Gamma-ray Burst 241006A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Oct 24 21:53:14 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1258721,   Seg_Num: 0
GRB_RA:          304.794d {+20h 19m 11s} (J2000),
                 305.209d {+20h 20m 50s} (current),
                 303.955d {+20h 15m 49s} (1950)
GRB_DEC:         -40.796d {-40d 47' 44"} (J2000),
                 -40.717d {-40d 43' 00"} (current),
                 -40.953d {-40d 57' 10"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       47844 [cnts]    Image_Peak=971 [image_cnts]
TRIGGER_DUR:     16.384 [sec] 
TRIGGER_INDEX:   479     E_range: 25-100 keV
BKG_INTEN:       174753 [cnts]
BKG_TIME:        78621.69 SOD {21:50:21.69} UT
BKG_DUR:         64 [sec]
GRB_DATE:        20589 TJD;   280 DOY;   24/10/06
GRB_TIME:        78718.27 SOD {21:51:58.27} UT
GRB_PHI:          49.54 [deg]
GRB_THETA:        24.56 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     13.41 [sigma]
IMAGE_SIGNIF:    11.04 [sigma]
MERIT_PARAMS:     +1  +0  +0  +4  +2  +0  +0  +0 +21  +0 
SUN_POSTN:       193.01d {+12h 52m 02s}   -5.57d {-05d 34' 20"}
SUN_DIST:        102.81 [deg]   Sun_angle= -7.5 [hr] (East of Sun)
MOON_POSTN:      236.09d {+15h 44m 22s}  -24.13d {-24d 07' 43"}
MOON_DIST:        59.12 [deg]
MOON_ILLUM:      15 [%]
GAL_COORDS:        0.13,-33.34 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      297.49,-20.62 [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 = 12.78,-20.30 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Oct 24 21:55:05 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1258721,   Seg_Num: 0
GRB_RA:          304.7429d {+20h 18m 58.2s} (J2000),
                 305.1576d {+20h 20m 37.8s} (current),
                 303.9033d {+20h 15m 36.7s} (1950)
GRB_DEC:         -40.8051d {-40d 48' 18.3"} (J2000),
                 -40.7261d {-40d 43' 34.0"} (current),
                 -40.9621d {-40d 57' 43.5"} (1950)
GRB_ERROR:       6.1 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       23 [cnts]
IMG_START_DATE:  20589 TJD;   280 DOY;   24/10/06
IMG_START_TIME:  78863.57 SOD {21:54:23.57} UT,   145.3 [sec] since BAT Trigger Time
CENTROID_X:      245.54,  raw= 246  [pixels]
CENTROID_Y:      292.72,  raw= 293  [pixels]
ROLL:            251.19 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -14.08
GRB_POS_XRT_Z:   -155.70
IMAGE_URL:       sw01258721000msxps_rw.img
SUN_POSTN:       193.01d {+12h 52m 02s}   -5.57d {-05d 34' 22"}
SUN_DIST:        102.77 [deg]   Sun_angle= -7.5 [hr] (East of Sun)
MOON_POSTN:      236.11d {+15h 44m 26s}  -24.13d {-24d 07' 59"}
MOON_DIST:        59.07 [deg]
MOON_ILLUM:      15 [%]
GAL_COORDS:        0.12,-33.30 [deg] galactic lon,lat of the burst
ECL_COORDS:      297.45,-20.62 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Oct 24 21:55:08 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1258721,   Seg_Num: 0
GRB_RA:          304.7429d {+20h 18m 58.2s} (J2000),
                 305.1576d {+20h 20m 37.8s} (current),
                 303.9033d {+20h 15m 36.7s} (1950)
GRB_DEC:         -40.8051d {-40d 48' 18.3"} (J2000),
                 -40.7261d {-40d 43' 34.0"} (current),
                 -40.9621d {-40d 57' 43.5"} (1950)
GRB_ERROR:       6.1 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       23 [cnts]
IMG_START_DATE:  20589 TJD;   280 DOY;   24/10/06
IMG_START_TIME:  78863.57 SOD {21:54:23.57} UT,   145.3 [sec] since BAT Trigger Time
CENTROID_X:      245.54,  raw= 246  [pixels]
CENTROID_Y:      292.72,  raw= 293  [pixels]
ROLL:            251.19 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -14.08
GRB_POS_XRT_Z:   -155.70
IMAGE_URL:       sw01258721000msxps_rw.img
SUN_POSTN:       193.01d {+12h 52m 02s}   -5.57d {-05d 34' 22"}
SUN_DIST:        102.77 [deg]   Sun_angle= -7.5 [hr] (East of Sun)
MOON_POSTN:      236.11d {+15h 44m 26s}  -24.13d {-24d 08' 00"}
MOON_DIST:        59.07 [deg]
MOON_ILLUM:      15 [%]
GAL_COORDS:        0.12,-33.30 [deg] galactic lon,lat of the burst
