Gamma-ray Burst 090625B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 25 Jun 09 13:26:37 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      44
TRIGGER_NUM:     267629184
GRB_RA:           19.400d {+01h 17m 36s} (J2000),
                  19.485d {+01h 17m 56s} (current),
                  18.953d {+01h 15m 49s} (1950)
GRB_DEC:         -64.583d {-64d 34' 59"} (J2000),
                 -64.534d {-64d 32' 00"} (current),
                 -64.846d {-64d 50' 46"} (1950)
GRB_ERROR:       29.13 [deg radius, statistical plus systematic]
GRB_INTEN:       71 [cnts/sec]
DATA_SIGNIF:     4.50 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        15007 TJD;   176 DOY;   09/06/25
GRB_TIME:        48382.51 SOD {13:26:22.51} UT
GRB_PHI:         260.98 [deg]
GRB_THETA:       125.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.20
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      80%  GRB
2nd_MOST_LIKELY:  17%  Distant Particles
DETECTORS:       0,0,0, 0,1,0, 0,0,1, 0,0,0, 0,0,
SUN_POSTN:        94.49d {+06h 17m 57s}  +23.37d {+23d 22' 25"}
SUN_DIST:        104.83 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      134.95d {+08h 59m 48s}  +16.02d {+16d 01' 21"}
MOON_DIST:       115.27 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      298.35,-52.31 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      330.56,-62.30 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 245.10,24.18 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 25 Jun 09 13:26:45 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      57
TRIGGER_NUM:     267629184
GRB_RA:           16.250d {+01h 05m 00s} (J2000),
                  16.346d {+01h 05m 23s} (current),
                  15.742d {+01h 02m 58s} (1950)
GRB_DEC:         -59.800d {-59d 47' 59"} (J2000),
                 -59.749d {-59d 44' 57"} (current),
                 -60.068d {-60d 04' 02"} (1950)
GRB_ERROR:       13.52 [deg radius, statistical plus systematic]
GRB_INTEN:       134 [cnts/sec]
DATA_SIGNIF:     8.60 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        15007 TJD;   176 DOY;   09/06/25
GRB_TIME:        48382.51 SOD {13:26:22.51} UT
GRB_PHI:         260.98 [deg]
GRB_THETA:       120.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.95
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      77%  GRB
2nd_MOST_LIKELY:  20%  Distant Particles
DETECTORS:       0,0,0, 0,1,0, 0,0,1, 0,0,0, 0,0,
SUN_POSTN:        94.49d {+06h 17m 57s}  +23.37d {+23d 22' 25"}
SUN_DIST:        104.34 [deg]   Sun_angle= 5.2 [hr] (West of Sun)
MOON_POSTN:      134.95d {+08h 59m 48s}  +16.02d {+16d 01' 19"}
MOON_DIST:       118.05 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      299.78,-57.25 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      336.04,-58.10 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 245.10,24.18 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 25 Jun 09 13:27:15 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      56
TRIGGER_NUM:     267629184
GRB_RA:          357.420d {+23h 49m 41s} (J2000),
                 357.546d {+23h 50m 11s} (current),
                 356.750d {+23h 47m 00s} (1950)
GRB_DEC:         -64.270d {-64d 16' 11"} (J2000),
                 -64.217d {-64d 13' 01"} (current),
                 -64.548d {-64d 32' 52"} (1950)
GRB_ERROR:       6.29 [deg radius, statistical only]
DATA_SIGNIF:     12.10 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        15007 TJD;   176 DOY;   09/06/25
GRB_TIME:        48382.51 SOD {13:26:22.51} UT
GRB_PHI:         250.00 [deg]
GRB_THETA:       123.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   413 (Gnd S/W Version number)
SUN_POSTN:        94.49d {+06h 17m 57s}  +23.37d {+23d 22' 25"}
SUN_DIST:        113.92 [deg]   Sun_angle= 6.5 [hr] (West of Sun)
