Gamma-ray Burst 181013A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 13 Oct 18 02:40:00 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     866783,   Seg_Num: 0
GRB_RA:          207.601d {+13h 50m 24s} (J2000),
                 207.800d {+13h 51m 12s} (current),
                 207.069d {+13h 48m 16s} (1950)
GRB_DEC:         +40.179d {+40d 10' 43"} (J2000),
                 +40.086d {+40d 05' 10"} (current),
                 +40.426d {+40d 25' 34"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       4620 [cnts]    Image_Peak=183 [image_cnts]
TRIGGER_DUR:     2.048 [sec] 
TRIGGER_INDEX:   473     E_range: 25-100 keV
BKG_INTEN:       47937 [cnts]
BKG_TIME:        9538.25 SOD {02:38:58.25} UT
BKG_DUR:         24 [sec]
GRB_DATE:        18404 TJD;   286 DOY;   18/10/13
GRB_TIME:        9569.67 SOD {02:39:29.67} UT
GRB_PHI:         -140.27 [deg]
GRB_THETA:        25.01 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     7.54 [sigma]
IMAGE_SIGNIF:    7.72 [sigma]
MERIT_PARAMS:     +1  +0  +0  +1  +2  -2  +0  +0 -66  +0 
SUN_POSTN:       198.20d {+13h 12m 49s}   -7.71d {-07d 42' 41"}
SUN_DIST:         48.61 [deg]   Sun_angle= -0.6 [hr] (East of Sun)
MOON_POSTN:      247.99d {+16h 31m 57s}  -17.85d {-17d 50' 50"}
MOON_DIST:        68.96 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:       83.60, 72.14 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      185.75, 47.12 [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 = 71.27,14.71 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 13 Oct 18 02:45:01 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     866783,   Seg_Num: 0
GRB_RA:          207.601d {+13h 50m 24s} (J2000),
                 207.800d {+13h 51m 12s} (current),
                 207.069d {+13h 48m 16s} (1950)
GRB_DEC:         +40.179d {+40d 10' 43"} (J2000),
                 +40.086d {+40d 05' 10"} (current),
                 +40.426d {+40d 25' 34"} (1950)
GRB_DATE:        18404 TJD;   286 DOY;   18/10/13
GRB_TIME:        9569.67 SOD {02:39:29.67} UT
TRIGGER_INDEX:   473
GRB_PHI:         -140.27 [deg]
GRB_THETA:        25.01 [deg]
DELTA_TIME:      320.00 [sec]
TRIGGER_DUR:     2.048 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     7.54 [sigma]
IMAGE_SIGNIF:    7.72 [sigma]
LC_URL:          sw00866783000msb.lc
SUN_POSTN:       198.21d {+13h 12m 50s}   -7.71d {-07d 42' 45"}
SUN_DIST:         48.61 [deg]   Sun_angle= -0.6 [hr] (East of Sun)
MOON_POSTN:      248.03d {+16h 32m 08s}  -17.86d {-17d 51' 22"}
MOON_DIST:        68.99 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:       83.60, 72.14 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      185.75, 47.12 [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 = 71.27,14.71 [deg].  
COMMENTS:        The 3rd packet (of 3) was missing in the lightcurve data stream.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 13 Oct 18 02:58:11 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     866783,   Seg_Num: 0
POINT_RA:        207.604d {+13h 50m 25s} (J2000)
POINT_DEC:       +40.204d {+40d 12' 14"} (J2000)
IMG_START_DATE:  18404 TJD;   286 DOY;   18/10/13
IMG_START_TIME:  9672.77 SOD {02:41:12.77} UT,   103.1 [sec] since BAT Trigger Time
COUNTS:          3    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    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:     Sat 13 Oct 18 02:59:20 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     866783,   Seg_Num: 0
POINT_RA:        207.604d {+13h 50m 25s} (J2000)
POINT_DEC:       +40.204d {+40d 12' 14"} (J2000)
POINT_ROLL:      192.399d
IMG_START_DATE:  18404 TJD;   286 DOY;   18/10/13
IMG_START_TIME:  9676.57 SOD {02:41:16.57} UT,   106.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.606
N_STARS:         8
X_OFFSET:        624 [pixels]
Y_OFFSET:        440 [pixels]
X_MAX:           1583 [pixels]
Y_MAX:           1399 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw00866783000msufc0106.fits
SUN_POSTN:       198.22d {+13h 12m 52s}   -7.72d {-07d 42' 59"}
SUN_DIST:         48.64 [deg]   Sun_angle= -0.6 [hr] (East of Sun)
MOON_POSTN:      248.16d {+16h 32m 39s}  -17.88d {-17d 52' 53"}
MOON_DIST:        69.10 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:       83.66, 72.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      185.73, 47.14 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 13 Oct 18 02:59:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     866783,   Seg_Num: 0
POINT_RA:        207.604d {+13h 50m 25s} (J2000)
POINT_DEC:       +40.204d {+40d 12' 14"} (J2000)
POINT_ROLL:      192.399d
IMG_START_DATE:  18404 TJD;   286 DOY;   18/10/13
IMG_START_TIME:  9676.57 SOD {02:41:16.57} UT,   106.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.606
N_STARS:         8
