Gamma-ray Burst 090726

(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:     Sun 26 Jul 09 22:43:32 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     358422,   Seg_Num: 0
GRB_RA:          248.819d {+16h 35m 16s} (J2000),
                 248.780d {+16h 35m 07s} (current),
                 249.023d {+16h 36m 06s} (1950)
GRB_DEC:         +72.871d {+72d 52' 15"} (J2000),
                 +72.852d {+72d 51' 06"} (current),
                 +72.971d {+72d 58' 16"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       48296 [cnts]    Image_Peak=1020 [image_cnts]
TRIGGER_DUR:     12.160 [sec] 
TRIGGER_INDEX:   478     E_range: 25-100 keV
BKG_INTEN:       233596 [cnts]
BKG_TIME:        81651.05 SOD {22:40:51.05} UT
BKG_DUR:         64 [sec]
GRB_DATE:        15038 TJD;   207 DOY;   09/07/26
GRB_TIME:        81747.75 SOD {22:42:27.75} UT
GRB_PHI:         -171.98 [deg]
GRB_THETA:        28.48 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.96 [sigma]
IMAGE_SIGNIF:    11.07 [sigma]
MERIT_PARAMS:     +1  +0  +0  +4  +2  +1  +0  +0 -16  +0 
SUN_POSTN:       126.38d {+08h 25m 32s}  +19.24d {+19d 14' 23"}
SUN_DIST:         80.46 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      187.29d {+12h 29m 10s}   -8.52d {-08d 31' 03"}
MOON_DIST:        90.13 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      105.46, 35.63 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      129.70, 80.41 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is a rate 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 = 142.65,13.30 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 26 Jul 09 22:46:18 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     358422,   Seg_Num: 0
GRB_RA:          248.819d {+16h 35m 16s} (J2000),
                 248.780d {+16h 35m 07s} (current),
                 249.023d {+16h 36m 06s} (1950)
GRB_DEC:         +72.871d {+72d 52' 15"} (J2000),
                 +72.852d {+72d 51' 06"} (current),
                 +72.971d {+72d 58' 16"} (1950)
GRB_DATE:        15038 TJD;   207 DOY;   09/07/26
GRB_TIME:        81747.75 SOD {22:42:27.75} UT
TRIGGER_INDEX:   478
GRB_PHI:         -171.98 [deg]
GRB_THETA:        28.48 [deg]
DELTA_TIME:      -69.00 [sec]
TRIGGER_DUR:     12.160 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.96 [sigma]
IMAGE_SIGNIF:    11.07 [sigma]
LC_URL:          sw00358422000msb.lc
SUN_POSTN:       126.39d {+08h 25m 33s}  +19.24d {+19d 14' 21"}
SUN_DIST:         80.46 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      187.32d {+12h 29m 16s}   -8.53d {-08d 31' 44"}
MOON_DIST:        90.14 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      105.46, 35.63 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      129.70, 80.41 [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 a rate 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 = 142.65,13.30 [deg].

GCN Circular #9706
K. L. Page (U Leicester), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), D. M. Palmer (LANL), A. Rowlinson (U Leicester), M. H. Siegel (PSU), M. A. Stark (PSU) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:
At 22:42:27 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090726 (trigger=358422). Swift did not slew immediately to the burst due to an Earth constraint. The BAT on-board calculated location is RA, Dec 248.819, +72.871 which is
```
   RA(J2000) = 16h 35m 16s
   Dec(J2000) = +72d 52' 15"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a small precursor at T-20 followed by a single FRED structure overlaid with rapid variability with a duration of about 50 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~10 sec after the trigger.
Swift will not slew until T0+48.9 minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is K. L. Page (kpa AT star.le.ac.uk). 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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 26 Jul 09 23:36:16 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     358422,   Seg_Num: 0
GRB_RA:          249.3441d {+16h 37m 22.58s} (J2000),
                 249.3041d {+16h 37m 12.97s} (current),
                 249.5573d {+16h 38m 13.74s} (1950)
GRB_DEC:         +72.9700d {+72d 58' 11.9"} (J2000),
                 +72.9512d {+72d 57' 04.2"} (current),
                 +73.0677d {+73d 04' 03.8"} (1950)
GRB_ERROR:       5.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       3.80e-08 [erg/cm2/sec]
GRB_SIGNIF:      7.54 [sigma]
IMG_START_DATE:  15038 TJD;   207 DOY;   09/07/26
IMG_START_TIME:  84809.49 SOD {23:33:29.49} UT,   3061.7 [sec] since BAT Trigger Time
TAM[0-3]:        327.63 237.23 261.45 243.73
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       126.42d {+08h 25m 41s}  +19.23d {+19d 13' 53"}
SUN_DIST:         80.53 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      187.75d {+12h 31m 00s}   -8.73d {-08d 43' 52"}
MOON_DIST:        90.41 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      105.49, 35.44 [deg] galactic lon,lat of the burst
ECL_COORDS:      128.71, 80.49 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 11.00 arcmin from the BAT position.  