MOON_POSTN:      134.96d {+08h 59m 49s}  +16.02d {+16d 01' 12"}
MOON_DIST:       123.80 [deg]
MOON_ILLUM:      11 [%]
GAL_COORDS:      313.64,-51.55 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      319.06,-54.96 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Thu 25 Jun 09 13:26:41 UT
NOTICE_TYPE:    INTEGRAL Wakeup
TRIGGER_NUM:    5891,   Sub_Num: 0
GRB_RA:           2.2575d {+00h 09m 02s} (J2000),
                  2.3742d {+00h 09m 30s} (current),
                  1.6381d {+00h 06m 33s} (1950)
GRB_DEC:        -65.7652d {-65d 45' 54"} (J2000),
                -65.7125d {-65d 42' 44"} (current),
                -66.0435d {-66d 02' 36"} (1950)
GRB_ERROR:      2.97 [arcmin, radius, statistical only]
GRB_INTEN:      10.86 [sigma]
GRB_TIME:       48385.08 SOD {13:26:25.08} UT
GRB_DATE:       15007 TJD;   176 DOY;   09/06/25
SC_RA:           18.48 [deg] (J2000)
SC_DEC:         -75.79 [deg] (J2000)
SUN_POSTN:       94.49d {+06h 17m 57s}  +23.37d {+23d 22' 25"}
SUN_DIST:       112.06 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:     134.95d {+08h 59m 48s}  +16.02d {+16d 01' 20"}
MOON_DIST:      121.27 [deg]
GAL_COORDS:     309.79,-50.79 [deg] galactic lon,lat of the burst
ECL_COORDS:     319.70,-57.46 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Possibly real GRB event

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Thu 25 Jun 09 13:29:40 UT
NOTICE_TYPE:    INTEGRAL Refined
TRIGGER_NUM:    5891,   Sub_Num: 1
GRB_RA:           2.2657d {+00h 09m 04s} (J2000),
                  2.3824d {+00h 09m 32s} (current),
                  1.6464d {+00h 06m 35s} (1950)
GRB_DEC:        -65.7497d {-65d 44' 58"} (J2000),
                -65.6970d {-65d 41' 48"} (current),
                -66.0280d {-66d 01' 40"} (1950)
GRB_ERROR:      2.82 [arcmin, radius, statistical only]
GRB_INTEN:      13.37 [sigma]
GRB_TIME:       48389.80 SOD {13:26:29.80} UT
GRB_DATE:       15007 TJD;   176 DOY;   09/06/25
SC_RA:           18.48 [deg] (J2000)
SC_DEC:         -75.79 [deg] (J2000)
SUN_POSTN:       94.49d {+06h 17m 57s}  +23.37d {+23d 22' 24"}
SUN_DIST:       112.05 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:     134.98d {+08h 59m 55s}  +16.01d {+16d 00' 40"}
MOON_DIST:      121.27 [deg]
GAL_COORDS:     309.79,-50.81 [deg] galactic lon,lat of the burst
ECL_COORDS:     319.72,-57.46 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Possibly real GRB event

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Thu 25 Jun 09 14:16:04 UT
NOTICE_TYPE:    INTEGRAL Offline
TRIGGER_NUM:    5892,   Sub_Num: 0
GRB_RA:           2.2625d {+00h 09m 03s} (J2000),
                  2.3792d {+00h 09m 31s} (current),
                  1.6432d {+00h 06m 34s} (1950)
GRB_DEC:        -65.7815d {-65d 46' 53"} (J2000),
                -65.7288d {-65d 43' 43"} (current),
                -66.0598d {-66d 03' 34"} (1950)
GRB_ERROR:      1.68 [arcmin, radius, statistical only]
GRB_INTEN:      13.37 [sigma]
GRB_TIME:       48389.80 SOD {13:26:29.80} UT
GRB_DATE:       15007 TJD;   176 DOY;   09/06/25
SC_RA:           19.07 [deg] (J2000)
SC_DEC:         -75.80 [deg] (J2000)
SUN_POSTN:       94.52d {+06h 18m 05s}  +23.37d {+23d 22' 21"}
SUN_DIST:       112.07 [deg]   Sun_angle= 6.1 [hr] (West of Sun)
MOON_POSTN:     135.44d {+09h 01m 46s}  +15.84d {+15d 50' 10"}
MOON_DIST:      121.25 [deg]
GAL_COORDS:     309.78,-50.78 [deg] galactic lon,lat of the burst
ECL_COORDS:     319.68,-57.48 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       refined_coordinates_after_offline_analysis

red DSS finding chart ps-file
GCN Circular #9572
D.Gotz (CEA-Saclay), S.Mereghetti, A.Paizis (IASF-Milano), A. Neronov, V.Beckmann, M. Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report:
A long GRB with duration of about 11 s has been detected by IBAS in IBIS/ISGRI data at 13:26:21 UT on June 25th.
