Gamma-ray Burst 130725A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN Circular #15026
S. D. Barthelmy (GSFC), M. M. Chester (PSU), D. Grupe (PSU), D. M. Palmer (LANL), P. Romano (INAF-IASFPA) and B.-B. Zhang (PSU/UAH) report on behalf of the Swift Team:
At 11:37:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located an unknown source (trigger=563980). This occurred during an episode of intermitant TDRSS connection, so most of the telemetry messages were not received. Swift did not slew to the source.
Due to the telemetry gaps, we will not know the location or the characteristics of this source until ground-linked data is available.

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 25 Jul 13 12:42:00 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     563980,   Seg_Num: 0
POINT_RA:        229.999d {+15h 20m 00s} (J2000)
POINT_DEC:        +0.634d {+00d 38' 03"} (J2000)
IMG_START_DATE:  16498 TJD;   206 DOY;   13/07/25
IMG_START_TIME:  44925.84 SOD {12:28:45.84} UT,   14966.6 [sec] since BAT Trigger Time
COUNTS:          2    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 25 Jul 13 12:42:52 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     563980,   Seg_Num: 0
POINT_RA:        229.999d {+15h 20m 00s} (J2000)
POINT_DEC:        +0.634d {+00d 38' 03"} (J2000)
POINT_ROLL:      290.374d
IMG_START_DATE:  16498 TJD;   206 DOY;   13/07/25
IMG_START_TIME:  44928.82 SOD {12:28:48.82} UT,   14969.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.228
N_STARS:         33
X_OFFSET:        244 [pixels]
Y_OFFSET:        708 [pixels]
X_MAX:           1203 [pixels]
Y_MAX:           1667 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    13
SL_URL:          sw00563980000msufc274169.fits
SUN_POSTN:       125.02d {+08h 20m 05s}  +19.55d {+19d 32' 46"}
SUN_DIST:        104.06 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      340.75d {+22h 42m 59s}   -3.33d {-03d 19' 56"}
MOON_DIST:       110.57 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:        2.57, 45.60 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      227.37, 18.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 25 Jul 13 12:43:22 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     563980,   Seg_Num: 0
POINT_RA:        229.999d {+15h 20m 00s} (J2000)
POINT_DEC:        +0.634d {+00d 38' 03"} (J2000)
POINT_ROLL:      290.374d
IMG_START_DATE:  16498 TJD;   206 DOY;   13/07/25
IMG_START_TIME:  44928.82 SOD {12:28:48.82} UT,   14969.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.228
N_STARS:         33
X_OFFSET:        244 [pixels]
Y_OFFSET:        708 [pixels]
X_MAX:           1203 [pixels]
Y_MAX:           1667 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    13
SL_URL:          sw00563980000msufc274169.fits
SUN_POSTN:       125.02d {+08h 20m 05s}  +19.55d {+19d 32' 45"}
SUN_DIST:        104.06 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      340.75d {+22h 43m 00s}   -3.33d {-03d 19' 50"}
MOON_DIST:       110.58 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:        2.57, 45.60 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      227.37, 18.35 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 25 Jul 13 12:45:02 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     563980,   Seg_Num: 0
POINT_RA:        229.999d {+15h 20m 00s} (J2000)
POINT_DEC:        +0.634d {+00d 38' 03"} (J2000)
ROLL:            290.374d
IMG_START_DATE:  16498 TJD;   206 DOY;   13/07/25
IMG_START_TIME:  44928.82 SOD {12:28:48.82} UT,   14969.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     396448139
X_OFFSET:        563 [pixels]
Y_OFFSET:        1027 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       723
Y_GRB_POS:       1187
BINNING_INDEX:   1
IM_URL:          sw00563980000msuni274180.fits
SUN_POSTN:       125.02d {+08h 20m 05s}  +19.55d {+19d 32' 44"}
SUN_DIST:        104.06 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      340.77d {+22h 43m 04s}   -3.33d {-03d 19' 29"}
MOON_DIST:       110.59 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:        2.57, 45.60 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      227.37, 18.35 [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:     Thu 25 Jul 13 12:45:23 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     563980,   Seg_Num: 0