COMMENTS:        WARNING: The centroided position is more than 100 rows or columns from the center of the FOV.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 26 Jul 09 23:36:26 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     358422,   Seg_Num: 0
GRB_RA:          249.3441d {+16h 37m 22.5s} (J2000),
                 249.3041d {+16h 37m 12.9s} (current),
                 249.5573d {+16h 38m 13.7s} (1950)
GRB_DEC:         +72.9700d {+72d 58' 11.9"} (J2000),
                 +72.9512d {+72d 57' 04.2"} (current),
                 +73.0677d {+73d 04' 03.8"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       57 [cnts]
IMG_START_DATE:  15038 TJD;   207 DOY;   09/07/26
IMG_START_TIME:  84809.49 SOD {23:33:29.49} UT,   3061.7 [sec] since BAT Trigger Time
CENTROID_X:      429.15,  raw= 429  [pixels]
CENTROID_Y:      49.78,  raw= 50  [pixels]
ROLL:            306.05 [deg]
GAIN:            1
MODE:            2, Short Image mode
WAVEFORM:        134
EXPO_TIME:       0.10 [sec]
GRB_POS_XRT_Y:   -585.12
GRB_POS_XRT_Z:   299.04
IMAGE_URL:       sw00358422000msxps_rw.img
SUN_POSTN:       126.42d {+08h 25m 41s}  +19.23d {+19d 13' 53"}
SUN_DIST:         80.53 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      187.75d {+12h 31m 00s}   -8.73d {-08d 43' 54"}
MOON_DIST:        90.41 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      105.49, 35.44 [deg] galactic lon,lat of the burst
ECL_COORDS:      128.71, 80.49 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.  
COMMENTS:        WARNING: The centroided position is more than 100 rows or columns from the center of the FOV.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 26 Jul 09 23:36:32 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     358422,   Seg_Num: 0
GRB_RA:          249.3441d {+16h 37m 22.5s} (J2000),
                 249.3041d {+16h 37m 12.9s} (current),
                 249.5573d {+16h 38m 13.7s} (1950)
GRB_DEC:         +72.9700d {+72d 58' 11.9"} (J2000),
                 +72.9512d {+72d 57' 04.2"} (current),
                 +73.0677d {+73d 04' 03.8"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       57 [cnts]
IMG_START_DATE:  15038 TJD;   207 DOY;   09/07/26
IMG_START_TIME:  84809.49 SOD {23:33:29.49} UT,   3061.7 [sec] since BAT Trigger Time
CENTROID_X:      429.15,  raw= 429  [pixels]
CENTROID_Y:      49.78,  raw= 50  [pixels]
ROLL:            306.05 [deg]
GAIN:            1
MODE:            2, Short Image mode
WAVEFORM:        134
EXPO_TIME:       0.10 [sec]
GRB_POS_XRT_Y:   -585.12
GRB_POS_XRT_Z:   299.04
IMAGE_URL:       sw00358422000msxps_rw.img
SUN_POSTN:       126.42d {+08h 25m 41s}  +19.23d {+19d 13' 53"}
SUN_DIST:         80.53 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      187.75d {+12h 31m 00s}   -8.73d {-08d 43' 56"}
MOON_DIST:        90.41 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      105.49, 35.44 [deg] galactic lon,lat of the burst
ECL_COORDS:      128.71, 80.49 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 26 Jul 09 23:47:24 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     358422,   Seg_Num: 0
POINT_RA:        248.782d {+16h 35m 08s} (J2000)
POINT_DEC:       +72.886d {+72d 53' 10"} (J2000)
POINT_ROLL:      306.041d
IMG_START_DATE:  15038 TJD;   207 DOY;   09/07/26
IMG_START_TIME:  85357.99 SOD {23:42:37.99} UT,   3610.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.446
N_STARS:         37
X_OFFSET:        344 [pixels]
Y_OFFSET:        578 [pixels]
X_MAX:           1303 [pixels]
Y_MAX:           1537 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00358422000msufc3610.fits
SUN_POSTN:       126.43d {+08h 25m 43s}  +19.23d {+19d 13' 47"}
SUN_DIST:         80.44 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      187.84d {+12h 31m 23s}   -8.78d {-08d 46' 34"}
