Gamma-ray Burst 091230

(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 30 Dec 09 06:27:55 UT
NOTICE_TYPE:    INTEGRAL Wakeup
TRIGGER_NUM:    5967,   Sub_Num: 0
GRB_RA:         132.9634d {+08h 51m 51s} (J2000),
                133.0356d {+08h 52m 09s} (current),
                132.6019d {+08h 50m 24s} (1950)
GRB_DEC:        -53.8817d {-53d 52' 53"} (J2000),
                -53.9197d {-53d 55' 10"} (current),
                -53.6926d {-53d 41' 33"} (1950)
GRB_ERROR:      3.20 [arcmin, radius, statistical only]
GRB_INTEN:      8.63 [sigma]
GRB_TIME:       23262.25 SOD {06:27:42.25} UT
GRB_DATE:       15195 TJD;   364 DOY;   09/12/30
SC_RA:          124.89 [deg] (J2000)
SC_DEC:         -47.24 [deg] (J2000)
SUN_POSTN:      279.45d {+18h 37m 49s}  -23.15d {-23d 09' 10"}
SUN_DIST:        97.66 [deg]   Sun_angle= 9.8 [hr] (West of Sun)
MOON_POSTN:      76.12d {+05h 04m 30s}  +25.73d {+25d 43' 50"}
MOON_DIST:       93.51 [deg]
GAL_COORDS:     272.08, -6.04 [deg] galactic lon,lat of the burst
ECL_COORDS:     169.50,-65.89 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Possibly real GRB event

red DSS finding chart ps-file

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Wed 30 Dec 09 06:30:54 UT
NOTICE_TYPE:    INTEGRAL Refined
TRIGGER_NUM:    5967,   Sub_Num: 1
GRB_RA:         132.9523d {+08h 51m 49s} (J2000),
                133.0245d {+08h 52m 06s} (current),
                132.5913d {+08h 50m 22s} (1950)
GRB_DEC:        -53.9148d {-53d 54' 52"} (J2000),
                -53.9527d {-53d 57' 09"} (current),
                -53.7257d {-53d 43' 32"} (1950)
GRB_ERROR:      3.12 [arcmin, radius, statistical only]
GRB_INTEN:      9.28 [sigma]
GRB_TIME:       23285.25 SOD {06:28:05.25} UT
GRB_DATE:       15195 TJD;   364 DOY;   09/12/30
SC_RA:          124.89 [deg] (J2000)
SC_DEC:         -47.24 [deg] (J2000)
SUN_POSTN:      279.45d {+18h 37m 49s}  -23.15d {-23d 09' 09"}
SUN_DIST:        97.64 [deg]   Sun_angle= 9.8 [hr] (West of Sun)
MOON_POSTN:      76.16d {+05h 04m 38s}  +25.73d {+25d 43' 53"}
MOON_DIST:       93.51 [deg]
GAL_COORDS:     272.10, -6.07 [deg] galactic lon,lat of the burst
ECL_COORDS:     169.54,-65.91 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:           
COMMENTS:        NOTE: This INTEGRAL event is spatially(0.00<0.1deg) and temporally(23.0<100sec) coincident with the INTEGRAL event (trignum=5967).  
COMMENTS:       Possibly real GRB event

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Wed 30 Dec 09 07:38:24 UT
NOTICE_TYPE:    INTEGRAL Offline
TRIGGER_NUM:    5967,   Sub_Num: 2
GRB_RA:         132.9146d {+08h 51m 40s} (J2000),
                132.9868d {+08h 51m 57s} (current),
                132.5534d {+08h 50m 13s} (1950)
GRB_DEC:        -53.8825d {-53d 52' 56"} (J2000),
                -53.9204d {-53d 55' 12"} (current),
                -53.6936d {-53d 41' 36"} (1950)
GRB_ERROR:      3.00 [arcmin, radius, statistical only]
GRB_INTEN:      9.28 [sigma]
GRB_TIME:       23285.25 SOD {06:28:05.25} UT
GRB_DATE:       15195 TJD;   364 DOY;   09/12/30
SC_RA:          124.89 [deg] (J2000)
SC_DEC:         -47.24 [deg] (J2000)
SUN_POSTN:      279.51d {+18h 38m 02s}  -23.15d {-23d 08' 58"}
SUN_DIST:        97.70 [deg]   Sun_angle= 9.8 [hr] (West of Sun)
MOON_POSTN:      76.92d {+05h 07m 40s}  +25.74d {+25d 44' 36"}
MOON_DIST:       93.15 [deg]
GAL_COORDS:     272.06, -6.06 [deg] galactic lon,lat of the burst
ECL_COORDS:     169.45,-65.90 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:           
COMMENTS:        NOTE: This INTEGRAL event is spatially(0.00<0.1deg) and temporally(23.0<100sec) coincident with the INTEGRAL event (trignum=5967).  
COMMENTS:       refined_coordinates_after_offline_analysis

