Gamma-ray Burst 181003A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 03 Oct 18 05:11:44 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     865179,   Seg_Num: 0
GRB_RA:           52.569d {+03h 30m 17s} (J2000),
                  52.753d {+03h 31m 01s} (current),
                  52.078d {+03h 28m 19s} (1950)
GRB_DEC:         -34.023d {-34d 01' 23"} (J2000),
                 -33.960d {-33d 57' 35"} (current),
                 -34.193d {-34d 11' 35"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       10846 [cnts]    Image_Peak=313 [image_cnts]
TRIGGER_DUR:     4.096 [sec] 
TRIGGER_INDEX:   298     E_range: 25-100 keV
BKG_INTEN:       94852 [cnts]
BKG_TIME:        18610.30 SOD {05:10:10.30} UT
BKG_DUR:         40 [sec]
GRB_DATE:        18394 TJD;   276 DOY;   18/10/03
GRB_TIME:        18663.23 SOD {05:11:03.23} UT
GRB_PHI:          48.25 [deg]
GRB_THETA:        12.13 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     8.24 [sigma]
IMAGE_SIGNIF:    7.68 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +2  -2  +0  +0 +56  +0 
SUN_POSTN:       189.15d {+12h 36m 35s}   -3.94d {-03d 56' 28"}
SUN_DIST:        124.11 [deg]   Sun_angle= 9.1 [hr] (West of Sun)
MOON_POSTN:      112.07d {+07h 28m 16s}  +20.82d {+20d 49' 23"}
MOON_DIST:        78.64 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      234.31,-55.35 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       37.12,-50.82 [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 = 42.66,18.99 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 03 Oct 18 05:15:03 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     865179,   Seg_Num: 0
GRB_RA:           52.569d {+03h 30m 17s} (J2000),
                  52.753d {+03h 31m 01s} (current),
                  52.078d {+03h 28m 19s} (1950)
GRB_DEC:         -34.023d {-34d 01' 23"} (J2000),
                 -33.960d {-33d 57' 35"} (current),
                 -34.193d {-34d 11' 35"} (1950)
GRB_DATE:        18394 TJD;   276 DOY;   18/10/03
GRB_TIME:        18663.23 SOD {05:11:03.23} UT
TRIGGER_INDEX:   298
GRB_PHI:          48.25 [deg]
GRB_THETA:        12.13 [deg]
DELTA_TIME:      -11.00 [sec]
TRIGGER_DUR:     4.096 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     8.24 [sigma]
IMAGE_SIGNIF:    7.68 [sigma]
LC_URL:          sw00865179000msb.lc
SUN_POSTN:       189.15d {+12h 36m 36s}   -3.94d {-03d 56' 31"}
SUN_DIST:        124.11 [deg]   Sun_angle= 9.1 [hr] (West of Sun)
MOON_POSTN:      112.10d {+07h 28m 25s}  +20.82d {+20d 49' 16"}
MOON_DIST:        78.66 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      234.31,-55.35 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       37.12,-50.82 [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 = 42.66,18.99 [deg].

GCN Circular #23295
A. P. Beardmore (U Leicester), M. J. Moss (George Washington University), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team:
At 05:11:03 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 181003A (trigger=865179). Swift did not slew immediately to the burst due to an observing constraint. The BAT on-board calculated location is RA, Dec 52.569, -34.023 which is
```
   RA(J2000) = 03h 30m 17s
   Dec(J2000) = -34d 01' 23"
```
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 30 sec. The peak count rate was ~600 counts/sec (15-350 keV), at ~0 sec after the trigger.
