        245.117d {+16h 20m 28s} (J2000)
POINT_DEC:       +58.131d {+58d 07' 52"} (J2000)
ROLL:            149.306d
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  6209.83 SOD {01:43:29.83} UT,   861.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     725593442
X_OFFSET:        886 [pixels]
Y_OFFSET:        571 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1046
Y_GRB_POS:       731
BINNING_INDEX:   1
IM_URL:          sw01205319000msuni0894.fits
SUN_POSTN:       278.80d {+18h 35m 12s}  -23.19d {-23d 11' 19"}
SUN_DIST:         85.94 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.86d {+09h 07m 27s}  +21.34d {+21d 20' 17"}
MOON_DIST:        81.16 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.48, 42.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      204.58, 75.86 [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:     Sat 30 Dec 23 01:52:53 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1205319,   Seg_Num: 0
POINT_RA:        245.117d {+16h 20m 28s} (J2000)
POINT_DEC:       +58.131d {+58d 07' 52"} (J2000)
ROLL:            149.306d
IMG_START_DATE:  20308 TJD;   364 DOY;   23/12/30
IMG_START_TIME:  6209.83 SOD {01:43:29.83} UT,   861.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     725593442
X_OFFSET:        886 [pixels]
Y_OFFSET:        571 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1046
Y_GRB_POS:       731
BINNING_INDEX:   1
IM_URL:          sw01205319000msuni0894.fits
SUN_POSTN:       278.80d {+18h 35m 12s}  -23.19d {-23d 11' 19"}
SUN_DIST:         85.94 [deg]   Sun_angle= 2.2 [hr] (West of Sun)
MOON_POSTN:      136.86d {+09h 07m 27s}  +21.34d {+21d 20' 16"}
MOON_DIST:        81.16 [deg]
MOON_ILLUM:      91 [%]
GAL_COORDS:       88.48, 42.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      204.58, 75.86 [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 Circular #35437
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 231230A, we find an enhanced XRT position of the afterglow: RA, Dec: 245.21382, 58.12618 which is equivalent to:
```
   RA (J2000)  = 16 20 51.32
   Dec (J2000) = +58 07 34.2
```
with an uncertainty of 1.9 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/1205319.
Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular #35439
Z. Zhu, D. Xu (NAOC) report on behalf a larger collaboration:
We observed the position of GRB 231230A (Moss et al., GCN 35436) using the Nordic Optical Telescope equipped with the ALFOSC images. Observations were carried out with the SDSS r and z filters, with an exposure time of 3x300 s and 5x200 s respectively.
No new objects were dectected in our stacked image within or around the enhanced XRT position (Evans et al., GCN 35437), down to magnitudes r > 23.4 @ T-mid = 4.02 hr and z > 22.7 @ T-mid = 4.32 hr, calibrated with the nearby Pan-STARRS field.
GCN Circular #35440
N. P. M. Kuin (UCL-MSSL) and M. J. Moss (GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 231230A 1511 s after the BAT trigger (Moss et al., GCN Circ. 35436). No optical afterglow consistent with the XRT position 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 initial exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white             1511         1705           39         >18.9
b                 1661         1681           19         >18.5
w1                1612         1632           19         >18.0
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.014 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #35441
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 2051 s of XRT Photon Counting mode data and 3 UVOT images for GRB 231230A, 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 = 245.21436, +58.12396 which is equivalent to:
```
RA (J2000): 16h 20m 51.45s
Dec (J2000): +58d 07' 26.2"
```
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 #35442
A. Kumar; B. P. Gompertz; G. Ramsay; R. Starling; K. Ulaczyk; K. Ackley; M. J. Dyer; J. Lyman; F. Jimenez-Ibarra; D. O'Neill; 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 collaboration:
The Gravitational-wave Optical Transient Observer (GOTO, Steeghs et al. 2022) performed a targeted observation in response to Fermi and Swift detected GRB 231230A (Fermi GBM Team, GCN 35434; Moss et al., GCN 35436) at 05:32:28; 05:47:36 and 06:40:25 UT on 2023-12-30 (at respectively ~4.1, 4.3 and 5.2 hours after the trigger). Each set of observations consisted of 4x90s exposures in the GOTO L-band (400-700 nm).
Images were processed immediately after acquisition using the GOTO pipeline. No optical counterpart is detected within the enhanced Swift-XRT position (Evans et al., GCN 35437; Osborne et al., GCN 35441) in any of the three sets of observations up to the 5-sigma limits of L > 18.7, 19.0 and 19.5 magnitudes (AB), respectively. The upper limits are consistent with those reported by Zhu et al., GCN 35439 and Kuin et al., GCN 35440.
Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.
GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and 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 Astronomical 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).
GCN Circular #35443
A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), J. D. Gropp (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 9.1 ks of XRT data for GRB 231230A, from 127 s to 41.2 ks after the BAT trigger. The data comprise 68 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode.