GCN Circular #10298
D.Gotz (CEA-Saclay), S. Mereghetti, A.Paizis (IASF-Milano), E.Bozzo, L.Gibaud, C.Ferrigno, M. Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report:
A GRB with duration of about 120 s has been detected by IBAS in IBIS/ISGRI data at 06:27:30 UT on December 30.
The refined coordinates (J2000) are:
```
RA:  132.9146 [degrees]  
DEC: -53.8825  [degrees]
```
with an uncertainty of 2.5 arcmin (90% c.l.).
A plot of the light curve will be posted at
http://ibas.iasf-milano.inaf.it/IBAS_Results.html
This message can be cited.
GCN Circular #10299
R. Filgas, T. Kruehler and J. Greiner (all MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 091230 (INTEGRAL trigger #5967, D. Gotz et al., GCN #10298) simultaneously in g'r'i'z'JHK with GROND mounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile).
Observations started on 30 Dec. 2009 at 06:30:27 UT, 2.9 min after the burst.
Image subtraction reveals a variable point source inside the INTEGRAL error circle (D. Gotz et al., GCN #10298) at RA (J2000.0) = 08:51:39.18 DEC (J2000.0) = -53:53:52.7 with an uncertainty of 0.5" in each coordinate. This is 56" from the refined INTEGRAL position.
Preliminary photometry yields the following magnitudes in stacked images:
```
Filter  T_mid[s] Exp[s]  AB Mag  MagErr
---------------------------------------
g'      390       4x 66  21.63   0.07
r'      390       4x 66  20.76   0.04
i'      390       4x 66  20.45   0.05
z'      390       4x 66  20.22   0.05
J       403      24x 10  19.75   0.12
H       403      24x 10  19.58   0.14
K       403      24x 10  19.26   0.15
```
The quoted error is statistical only. There is an additional systematic error in the absolute calibration using the GROND zeropoints and 2MASS field stars which is expected to be in the 0.1 to 0.2 mag range.
The object fades by two magnitudes to r' =3D 22.8 =B1 0.1 until the end of our optical observations two hours after the trigger - thus we propose this object as the optical/NIR afterglow of GRB 091230.
GCN Circular #10300
A. P. Beardmore (U. Leicester) and H. A. Krimm (CRESST/GSFC/USRA) report on behalf of the Swift-XRT team:
At 2009-12-30 15:25UT Swift performed a TOO observation of the INTEGRAL discovered long GRB 091230 (Gotz et al., GCN Circ. 10298). In 3.7 ks of XRT Photon Counting (PC) mode data, taken from 32.3 ks to 39.4 ks after the INTEGRAL trigger, we find an X-ray source within the INTEGRAL error circle, with a 0.3-10 keV count rate of 0.01 count/s. Using 1096 s of PC mode data and 1 UVOT image, the enhanced XRT position for this source (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue, as described by Goad et al., 2007, A&A, 476, 1401 and Evans et al., 2009, MNRAS, 397, 1177) is: RA, Dec = 132.91150, -53.89780, which is equivalent to:
```
RA (J2000): 08 51 38.77
Dec(J2000): -53 53 52.0
```
with an uncertainty of 2.7 arcsec (radius, 90% confidence). This position lies 3.8 arcsec from the location of the Grond optical/NIR afterglow candidate (Filgas et al., GCN Circ. 10299).
At this stage, we cannot tell whether the X-ray source is fading, but its coincidence with the Grond candidate suggests it is likely the X-ray counterpart to GRB 091230.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020124.
This circular is an official product of the Swift-XRT team.
GCN Circular #10302
M. H. Siegel (PSU) and H. A. Krimm (CRESST/GSFC/USRA) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 091230 32291 s after the Integral detection (Gotz et al., GCN Circ. 10298). We do not detect the afterglow reported by GROND (Filgas et al., GCN Circ. 10299) and Swift-XRT (Beardmore et al., GCN Cic. 10300).
Preliminary 3-sigma upper limits are:
```
FILTER     T_start(s)  T_stop    Exposure     Mag/3UL
=============================================================
white      32291        42824     3898        >22.2
```
The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.36 (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627).

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Jochen Greiner, last update: 31-Dec-2009 [Disclaimer]