Due to an observing constraint, Swift will not slew until T0+46.3 minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk). 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/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 03 Oct 18 06:02:44 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     865179,   Seg_Num: 0
POINT_RA:         52.523d {+03h 30m 05s} (J2000)
POINT_DEC:       -34.021d {-34d 01' 15"} (J2000)
IMG_START_DATE:  18394 TJD;   276 DOY;   18/10/03
IMG_START_TIME:  21752.62 SOD {06:02:32.62} UT,   3089.4 [sec] since BAT Trigger Time
COUNTS:          1    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        0    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 03 Oct 18 06:05:23 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     865179,   Seg_Num: 0
POINT_RA:         52.523d {+03h 30m 05s} (J2000)
POINT_DEC:       -34.021d {-34d 01' 15"} (J2000)
POINT_ROLL:      124.026d
IMG_START_DATE:  18394 TJD;   276 DOY;   18/10/03
IMG_START_TIME:  21757.33 SOD {06:02:37.33} UT,   3094.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.473
N_STARS:         24
X_OFFSET:        603 [pixels]
Y_OFFSET:        299 [pixels]
X_MAX:           1562 [pixels]
Y_MAX:           1258 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00865179000msufc3094.fits
SUN_POSTN:       189.18d {+12h 36m 43s}   -3.96d {-03d 57' 20"}
SUN_DIST:        124.15 [deg]   Sun_angle= 9.1 [hr] (West of Sun)
MOON_POSTN:      112.63d {+07h 30m 32s}  +20.79d {+20d 47' 23"}
MOON_DIST:        79.03 [deg]
MOON_ILLUM:      41 [%]
GAL_COORDS:      234.30,-55.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       37.07,-50.80 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 03 Oct 18 06:05:41 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     865179,   Seg_Num: 0
POINT_RA:         52.523d {+03h 30m 05s} (J2000)
POINT_DEC:       -34.021d {-34d 01' 15"} (J2000)
POINT_ROLL:      124.026d
IMG_START_DATE:  18394 TJD;   276 DOY;   18/10/03
IMG_START_TIME:  21757.33 SOD {06:02:37.33} UT,   3094.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.473
N_STARS:         24
X_OFFSET:        603 [pixels]
Y_OFFSET:        299 [pixels]
X_MAX:           1562 [pixels]
Y_MAX:           1258 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00865179000msufc3094.fits
SUN_POSTN:       189.18d {+12h 36m 43s}   -3.96d {-03d 57' 20"}
SUN_DIST:        124.15 [deg]   Sun_angle= 9.1 [hr] (West of Sun)
MOON_POSTN:      112.64d {+07h 30m 32s}  +20.79d {+20d 47' 22"}
MOON_DIST:        79.03 [deg]
MOON_ILLUM:      40 [%]
GAL_COORDS:      234.30,-55.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       37.07,-50.80 [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:     Wed 03 Oct 18 06:06:45 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     865179,   Seg_Num: 0
POINT_RA:         52.523d {+03h 30m 05s} (J2000)
POINT_DEC:       -34.021d {-34d 01' 15"} (J2000)
ROLL:            124.026d
IMG_START_DATE:  18394 TJD;   276 DOY;   18/10/03
IMG_START_TIME:  21757.33 SOD {06:02:37.33} UT,   3094.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     560239379
X_OFFSET:        922 [pixels]
Y_OFFSET:        618 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1082
Y_GRB_POS:       778
BINNING_INDEX:   1
IM_URL:          sw00865179000msuni3116.fits
SUN_POSTN:       189.18d {+12h 36m 43s}   -3.96d {-03d 57' 21"}
SUN_DIST:        124.15 [deg]   Sun_angle= 9.1 [hr] (West of Sun)
MOON_POSTN:      112.65d {+07h 30m 35s}  +20.79d {+20d 47' 20"}
MOON_DIST:        79.04 [deg]
MOON_ILLUM:      40 [%]
GAL_COORDS:      234.30,-55.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       37.07,-50.80 [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:     Wed 03 Oct 18 06:07:00 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     865179,   Seg_Num: 0
POINT_RA:         52.523d {+03h 30m 05s} (J2000)
POINT_DEC:       -34.021d {-34d 01' 15"} (J2000)