ECL_COORDS:      297.45,-20.62 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Oct 24 21:54:55 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1258721,   Seg_Num: 0
GRB_RA:          304.7429d {+20h 18m 58.29s} (J2000),
                 305.1576d {+20h 20m 37.83s} (current),
                 303.9033d {+20h 15m 36.79s} (1950)
GRB_DEC:         -40.8051d {-40d 48' 18.3"} (J2000),
                 -40.7261d {-40d 43' 34.0"} (current),
                 -40.9621d {-40d 57' 43.5"} (1950)
GRB_ERROR:       6.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       4.75e-10 [erg/cm2/sec]
GRB_SIGNIF:      4.79 [sigma]
IMG_START_DATE:  20589 TJD;   280 DOY;   24/10/06
IMG_START_TIME:  78863.57 SOD {21:54:23.57} UT,   145.3 [sec] since BAT Trigger Time
TAM[0-3]:        327.63 237.16 261.57 243.80
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       193.01d {+12h 52m 02s}   -5.57d {-05d 34' 22"}
SUN_DIST:        102.77 [deg]   Sun_angle= -7.5 [hr] (East of Sun)
MOON_POSTN:      236.11d {+15h 44m 25s}  -24.13d {-24d 07' 57"}
MOON_DIST:        59.07 [deg]
MOON_ILLUM:      15 [%]
GAL_COORDS:        0.12,-33.30 [deg] galactic lon,lat of the burst
ECL_COORDS:      297.45,-20.62 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 2.39 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Oct 24 21:55:51 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1258721,   Seg_Num: 0
GRB_RA:          304.794d {+20h 19m 11s} (J2000),
                 305.209d {+20h 20m 50s} (current),
                 303.955d {+20h 15m 49s} (1950)
GRB_DEC:         -40.796d {-40d 47' 44"} (J2000),
                 -40.717d {-40d 43' 00"} (current),
                 -40.953d {-40d 57' 10"} (1950)
GRB_DATE:        20589 TJD;   280 DOY;   24/10/06
GRB_TIME:        78718.27 SOD {21:51:58.27} UT
TRIGGER_INDEX:   479
GRB_PHI:          49.54 [deg]
GRB_THETA:        24.56 [deg]
DELTA_TIME:      -56.00 [sec]
TRIGGER_DUR:     16.384 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     13.41 [sigma]
IMAGE_SIGNIF:    11.04 [sigma]
LC_URL:          sw01258721000msb.lc
SUN_POSTN:       193.01d {+12h 52m 03s}   -5.57d {-05d 34' 22"}
SUN_DIST:        102.81 [deg]   Sun_angle= -7.5 [hr] (East of Sun)
MOON_POSTN:      236.11d {+15h 44m 27s}  -24.14d {-24d 08' 05"}
MOON_DIST:        59.10 [deg]
MOON_ILLUM:      15 [%]
GAL_COORDS:        0.13,-33.34 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      297.49,-20.62 [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 = 12.78,-20.30 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Oct 24 22:00:38 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1258721,   Seg_Num: 0
POINT_RA:        304.798d {+20h 19m 11s} (J2000)
POINT_DEC:       -40.796d {-40d 47' 44"} (J2000)
POINT_ROLL:      251.188d
IMG_START_DATE:  20589 TJD;   280 DOY;   24/10/06
IMG_START_TIME:  79067.78 SOD {21:57:47.78} UT,   349.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.460
N_STARS:         138
X_OFFSET:        495 [pixels]
Y_OFFSET:        552 [pixels]
X_MAX:           1454 [pixels]
Y_MAX:           1511 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw01258721000msufc0349.fits
SUN_POSTN:       193.01d {+12h 52m 03s}   -5.57d {-05d 34' 27"}
SUN_DIST:        102.81 [deg]   Sun_angle= -7.5 [hr] (East of Sun)
MOON_POSTN:      236.16d {+15h 44m 38s}  -24.15d {-24d 08' 45"}
MOON_DIST:        59.06 [deg]
MOON_ILLUM:      15 [%]
GAL_COORDS:        0.13,-33.34 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.49,-20.62 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 06 Oct 24 22:00:54 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1258721,   Seg_Num: 0
POINT_RA:        304.798d {+20h 19m 11s} (J2000)
POINT_DEC:       -40.796d {-40d 47' 44"} (J2000)
POINT_ROLL:      251.188d
IMG_START_DATE:  20589 TJD;   280 DOY;   24/10/06
IMG_START_TIME:  79067.78 SOD {21:57:47.78} UT,   349.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.460
N_STARS:         138