X_OFFSET:        624 [pixels]
Y_OFFSET:        440 [pixels]
X_MAX:           1583 [pixels]
Y_MAX:           1399 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw00866783000msufc0106.fits
SUN_POSTN:       198.22d {+13h 12m 52s}   -7.72d {-07d 43' 00"}
SUN_DIST:         48.64 [deg]   Sun_angle= -0.6 [hr] (East of Sun)
MOON_POSTN:      248.16d {+16h 32m 40s}  -17.88d {-17d 52' 55"}
MOON_DIST:        69.10 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:       83.66, 72.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      185.73, 47.14 [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 13 Oct 18 03:01:26 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     866783,   Seg_Num: 0
POINT_RA:        207.604d {+13h 50m 25s} (J2000)
POINT_DEC:       +40.204d {+40d 12' 14"} (J2000)
ROLL:            192.399d
IMG_START_DATE:  18404 TJD;   286 DOY;   18/10/13
IMG_START_TIME:  9676.57 SOD {02:41:16.57} UT,   106.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     561091298
X_OFFSET:        943 [pixels]
Y_OFFSET:        759 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1103
Y_GRB_POS:       919
BINNING_INDEX:   1
IM_URL:          sw00866783000msuni0128.fits
SUN_POSTN:       198.22d {+13h 12m 52s}   -7.72d {-07d 43' 01"}
SUN_DIST:         48.64 [deg]   Sun_angle= -0.6 [hr] (East of Sun)
MOON_POSTN:      248.18d {+16h 32m 44s}  -17.89d {-17d 53' 07"}
MOON_DIST:        69.11 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:       83.66, 72.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      185.73, 47.14 [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 13 Oct 18 03:01:41 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     866783,   Seg_Num: 0
POINT_RA:        207.604d {+13h 50m 25s} (J2000)
POINT_DEC:       +40.204d {+40d 12' 14"} (J2000)
ROLL:            192.399d
IMG_START_DATE:  18404 TJD;   286 DOY;   18/10/13
IMG_START_TIME:  9676.57 SOD {02:41:16.57} UT,   106.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     561091298
X_OFFSET:        943 [pixels]
Y_OFFSET:        759 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1103
Y_GRB_POS:       919
BINNING_INDEX:   1
IM_URL:          sw00866783000msuni0128.fits
SUN_POSTN:       198.22d {+13h 12m 52s}   -7.72d {-07d 43' 01"}
SUN_DIST:         48.64 [deg]   Sun_angle= -0.6 [hr] (East of Sun)
MOON_POSTN:      248.18d {+16h 32m 44s}  -17.89d {-17d 53' 08"}
MOON_DIST:        69.11 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:       83.66, 72.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      185.73, 47.14 [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:     Sat 13 Oct 18 03:04:44 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     866783,   Seg_Num: 0
POINT_RA:        207.603d {+13h 50m 25s} (J2000)
POINT_DEC:       +40.205d {+40d 12' 17"} (J2000)
POINT_ROLL:      192.397d
IMG_START_DATE:  18404 TJD;   286 DOY;   18/10/13
IMG_START_TIME:  9835.57 SOD {02:43:55.57} UT,   265.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.694
N_STARS:         13
X_OFFSET:        384 [pixels]
Y_OFFSET:        200 [pixels]
X_MAX:           1823 [pixels]
Y_MAX:           1639 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00866783000msufc0265.fits
SUN_POSTN:       198.22d {+13h 12m 53s}   -7.72d {-07d 43' 04"}
SUN_DIST:         48.64 [deg]   Sun_angle= -0.6 [hr] (East of Sun)
MOON_POSTN:      248.21d {+16h 32m 51s}  -17.89d {-17d 53' 28"}
MOON_DIST:        69.13 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:       83.66, 72.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      185.73, 47.14 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 13 Oct 18 03:04:52 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     866783,   Seg_Num: 0
POINT_RA:        207.603d {+13h 50m 25s} (J2000)
POINT_DEC:       +40.205d {+40d 12' 17"} (J2000)
POINT_ROLL:      192.397d
IMG_START_DATE:  18404 TJD;   286 DOY;   18/10/13
IMG_START_TIME:  9835.57 SOD {02:43:55.57} UT,   265.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.694
N_STARS:         13
X_OFFSET:        384 [pixels]
Y_OFFSET:        200 [pixels]
X_MAX:           1823 [pixels]
Y_MAX:           1639 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00866783000msufc0265.fits
SUN_POSTN:       198.22d {+13h 12m 53s}   -7.72d {-07d 43' 04"}
SUN_DIST:         48.64 [deg]   Sun_angle= -0.6 [hr] (East of Sun)
MOON_POSTN:      248.21d {+16h 32m 51s}  -17.89d {-17d 53' 29"}
MOON_DIST:        69.13 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:       83.66, 72.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      185.73, 47.14 [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 13 Oct 18 03:05:56 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     866783,   Seg_Num: 0