ROLL:            124.026d
IMG_START_DATE:  18394 TJD;   276 DOY;   18/10/03
IMG_START_TIME:  21757.33 SOD {06:02:37.33} UT,   3094.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     560239379
X_OFFSET:        922 [pixels]
Y_OFFSET:        618 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1082
Y_GRB_POS:       778
BINNING_INDEX:   1
IM_URL:          sw00865179000msuni3116.fits
SUN_POSTN:       189.18d {+12h 36m 44s}   -3.96d {-03d 57' 21"}
SUN_DIST:        124.15 [deg]   Sun_angle= 9.1 [hr] (West of Sun)
MOON_POSTN:      112.65d {+07h 30m 36s}  +20.79d {+20d 47' 19"}
MOON_DIST:        79.04 [deg]
MOON_ILLUM:      40 [%]
GAL_COORDS:      234.30,-55.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       37.07,-50.80 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 03 Oct 18 06:34:27 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     865179,   Seg_Num: 0
GRB_RA:           52.5290d {+03h 30m 06.96s} (J2000),
                  52.7135d {+03h 30m 51.23s} (current),
                  52.0373d {+03h 28m 08.95s} (1950)
GRB_DEC:         -33.9644d {-33d 57' 51.8"} (J2000),
                 -33.9010d {-33d 54' 03.6"} (current),
                 -34.1347d {-34d 08' 04.9"} (1950)
GRB_ERROR:       4.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18394 TJD;   276 DOY;   18/10/03
IMG_START_TIME:  21760.00 SOD {06:02:40.00} UT,   3096.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       189.20d {+12h 36m 48s}   -3.96d {-03d 57' 48"}
SUN_DIST:        124.19 [deg]   Sun_angle= 9.1 [hr] (West of Sun)
MOON_POSTN:      112.94d {+07h 31m 45s}  +20.77d {+20d 46' 15"}
MOON_DIST:        79.19 [deg]
MOON_ILLUM:      40 [%]
GAL_COORDS:      234.20,-55.38 [deg] galactic lon,lat of the burst
ECL_COORDS:       37.11,-50.75 [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 10% < P(seren) < 15%.

GCN Circular #23296
P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU), M. Perri (ASDC) and G. Tagliaferri (INAF-OAB) report on behalf of the Swift-XRT team:
The XRT began observing the field of GRB 181003A at 06:02:32.6 UT, 3089.4 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 52.52910, -33.96445 which is equivalent to:
```
   RA(J2000)  = 03h 30m 06.98s
   Dec(J2000) = -33d 57' 52.0"
```
with an uncertainty of 4.5 arcseconds (radius, 90% containment). This location is 242 arcseconds from the BAT onboard position. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. As this position is significantly outside the BAT error circle, it is probably unrelated to the trigger.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.24 x 10^20 cm^-2 (Willingale et al. 2013).

GCN Circular #23299
V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa,A.Kuznetsov, V.V.Chazov, D. Vlasenko Lomonosov Moscow State University, Sternberg Astronomical Institute
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias
Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias
D. Buckley, South African Astronomical Observatory
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
O. Gres, N.M. Budnev, Yu.Ishmuhametova Applied Physics Institute of Irkutsk State University
V. Yurkov, A. Gabovich, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk
MASTER-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) was pointed to Swift GRB181003A (Beardmore et al. GCN 23295, Evans et al. GCN 23296) 4 sec after notice time and 59 sec after trigger time at 2018-10-03 05:12:02 UT, with upper limit up to 19.1 mag. The observations started on zenit distance = 65 deg. The sun altitude was -23.8 deg.
MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) was pointed to the GRB181003A 10 sec after notice time and 64 sec after trigger time at 2018-10-03 05:12:08 UT, with upper limit up to 20.3 mag. The observations started on zenit distance = 27 deg. The sun altitude was -53.3 deg.
The galactic latitude b = -60 deg., longitude l = 98 deg.
