Gamma-ray Burst 070925

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Tue 25 Sep 07 15:53:16 UT
NOTICE_TYPE:    INTEGRAL Wakeup
TRIGGER_NUM:    4729,   Sub_Num: 0
GRB_RA:         253.1867d {+16h 52m 45s} (J2000),
                253.3024d {+16h 53m 13s} (current),
                252.4388d {+16h 49m 45s} (1950)
GRB_DEC:        -22.0206d {-22d 01' 13"} (J2000),
                -22.0330d {-22d 01' 58"} (current),
                -21.9383d {-21d 56' 17"} (1950)
GRB_ERROR:      3.12 [arcmin, radius, statistical only]
GRB_INTEN:      9.29 [sigma]
GRB_TIME:       57163.63 SOD {15:52:43.63} UT
GRB_DATE:       14368 TJD;   268 DOY;   07/09/25
SC_RA:          261.16 [deg] (J2000)
SC_DEC:         -27.84 [deg] (J2000)
SUN_POSTN:      182.02d {+12h 08m 05s}   -0.88d {-00d 52' 32"}
SUN_DIST:        72.35 [deg]   Sun_angle= -4.8 [hr] (East of Sun)
MOON_POSTN:     346.82d {+23h 07m 17s}   -4.75d {-04d 44' 51"}
MOON_DIST:       91.47 [deg]
GAL_COORDS:     358.95, 13.74 [deg] galactic lon,lat of the burst
ECL_COORDS:     254.44,  0.52 [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:    Tue 25 Sep 07 15:53:37 UT
NOTICE_TYPE:    INTEGRAL Refined
TRIGGER_NUM:    4729,   Sub_Num: 1
GRB_RA:         253.1988d {+16h 52m 48s} (J2000),
                253.3145d {+16h 53m 15s} (current),
                252.4510d {+16h 49m 48s} (1950)
GRB_DEC:        -22.0084d {-22d 00' 29"} (J2000),
                -22.0208d {-22d 01' 14"} (current),
                -21.9262d {-21d 55' 33"} (1950)
GRB_ERROR:      2.60 [arcmin, radius, statistical only]
GRB_INTEN:      22.60 [sigma]
GRB_TIME:       57173.63 SOD {15:52:53.63} UT
GRB_DATE:       14368 TJD;   268 DOY;   07/09/25
SC_RA:          261.16 [deg] (J2000)
SC_DEC:         -27.84 [deg] (J2000)
SUN_POSTN:      182.02d {+12h 08m 05s}   -0.88d {-00d 52' 32"}
SUN_DIST:        72.36 [deg]   Sun_angle= -4.8 [hr] (East of Sun)
MOON_POSTN:     346.83d {+23h 07m 18s}   -4.75d {-04d 44' 45"}
MOON_DIST:       91.46 [deg]
GAL_COORDS:     358.97, 13.74 [deg] galactic lon,lat of the burst
ECL_COORDS:     254.45,  0.53 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Possibly real GRB event

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Tue 25 Sep 07 15:56:17 UT
NOTICE_TYPE:    INTEGRAL Refined
TRIGGER_NUM:    4729,   Sub_Num: 2
GRB_RA:         253.1958d {+16h 52m 47s} (J2000),
                253.3115d {+16h 53m 15s} (current),
                252.4479d {+16h 49m 48s} (1950)
GRB_DEC:        -22.0101d {-22d 00' 35"} (J2000),
                -22.0225d {-22d 01' 20"} (current),
                -21.9279d {-21d 55' 39"} (1950)
GRB_ERROR:      2.60 [arcmin, radius, statistical only]
GRB_INTEN:      22.77 [sigma]
GRB_TIME:       57176.63 SOD {15:52:56.63} UT
GRB_DATE:       14368 TJD;   268 DOY;   07/09/25
SC_RA:          261.16 [deg] (J2000)
SC_DEC:         -27.84 [deg] (J2000)
SUN_POSTN:      182.02d {+12h 08m 06s}   -0.88d {-00d 52' 35"}
SUN_DIST:        72.36 [deg]   Sun_angle= -4.8 [hr] (East of Sun)
MOON_POSTN:     346.85d {+23h 07m 24s}   -4.73d {-04d 44' 00"}
MOON_DIST:       91.49 [deg]
GAL_COORDS:     358.96, 13.74 [deg] galactic lon,lat of the burst
ECL_COORDS:     254.45,  0.53 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Possibly real GRB event