POINT_RA:        229.999d {+15h 20m 00s} (J2000)
POINT_DEC:        +0.634d {+00d 38' 03"} (J2000)
ROLL:            290.374d
IMG_START_DATE:  16498 TJD;   206 DOY;   13/07/25
IMG_START_TIME:  44928.82 SOD {12:28:48.82} UT,   14969.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     396448139
X_OFFSET:        563 [pixels]
Y_OFFSET:        1027 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       723
Y_GRB_POS:       1187
BINNING_INDEX:   1
IM_URL:          sw00563980000msuni274180.fits
SUN_POSTN:       125.02d {+08h 20m 05s}  +19.55d {+19d 32' 44"}
SUN_DIST:        104.06 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      340.77d {+22h 43m 05s}   -3.32d {-03d 19' 25"}
MOON_DIST:       110.60 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:        2.57, 45.60 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      227.37, 18.35 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 25 Jul 13 13:27:00 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     563980,   Seg_Num: 0
GRB_RA:          230.0332d {+15h 20m 07.96s} (J2000),
                 230.2064d {+15h 20m 49.53s} (current),
                 229.3953d {+15h 17m 34.88s} (1950)
GRB_DEC:          +0.6274d {+00d 37' 38.6"} (J2000),
                  +0.5790d {+00d 34' 44.3"} (current),
                  +0.8074d {+00d 48' 26.7"} (1950)
GRB_ERROR:       5.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       9.90e-13 [erg/cm2/sec]
GRB_SIGNIF:      5.00 [sigma]
IMG_START_DATE:  16498 TJD;   206 DOY;   13/07/25
IMG_START_TIME:  46094.00 SOD {12:48:14.00} UT,   16134.8 [sec] since BAT Trigger Time
TAM[0-3]:        327.61 237.19 261.35 242.66
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       125.05d {+08h 20m 12s}  +19.54d {+19d 32' 21"}
SUN_DIST:        104.06 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      341.16d {+22h 44m 38s}   -3.18d {-03d 11' 00"}
MOON_DIST:       110.95 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:        2.60, 45.57 [deg] galactic lon,lat of the burst
ECL_COORDS:      227.41, 18.35 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values are not valid.   
COMMENTS:        Time since BAT trigger is approx. 4300 s, not 90s.

GCN Circular #15028
B.-B. Zhang (PSU/UAH), S. D. Barthelmy (GSFC), M. M. Chester (PSU), D. Grupe (PSU), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), S. R. Oates (MSSL-UCL), H. A. Krimm (USRA/CRESST/GSFC), J. A. Kennea (PSU), Daniele Malesani (DARK/NBI), M. H. Siegel (PSU) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift Team:
At 11:37:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130725A (trigger=563980). Swift slewed to the burst. This burst was not identified in real-time due to telemetry gaps.
The BAT on-board calculated location is RA, Dec 230.034,+0.624 which is
```
  RA(J2000) = 15h 20m 8s
  Dec(J2000) = +00d 37' 26"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 15 sec. The peak count rate was ~600 counts/sec (15-350 keV), at ~5 sec after the trigger.
The XRT began observing the field at 12:28:46 UT, 3094 seconds after the BAT trigger. Using 2.28 ks of ground-linked XRT data, we found an uncatalogued X-ray source located at RA, Dec = 230.033,+0.627, which is equivalent to:
```
RA(J2000)  = +15h 20m 07.92s
Dec(J2000) = 00d 37' 40.2"
with an uncertainty of 4.0 arc seconds (radius, 90% containment). 
```
UVOT took a finding chart exposure of 150 seconds with the White filter 3097 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. 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 0.06.
Further analysis is on-going. This circular is an official product of the Swift team.
GCN Circular #15031
T. N. Ukwatta (MSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), B.-B. Zhang (PSU/UAH) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+731 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130725A (trigger #563980) (Zhang, et al., GCN Circ. 15028). The BAT ground-calculated position is RA, Dec = 230.060, 0.624 deg which is
```
     RA(J2000)  =  15h 20m 14.4s
     Dec(J2000) = +00d 37' 26.8"
```
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 39%.