We obtained the following upper limits:

Tmid-T0  |  MASTER observatory |Filt.| Exp.,s| m_lim | Comment
_________|_____________________|_____|_______|_______|________

       89 |          MASTER-IAC |  P- |    10 | 16.29 |
       89 |          MASTER-IAC |  P- |    50 | 17.38 |  Coadd
       89 |          MASTER-IAC |  P- |   710 | 19.12 |  Coadd
       96 |         MASTER-OAFA |   C |    10 | 16.88 |
       96 |         MASTER-OAFA |   C |    70 | 18.69 |  Coadd
       96 |         MASTER-OAFA |   C |   550 | 19.83 |  Coadd
      131 |          MASTER-IAC |  P- |    20 | 16.75 |
      176 |         MASTER-OAFA |   C |    20 | 17.54 |
      185 |          MASTER-IAC |  P- |    20 | 16.75 |
      242 |          MASTER-IAC |  P- |    30 | 17.31 |
      242 |          MASTER-IAC |  P- |   120 | 17.94 |  Coadd
      272 |         MASTER-OAFA |   C |    40 | 18.17 |
      312 |          MASTER-IAC |  P- |    40 | 17.05 |
      393 |         MASTER-OAFA |   C |    50 |  18.4 |
      393 |         MASTER-OAFA |   C |   210 |  19.3 |  Coadd
      399 |          MASTER-IAC |  P- |    50 | 17.53 |
      500 |          MASTER-IAC |  P- |    70 | 17.66 |
      500 |          MASTER-IAC |  P- |   250 | 18.41 |  Coadd
      531 |         MASTER-OAFA |   C |    70 |  18.7 |
      632 |          MASTER-IAC |  P- |    80 | 17.66 |
      701 |         MASTER-OAFA |   C |    90 | 18.81 |
      774 |          MASTER-IAC |  P- |   100 | 17.92 |
      900 |         MASTER-OAFA |   C |   120 | 19.05 |
      900 |         MASTER-OAFA |   C |   450 | 19.72 |  Coadd
      951 |          MASTER-IAC |  P- |   130 | 17.92 |
     1145 |         MASTER-OAFA |   C |   150 | 19.18 |
     1170 |          MASTER-IAC |  P- |   160 | 17.92 |
     1434 |         MASTER-OAFA |   C |   180 | 19.31 |
     1434 |         MASTER-OAFA |   C |  1800 | 20.16 |  Coadd
     1436 |          MASTER-IAC |  P- |   180 | 18.15 |
     1436 |          MASTER-IAC |  P- |  1800 | 19.11 |  Coadd
     1749 |          MASTER-IAC |  P- |   180 | 18.16 |
     1749 |          MASTER-IAC |  P- |   540 |    19 |  Coadd
     1764 |         MASTER-OAFA |   C |   180 | 19.26 |
     1764 |         MASTER-OAFA |   C |   540 | 19.84 |  Coadd
     2070 |          MASTER-IAC |  P- |   180 | 18.16 |
     2097 |         MASTER-OAFA |   C |   180 | 19.27 |
     2382 |          MASTER-IAC |  P- |   180 | 18.16 |
     2429 |         MASTER-OAFA |   C |   180 |  19.3 |
     2709 |          MASTER-IAC |  P- |   180 | 18.14 |
     2709 |          MASTER-IAC |  P- |   540 | 18.97 |  Coadd
     2760 |         MASTER-OAFA |   C |   180 | 19.26 |
     2760 |         MASTER-OAFA |   C |   540 | 19.81 |  Coadd
     3027 |          MASTER-IAC |  P- |   180 | 18.14 |
     3093 |         MASTER-OAFA |   C |   180 | 19.26 |
     3428 |         MASTER-OAFA |   C |   180 | 19.25 |
     3761 |         MASTER-OAFA |   C |   180 |  19.3 |
     3761 |         MASTER-OAFA |   C |   540 |  19.9 |  Coadd
     3887 |          MASTER-IAC |  P- |   180 | 17.93 |
     4094 |         MASTER-OAFA |   C |   180 | 19.27 |
     4203 |          MASTER-IAC |  P- |   180 | 17.89 |
     4203 |          MASTER-IAC |  P- |   540 | 18.43 |  Coadd
     4428 |         MASTER-OAFA |   C |   180 |  19.3 |
     4515 |          MASTER-IAC |  P- |   180 | 17.73 |
     4758 |         MASTER-OAFA |   C |   180 |  19.3 |
     4758 |         MASTER-OAFA |   C |   540 | 19.85 |  Coadd
     4758 |         MASTER-OAFA |   C |  1800 | 20.26 |  Coadd
     4835 |          MASTER-IAC |  P- |   180 | 17.45 |
     5093 |         MASTER-OAFA |   C |   180 |  19.3 |
     5151 |          MASTER-IAC |  P- |   180 | 17.08 |
     5151 |          MASTER-IAC |  P- |   540 | 17.39 |  Coadd

Filter C is unfiltred band (clear), calibrated by USNO B1 thousands field stars as 0.2B+0.8R.
The observation and reduction will continue. The message may be cited.