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Tue 25 Sep 07 16:52:08 UT
NOTICE_TYPE:    INTEGRAL Offline
TRIGGER_NUM:    4729,   Sub_Num: 3
GRB_RA:         253.2178d {+16h 52m 52s} (J2000),
                253.3336d {+16h 53m 20s} (current),
                252.4699d {+16h 49m 53s} (1950)
GRB_DEC:        -22.0353d {-22d 02' 06"} (J2000),
                -22.0477d {-22d 02' 51"} (current),
                -21.9532d {-21d 57' 10"} (1950)
GRB_ERROR:      2.00 [arcmin, radius, statistical only]
GRB_INTEN:      22.77 [sigma]
GRB_TIME:       57176.63 SOD {15:52:56.63} UT
GRB_DATE:       14368 TJD;   268 DOY;   07/09/25
SC_RA:          261.16 [deg] (J2000)
SC_DEC:         -27.84 [deg] (J2000)
SUN_POSTN:      182.06d {+12h 08m 14s}   -0.89d {-00d 53' 29"}
SUN_DIST:        72.34 [deg]   Sun_angle= -4.8 [hr] (East of Sun)
MOON_POSTN:     347.35d {+23h 09m 25s}   -4.47d {-04d 28' 06"}
MOON_DIST:       92.04 [deg]
GAL_COORDS:     358.95, 13.71 [deg] galactic lon,lat of the burst
ECL_COORDS:     254.48,  0.50 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       refined_coordinates_after_offline_analysis

GCN Circular #6823
S.Mereghetti, A.Paizis (IASF-Milano), D.Gotz (CEA-Saclay), D.Petry, V.Beckmann, M. Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report:
A GRB lasting about 30 s has been detected by IBAS in IBIS/ISGRI data at 15:52:32 UT of September 25. The coordinates (J2000) are:
```
RA:  253.218 [degrees] 
DEC: -22.0355 [degrees]
```
with an uncertainty of 2 arcmin (90% c.l.).
The light curve is affected by gaps due to telemetry saturation. The peak flux in the 20-200 keV range is 2 ph/cmq/s (1-s integration time) and the fluence over the same energy range is larger than 2x10e-6 erg/cmq.
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 #6826
L. Vetere, J. L. Racusin (PSU) report on behalf of the Swift-XRT team:
We have analysed 2.5 ks of Swift XRT data for GRB 070925 (Mereghetti et al., GCN 6823) beginning 12 ks after the IBAS trigger. An uncatalogued X-ray source is clearly detected at RA, Dec= 253.21700, -22.02856 degrees, which is equivalent to:
```
RA (J2000) =  16h 52m 52.1s
Dec(J2000) = -22d 01' 41.0"
```
with an estimated uncertainty of 6.0 arcsec (radius, 90% containment including boresight uncertainty). This is 8 arcsec from the IBAS position (Mereghetti et al., GCN 6823) within its error circle. The source has a count rate of 1.6e-2 +/- 0.3e-2 counts s-1. At present we are unable to determine whether the source is fading, however observations are ongoing.
This circular is an official product of the Swift-XRT team.
GCN Circular #6827
J.S. Bloom (UC Berkeley), D. A. Perley (UC Berkeley), H.-W. Chen (U Chicago), an d J.X. Prochaska (UCO/Lick) report on behalf of a larger collaboration:
"We observed the field of GRB 070925 (Mereghetti et al., GCN 6823) in r-band with the Gemini South 8-m telescope for a total of 900 sec starting at 2007-09-26 00:00:59 UT. The stacked image has a mean seeing of ~ 1.0 arcsec. Within the XRT (Vetere et al. GCN 6826) there are two apparent binary systems, both apparent in DSS imaging (mid-points 16:52:52.5, -22:01:41 and 16:52:52.1, -22:01:41). We detect no other sources in the error circle to r~24.5.
This message may be cited. "
GCN Circular #6828
L. Vetere, C. Pagani (PSU) report on behalf of the Swift-XRT team:
Additional Swift-XRT observations have been performed of the possible X-ray afterglow of GRB 070925 (Vetere et al., GCN 6826). The count rate at T+72h is ~3e-3 counts/s. Between 1.3e4 and 1.4e5 seconds after the burst, the source has faded following a power-law decay slope of alpha = 1.2 +/- 0.3, confirming that it is, indeed, the afterglow. If the burst keeps decaying at the current rate the predicted count rate at T+96h is 5.6e-4 counts/s.
This circular is an official product of the Swift-XRT team.

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Jochen Greiner, last update: 27-Sep-2007 [Disclaimer]