POINT_RA:        207.603d {+13h 50m 25s} (J2000)
POINT_DEC:       +40.205d {+40d 12' 17"} (J2000)
ROLL:            192.397d
IMG_START_DATE:  18404 TJD;   286 DOY;   18/10/13
IMG_START_TIME:  9835.57 SOD {02:43:55.57} UT,   265.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     561091457
X_OFFSET:        943 [pixels]
Y_OFFSET:        759 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1103
Y_GRB_POS:       919
BINNING_INDEX:   1
IM_URL:          sw00866783000msuni0287.fits
SUN_POSTN:       198.22d {+13h 12m 53s}   -7.72d {-07d 43' 05"}
SUN_DIST:         48.64 [deg]   Sun_angle= -0.6 [hr] (East of Sun)
MOON_POSTN:      248.22d {+16h 32m 53s}  -17.89d {-17d 53' 35"}
MOON_DIST:        69.14 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:       83.66, 72.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      185.73, 47.14 [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 13 Oct 18 03:06:10 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     866783,   Seg_Num: 0
POINT_RA:        207.603d {+13h 50m 25s} (J2000)
POINT_DEC:       +40.205d {+40d 12' 17"} (J2000)
ROLL:            192.397d
IMG_START_DATE:  18404 TJD;   286 DOY;   18/10/13
IMG_START_TIME:  9835.57 SOD {02:43:55.57} UT,   265.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     561091457
X_OFFSET:        943 [pixels]
Y_OFFSET:        759 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1103
Y_GRB_POS:       919
BINNING_INDEX:   1
IM_URL:          sw00866783000msuni0287.fits
SUN_POSTN:       198.22d {+13h 12m 53s}   -7.72d {-07d 43' 05"}
SUN_DIST:         48.64 [deg]   Sun_angle= -0.6 [hr] (East of Sun)
MOON_POSTN:      248.22d {+16h 32m 54s}  -17.89d {-17d 53' 37"}
MOON_DIST:        69.14 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:       83.66, 72.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      185.73, 47.14 [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 Circular #23332
P. D'Avanzo (INAF-OAB), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), D. M. Palmer (LANL), B. Sbarufatti (PSU) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 02:39:29 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 181013A (trigger=866783). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 207.601, +40.179, which is
```
   RA(J2000)  =  13h 50m 24s
   Dec(J2000) = +40d 10' 43"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows several peaks with a duration of about 25 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 02:41:12.7 UT, 103.1 seconds after the BAT trigger. No source was detected in 1.9 ks of promptly downlinked data, which covered 96% of the BAT error circle. We are waiting for the full dataset to detect and localise the XRT counterpart.
UVOT took a finding chart exposure of 150 seconds with the White filter starting 106 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 25% of the BAT 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 BAT 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 0.01.
Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT brera.inaf.it). 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 Circular #23333
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, Moscow State University
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk Irkutsk State University
V. Yurkov, A. Gabovich, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk
R. Podesta, Carlos Lopez and F. Podesta Observatorio Astronomico Felix Aguilar (OAFA)
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, S. Potter, A. Kniazev, M. Kotze South African Astronomical Observatory
MASTER-Kislovodsk robotic telescope (MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the GRB181013A (D'Avanzo et al., GCN 23332) 21 sec after notice time and 54 sec after trigger time at 2018-10-13 02:40:23 UT . On our first (10s exposure) set we haven`t found optical transient within SWIFT error-box (ra=207.596 dec=40.1783 r=0.05). The 5-sigma upper limit has been about 13.2 mag The message may be cited.
====================================================================
The galactic latitude b = 72 deg., longitude l = 82 deg. The observations made on zenit distance = 71 deg.The moon (18 % bright part) below the horizon (The altitude of the Moon is -50 deg. ). Observations started at twilight. The sun altitude is -7.8 deg. The object can be observed till sunrise at 2018-10-13 03:20:48.
MASTER-Tavrida robotic telescope (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 GRB181013.11 129 sec after notice time and 202 sec after trigger time at 2018-10-13 02:42:51 UT. On our first (40s exposure) set we haven`t found optical transient within SWIFT error-box (ra=207.596 dec=40.1781 r=0.1). The 5-sigma upper limit has been about 17.4 mag The message may be cited.