MOON_DIST:        90.24 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      105.48, 35.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      129.66, 80.39 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 26 Jul 09 23:47:24 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     358422,   Seg_Num: 0
POINT_RA:        248.782d {+16h 35m 08s} (J2000)
POINT_DEC:       +72.886d {+72d 53' 10"} (J2000)
POINT_ROLL:      306.041d
IMG_START_DATE:  15038 TJD;   207 DOY;   09/07/26
IMG_START_TIME:  85357.99 SOD {23:42:37.99} UT,   3610.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.446
N_STARS:         37
X_OFFSET:        344 [pixels]
Y_OFFSET:        578 [pixels]
X_MAX:           1303 [pixels]
Y_MAX:           1537 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00358422000msufc3610.fits
SUN_POSTN:       126.43d {+08h 25m 43s}  +19.23d {+19d 13' 47"}
SUN_DIST:         80.44 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      187.84d {+12h 31m 23s}   -8.78d {-08d 46' 34"}
MOON_DIST:        90.24 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      105.48, 35.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      129.66, 80.39 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 26 Jul 09 23:48:50 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     358422,   Seg_Num: 0
POINT_RA:        248.782d {+16h 35m 08s} (J2000)
POINT_DEC:       +72.886d {+72d 53' 10"} (J2000)
ROLL:            306.041d
IMG_START_DATE:  15038 TJD;   207 DOY;   09/07/26
IMG_START_TIME:  85357.99 SOD {23:42:37.99} UT,   3610.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     270344562
X_OFFSET:        663 [pixels]
Y_OFFSET:        897 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       823
Y_GRB_POS:       1057
BINNING_INDEX:   1
IM_URL:          sw00358422000msuni3615.fits
SUN_POSTN:       126.43d {+08h 25m 43s}  +19.23d {+19d 13' 46"}
SUN_DIST:         80.44 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      187.86d {+12h 31m 26s}   -8.78d {-08d 46' 54"}
MOON_DIST:        90.24 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      105.48, 35.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      129.66, 80.39 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 26 Jul 09 23:49:09 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     358422,   Seg_Num: 0
POINT_RA:        248.782d {+16h 35m 08s} (J2000)
POINT_DEC:       +72.886d {+72d 53' 10"} (J2000)
ROLL:            306.041d
IMG_START_DATE:  15038 TJD;   207 DOY;   09/07/26
IMG_START_TIME:  85357.99 SOD {23:42:37.99} UT,   3610.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     270344562
X_OFFSET:        663 [pixels]
Y_OFFSET:        897 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       823
Y_GRB_POS:       1057
BINNING_INDEX:   1
IM_URL:          sw00358422000msuni3615.fits
SUN_POSTN:       126.43d {+08h 25m 43s}  +19.23d {+19d 13' 46"}
SUN_DIST:         80.44 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      187.86d {+12h 31m 26s}   -8.78d {-08d 47' 00"}
MOON_DIST:        90.24 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      105.48, 35.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      129.66, 80.39 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #9707
K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:
Following a delay caused by an Earth-limb constraint, the Swift-XRT started observing GRB 090726 about 49 minutes after the trigger, at 23:36:32 UT. The XRT initially centroided on a cosmic ray; however, using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec = 248.6788, 72.8843 (degrees) which is equivalent to:
```
RA  (J2000.0) = 16 34 42.90
DEC (J2000.0) = +72 53 03.3
```
with an uncertainty of 2.2 arcsec (radius, 90% containment). This location is 156.1 arcseconds from the BAT onboard position, inside the BAT error circle.
It is not possible to determine whether the source is fading at this time.
This circular is an official product of the Swift-XRT team.