The mask-weighted light curve shows a double-peaked structure lasting from approximately T+0 to T+20 seconds. This is followed by lower-level emission out to ~T+100 seconds. The source went out of the field of view at ~T+450 seconds, following a pre-planned slew. T90 (15-350 keV) is 101.8 +- 20.5 sec (estimated error including systematics).
The time-averaged spectrum from T-9.83 to T+103.40 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.60 +- 0.30. The fluence in the 15-150 keV band is 9.7 +- 1.7 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+3.11 sec in the 15-150 keV band is 0.6 +- 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/563980/BA/
GCN Circular #15033
D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 130725A (Zhang et al., GCNC 15028) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory.
The observation started on 2013-07-25 13:34:52 UT (~2.0 h after the burst). We detected the afterglow candidate within the XRT error circle (Zhang et al., GCNC 15028) in only Rc band.
Photometric result and three sigma upper limits of the OT are listed below. We used SDSS catalog for flux calibration.
```
#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc  Rc_err  Ic
----------------------------------------------------------------------
0.10534    14:08:53   2280.0    >21.3   20.8 0.2   >19.8
----------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #15035
F.J. Virgili (LJMU), C. Guidorzi (U. Ferrara), J. Japelj, D. Kopac (U. Ljubljana), A. Melandri (INAF-OAB) report:
"The 2-m Faulkes Telescope South robotically followed up GRB 130725A (SWIFT trigger 563980; Zhang et al. GCN 15028) beginning 111.9 min after the GRB trigger time. No optical counterpart is detected within the XRT error circle to the following conservative limits:
```
Midtime from GRB    Exposure    Filter    Magnitude
      (min)                        (s)
-------------------------------------------------------------------------
      112.2                  3x10s           r'         > 18.9
      117.1                  1x10s           i'         > 17
-------------------------------------------------------------------------
```
Values are calibrated against nearby SDSS field stars.
GCN Circular #15036
S. R. Oates (UCL-MSSL) and B.-B. Zhang (PUS/UAH) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 130725A (Zhang et al., GCN Circ. 15028) 3097 s after the BAT trigger (trigger=563980). No optical afterglow consistent with the XRT position is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC          3097         3247          147         >21.1
white             3097         4480          344         >21.0
v                 3255        10746         1278         >20.4
b                 4075         5690          373         >20.4
u                 3870        17226         1118         >21.0
w1                3665        16476         1279         >21.0
m2                3460        11458         1089         >21.0
w2                4486         9832         1082         >21.1
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.06 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #15042
B.-B. Zhang (PSU/UAH) reports on behalf of the Swift-XRT team:
We have analysed 6.8 ks of XRT data for GRB 130725A, from 3.1 ks to 17.2 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. Using 3850 s of PC mode data and 5 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 230.03240, +0.62761 which is equivalent to:
```
RA (J2000): 15h 20m 07.78s
Dec(J2000): +00d 37' 39.4"
```
with an uncertainty of 1.8 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay index of alpha=0.7 (+0.4, -0.3).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.5 (+0.6, -0.5). The best-fitting absorption column is 9 (+11, -5) x 10^20 cm^-2, consistent with the Galactic value of 4.3 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 2.9 x 10^-11 (4.5 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     9 (+11, -5) x 10^20 cm^-2
Galactic foreground: 4.3 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2.5 (+0.6, -0.5)
```
If the light curve continues to decay with a power-law decay index of 0.7, the count rate at T+24 hours will be 2.9 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.5 x 10^-14 (1.3 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/00563980.
This circular is an official product of the Swift-XRT team.
GCN Report 452.1
GCN_Report 452.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_452_1.pdf by B.-B. Zhang at PSU/UAH titled: "Swift Observations of GRB 130725A"

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Jochen Greiner, last update: 26-Apr-2014 [Disclaimer]