Gamma-ray Burst 161223A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 23 Dec 16 19:11:18 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     728094,   Seg_Num: 0
GRB_RA:          259.877d {+17h 19m 31s} (J2000),
                 260.138d {+17h 20m 33s} (current),
                 259.109d {+17h 16m 26s} (1950)
GRB_DEC:         -25.010d {-25d 00' 36"} (J2000),
                 -25.027d {-25d 01' 35"} (current),
                 -24.960d {-24d 57' 33"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=2877 [image_cnts]
TRIGGER_DUR:     496.000 [sec]   (=8.3 [min])
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        17745 TJD;   358 DOY;   16/12/23
GRB_TIME:        68486.64 SOD {19:01:26.64} UT
GRB_PHI:         -102.88 [deg]
GRB_THETA:        38.13 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.65 [sigma]
MERIT_PARAMS:     +1  +0  +0  +8  +1  -2 -100  +1 -97  +0 
SUN_POSTN:       272.62d {+18h 10m 28s}  -23.41d {-23d 24' 52"}
SUN_DIST:         11.49 [deg]   Sun_angle= 0.8 [hr] (West of Sun)
MOON_POSTN:      211.54d {+14h 06m 10s}   -8.30d {-08d 18' 00"}
MOON_DIST:        49.15 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:        0.13,  7.01 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      260.83, -1.89 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger integration interval;  
COMMENTS:        probably due to it occurring during a Malindi downlink session.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
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 = 230.16,-10.54 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 23 Dec 16 19:13:39 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     728094,   Seg_Num: 0
GRB_RA:          259.877d {+17h 19m 31s} (J2000),
                 260.138d {+17h 20m 33s} (current),
                 259.109d {+17h 16m 26s} (1950)
GRB_DEC:         -25.010d {-25d 00' 36"} (J2000),
                 -25.027d {-25d 01' 35"} (current),
                 -24.960d {-24d 57' 33"} (1950)
GRB_DATE:        17745 TJD;   358 DOY;   16/12/23
GRB_TIME:        68486.64 SOD {19:01:26.64} UT
TRIGGER_INDEX:   20000
GRB_PHI:         -102.88 [deg]
GRB_THETA:        38.13 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     496.000 [sec]   (=8.3 [min])
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.65 [sigma]
LC_URL:          sw00728094000msb.lc
SUN_POSTN:       272.62d {+18h 10m 28s}  -23.41d {-23d 24' 52"}
SUN_DIST:         11.49 [deg]   Sun_angle= 0.8 [hr] (West of Sun)
MOON_POSTN:      211.56d {+14h 06m 14s}   -8.31d {-08d 18' 21"}
MOON_DIST:        49.13 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:        0.13,  7.01 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      260.83, -1.89 [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 an image 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 = 230.16,-10.54 [deg].  
COMMENTS:        This lightcurve contains more than 50 illegal values -- probably an empty lightcurve.  
COMMENTS:        So the FITS file will have empty/missing rows -- possibly all rows will be missing.  
COMMENTS:        One explanation is a long Image-trigger(>~10min); another is corrupted tlm.

GCN Circular #20333
A. Cholden-Brown (PSU), S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), M. H. Siegel (PSU) and T. N. Ukwatta (LANL) report on behalf of the Swift Team:
At 19:01:26 UT, the Swift Burst Alert Telescope (BAT) triggered and located a possible source (trigger=728094). Swift slewed immediately to the location. The BAT on-board calculated location is RA, Dec 259.877, -25.010 which is
```
   RA(J2000)  =  17h 19m 31s
   Dec(J2000) = -25d 00' 36"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). Because of the duration of the image trigger (8.3 minutes) no BAT lightcurve data is immediately available.
Due to a Sun observing constraint, Swift cannot slew to the BAT position until 13:22 UT on 2017 January 27. There will thus be no XRT or UVOT data for this trigger before this time.
Since this is a long image trigger and we have no BAT light curve information nor do we have any XRT and UVOT data because of the Sun constraint, all we can say at this time is that it is about equal probability that it is noise (image significance is 7.6 sigma), or a GRB, or another type of astrophysical source. We note that it is ~7 deg from the Galactic Center.
Burst Advocate for this burst is A. Cholden-Brown (aaronb AT swift.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 Circular #20336
M. Stamatikos (OSU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), 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 trigger #728094 (Cholden-Brown, et al., GCN Circ. 20333). The BAT ground-calculated position is RA, Dec = 259.877, -25.010 deg which is
```
   RA(J2000)  =  17h 19m 30.5s 
   Dec(J2000) = -25d 00' -37.4" 
```
with an uncertainty of 3.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 12%.
The mask-weighted light curve is featureless, with a hint of some weak emission throughout the duration when the source was in the BAT field of view from ~T-39.0 to ~T+644.0 sec. However, the very low significance (5.7 sigma) suggests that this might be due to noise fluctuation. With the lack of afterglow observations because of the Sun constraint, it remains difficult to determine the source nature.
The time-averaged spectrum from T-39.0 to T+644.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.70 +- 0.20. The fluence in the 15-150 keV band is 7.5 +- 1.0 x 10^-6 erg/cm2. 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/728094/BA/

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Jochen Greiner, last update: 23-Dec-2016 [Disclaimer]