Gamma-ray Burst 171211A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 11 Dec 17 09:27:53 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     796469,   Seg_Num: 0
GRB_RA:           98.108d {+06h 32m 26s} (J2000),
                  98.175d {+06h 32m 42s} (current),
                  97.920d {+06h 31m 41s} (1950)
GRB_DEC:         -58.670d {-58d 40' 10"} (J2000),
                 -58.684d {-58d 41' 00"} (current),
                 -58.631d {-58d 37' 50"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3298 [cnts]    Image_Peak=239 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   146     E_range: 25-100 keV
BKG_INTEN:       17476 [cnts]
BKG_TIME:        34035.86 SOD {09:27:15.86} UT
BKG_DUR:         8 [sec]
GRB_DATE:        18098 TJD;   345 DOY;   17/12/11
GRB_TIME:        34052.94 SOD {09:27:32.94} UT
GRB_PHI:          -2.17 [deg]
GRB_THETA:        39.58 [deg]
SOLN_STATUS:     0x2003
RATE_SIGNIF:     21.04 [sigma]
IMAGE_SIGNIF:    11.03 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  +0  +0  +0 +11  +0 
SUN_POSTN:       258.61d {+17h 14m 27s}  -23.02d {-23d 01' 23"}
SUN_DIST:         96.70 [deg]   Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN:      183.62d {+12h 14m 29s}   +2.37d {+02d 22' 07"}
MOON_DIST:        89.66 [deg]
MOON_ILLUM:      39 [%]
GAL_COORDS:      267.95,-25.33 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      118.96,-81.29 [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:        There is a bright star (mag=5.70) 6.21 arcmin from this position.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 248.96,14.71 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 11 Dec 17 09:29:10 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     796469,   Seg_Num: 0
POINT_RA:         98.096d {+06h 32m 23s} (J2000)
POINT_DEC:       -58.677d {-58d 40' 36"} (J2000)
IMG_START_DATE:  18098 TJD;   345 DOY;   17/12/11
IMG_START_TIME:  34144.79 SOD {09:29:04.79} UT,   91.8 [sec] since BAT Trigger Time
COUNTS:          15    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:     Mon 11 Dec 17 09:31:19 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     796469,   Seg_Num: 0
GRB_RA:           98.108d {+06h 32m 26s} (J2000),
                  98.175d {+06h 32m 42s} (current),
                  97.920d {+06h 31m 41s} (1950)
GRB_DEC:         -58.670d {-58d 40' 10"} (J2000),
                 -58.684d {-58d 41' 00"} (current),
                 -58.631d {-58d 37' 50"} (1950)
GRB_DATE:        18098 TJD;   345 DOY;   17/12/11
GRB_TIME:        34052.94 SOD {09:27:32.94} UT
TRIGGER_INDEX:   146
GRB_PHI:          -2.17 [deg]
GRB_THETA:        39.58 [deg]
DELTA_TIME:      51.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x2003
RATE_SIGNIF:     21.04 [sigma]
IMAGE_SIGNIF:    11.03 [sigma]
LC_URL:          sw00796469000msb.lc
SUN_POSTN:       258.61d {+17h 14m 27s}  -23.02d {-23d 01' 24"}
SUN_DIST:         96.70 [deg]   Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN:      183.65d {+12h 14m 36s}   +2.36d {+02d 21' 30"}
MOON_DIST:        89.67 [deg]
MOON_ILLUM:      39 [%]
GAL_COORDS:      267.95,-25.33 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      118.96,-81.29 [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:        There is a bright star (mag=5.70) 6.21 arcmin from this position.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 248.96,14.71 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 11 Dec 17 09:32:53 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     796469,   Seg_Num: 0
GRB_RA:           98.1323d {+06h 32m 31.75s} (J2000),
                  98.1996d {+06h 32m 47.89s} (current),
                  97.9447d {+06h 31m 46.72s} (1950)
GRB_DEC:         -58.6920d {-58d 41' 31.2"} (J2000),
                 -58.7062d {-58d 42' 22.2"} (current),
                 -58.6531d {-58d 39' 11.0"} (1950)
GRB_ERROR:       4.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18098 TJD;   345 DOY;   17/12/11
IMG_START_TIME:  34175.00 SOD {09:29:35.00} UT,   122.1 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       258.62d {+17h 14m 28s}  -23.02d {-23d 01' 24"}
SUN_DIST:         96.67 [deg]   Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN:      183.66d {+12h 14m 39s}   +2.35d {+02d 21' 13"}
MOON_DIST:        89.66 [deg]
MOON_ILLUM:      39 [%]
GAL_COORDS:      267.98,-25.32 [deg] galactic lon,lat of the burst
ECL_COORDS:      119.09,-81.30 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        There is a bright star (mag=5.70) 5.71 arcmin from the XRT position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN Circular #22234
J.D. Gropp (PSU), A. P. Beardmore (U Leicester), A. A. Breeveld (UCL-MSSL), P. D'Avanzo (INAF-OAB), P. A. Evans (U Leicester), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC) and K. L. Page (U Leicester) report on behalf of the Swift Team:
At 09:27:32 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 171211A (trigger=796469). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 98.108, -58.670 which is
```
   RA(J2000) = 06h 32m 26s
   Dec(J2000) = -58d 40' 10"
```
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 3 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 09:29:04.7 UT, 91.9 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 98.13327, -58.69205 which is equivalent to:
```
   RA(J2000)  = 06h 32m 31.98s
   Dec(J2000) = -58d 41' 31.4"
```
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 92 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 http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 8.89 x 10^20 cm^-2 (Willingale et al. 2013).