X_OFFSET:        495 [pixels]
Y_OFFSET:        552 [pixels]
X_MAX:           1454 [pixels]
Y_MAX:           1511 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw01258721000msufc0349.fits
SUN_POSTN:       193.01d {+12h 52m 03s}   -5.57d {-05d 34' 27"}
SUN_DIST:        102.81 [deg]   Sun_angle= -7.5 [hr] (East of Sun)
MOON_POSTN:      236.16d {+15h 44m 38s}  -24.15d {-24d 08' 48"}
MOON_DIST:        59.06 [deg]
MOON_ILLUM:      15 [%]
GAL_COORDS:        0.13,-33.34 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.49,-20.62 [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:     Sun 06 Oct 24 22:01:14 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1258721,   Seg_Num: 0
GRB_RA:          304.7424d {+20h 18m 58.17s} (J2000),
                 305.1571d {+20h 20m 37.71s} (current),
                 303.9028d {+20h 15m 36.67s} (1950)
GRB_DEC:         -40.8051d {-40d 48' 18.3"} (J2000),
                 -40.7261d {-40d 43' 34.0"} (current),
                 -40.9621d {-40d 57' 43.4"} (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:  20589 TJD;   280 DOY;   24/10/06
IMG_START_TIME:  79038.00 SOD {21:57:18.00} UT,   319.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       193.01d {+12h 52m 03s}   -5.57d {-05d 34' 28"}
SUN_DIST:        102.76 [deg]   Sun_angle= -7.5 [hr] (East of Sun)
MOON_POSTN:      236.16d {+15h 44m 39s}  -24.15d {-24d 08' 50"}
MOON_DIST:        59.02 [deg]
MOON_ILLUM:      15 [%]
GAL_COORDS:        0.12,-33.30 [deg] galactic lon,lat of the burst
ECL_COORDS:      297.44,-20.62 [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:     Sun 06 Oct 24 22:02:05 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1258721,   Seg_Num: 0
POINT_RA:        304.798d {+20h 19m 11s} (J2000)
POINT_DEC:       -40.796d {-40d 47' 44"} (J2000)
ROLL:            251.188d
IMG_START_DATE:  20589 TJD;   280 DOY;   24/10/06
IMG_START_TIME:  79067.78 SOD {21:57:47.78} UT,   349.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     749944702
X_OFFSET:        814 [pixels]
Y_OFFSET:        871 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       974
Y_GRB_POS:       1031
BINNING_INDEX:   1
IM_URL:          sw01258721000msuni0384.fits
SUN_POSTN:       193.01d {+12h 52m 04s}   -5.57d {-05d 34' 28"}
SUN_DIST:        102.80 [deg]   Sun_angle= -7.5 [hr] (East of Sun)
MOON_POSTN:      236.17d {+15h 44m 41s}  -24.15d {-24d 08' 58"}
MOON_DIST:        59.05 [deg]
MOON_ILLUM:      15 [%]
GAL_COORDS:        0.13,-33.34 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.49,-20.62 [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:     Sun 06 Oct 24 22:02:10 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1258721,   Seg_Num: 0
POINT_RA:        304.798d {+20h 19m 11s} (J2000)
POINT_DEC:       -40.796d {-40d 47' 44"} (J2000)
ROLL:            251.188d
IMG_START_DATE:  20589 TJD;   280 DOY;   24/10/06
IMG_START_TIME:  79067.78 SOD {21:57:47.78} UT,   349.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     749944702
X_OFFSET:        814 [pixels]
Y_OFFSET:        871 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       974
Y_GRB_POS:       1031
BINNING_INDEX:   1
IM_URL:          sw01258721000msuni0384.fits
SUN_POSTN:       193.01d {+12h 52m 04s}   -5.57d {-05d 34' 28"}
SUN_DIST:        102.80 [deg]   Sun_angle= -7.5 [hr] (East of Sun)
MOON_POSTN:      236.17d {+15h 44m 41s}  -24.15d {-24d 08' 58"}
MOON_DIST:        59.05 [deg]
MOON_ILLUM:      15 [%]
GAL_COORDS:        0.13,-33.34 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.49,-20.62 [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 #37721
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-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 GRB241006.91 (trigger No 1258721,20h 19m 10.56s , -40d 47m 45.6s, R=0.05) errorbox 15 sec after notice time and 97 sec after trigger time at 2024-10-06 21:53:35 UT, with upper limit up to 18.3 mag. The observations began at zenith distance = 48 deg. The sun altitude is -51.7 deg.
