Gamma-ray Burst 131218A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Wed 18 Dec 13 21:05:42 UT
NOTICE_TYPE:    INTEGRAL Wakeup
TRIGGER_NUM:    6409,   Sub_Num: 0
GRB_RA:         113.8247d {+07h 35m 18s} (J2000),
                113.8530d {+07h 35m 25s} (current),
                113.7221d {+07h 34m 53s} (1950)
GRB_DEC:        -64.7120d {-64d 42' 42"} (J2000),
                -64.7434d {-64d 44' 35"} (current),
                -64.5997d {-64d 35' 58"} (1950)
GRB_ERROR:      3.08 [arcmin, radius, statistical only]
GRB_INTEN:      9.56 [sigma]
GRB_TIME:       75936.40 SOD {21:05:36.40} UT
GRB_DATE:       16644 TJD;   352 DOY;   13/12/18
SC_RA:           91.08 [deg] (J2000)
SC_DEC:         -69.65 [deg] (J2000)
SUN_POSTN:      266.85d {+17h 47m 25s}  -23.41d {-23d 24' 19"}
SUN_DIST:        89.41 [deg]   Sun_angle= 10.2 [hr] (West of Sun)
MOON_POSTN:     103.99d {+06h 55m 58s}  +18.11d {+18d 06' 39"}
MOON_DIST:       83.20 [deg]
GAL_COORDS:     276.45,-19.88 [deg] galactic lon,lat of the burst
ECL_COORDS:     180.38,-80.06 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Time_Scale=10.0000 and Time_Error=10.0000.  
COMMENTS:       Possibly real GRB event

red DSS finding chart ps-file

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Wed 18 Dec 13 21:08:41 UT
NOTICE_TYPE:    INTEGRAL Refined
TRIGGER_NUM:    6409,   Sub_Num: 1
GRB_RA:         113.8004d {+07h 35m 12s} (J2000),
                113.8287d {+07h 35m 19s} (current),
                113.6979d {+07h 34m 47s} (1950)
GRB_DEC:        -64.7095d {-64d 42' 33"} (J2000),
                -64.7409d {-64d 44' 26"} (current),
                -64.5974d {-64d 35' 50"} (1950)
GRB_ERROR:      2.78 [arcmin, radius, statistical only]
GRB_INTEN:      13.90 [sigma]
GRB_TIME:       75951.40 SOD {21:05:51.40} UT
GRB_DATE:       16644 TJD;   352 DOY;   13/12/18
SC_RA:           91.08 [deg] (J2000)
SC_DEC:         -69.65 [deg] (J2000)
SUN_POSTN:      266.86d {+17h 47m 25s}  -23.41d {-23d 24' 19"}
SUN_DIST:        89.41 [deg]   Sun_angle= 10.2 [hr] (West of Sun)
MOON_POSTN:     104.02d {+06h 56m 04s}  +18.11d {+18d 06' 27"}
MOON_DIST:       83.19 [deg]
GAL_COORDS:     276.44,-19.88 [deg] galactic lon,lat of the burst
ECL_COORDS:     180.34,-80.07 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Time_Scale=20.0000 and Time_Error=20.0000.  
COMMENTS:       Possibly real GRB event

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Wed 18 Dec 13 22:08:14 UT
NOTICE_TYPE:    INTEGRAL Offline
TRIGGER_NUM:    6409,   Sub_Num: 2
GRB_RA:         113.7806d {+07h 35m 07s} (J2000),
                113.8086d {+07h 35m 14s} (current),
                113.6787d {+07h 34m 43s} (1950)
GRB_DEC:        -64.7371d {-64d 44' 13"} (J2000),
                -64.7685d {-64d 46' 06"} (current),
                -64.6251d {-64d 37' 29"} (1950)
GRB_ERROR:      1.80 [arcmin, radius, statistical only]
GRB_INTEN:      13.90 [sigma]
GRB_TIME:       75951.40 SOD {21:05:51.40} UT
GRB_DATE:       16644 TJD;   352 DOY;   13/12/18
SC_RA:           91.08 [deg] (J2000)
SC_DEC:         -69.65 [deg] (J2000)
SUN_POSTN:      266.90d {+17h 47m 36s}  -23.41d {-23d 24' 22"}
SUN_DIST:        89.40 [deg]   Sun_angle= 10.2 [hr] (West of Sun)
MOON_POSTN:     104.53d {+06h 58m 07s}  +18.04d {+18d 02' 34"}
MOON_DIST:       83.12 [deg]
GAL_COORDS:     276.47,-19.90 [deg] galactic lon,lat of the burst
ECL_COORDS:     180.47,-80.09 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Time_Scale=20.0000 and Time_Error=20.0000.  
COMMENTS:       refined_coordinates_after_offline_analysis