====================================================================
The galactic latitude b = 72 deg., longitude l = 82 deg. The observations made on zenit distance = 75 deg.The moon (18 % bright part) below the horizon (The altitude of the Moon is -54 deg. ). Observations started at twilight. The sun altitude is -13.6 deg. The object can be observed till sunrise at 2018-10-13 03:56:18.
This message can be cited.
GCN Circular #23334
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A.P. Beardmore (U. Leicester) and P. D'Avanzo (INAF-OAB) report on behalf of the Swift-XRT team:
We have analysed 190 s of Photon Counting (PC) mode XRT data for the Swift/BAT-detected burst GRB 181013A (D'Avanzo et al. GCN Circ. 23332), collected between T0+115 s and T0+306 s.
An uncatalogued X-ray source is detected consistent with being within 296 arcsec of the Swift/BAT position and is above the RASS limit and fading with 3-sigma significance, and is therefore likely the GRB afterglow. The position of this source is RA, Dec=207.6518, +40.1082 which is equivalent to:
```
RA (J2000): 13:50:36.43
Dec(J2000): +40:06:29.5
```
with an uncertainty of 3.9 arcsec (radius, 90% confidence). This position is 4.8 arcmin from the Swift/BAT position.
The light curve can be modelled with a power-law decay with a decay index of alpha=7.6 (+0.4, -1.0).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 0.98 (+0.30, -0.19). The best-fitting absorption column is consistent with the Galactic value of 9.4 x 10^19 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 6.2 x 10^-11 (6.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     9 (+/-90) x 10^19 cm^-2
Galactic foreground: 9.4 x 10^19 cm^-2
Excess significance: <1.6 sigma
Photon index:	     0.98 (+0.30, -0.19)
```
If the light curve continues to decay with a power-law decay index of 7.6, the count rate at T+24 hours will be 5.9 x 10^-21 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.6 x 10^-31 (3.6 x 10^-31) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis of the likely afterglow are at http://www.swift.ac.uk/ToO_GRBs/00866783/Source1.php. The results of the full analysis of the XRT observations are available at http://www.swift.ac.uk/ToO_GRBs/00866783.
This circular is an official product of the Swift-XRT team.
GCN Circular #23335
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), P. D'Avanzo (INAF-OAB), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), 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-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 181013A (trigger #866783) (D'Avanzo, et al., GCN Circ. 23332). The BAT ground-calculated position is RA, Dec = 207.661, 40.107 deg, which is
```
   RA(J2000)  =  13h 50m 38.5s 
   Dec(J2000) = +40d 06' 26.8" 
```
with an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 81%.
The mask-weighted light curve shows peaks starting at ~T-5 sec and ending at ~T+120 sec. T90 (15-350 keV) is 104.1 +- 53.5 sec (estimated error including systematics).
The time-averaged spectrum from T+18.37 to T+123.97 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.82 +- 0.75. The fluence in the 15-150 keV band is 3.0 +- 1.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+18.80 sec in the 15-150 keV band is 0.5 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/866783/BA/
GCN Circular #23336
N. P. M. Kuin (UCL-MSSL) and P. D'Avanzo (INAF-OAB) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 181013A 106 s after the BAT trigger (D'Avanzo et al., GCN Circ. 23332). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 23334) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           867         1017          147         >20.2
u_FC               266          516          246         >19.1
white              867         1017          147         >20.2
u                  266          516          246         >19.1
w1                 818         7875          471         >20.4
m2                6035         7669          393         >19.6
w2                5624         7260          393         >20.8
```
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 #23341
E. Mazaeva (IKI), S. Belkin (IKI), A. Pozanenko (IKI), R. Inasaridze (AbAO), V. Ayvazian (AbAO), O. Kvaratskhelia (AbAO), G. Kapanadze (AbAO), A. Volnova (IKI), I. Molotov (KIAM) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 181013A (D'Avanzoet al., GCN 23332) with AS-32 (0.7m) telescope of Abastumani Observatory starting on Oct. 13 (UT) 15:23:15 . We do not detect any object within XRT position (Osborne et al., GCN 23334). Preliminary photometry of the field is following:
```
Date              UT start     t-T0            Filter Exp.   OT    Err. UL
                                        (mid, days)         (s)

2018-10-13 15:23:15    0.54312    R      58*60  n/d   n/d  21.0
```
The photometry is based on nearby SDSS-DR12 stars
```
SDSS-DR12_id R(Lupton)
J135025.82+400818.8 16.99
J135102.99+401021.5 16.36
J135015.70+400244.5 13.69
J135009.92+400351.8 13.87
J135009.71+400308.0 14.87 
```

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Jochen Greiner, last update: 15-Oct-2018 [Disclaimer]