Gamma-ray Burst 170206B

(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:     Mon 06 Feb 17 22:03:46 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     737125,   Seg_Num: 0
POINT_RA:        271.763d {+18h 07m 03s} (J2000)
POINT_DEC:       +11.242d {+11d 14' 32"} (J2000)
ROLL:            117.686d
IMG_START_DATE:  17790 TJD;    37 DOY;   17/02/06
IMG_START_TIME:  79150.98 SOD {21:59:10.98} UT
FILTER:          10, White
EXPOSURE_ID:     508111169
X_OFFSET:        1008 [pixels]
Y_OFFSET:        802 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1168
Y_GRB_POS:       962
BINNING_INDEX:   1
IM_URL:          sw00737125000msuni508111169.fits
SUN_POSTN:       320.75d {+21h 23m 01s}  -15.34d {-15d 20' 13"}
SUN_DIST:         55.14 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       84.48d {+05h 37m 56s}  +18.48d {+18d 28' 32"}
MOON_DIST:       149.38 [deg]
MOON_ILLUM:      80 [%]
GAL_COORDS:       38.12, 14.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      272.10, 34.67 [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:     Mon 06 Feb 17 22:03:42 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     737125,   Seg_Num: 0
POINT_RA:        271.763d {+18h 07m 03s} (J2000)
POINT_DEC:       +11.242d {+11d 14' 32"} (J2000)
POINT_ROLL:      117.686d
IMG_START_DATE:  17790 TJD;    37 DOY;   17/02/06
IMG_START_TIME:  79150.98 SOD {21:59:10.98} UT
FILTER:          10, White
BKG_MEAN:        3.895
N_STARS:         190
X_OFFSET:        689 [pixels]
Y_OFFSET:        483 [pixels]
X_MAX:           1648 [pixels]
Y_MAX:           1442 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00737125000msufc508111150.fits
SUN_POSTN:       320.75d {+21h 23m 01s}  -15.34d {-15d 20' 13"}
SUN_DIST:         55.14 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       84.48d {+05h 37m 55s}  +18.48d {+18d 28' 32"}
MOON_DIST:       149.38 [deg]
MOON_ILLUM:      80 [%]
GAL_COORDS:       38.12, 14.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      272.10, 34.67 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 06 Feb 17 22:03:50 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     737125,   Seg_Num: 0
POINT_RA:        271.763d {+18h 07m 03s} (J2000)
POINT_DEC:       +11.242d {+11d 14' 32"} (J2000)
ROLL:            117.686d
IMG_START_DATE:  17790 TJD;    37 DOY;   17/02/06
IMG_START_TIME:  79150.98 SOD {21:59:10.98} UT
FILTER:          10, White
EXPOSURE_ID:     508111169
X_OFFSET:        1008 [pixels]
Y_OFFSET:        802 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1168
Y_GRB_POS:       962
BINNING_INDEX:   1
IM_URL:          sw00737125000msuni508111169.fits
SUN_POSTN:       320.75d {+21h 23m 01s}  -15.34d {-15d 20' 13"}
SUN_DIST:         55.14 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       84.48d {+05h 37m 56s}  +18.48d {+18d 28' 32"}
MOON_DIST:       149.38 [deg]
MOON_ILLUM:      80 [%]
GAL_COORDS:       38.12, 14.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      272.10, 34.67 [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:     Mon 06 Feb 17 22:03:51 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     737125,   Seg_Num: 0
POINT_RA:        271.763d {+18h 07m 03s} (J2000)
POINT_DEC:       +11.242d {+11d 14' 32"} (J2000)
POINT_ROLL:      117.686d
IMG_START_DATE:  17790 TJD;    37 DOY;   17/02/06
IMG_START_TIME:  79150.98 SOD {21:59:10.98} UT
FILTER:          10, White
BKG_MEAN:        3.895
N_STARS:         190
X_OFFSET:        689 [pixels]
Y_OFFSET:        483 [pixels]
X_MAX:           1648 [pixels]
Y_MAX:           1442 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00737125000msufc508111150.fits
SUN_POSTN:       320.75d {+21h 23m 01s}  -15.34d {-15d 20' 12"}
SUN_DIST:         55.14 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       84.48d {+05h 37m 56s}  +18.48d {+18d 28' 32"}
MOON_DIST:       149.38 [deg]
MOON_ILLUM:      80 [%]
GAL_COORDS:       38.12, 14.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      272.10, 34.67 [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:     Mon 06 Feb 17 22:10:18 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     737125,   Seg_Num: 0
POINT_RA:        271.761d {+18h 07m 03s} (J2000)
