Gamma-ray Burst 161224A

(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 24 Dec 16 22:14:59 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     728268,   Seg_Num: 0
GRB_RA:          204.825d {+13h 39m 18s} (J2000),
                 205.055d {+13h 40m 13s} (current),
                 204.147d {+13h 36m 35s} (1950)
GRB_DEC:         -18.028d {-18d 01' 41"} (J2000),
                 -18.114d {-18d 06' 50"} (current),
                 -17.775d {-17d 46' 29"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1505 [image_cnts]
TRIGGER_DUR:     64.000 [sec] 
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:        17746 TJD;   359 DOY;   16/12/24
GRB_TIME:        80014.64 SOD {22:13:34.64} UT
GRB_PHI:         -13.31 [deg]
GRB_THETA:        44.04 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    10.73 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  +0  -5  +0 -43  +0 
SUN_POSTN:       273.87d {+18h 15m 28s}  -23.39d {-23d 23' 19"}
SUN_DIST:         63.98 [deg]   Sun_angle= 4.6 [hr] (West of Sun)
MOON_POSTN:      224.53d {+14h 58m 08s}  -11.97d {-11d 58' 24"}
MOON_DIST:        19.77 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      318.67, 43.38 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      209.56, -7.19 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
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 = 174.31,-10.78 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 24 Dec 16 22:17:34 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     728268,   Seg_Num: 0
GRB_RA:          204.825d {+13h 39m 18s} (J2000),
                 205.055d {+13h 40m 13s} (current),
                 204.147d {+13h 36m 35s} (1950)
GRB_DEC:         -18.028d {-18d 01' 41"} (J2000),
                 -18.114d {-18d 06' 50"} (current),
                 -17.775d {-17d 46' 29"} (1950)
GRB_DATE:        17746 TJD;   359 DOY;   16/12/24
GRB_TIME:        80014.64 SOD {22:13:34.64} UT
TRIGGER_INDEX:   20000
GRB_PHI:         -13.31 [deg]
GRB_THETA:        44.04 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     64.000 [sec] 
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    10.73 [sigma]
LC_URL:          sw00728268000msb.lc
SUN_POSTN:       273.87d {+18h 15m 28s}  -23.39d {-23d 23' 19"}
SUN_DIST:         63.98 [deg]   Sun_angle= 4.6 [hr] (West of Sun)
MOON_POSTN:      224.56d {+14h 58m 13s}  -11.98d {-11d 58' 44"}
MOON_DIST:        19.79 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      318.67, 43.38 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      209.56, -7.19 [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 = 174.31,-10.78 [deg].

GCN Circular #20337
T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), A. Cholden-Brown (PSU), 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), 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 161224A (trigger #728268) (Cholden-Brown et al., GCN Circ. 20335). The BAT ground-calculated position is RA, Dec = 204.820, -18.028 deg which is
```
   RA(J2000)  =  13h 39m 16.9s 
   Dec(J2000) = -18d 01' 41.7" 
```
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 48%.
The mask-weighted light curve shows a single pulse structure that starts at ~ T+12 s, peaks at ~T+33 s, and ends at ~T+65 s. T90 (15-350 keV) is 47.04 +- 12.12 sec (estimated error including systematics).
The time-averaged spectrum from T+12.46 to T+65.18 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index -0.21 +- 1.56, and Epeak of 34.5 +- 5.6 keV (chi squared 44.84 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is (8.2 +- 1.3) x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+32.88 sec in the 15-150 keV band is 0.8 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.21 +- 0.21 (chi squared 57.66 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/728268/BA/
GCN Circular #20338
A. Cholden-Brown (PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
We have analysed 4.9 ks of XRT data for GRB 161224A, from 28.3 ks to 52.2 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. A fading X-ray source is found in the BAT error region. Using 617 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 = 204.81579, -18.02909 which is equivalent to:
```
RA (J2000): 13h 39m 15.79s
Dec(J2000): -18d 01' 44.7"
```
with an uncertainty of 4.1 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay index of alpha=2.8 (+0.8, -2.1).
If the light curve continues to decay with a power-law decay index of 2.8, the count rate at T+24 hours will be 8.4 x 10^-4 count s^-1
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00728268.
This circular is an official product of the Swift-XRT team.
GCN Circular #20339
N. P. M. Kuin (UCL-MSSL) and A. Cholden-Brown (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 161224A 28.3ks after the BAT trigger after a Sun constraint (Cholden-Brown et al., GCN Circ. 20335). At the position of the XRT source (Cholden-Brown and Evans, GCN Circ. 20338) no uv-optical source was found to the upper limits below.
Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter  T_start(s) T_stop(s)  Exp(s)    Mag
u       44266.0    44786.3     508      >19.99
v       28322.2    50899.7    1770      >19.90
uvw1    35223.6    41032.4     786      >19.91
uvw2    46285.0    46772.6     480      >19.88
uvm2    29234.3    35216.6    1198      >20.48
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.096 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #20340
E. Mazaeva (IKI), I. Reva (Fesenkov Astrophysical Institute), A. Kusakin (Fesenkov Astrophysical Institute), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 161224A (Swift trigger=728268, Cholden-Brownet al., GCN 20333) with Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory. We obtained several images in R filter starting on Dec. 25 (UT) 00:13:31 and Dec. 25 (UT) 23:45:12. We do not detect any evident variable source in the BAT ground-calculated position (Ukwatta al., GCN 20337). Within enhanced XRT position (Cholden-Brownet al., GCN 20338) we not detected any source. Preliminary photometry of the field is following
```
Date       UT start   t-T0   Filter   Exp.   OT   Err.  UL
                       (mid, days)     (s)
2016-12-25 00:13:31   0.10201  R      16*180 n/d n/d   21.1
2016-12-25 23:45:12   1.07646  R      11*180 n/d n/d   20.7
```
Photometry is based on nearby USNO-B1.0 stars
```
0719-0341418 17.14
0720-0349085 17.50
0720-0348989 16.94
0719-0341338 15.94
```
A finding chart can be found in http://grb.rssi.ru/GRB161224A/GRB161224A_20161225_TSHAO_fc.png

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Jochen Greiner, last update: 26-Dec-2016 [Disclaimer]