The light curve can be modelled with an initial power-law decay with an index of alpha=0.835 (+0.027, -0.028), followed by a break at T+17.4 ks to an alpha of 2.0 (+/-0.4).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.93 (+/-0.13). The best-fitting absorption column is 4.0 (+0.7, -0.6) x 10^21 cm^-2, in excess of the Galactic value of 1.3 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 4.1 x 10^-11 (6.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     4.0 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 1.3 x 10^20 cm^-2
Excess significance: 9.9 sigma
Photon index:	     1.93 (+/-0.13)
```
If the light curve continues to decay with a power-law decay index of 2.0, the count rate at T+24 hours will be 5.1 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.1 x 10^-13 (3.1 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/01205319.
This circular is an official product of the Swift-XRT team.
GCN Circular #35444
C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 01:29:10.05 UT on 30 December 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB231230A (trigger 725592555/231230062). which was also detected by Swift-BAT (Moss et al. 2023, GCN 35436). The Fermi GBM Real-time Localization (GCN 35434) is consistent with the Swift-BAT position.
The angle from the Fermi LAT boresight is 157 degrees.
The GBM light curve consists of multiple spikes with a duration (T90) of about 17 s (50-300 keV). The time-averaged spectrum from T0-2.6 to T0+17.9 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.2 +/- 0.2 and the cutoff energy, parameterized as Epeak, is 220 +/- 40 keV.
The event fluence (10-1000 keV) in this time interval is (6.1 +/- 0.5)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+9.3 s in the 10-1000 keV band is 5 +/- 1 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 #35474
S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (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 231230A (trigger #1205319) (Moss, et al., GCN Circ. 35436). The BAT ground-calculated position is RA, Dec = 245.223, 58.132 deg which is
```
   RA(J2000)  =  16h 20m 53.5s
   Dec(J2000) = +58d 07' 54.2"
```
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 35%.
The mask-weighted light curve shows a complex structure extending from around T+0 to T+20. T90 (15-350 keV) is 15.2 +- 0.9 sec (estimated error including systematics).
The time-averaged spectrum from T+0.26 to T+17.26 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.28 +- 0.10. The fluence in the 15-150 keV band is 2.1 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+7.64 sec in the 15-150 keV band is 2.2 +- 0.4 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/1205319/BA/
GCN Circular #35559
Chenyu Wang, Zirui Yang and Longhao Li report on behalf of the GRID Collaboration:
GRID-04 reports the detection of the long-duration GRB 231230A, which was a= lso detected by Swift/BAT and=C2=A0Fermi/GBM(GCN Circular 35434=C2=A0and 35= 436).
The event was triggered with GRID on 2023-12-30 at=C2=A001:29:08=E2=80=8B= =C2=A0UTC.=C2=A0The=C2=A0GRID=C2=A0light=C2=A0curve=C2=A0consists=C2=A0of= =C2=A0multiple=C2=A0spikes=C2=A0with=C2=A0a=C2=A0duration=C2=A0(T90)=C2=A0o= f=C2=A0about=C2=A017=C2=A0+/-=C2=A01=C2=A0s=C2=A0(30-2000=C2=A0keV). The=C2=A0time-averaged=C2=A0spectrum=C2=A0from=C2=A0T0+0.4=C2=A0to=C2=A0T0+= 17.3=C2=A0s=C2=A0is=C2=A0best=C2=A0fit=C2=A0by=C2=A0a=C2=A0power=C2=A0law= =C2=A0function=C2=A0with=C2=A0an=C2=A0exponential=C2=A0high-energy=C2=A0cut= off.=C2=A0The=C2=A0power=C2=A0law=C2=A0index=C2=A0is=C2=A0-1.03=C2=A0+/-=C2= =A00.2=C2=A0and=C2=A0the=C2=A0cutoff=C2=A0energy,=C2=A0parameterized=C2=A0a= s=C2=A0Epeak,=C2=A0is=C2=A0132=C2=A0+/-=C2=A045=C2=A0keV.=C2=A0The=C2=A0eve= nt=C2=A0fluence=C2=A0(10-1000=C2=A0keV)=C2=A0in=C2=A0this=C2=A0time=C2=A0in= terval=C2=A0is=C2=A0about=C2=A06.0E-06=C2=A0erg/cm^2.=E2=80=8B
The GRID light curve of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB231230A/GRID_231230A_ltcv.pdf The GRID spectrum of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB231230A/GRID_231230A_spec_cpl.pdf
GRID is a student-led project to monitor the transient gamma-ray sky with m= ultiple detectors onboard different nanosatellites in the era of multi-mess= enger astronomy. For more information about GRID, please refer to the follo= wing references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.=E2=80=8B=E2=80=8B

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Jochen Greiner, last update: 18-Jan-2024 [Disclaimer]