The galactic latitude b = -34 deg., longitude l = 0 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2628121
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

     108 |         MASTER-SAAO |   C |    20 | 18.3 |        
     147 |         MASTER-SAAO |   C |    20 | 18.3 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #37722
R. Gupta (NASA GSFC), M. J. Moss (GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team:
At 21:51:58 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 241006A (trigger=1258721). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 304.794, -40.796 which is
```
   RA(J2000) = 20h 19m 11s
   Dec(J2000) = -40d 47' 44"
```
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 30 sec. The peak count rate was ~700 counts/sec (15-350 keV), at ~-1 sec after the trigger.
The XRT began observing the field at 21:54:23.5 UT, 145.3 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source with an enhanced position: RA, Dec 304.74258, -40.80514 which is equivalent to:
```
   RA(J2000)  = 20h 18m 58.22s
   Dec(J2000) = -40d 48' 18.5"
```
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 143 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 (4.92 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.5 (+3.24/-2.77) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 4.75e-10 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 349 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 none of the XRT error circle. 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 0.065.
Burst Advocate for this burst is R. Gupta (rahulbhu.c157 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 Circular #37724
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 391 s of XRT Photon Counting mode data and 1 UVOT images for GRB 241006A, 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 = 304.74263, -40.80500 which is equivalent to:
```
RA (J2000): 20h 18m 58.23s
Dec (J2000): -40d 48' 18.0"
```
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 Circular #37728
SVOM/VT commissioning team: Y. L. Qiu, L. P. Xin, H. L. Li, C. Wu, X. H. Ha= n, W. J. Xie, H. B. Cai, Y. Xu, Y. J. Xiao, P. P. Zhang, J. S. Deng, L. La= n, X. M. Lu, R. S. Zhang (NAOC), J. Zhang, L. J. Dan, G. Y. Zou, C. J. Wan= g, Y. F. Du, C. Huang (XIOPM), D. Turpin (CEA), Z. P. Jin, H. Zhou (PMO)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (I= HEP), St=C3=A9phane Basa (LAM), Jean-Luc Atteia (IRAP), Arnaud Claret (CEA)= , Zi-Gao Dai (USTC), Fr=C3=A9d=C3=A9ric Daigne (IAP), Jin-Song Deng (NAOC),= Andrea Goldwurm (APC), Diego G=C3=B6tz (CEA), Xu-Hui Han (NAOC), Cyril Lac= haud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs.Par= is), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Bing Zhang (UNLV= )
report on behalf of the SVOM team:
During the commissioning phase of SVOM mission, we observed the GRB 241006A detected by Swift/BAT (Gupta et al. GCN 37722) with SVOM/VT telescope in T= oO mode. The observation started at 2024-10-07T03:15:07 UT, approximately 5= .38 hours after the burst, with a total exposure time of 5220 seconds. The VT telescope conducted observations simultaneously in two channels: VT_B (4= 00nm-650nm) and VT_R (650nm-1000nm).
Preliminary analysis shows that, no any source was detected within the erro= r circles of XRT (Beardmore et al., GCN 37724) with the 3 sigma limit magni= tudes of about 24.0 mag for VT_B and 23.8 mag for VT_R in the AB magnitude system, after stacking the images for both bands separately.
More observations with inferred wavelengths are encouraged to investigate t= he nature of the burst.
The SpaceVariable Objects Monitor (SVOM) is a China-France joint mission le= d by the Chinese National Space Administration (CNSA, China), National Cent= er for Space Studies (CNES, France) and the Chinese Academy of Sciences (CA= S, China), which is dedicated to observing gamma-ray bursts and other trans= ient phenomena in the energetic universe. VT was jointly developed by Xi'an= Institute of Optics and Precision Mechanics (XIOPM), CAS and National astr= onomical observatories (NAOC),CAS.