POINT_DEC:       +11.242d {+11d 14' 31"} (J2000)
POINT_ROLL:      117.683d
IMG_START_DATE:  17790 TJD;    37 DOY;   17/02/06
IMG_START_TIME:  79308.93 SOD {22:01:48.93} UT
FILTER:          7, U
BKG_MEAN:        1.287
N_STARS:         190
X_OFFSET:        449 [pixels]
Y_OFFSET:        243 [pixels]
X_MAX:           1888 [pixels]
Y_MAX:           1682 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00737125000msufc508111308.fits
SUN_POSTN:       320.76d {+21h 23m 02s}  -15.34d {-15d 20' 07"}
SUN_DIST:         55.14 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       84.55d {+05h 38m 12s}  +18.48d {+18d 28' 49"}
MOON_DIST:       149.39 [deg]
MOON_ILLUM:      80 [%]
GAL_COORDS:       38.12, 14.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      272.10, 34.67 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 06 Feb 17 22:10:43 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     737125,   Seg_Num: 0
POINT_RA:        271.761d {+18h 07m 03s} (J2000)
POINT_DEC:       +11.242d {+11d 14' 31"} (J2000)
POINT_ROLL:      117.683d
IMG_START_DATE:  17790 TJD;    37 DOY;   17/02/06
IMG_START_TIME:  79308.93 SOD {22:01:48.93} UT
FILTER:          7, U
BKG_MEAN:        1.287
N_STARS:         190
X_OFFSET:        449 [pixels]
Y_OFFSET:        243 [pixels]
X_MAX:           1888 [pixels]
Y_MAX:           1682 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00737125000msufc508111308.fits
SUN_POSTN:       320.76d {+21h 23m 02s}  -15.34d {-15d 20' 07"}
SUN_DIST:         55.14 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       84.55d {+05h 38m 13s}  +18.48d {+18d 28' 50"}
MOON_DIST:       149.39 [deg]
MOON_ILLUM:      80 [%]
GAL_COORDS:       38.12, 14.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      272.10, 34.67 [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:     Mon 06 Feb 17 22:11:42 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     737125,   Seg_Num: 0
POINT_RA:        271.761d {+18h 07m 03s} (J2000)
POINT_DEC:       +11.242d {+11d 14' 31"} (J2000)
ROLL:            117.683d
IMG_START_DATE:  17790 TJD;    37 DOY;   17/02/06
IMG_START_TIME:  79308.93 SOD {22:01:48.93} UT
FILTER:          7, U
EXPOSURE_ID:     508111327
X_OFFSET:        1008 [pixels]
Y_OFFSET:        802 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1168
Y_GRB_POS:       962
BINNING_INDEX:   1
IM_URL:          sw00737125000msuni508111327.fits
SUN_POSTN:       320.76d {+21h 23m 02s}  -15.34d {-15d 20' 06"}
SUN_DIST:         55.15 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       84.56d {+05h 38m 15s}  +18.48d {+18d 28' 53"}
MOON_DIST:       149.39 [deg]
MOON_ILLUM:      80 [%]
GAL_COORDS:       38.12, 14.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      272.10, 34.67 [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:     Mon 06 Feb 17 22:11:59 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     737125,   Seg_Num: 0
POINT_RA:        271.761d {+18h 07m 03s} (J2000)
POINT_DEC:       +11.242d {+11d 14' 31"} (J2000)
ROLL:            117.683d
IMG_START_DATE:  17790 TJD;    37 DOY;   17/02/06
IMG_START_TIME:  79308.93 SOD {22:01:48.93} UT
FILTER:          7, U
EXPOSURE_ID:     508111327
X_OFFSET:        1008 [pixels]
Y_OFFSET:        802 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1168
Y_GRB_POS:       962
BINNING_INDEX:   1
IM_URL:          sw00737125000msuni508111327.fits
SUN_POSTN:       320.76d {+21h 23m 02s}  -15.34d {-15d 20' 06"}
SUN_DIST:         55.15 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       84.57d {+05h 38m 16s}  +18.48d {+18d 28' 53"}
MOON_DIST:       149.39 [deg]
MOON_ILLUM:      80 [%]
GAL_COORDS:       38.12, 14.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      272.10, 34.67 [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:     Mon 06 Feb 17 22:18:48 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     737125,   Seg_Num: 0
POINT_RA:        271.761d {+18h 07m 03s} (J2000)
POINT_DEC:       +11.242d {+11d 14' 32"} (J2000)
POINT_ROLL:      117.683d
IMG_START_DATE:  17790 TJD;    37 DOY;   17/02/06
IMG_START_TIME:  79910.16 SOD {22:11:50.16} UT
FILTER:          10, White
BKG_MEAN:        5.466
N_STARS:         190