There is no UVOT data available because of a bright source in the field of view.
Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu). 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:     Mon 11 Dec 17 09:54:14 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     796469,   Seg_Num: 0
GRB_RA:           98.1337d {+06h 32m 32.08s} (J2000),
                  98.2010d {+06h 32m 48.23s} (current),
                  97.9461d {+06h 31m 47.05s} (1950)
GRB_DEC:         -58.6919d {-58d 41' 30.8"} (J2000),
                 -58.7061d {-58d 42' 21.9"} (current),
                 -58.6530d {-58d 39' 10.6"} (1950)
GRB_ERROR:       3.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18098 TJD;   345 DOY;   17/12/11
IMG_START_TIME:  34175.00 SOD {09:29:35.00} UT,   122.1 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       258.63d {+17h 14m 32s}  -23.02d {-23d 01' 28"}
SUN_DIST:         96.67 [deg]   Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN:      183.84d {+12h 15m 23s}   +2.29d {+02d 17' 21"}
MOON_DIST:        89.70 [deg]
MOON_ILLUM:      39 [%]
GAL_COORDS:      267.98,-25.32 [deg] galactic lon,lat of the burst
ECL_COORDS:      119.10,-81.30 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        There is a bright star (mag=5.70) 5.75 arcmin from the XRT position.  
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:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN Circular #22236
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 1720 s of XRT Photon Counting mode data and 2 UVOT images for GRB 171211A, 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 = 98.13542, -58.69209 which is equivalent to:
```
RA (J2000): 06h 32m 32.50s
Dec (J2000): -58d 41' 31.5"
```
with an uncertainty of 2.8 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 #22239
S.W.K. Emery (UCL-MSSL) and J. D. Gropp (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 171211A 362 s after the BAT trigger (Gropp et al., GCN Circ. 22234). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 22236) 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

v                    387         6321          491         >19.0
uvw1                 436         6731          491         >19.7
uvm2                5503         6526          393         >19.9
uvw2                 362         6939          668         >20.2
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.11 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #22240
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU) and J.D. Gropp report on behalf of the Swift-XRT team:
We have analysed 7.4 ks of XRT data for GRB 171211A (Gropp et al. GCN Circ. 22234), from 77 s to 24.5 ks after the BAT trigger. The data comprise 33 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 22236).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.28 (+0.08, -0.07).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.60 (+0.27, -0.23). The best-fitting absorption column is 1.3 (+1.0, -0.4) x 10^21 cm^-2, consistent with the Galactic value of 8.9 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 4.3 x 10^-11 (4.9 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.3 (+1.0, -0.4) x 10^21 cm^-2
Galactic foreground: 8.9 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.60 (+0.27, -0.23)
```
If the light curve continues to decay with a power-law decay index of 1.28, the count rate at T+24 hours will be 6.6 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.8 x 10^-14 (3.3 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00796469.
This circular is an official product of the Swift-XRT team.
GCN Circular #22241
H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), J. D. Gropp (PSU), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), J. P. Norris (BSU), 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-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 171211A (trigger #796469) (Gropp et al., GCN Circ. 22234). The BAT ground-calculated position is RA, Dec = 98.154, -58.689 deg which is
```
  RA(J2000)  =  06h 32m 36.9s
  Dec(J2000) = -58d 41' 19.0"
```
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 57%.
The mask-weighted light curve shows a single-peaked structure that starts and peaks at ~ T0, and ends at ~T+3 s. T90 (15-350 keV) is 2.32 +- 0.59 sec (estimated error including systematics).
The time-averaged spectrum from T+0.03 to T+2.70 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.77 +- 0.21. The fluence in the 15-150 keV band is 2.4 +- 0.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.03 sec in the 15-150 keV band is 2.3 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The duration and hardness of this burst show it to be intermediate between the short and long burst populations.
Using a 64-ms binned light curve, the lag analysis finds a lag of 0.144 (+0.106, -0.066) s for the 50-100 keV to 15-25 keV band. Despite the large error bars due to the weakness of this burst, this value is more consistent with those of a long GRB.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/796469/BA/
GCN Circular #22250
Y. Kitaoka, T. Sakamoto (AGU)
We observed the field of GRB 171211A detected by Swift (Gropp et al., GCN Circ. 22234) with the iTelescope.Net (http://www.itelescope.net) T27 (Planewave 27") telescope located at the AstroCamp Observatory (Siding Spring Observatory, AU). 8 images of 60 sec exposures were taken in the I filter starting from December 11 on 11:41:37 (UT) about 134 minutes after the trigger and stopped on 11:54:45 (UT). We do not detect the optical afterglow both in the individual images and the stacked image at the X-ray afterglow position. The estimated five sigma upper limit of the combined image (total exposure of 480 sec) is ~17.2 using the USNO-B1 catalog.

Back to JG's homepage

Jochen Greiner, last update: 13-Dec-2017 [Disclaimer]