GCN Circular #23300
C. Guidorzi, R. Martone (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU), A. Cucchiara, D. Morris (U. of Virgin Islands) on behalf of a large collaboration report:
We automatically observed Swift GRB 181003A (Beardmore et al. GCN 23295) with one LCO 1-m unit at Cerro Tololo from October 03, 05:26:07 UT (corresponding to 15 minutes from the GRB trigger time) with the SDSS r' filter. Within the Swift-XRT error circle (Evans et al. GCN 23296) we marginally detect an uncatalogued source with r'=22.11 +- 0.25 mag from a 9x60s exposure at a mid time of 0.35 hours post GRB, as calibrated against nearby Pan-STARRS objects, at the following position:
```
RA(J2000) =� 03:30:06.86
DEC(J2000)= -33:57:54.2
```
with an error radius of about 1".
GCN Circular #23303
GRB 181003A: Swift/UVOT Upper Limits
S. J. LaPorte (PSU) and A. P. Beardmore (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 181003A 3095 s after the BAT trigger (Beardmore et al., GCN Circ. 23295). No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 23296) 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

b              5040         5240           196            >20.83  
uvm2           3452         3652           196            >19.46 
u              3862         3902            39            >19.19 
v              3427         3447           196            >19.79 
uvw1           3658         3857           196            >19.85
uvw2           5451         5597           144            >19.37 
white          3091         3240           294            >21.73  
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #23305
A. Tohuvavohu (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), S. J. LaPorte (PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Swift/BAT-detected burst GRB 181003A (Beardmore et al. GCN Circ. 23295), collecting 8.6 ks of Photon Counting (PC) mode data between T0+3.1 ks and T0+34.3 ks.
Six uncatalogued X-ray sources are detected consistent with being within 296 arcsec of the Swift/BAT position, of which one ("Source 1") is fading with 3-sigma significance, and is therefore likely the GRB afterglow. Using 1905 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 52.52869, -33.96466 which is equivalent to:
```
RA (J2000): 03h 30m 06.89s
Dec(J2000): -33d 57' 52.8"
```
with an uncertainty of 6.3 arcsec (radius, 90% confidence). This position is 4.0 arcmin from the Swift/BAT position. The source is fading with alpha >0.8.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00865179. The results of the full analysis of the XRT observations are available at http://www.swift.ac.uk/ToO_GRBs/00865179.
This circular is an official product of the Swift-XRT team.
GCN Circular #23306
H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC), A. P. Beardmore, J. R. Cummings (CPI), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (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 181003A (trigger #865179) (Beardmore et al., GCN Circ. 23295). The BAT ground-calculated position is RA, Dec = 52.481, -33.991 deg which is
```
  RA(J2000)  =  03h 29m 55.4s
  Dec(J2000) = -33d 59' 25.8"
```
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%.
The mask-weighted light curve shows a weak structure that starts at ~T-10 s and ends at ~ T+20 s. The burst went out of the BAT field of view at ~T+97 s. T90 (15-350 keV) is 21.5 +- 4.8 sec (estimated error including systematics).
The time-averaged spectrum from T-11.20 to T+18.01 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index -0.20 +- 1.12, and Epeak of 56.5 +- 14.4 keV (chi squared 52.40 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 4.2 +- 0.7 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+1.86 sec in the 15-150 keV band is 0.6 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.54 +- 0.19 (chi squared 63.13 for 57 d.o.f.). 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/865179/BA/
GCN Circular #23307
Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jes�s Gonz�lez (UNAM), Carlos Rom�n-Z��iga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:
We observed the field of GRB 181003A (Beardmore et al., GCN Circ. 23295) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on Sierra San Pedro M�rtir from 2018/10 4.32 to 2018/10 4.46 UTC (26.59 to 29.89 hours after the BAT trigger), obtaining a total of 1.41 hours exposure in the r and i bands and 0.58 hours exposure in the Z, Y, J, and H bands.
For a source within the Swift-XRT error circle (Tohuvavohu et al., GCN Circ. 23305), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following 3-sigma upper limits:
```
  r	> 23.40
  i	> 23.15
  Z	> 22.01
  Y	> 21.53
  J	> 21.19
  H	> 20.73
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron�mico Nacional in San Pedro M�rtir.

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Jochen Greiner, last update: 04-Oct-2018 [Disclaimer]