GCN Circular #37729
N.P.M. Kuin and R. Gupta (NASA GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 241006A 350 s after the BAT trigger (Gupta et al., GCN Circ. 37722). No optical afterglow consistent with the XRT position has been 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           350          499          147         >21.0
white              350          625          167         >21.0
v                  656          676           19         >17.4
b                  580          600           19         >19.0
u                  556          575           19         >17.9
w1                 531          715           28         >18.8
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.065 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #37730
J. Durbak (UMD), O. Guiffreda (UMD), S. Atri (U Rome), A. S. Kutyrev (NASA/GSFC), E. Troja (U Rome), K. De (MIT), S. B. Cenko (NASA/GSFC)
Following the Swift BAT detection (GCN 37722), we observed the transient field in J-filter with PRIME ~45 minutes after Swift BAT detection in cloudy conditions.
At the enhanced XRT position (GCN 37728), we detect no uncatalogued sources in J-band. Using nearby VISTA Hemispherical Survey (VHS) stars for preliminary calibration we derive a limiting magnitude of <18.7 AB, not corrected for Galactic extinction.
PRIME is a 1.8m telescope with 1.56 square degree FOV (0.5 arcsec/pixel) located in Sutherland, South Africa at the South African Astronomical Observatory (SAAO) (Kutyrev et al. 2023, Yama et al. 2023, Durbak et al. 2024).
We thank the Osaka University observers at PRIME and the staff at SAAO for their support with these observations.
GCN Circular #37732
B. Sbarufatti (INAF-OAB), D.N. Burrows (PSU), M. A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 7.8 ks of XRT data for GRB 241006A, from 295 s to 50.5 ks after the BAT trigger. The data comprise 23 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode.
The light curve can be modelled with a power-law decay with a decay index of alpha=3.3 (+0.4, -0.3).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.73 (+0.28, -0.20). The best-fitting absorption column is 6.4 (+8.3, -1.5) x 10^20 cm^-2, consistent with the Galactic value of 4.9 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 3.9 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     6.4 (+8.3, -1.5) x 10^20 cm^-2
Galactic foreground: 4.9 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.73 (+0.28, -0.20)
```
If the light curve continues to decay with a power-law decay index of 3.3, the count rate at T+24 hours will be 3.1 x 10^-8 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x 10^-18 (1.3 x 10^-18) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01258721.
This circular is an official product of the Swift-XRT team.

GCN Circular #37738
T. Hussenot-Desenonges (IJCLAB), Y. Rajabov (UBAI), M. Tanasan (NARIT), I. Abdi (AUS), R.Strausbaugh (EIU), S. Antier (OCA), S. Karpov (FZU), M. Coughlin (UMN), C. Andrade (UMN), I. Tosta e Melo (UniCT-DFA), P. Hello, N. Leroy (IJCLAB), P-A Duverne (APC), T. Pradier (Unistra/IPHC), N. Guessoum (AUS), L. De Almeida, W. Corradi, N. Sasaki, F. Navarete, L. Braga (LNA), K. Noysena (NARIT) on behalf of the GRANDMA collaboration.
We performed observations with the GRANDMA network on the field of GRB 241006A, detected by Swift-BAT (GCN 37722). The first images were taken at OPD starting from 2024-10-07T01:01:42, 3 hours after the GRB trigger, in the I and R filters. TRT-SBO also observed the field in R and I filters starting from 2024-10-07T09:26:52, 11.5 hours after the trigger.