X_OFFSET:        449 [pixels]
Y_OFFSET:        243 [pixels]
X_MAX:           1888 [pixels]
Y_MAX:           1682 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw00737125000msufc508111910.fits
SUN_POSTN:       320.76d {+21h 23m 03s}  -15.33d {-15d 20' 01"}
SUN_DIST:         55.15 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       84.64d {+05h 38m 33s}  +18.49d {+18d 29' 11"}
MOON_DIST:       149.40 [deg]
MOON_ILLUM:      80 [%]
GAL_COORDS:       38.12, 14.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      272.10, 34.67 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 06 Feb 17 22:19:08 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     737125,   Seg_Num: 0
POINT_RA:        271.761d {+18h 07m 03s} (J2000)
POINT_DEC:       +11.242d {+11d 14' 32"} (J2000)
POINT_ROLL:      117.683d
IMG_START_DATE:  17790 TJD;    37 DOY;   17/02/06
IMG_START_TIME:  79910.16 SOD {22:11:50.16} UT
FILTER:          10, White
BKG_MEAN:        5.466
N_STARS:         190
X_OFFSET:        449 [pixels]
Y_OFFSET:        243 [pixels]
X_MAX:           1888 [pixels]
Y_MAX:           1682 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw00737125000msufc508111910.fits
SUN_POSTN:       320.76d {+21h 23m 03s}  -15.33d {-15d 20' 01"}
SUN_DIST:         55.15 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       84.64d {+05h 38m 34s}  +18.49d {+18d 29' 12"}
MOON_DIST:       149.40 [deg]
MOON_ILLUM:      80 [%]
GAL_COORDS:       38.12, 14.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      272.10, 34.67 [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:     Mon 06 Feb 17 22:20:58 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     737125,   Seg_Num: 0
POINT_RA:        271.761d {+18h 07m 03s} (J2000)
POINT_DEC:       +11.242d {+11d 14' 32"} (J2000)
ROLL:            117.683d
IMG_START_DATE:  17790 TJD;    37 DOY;   17/02/06
IMG_START_TIME:  79910.16 SOD {22:11:50.16} UT
FILTER:          10, White
EXPOSURE_ID:     508111928
X_OFFSET:        1008 [pixels]
Y_OFFSET:        802 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1168
Y_GRB_POS:       962
BINNING_INDEX:   1
IM_URL:          sw00737125000msuni508111929.fits
SUN_POSTN:       320.76d {+21h 23m 04s}  -15.33d {-15d 20' 00"}
SUN_DIST:         55.15 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       84.66d {+05h 38m 39s}  +18.49d {+18d 29' 17"}
MOON_DIST:       149.41 [deg]
MOON_ILLUM:      80 [%]
GAL_COORDS:       38.12, 14.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      272.10, 34.67 [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:     Mon 06 Feb 17 22:21:08 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     737125,   Seg_Num: 0
POINT_RA:        271.761d {+18h 07m 03s} (J2000)
POINT_DEC:       +11.242d {+11d 14' 32"} (J2000)
ROLL:            117.683d
IMG_START_DATE:  17790 TJD;    37 DOY;   17/02/06
IMG_START_TIME:  79910.16 SOD {22:11:50.16} UT
FILTER:          10, White
EXPOSURE_ID:     508111928
X_OFFSET:        1008 [pixels]
Y_OFFSET:        802 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1168
Y_GRB_POS:       962
BINNING_INDEX:   1
IM_URL:          sw00737125000msuni508111929.fits
SUN_POSTN:       320.77d {+21h 23m 04s}  -15.33d {-15d 20' 00"}
SUN_DIST:         55.15 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:       84.66d {+05h 38m 39s}  +18.49d {+18d 29' 17"}
MOON_DIST:       149.41 [deg]
MOON_ILLUM:      80 [%]
GAL_COORDS:       38.12, 14.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      272.10, 34.67 [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 #20618
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), A. Cholden-Brown (PSU), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), B. Mingo (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU) and E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift Team:
At 21:57:25 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170206B (trigger=737125). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 271.786, +11.223, which is
```
  RA(J2000) = 18h 07m 09s
  Dec(J2000) = +11d 13' 23"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). Due to a processing outage, the real-time light curve is not available at this time.
Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 271.7708, 11.1943 which is equivalent to:
```
   RA(J2000)  = 18h 07m 04.98s
   Dec(J2000) = +11d 11' 39.4"
```
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (1.13 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 2.8 (+2.82/-2.42) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 250 seconds with the U filter. 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 18.0 mag. No correction has been made for the expected extinction of E(B-V) = 0.146.
Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT nasa.gov). 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 #20619
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using 1338 s of XRT Photon Counting mode data and 1 UVOT image, 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 = 271.77061, 11.19366 which is equivalent to:
```
RA (J2000):  18 07 04.95
Dec (J2000): +11 11 37.2       
```
with an uncertainty of 1.9 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 is an official product of the Swift-XRT team.
GCN Circular #20620
S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB) and A.Y. Lien report on behalf of the Swift-XRT team:
We have analysed 7.4 ks of XRT data for GRB 170206B (Lien et al. GCN Circ. 20618), from 88 s to 24.5 ks after the BAT trigger. The data comprise 7 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. Using 2057 s of PC mode data and 3 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 271.77062, +11.19383 which is equivalent to:
```
RA (J2000): 18h 07m 04.95s
Dec(J2000): +11d 11' 37.8"
```
with an uncertainty of 1.6 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay index of alpha=2.48 (+0.19, -0.20).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.46 (+0.18, -0.17). The best-fitting absorption column is 4.9 (+0.8, -0.7) x 10^21 cm^-2, in excess of the Galactic value of 1.1 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.1 x 10^-11 (6.9 x 10^-11) erg cm^-2 count^-1.
A summary of the WT-mode spectrum is thus:
```
Total column:        4.9 (+0.8, -0.7) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 8.5 sigma
Photon index:        2.46 (+0.18, -0.17)
```
If the light curve continues to decay with a power-law decay index of 2.48, the count rate at T+24 hours will be 2.5 x 10^-7 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.8 x 10^-18 (1.8 x 10^-17) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00737125.
This circular is an official product of the Swift-XRT team.
GCN Circular #20622
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), 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-239 to T+359 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170206B (trigger #737125) (Lien et al., GCN Circ. 20618). The BAT ground-calculated position is RA, Dec = 271.784, 11.175 deg which is
```
   RA(J2000)  =  18h 07m 08.2s
   Dec(J2000) = +11d 10' 28.3"
```
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 78%.
The mask-weighted light curve shows a weak pulse that starts at ~T0 and ends at ~T+15 s. T90 (15-350 keV) is 13.36 +- 2.67 sec (estimated error including systematics).
The time-averaged spectrum from T-0.33 to T+15.53 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.42 +- 0.27. The fluence in the 15-150 keV band is 3.2 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.32 sec in the 15-150 keV band is 0.4 +- 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/737125/BA/
GCN Circular #20626
S.W.K. Emery (UCL-MSSL) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170206B 106 s after the BAT trigger (Lien et al., GCN Circ. 20618). No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 20619) 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           106          255          147         >20.3
u_FC               264          513          246         >19.6
white              106         1534          392         >20.7
v                  594         1411           97         >18.2
b                  519         1510           97         >19.1
u                  226         1484          343         >19.7
w1                 643         1460           97         >18.6
w2                 569         1386           97         >19.1
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.146 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #20787
K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender (Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)
The AMI Large Array observed the Swift GRB 170206B (Lien et al., GCN 20618) as part of the 4pisky program; follow up observations were obtained up to 10 days post-burst. Our observations at 15 GHz on 2016 Feb 08.37, Feb 09.38, Feb 14.43 and Feb 15.46 (UT) do not reveal any radio source at the XRT location (Evans et al., GCN 20619), with 3sigma upper limits of 123 uJy, 108 uJy, 108 uJy and 108 uJy respectively.
We thank the AMI staff for scheduling these observations. The AMI-GRB database is a log of all GRB follow up observations with the AMI, and is available at http://4pisky.org/ami-grb/.

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Jochen Greiner, last update: 01-Mar-2017 [Disclaimer]