The refined coordinates (J2000) are:
```
 RA:    2.2626 [degrees]
 DEC: -65.7816 [degrees]
```
with an uncertainty of 1.7 arcmin (90% c.l.).
A preliminary analysis gives a peak flux in the 20-200 keV range of about 2 ph/cmq/s (1 s integration time) and a fluence over the same energy range of about 1.5e-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 #9573
J. Mao (INAF-OAB), D. N. Burrows (PSU), E. A. Hoversten (PSU), J. A. Kennea (PSU), K. L. Page (U Leicester), M. A. Stark (PSU) and R. L. C. Starling (U Leicester) report on behalf of the Swift Team:
Swift executed a Target of Opportunity observation of the INTEGRAL GRB 090625B, slewing to the burst at 14:24 UT.
XRT observations began at 14:30:13. The observation begins too late after the burst for us to determine whether any sources in the field of view are fading. However, we find a faint X-ray source located at RA,Dec = 2.2618, -65.7803 which is equivalent to:
```
RA  (J2000.0) =  00 09 2.83
DEC (J2000.0) =  -65 46 49.2
```
with an uncertainty of 4.1 arcsec (radius, 90% containment).
UVOT observations are being made, but data will not be available until a ground downlink.
Burst Advocate for this burst is J. Mao (jirong.mao AT brera.inaf.it). 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 #9574
C. Guidorzi (U. Ferrara), D. Bersier (Liverpool JMU), P. O'Brien, N. Tanvir (U. Leicester) on behalf of a large collaboration report:
On 2009 June 25 at 13:28:21 UT the 2-m Faulkes Telescope South automatically began observing the INTEGRAL GRB 090625B (Gotz et al., GCN Circ. 9572).
Observations started 120 seconds after the IBAS trigger time and were performed using the B, V, R and i' filters. We could not find any uncatalogued object inside the XRT error circle (Mao et al., GCN Circ. 9573) down to the following limiting magnitudes:
For single frames:
```
Mid Time   Exposure  Filter   Limit
  (s)       (s)              (mag)
-------------------------------------
141         3x10      R       > 19.3
526           10      i'      > 18.5
-------------------------------------
```
For coadded frames:
```
Time Range Exposure  Filter   Limit
  (min)     (s)               (mag)
-------------------------------------
22.5-45.2    420      R       > 21.0
25.4-48.2    420      i'      > 20.3
-------------------------------------
```
Calibration was performed using a few USNOB1 nearby stars, adopting R2 and I values.
GCN Circular #9578
T. Kruehler, F. Olivares, and J. Greiner (all MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 090625B (Gotz et al., GCN #9572) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPI/ESO telescope at La Silla Observatory (Chile).
Observations started on 26 June 2009 at 03:58 UT, 14.5 hours after the burst, continued until 05:58 UT and were performed under variable sky conditions. In stacked images of 75 min total integration time in griz and 60 min in JHK, we do not detect any object within the XRT error circle (Mao et al., GCN #9573), down to the following limiting magnitudes (all in the AB system):
```
g' > 23.6
r' > 23.8
i' > 23.1
z' > 22.7
J  > 21.5
H  > 21.0
K  > 20.5
```
These upper limits were derived using USNO-B1 and 2MASS field stars as reference. No correction has been made for the Galactic foreground extinction corresponding to E(B-V) of 0.02 mag (Schlegel et al., 1998).