GCN Circular #9708
M. H. Siegel (PSU), M. A. Stark (PSU) and K.L. Page (U. Leicester) report on behalf of the Swift UVOT team:
UVOT observed GRB 090726 (Page et al., GCN Circ 9706) with a finding chart exposure of 150 seconds with the White filter starting 3610 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle reported by Page et al. (GCN Cic 9707). The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04.
GCN Circular #9709
A. Moskvitin, T. Fatkhullin & A. Valeev (SAO-RAS Niznijh Arkhyz, Russia), on behalf of a larger colaboration, report:
We have observed the field of GRB090618 (Page et al., GCN 9706) with the 1-m telesecope of the SAO RAS in Caucasus. Within the XRT error circle (Page et al., GCN 9707) we detected one object which not present in the DSS. The object's coordinates are:
```
    R.A. (J2000.0) = 16:34:43.044
    DEC. (J2000.0) = +72:53:04.82
```
with uncertainty about 0.5 arcsec. Using the USNO A2.0 star 1628-0121951 (R2=14.51) as a calibration we estimated the object's brightness as following:
```
   R_mag         exp.(sec)       mid.time
                             (sec after the trigger)
18.26 +/- 0.05     60              2126
18.39 +/- 0.05     60              2252
18.33 +/- 0.05     60              2344
18.71 +/- 0.05    120              3183
18.97 +/- 0.05    180              4296
19.17 +/- 0.06    180              5492
19.28 +/- 0.07    240              6089
19.55 +/- 0.12    300              6824
```
According to its variability we concluded that the detected object is the OT of the GRB090726.
Further analysis are ongoing.
This message may be cited.
GCN Circular #9710
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 4286 s of XRT Photon Counting mode data and 7 UVOT images for GRB 090726, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 248.67985, +72.88426 which is equivalent to:
```
RA (J2000): 16h 34m 43.16s
Dec (J2000): +72d 53' 03.4"
```
with an uncertainty of 1.5 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, arXiv:0812.3662).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #9711
K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:
We have analysed the first five orbits of data collected for GRB 090726, comprising 9.4 ks between 3.6 and 28 ks after the trigger, all in Photon Counting mode. The enhanced XRT position for this burst was given by Evans et al. in GCN Circ. 9710.
The X-ray light-curve can be modelled with a single power-law with a decay index of alpha = 1.29 +/- 0.12.
A spectrum formed from these PC data can be fitted with an absorbed power-law of Gamma = 2.50 +0.26/-0.24 and a total absorbing column of NH = (1.2 +/- 0.5) x 10^21 cm^-2, which is in excess of the Galactic value (3.83 x 10^20 cm^-2; Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.1 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1.
If the light-curve continues to decay with alpha ~ 1.29, the predicted count rate at 24 hours is 3.4 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) flux of 1.1 x 10^-13 (1.7 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00358422.
This circular is an official product of the Swift-XRT team.
GCN Circular #9712
T. Fatkhullin (SAO RAS, Russia), J. Gorosabel (IAA-CSIC, Spain), A. de Ugarte Postigo (OAB-INAF, Italy), A. Moskvitin, A. Valeev, S. Fabrika, O. Sholukhova (SAO RAS, Russia), A. Castro-Tirado (IAA-CSIC, Spain) & V. Sokolov (SAO RAS, Russia) on behalf of a larger colaboration, report:
Following the detection of the GRB090726 optical transient (Moskvitin et al., GCN 9709) we observed the afterglow with the SAO RAS 6-m telescope in Caucasus using SCORPIO in the spectroscopic mode. The wavelength coverage and resolution were 3700-7800AA and FWHM=10A, respectively. One 10-min long exposure was obtained starting at 00:15 27 July 2009 UT (T-T0 = 1.545 hours after the trigger). A number of absoption lines were detected in the spectrum. These are SiI 1526.7, CIV 1548.2,1550.8, AlII 1670.8, SiII 1304.4,1309.3, SiIV 1393.7,1402.7, FeII 1608.4 as well as Ly alpha at common z = 2.71 which we interpret as the GRB090726 redshift.
This message may be cited.
P.S. We made a typo in GCN 9709. In the first line one should read "GRB090726" instead of "GRB090618". We apologize for our carelessness.