GCN Circular #15601
D. Gotz (CEA Saclay), S. Mereghetti (IASF-Milano), E. Bozzo, C. Ferrigno, R. Farinelli, (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report:
a gamma ray burst lasting about 6 s has been detected by IBAS in the IBIS/ISGRI data at 21:05:32 U.T. on December 18. Its refined coordinates (J2000) are:
```
  R.A.: 113.7807 deg
  DEC.: -64.7373 deg
```
with an uncertainty of 1.8 arc min (90% c.l.).
A preliminary estimation of the burst fluence is 5x10^-7 erg/cmsq in the 20-200 keV energy band.
A plot of the light curve will be posted at http://ibas.iasf-milano.inaf.it/IBAS_Results.html
GCN Circular #15602
Klotz A., Turpin D. (IRAP-CNRS-OMP), Gendre B., Boer M., Siellez K., Dereli H., Bardho O. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:
We imaged the field of GRB 131218A detected by INTEGRAL (trigger 6409) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile.
The observations started 3.41h after the GRB trigger which occured during day. The elevation of the field increased from 26 degrees above horizon and weather conditions were good.
We co-added a series of exposures but we do not detect any OT with a limiting magnitude of:
t0+3.41h to t0+4.98h : Rlim = 19.6
Magnitudes were estimated with the nearby NOMAD1 stars and are not corrected for galactic dust extinction.
N.B. Galactic coordinates are lon=276.4490 lat=-19.8751 and the galactic extinction in R band is about 0.4 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S.
This message may be cited.
GCN Circular #15603
A. Klotz (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. Coward (UWA), B. Gendre, M. Boer, K. Siellez, H. Dereli , O. Bardho (UNS-CNRS-OCA), A. Williams (PO-UWA), R. Martin (PO-UWA), D. Turpin (IRAP-CNRS-OMP) report:
We imaged the field of GRB 131218A detected by INTEGRAL (trigger 6409) with the Zadko robotic telescope (D=100cm) located at the observatory - Gingin, Australia.
The observations are R filtered, started 0.87 day after the GRB trigger. The limiting magnitude of the co added image is Rlim = 20.5.
In the error box provided by INTEGRAL notice we detect only one faint candidate not present on the DSS atlas:
```
RA(J2000.0) = 07h 35m 10.50s
DEC(J2000.0) = -64d 43' 19.4"
```
OT was R~20.0 0.87 day after GRB.
We have no more images so we cannnot conclude if it is a fading source or not. Additional images are programmed to be recorded in the next nights.
GCN Circular #15605
V. D'Elia (ASDC) and F.E. Marshall (NASA/GSFC) report on behalf of the Swift team:
We report on Swift observations of the field of the INTEGRAL discovered GRB131218A (Gotz et al. GCN Circ 15601), starting 17.5 hours after the trigger. Due to an observing constraint, only a very short exposure was carried out.
XRT began observing the field on 2013-12-19 at 14:32:15 UT, i.e., 62803 s after the trigger, for a total of 99 s. No source is detected within the INTEGRAL error circle. The 3-sigma upper limit on the count rate is ~9E-02 cts/s.
The Swift/UVOT began settled observations of the field of GRB 131218A 62782 s after the trigger. No optical afterglow consistent with the optical position (Klotz et al., GCN Circ. 15603) is detected in the initial UVOT exposure. The preliminary 3-sigma upper limit using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposure is:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

v                62782        62900          116         >19.8
```
The magnitude in the table is not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.17 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #15606
D. A. Kann, M. Tanga (both MPE Garching), S. Klose, S. Schmidl (both TLS Tautenburg) and J. Greiner (MPE Garching) report on behalf of the GROND collaboration:
We observed the field of GRB 131218A (INTEGRAL-6409, Gotz et al., GCN #15601) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at La Silla Observatory (Chile).
A first series of observations (integration time 6750 sec in the optical, 5400 sec in the NIR, midtime 0.24 days after the trigger, seeing 1".0 and airmass 1.5) yield the following image depths (AB magnitudes):
```
g' > 24.6,
r' > 24.9,
i' > 24.5,
z' > 24.4,
J > 22.4,
H > 21.8, and
K > 20.8.
```
A second set of observations (integration time 3750 sec in the optical, 3000 sec in the NIR, midtime 2.31 days after the trigger, seeing 0".9 and airmass 1.3) yield somewhat deeper limits in the optical, while they are somewhat shallower in the NIR.
Image subtraction between these two epochs shows no evidence for variable sources, both in the INTEGRAL error circle and around it, and therefore we can only place upper limits on the presence of any afterglow.
Magnitudes are calibrated against GROND zeropoints (g'r'i'z') and 2MASS stars (JHK), and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.17 mag in the direction of the burst (Schlegel et al. 1998).

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Jochen Greiner, last update: 22-Dec-2013 [Disclaimer]