GCN Circular #9580
J. Mao, R. Margutti (INAF-OAB) and C. Cristiano (U. Ferrara) report on behalf of the Swift-XRT team:
We have analyzed the first three orbit data (6.9 ks exposure) of the Swift ToO observation of the INTEGRAL burst GRB 090625B (Gotz, GCN Circ. 9572).
Swift-XRT observations started at 14:30:13 UT (Mao et al. GCN Circ. 9573), 4ks from trigger.
The source is fading with a best fit simple power law model index of alpha= 0.6+/- 0.3, confirming its nature of X-ray afterglow.
A spectrum extracted from PC mode data can be modelled with an absorbed power-law, with Gamma = 3.3 +1.1/-0.8 and NH = (3.7 +2.2/-1.7)x1021 cm^-2. The Galactic column in this direction is 2.1 x 1020 cm-2 (Kalberla et al. 2005).
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 2.8 x 10-11 (1.8 x 10-10) erg cm-2 count-1.
If the light curve continues to decay with a power-law decay index of 0.6, the count rate at T+24 hours will be 6.3x10-3 count s-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8x10-13 (1.1x10-12) erg cm-2 s-1.
This circular is an official product of the Swift-XRT team.
GCN Circular #9581
S. T. Holland (CRESST/GSFC/USRA) and J. Mao (INAF-OAB) report on the behalf of the Swift UVOT team:
The Swift/UVOT observed the field of GRB 090625B starting 3679 s after the INTEGRAL/IBAS detection (Gotz, et al., 2009, GCN Circ. 9572). We do not find any new source, relative to the DSS, USNO-B1.0, or 2MASS at the position of the XRT afterglow (Mao, et al. 2009, GCN Circ. 9573). Preliminary 3-sigma upper limits for detecting a source in the co-added images are
```
Filter   T_start    T_stop   Exp(s)      Mag
--------------------------------------------
v           3679      5007       318   >20.0
b           4192    11,398       413   >20.8
u           3987    67,218      6439   >21.7
uvw1        5218    17,045      1781   >21.5
uvm2        5012    16,139      1082   >21.0
uvw2        4602      4802       197   >20.1
white       3828      4596       344   >21.8
--------------------------------------------
```
The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight corresponding to a reddening of E_{B-V} = 0.02 mag (Schlegel, et al., 1998, ApJS, 500, 525). All photometry is on the UVOT photometry system described in Poole et al. (2008, MNRAS, 383, 627).
GCN Circular #9583
Arne Rau (MPE) reports on behalf of the Fermi GBM Team:
"At 13:26:22.51 UT on 25 June 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090625B (trigger 267629184 / 090625560) which was also detected by the INTEGRAL (Goetz et al. 2009, GCN 9572). The GBM on-ground location is consistent with the INTEGRAL position.
The angle from the Fermi LAT boresight is 125 degrees.
The GBM light curve consists of a single pulse with a duration (T90) of about 13.6 s (8-1000 keV). The time-averaged spectrum from T0-2.048 s to T0+6.144 s is well fit by a power law function with an exponential high energy cutoff. The power law index is -0.9 +/- 0.2 and the cutoff energy, parameterized as Epeak, is 165 +/- 28 keV (chi squared 429 for 453 d.o.f.).
The event fluence (8-1000 keV) in this time interval is (1.04 +/- 0.13)E-06 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+3.072 s in the 8-1000 keV band is 1.87 +/- 0.09 ph/s/cm^2.
A Band function fits the spectrum equally well (chi squared 424 for 454 d.o.f.) with Epeak= 100 +/- 32 keV, alpha = -0.4 +/- 0.5, and beta -2.0 +/- 0.2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."

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Jochen Greiner, last update: 26-Jun-2009 [Disclaimer]