GCN Circular #9714
Cyril Polasek (1), Jan Strobl (1), Martin Jelinek (2), Petr Kubanek (3), Matus Kocka (1), Martin Nekola (1), Martin Blazek (1) and Rene Hudec (1) (1. ASU Ondrejov, 2. IAA Granada, 3. GACE Valencia)
We observed the localization of the Swift GRB090726 (Page et al., GCN 9706) with the 50 cm telescope in Ondrejov (Czech Republic), starting at 22:45:41 UT, i.e. 194s after the GRB trigger.
We clearly detect the afterglow reported by Moskvitin et al. (GCN 9709) in its rising phase on the first image with magnitude ~ 18.3 (same calibration as GCN 9709).
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GCN Circular #9715
S. Maticic and J. Skvarc on behalf of PIKA observing program at Crni Vrh Observatory.
We present photometry of the source reported by Moskvitin, Fatkhullin and Valeev (GCN 9709). The object was observed from Crni Vrh Observatory with a 60 cm telescope using R filter and a CCD. First exposure started at 2009-07-26 22:44:31 UT. All twenty exposures were of 60 s. The table contains the time since the Swift GRB detection to the middle of exposure in seconds, R magnitude and formal 1-sigma magnitude error estimate. Comparison stars were 1629-0117020, 1628-0121875 and 1628-0121948 using R2 magnitudes from the USNO B1.0 catalogue.
```
Time     Mag     Err.
  [s]     [R]    [1-sigma]
----------------------------------
  153.8   18.44   0.04
  224.9   18.35   0.04
  296.0   17.86   0.04
  367.2   17.69   0.04
  438.0   17.68   0.04
  508.8   17.75   0.04
  579.6   17.82   0.04
  650.3   17.76   0.04
  721.0   17.76   0.04
  791.8   17.83   0.04
  862.5   17.71   0.04
  933.3   17.83   0.04
 1004.0   17.89   0.04
 1074.7   18.05   0.04
 1146.1   18.17   0.04
 1218.2   18.11   0.04
 1288.9   18.00   0.04
 1359.6   18.02   0.04
 1430.5   18.16   0.04
 1501.5   17.96   0.04
```
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GCN Circular #9716
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), C. B. Markwardt (GSFC/UMD), K. L. Page (U Leicester), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090726 (trigger #358422) (Page, et al., GCN Circ. 9706). The BAT ground-calculated position is RA, Dec = 248.681, 72.866 deg which is
```
   RA(J2000)  =  16h 34m 43.5s
   Dec(J2000) = +72d 51' 56.5"
```
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 85%.
The mask-weighted light curve shows a weak single peak starting at ~T-40 sec, peaking at ~T+5 aec, and ending at ~T+70 sec. T90 (15-350 keV) is 67.0 +/- 15.2 sec (estimated error including systematics).
The time-averaged spectrum from T-34.7 to T+47.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.25 +/- 0.19. The fluence in the 15-150 keV band is 8.6 +/- 1.0 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+7.30 sec in the 15-150 keV band is 0.7 +- 0.2 ph/cm2/sec. 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/358422/BA/
GCN Circular #9717
W.B. Landsman (NASA/GSFC) and K.Page (U. Leicester)report on behalf of=20 the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 090726,=20 3610s after the BAT trigger (Page et al., GCN Circ. 9706), and the=20 afterglow first reported by Moskvitin et al., (GCN Circ. 9709) is=20 detected in the UVOT white, v, and b filters.
The initial magnitudes and upper limits are as follows:
```
Filter   T_start(s)  Exp(s)    Mag
white     3610       147   20.62 =B1 0.18
white     4179       197   21.36 =B1 0.29
v         4589       197   19.98 =B1 0.36
b         3974       197   20.80 =B1 0.44
u         3769       197   >20.9 (3 sigma)
uvw1      5000       197   >20.6 (3 sigma)
uvm2      4794       197   >20.6 (3 sigma)
uvw2      4385       197   >21.0 (3 sigma)
```
The nondetections in the u and UV filters are consistent with the=20 redshift of z=3D 2.71 reported by Fatkhullin et al (GCN 9712)
The values quoted above are not corrected for the Galactic extinction=20 due to the reddening of E(B-V) =3D 0.045 in the direction of the burst. The photometry is on the UVOT photometric system described in Poole et=20 al. (2008, MNRAS, 383, 627).