We did not detect any optical counterparts of the Swift-XRT afterglow position (RaDec 304.74263 -40.80500, GCN 37724), with the following 5-sigma upperlimits at its coordinates:

+-------------+-------------+--------+----------+-----------+-------------+
| MJD (start) | T-T0 (days) | Filter | Exposure | Telescope | U.L. (Vega) |
|-------------+-------------+--------+----------+-----------+-------------+
| 60590.0429  | 0.1318      | I      | 16x360s  | OPD       | 19.6        |
|-------------+-------------+--------+----------+-----------+-------------+
| 60590.0556  | 0.1445      | R      | 9x360s   | OPD       | 20.1        |
|-------------+-------------+--------+----------+-----------+-------------+
| 60590.3937  | 0.4826      | R      | 5x300s   | TRT-SBO   | 21.6        |
|-------------+-------------+--------+----------+-----------+-------------+
| 60590.4079  | 0.4968      | I      | 5x300s   | TRT-SBO   | 20.0        |
+-------------+-------------+--------+----------+-----------+-------------+

We also searched the Swift-BAT field (RA, Dec 304.794, -40.796, uncertainty 3 arcmin) and did not detect any optical counterpart. The 5-sigma upperlimits on the field are:

+-------------+-------------+--------+----------+-----------+-------------+
| MJD (start) | T-T0 (days) | Filter | Exposure | Telescope | U.L. (Vega) |
|-------------+-------------+--------+----------+-----------+-------------+
| 60590.0429  | 0.1318      | I      | 16x360s  | OPD       | 19.4        |
|-------------+-------------+--------+----------+-----------+-------------+
| 60590.0556  | 0.1445      | R      | 9x360s   | OPD       | 20.0        |
|-------------+-------------+--------+----------+-----------+-------------+
| 60590.3937  | 0.4826      | R      | 5x300s   | TRT-SBO   | 21.5        |
|-------------+-------------+--------+----------+-----------+-------------+
| 60590.4079  | 0.4968      | I      | 5x300s   | TRT-SBO   | 19.9        |
+-------------+-------------+--------+----------+-----------+-------------+

All the data has been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022).
We use the SkyPortal application (skyportal.io) to monitor our observational campaign.
GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518)

GCN Circular #37753
R. Gupta (GSFC), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 241006A (trigger #1258721; Gupta et al., GCN Circ. 37722). The BAT ground-calculated position is RA, Dec = 304.782, -40.806 deg which is
```
   RA(J2000)  =  20h 19m 07.6s
   Dec(J2000) = -40d 48' 21.7"
```
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 65%.
The mask-weighted light curve shows a single-pulse structure that starts at ~T-7 s, peaks at ~T+10 s, and ends at ~T+50 s. T90 (15-350 keV) is 47.95 +- 9.72 sec (estimated error including systematics).
The time-averaged spectrum from T-7.14 to T+47.82 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.52 +- 0.19. The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+9.95 sec in the 15-150 keV band is 0.6 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1258721
GCN Circular #37770
A. Gulati (USyd), G. E. Anderson (Curtin), S. Chastain (UNM), J. K. Leung (UofT/HUJI), S. D. Ryder (Macquarie), A. J. van der Horst (GWU), and L. Rhodes (Oxford) on behalf of the ATCA PanRadio GRB collaboration
We observed GRB 241006A (Gupta et al., GCN 37722) as part of the Australia Telescope Compact Array (ATCA) "PanRadio GRB" Large Project C3542 (PI: G. Anderson) at 5.5 and 9 GHz, 5.2 hours post-merger on 2024-10-07 (03:03-14:32 UT) and 2.25 days post-merger on 2024-10-09 (04:30-08:30 UT).
No radio sources were detected near the Swift/XRT enhanced position (A.P. Beardmore et al., GCN 37724) in either observation epoch. The 3-sigma upper limits for the 9 GHz observations are 27 and 39 uJy respectively.
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.
GCN Circular #37816
K. Noonan (UVI), P. Gokuldass (ERAU), N. Orange (OrangeWave Innovative Science, LLC), D. Morris (NASA), T. Lombardi (Eckerd College), F. George (ERAU), R. Querrard (UVI), D. Smith (UVI), K. Smith (UVI) report:
We observed the field of GRB241006A (Gupta et al., GCN 37722) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 2024-10-07 starting at 23:05:40.9 (Tmid+25.7 hrs). We performed a series of exposures in an R filter with a total exposure of 3490s. The weather conditions were partly cloudy during the hours of observation with an average airmass of 1.9.
We do not detect any source within the enhanced XRT position (Beardmore et al. GCN 37724). This non-detection is consistent with the upper limits reported by SWIFT/UVOT (Kuin et al., GCN 37729), PRIME (Durbak et al., GCN 37730), GRANDMA (Hussenot-Desenonges et al., GCN 37738), and SVOM/VT (Qiu et al., GCN 37728). We report the following 3-sigma upper limit:
```
T_mid                ||Exposure   ||Filter   ||Limit 
T+ 25.7 hrs          || 3490s     || R       ||>20.46
```
The limit is estimated from comparison to nearby USNO B1 stars and is not corrected for Galactic extinction. The VIRT is still in the commissioning phase.
We acknowledge financial support from NASA EPSCoR award 80NNSC22M0063, NSF PAARE award 2319415, and NASA EPSCoR award 80NSSC24M0112. This message can be cited.

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