GCN Circular #9732
T. Sakamoto (UMBC/GSFC), D. Donato (ORAU/GSFC), N. Gehrels (GSFC), T. Okajima (JHU/GSFC), T.N. Ukwatta (GWU/GSFC), Y. Urata (NCU), C.A. Wallace (FGCU)
We observed the field of GRB 090726 detected by Swift (trigger #358422; Page et al., GCN Circ. 9706) with the 14-inch Goddard Robotic Telescope (GRT) located at the Goddard Geophysical and Astronomical Observatory (http://cddisa.gsfc.nasa.gov/ggao/).
89 set of 30 sec exposures were taken in the R filter starting from July 27 02:31:44 (UT) about 3.75 hours after the trigger and stopped on July 27 03:22:10 (UT). We do not detect the optical afterglow (Moskvitin et al., GCN Circ. 9709; Fatkhullin et al., GCN Circ. 9712; Polasek et al., GCN Circ. 9714; Maticic et al., GCN Circ. 9715; Landsman et al., GCN Circ. 9717) both in the individual images and the combined image. The estimated three sigma upper limit of the combined image (total exposure of 2670.0 sec) is ~18.9 mag using the USNO-B1 catalog.
GCN Report 234.1
GCN_Report 234.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_234_1.pdf by K.L. Page at U. Leicester titled: "Final Results on Swift GRB 090726"
GCN Circular #9741
A. Volnova (SAI MSU), E. Pavlenko, A. Sklyanov, O. Antoniuk (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 090726 (Page et al., GCN 9706) in R-filter on Jul. 27 between (UT) 18:19:22 - 20:28:58 with Shajn telescope of CrAO. We detect afterglow (Moskvitin et al., GCN 9709) in a stacked image. The photometry against nearby USNO-B1.0 stars is following:
T0+ Filter, Exposure, mag., err. (d) (s) 0.8626 R 114x60 23.60 +/- 0.25 While the index of power law approximation of the light curve during early observation (Moskvitin et al., GCN 9709) is ~ -1.0, the power law index between observation presented by Moskvitin et al. (GCN 9709) and our observation is -1.6, clearly suggesting a break between 0.079 and 0.863 days.
GCN Circular #9926
J. Haislip, D. Reichart, L. Cominsky, K. McLin, T. Graves, G. Spear, K. Ivarsen, A. LaCluyze, A. Foster, J. Moore, A. Oza, M. Schubel, J. Styblova, A. Trotter, J. A. Crain, and M. Nysewander report:
Skynet observed the Skynet/BAT localization of GRB 090726 (Page et al., GCN 9706) with the 14" GORT telescope at Hume Observatory in California beginning 5.9 hours after the the trigger in I.
We do not detect the afterglow (Page et al., GCN 9707; Moskvitin, Fatkhullin & Valeev, GCN 9709). Stacking only images that increase the limiting magnitude yields:
```
mean                                                   1-sig.   1-sig.
time                            3-sig.                 sys.     stat.
since                           lim.     cal.          cal.     cal.
trig.   tel.   exp.      fil.   mag.     stars         unc.     unc.
(h)            (# x s)                                 (mag)    (mag)

6.2     GORT   15 x 80   I      19.8     84 USNO B1    0.213    0.002
6.8     GORT   8 x 80    R      20.2     178 USNO B1   0.235    0.001
```
GCN Circular #10028
J. Kelemen (kelemen at konkoly.hu) on behalf of the GRB OT observing program at the Konkoly Observatory. We present photometry of the source reported by Moskvitin, Fatkhullin and Valeev (GCN 9709) which was found on a previous survey images made for asteroid astrometry. The object was observed from the Mountain Station of the Konkoly Observatory with a 60/90 cm Schmidt telescope using R filter and a CCD. The exposures were of 300 s. The table contains the time since the Swift GRB detection to the middle of exposure in seconds, R magnitude and formal 1-sigma magnitude error estimate. Comparison stars were from the USNO A2.0 catalogue. Aperture photometry results obtained using the ASTROMETRICA astrometry and photometry package.
```
 Time     Mag     Error.      Flag.
  [s]     [R]    [1-sigma]  
-------------------------------------
  2010   18.21   0.05
  2730   18.32   0.05
  4530   18.82   0.05
 78330   20.60   0.2      Upper Limit
-------------------------------------
```
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Jochen Greiner, last update: 16-Oct-2009 [Disclaimer]