Gamma-ray Burst 150722A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 22 Jul 15 09:59:11 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     649916,   Seg_Num: 0
GRB_RA:          218.272d {+14h 33m 05s} (J2000),
                 218.509d {+14h 34m 02s} (current),
                 217.511d {+14h 30m 03s} (1950)
GRB_DEC:         -35.197d {-35d 11' 46"} (J2000),
                 -35.264d {-35d 15' 51"} (current),
                 -34.977d {-34d 58' 35"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1962 [image_cnts]
TRIGGER_DUR:     64.000 [sec] 
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        17225 TJD;   203 DOY;   15/07/22
GRB_TIME:        35873.11 SOD {09:57:53.11} UT
GRB_PHI:         -24.61 [deg]
GRB_THETA:        23.35 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    8.92 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  -1  +0  +0 +28  +0 
SUN_POSTN:       121.45d {+08h 05m 49s}  +20.29d {+20d 17' 40"}
SUN_DIST:        107.12 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      189.56d {+12h 38m 15s}   -3.37d {-03d 22' 19"}
MOON_DIST:        41.65 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      325.36, 23.21 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      227.23,-19.12 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
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 = 215.36,-3.25 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 22 Jul 15 10:01:52 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     649916,   Seg_Num: 0
GRB_RA:          218.272d {+14h 33m 05s} (J2000),
                 218.509d {+14h 34m 02s} (current),
                 217.511d {+14h 30m 03s} (1950)
GRB_DEC:         -35.197d {-35d 11' 46"} (J2000),
                 -35.264d {-35d 15' 51"} (current),
                 -34.977d {-34d 58' 35"} (1950)
GRB_DATE:        17225 TJD;   203 DOY;   15/07/22
GRB_TIME:        35873.11 SOD {09:57:53.11} UT
TRIGGER_INDEX:   20000
GRB_PHI:         -24.61 [deg]
GRB_THETA:        23.35 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     64.000 [sec] 
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    8.92 [sigma]
LC_URL:          sw00649916000msb.lc
SUN_POSTN:       121.46d {+08h 05m 49s}  +20.29d {+20d 17' 39"}
SUN_DIST:        107.11 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      189.59d {+12h 38m 20s}   -3.38d {-03d 22' 43"}
MOON_DIST:        41.63 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      325.36, 23.21 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      227.23,-19.12 [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 an image 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 = 215.36,-3.25 [deg].

GCN Circular #18042
F. E. Marshall (NASA/GSFC), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC) and K. L. Page (U Leicester) report on behalf of the Swift Team:
At 09:57:53 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150722A (trigger=649916). Swift did not slew immediately due to earth limb observing constraint. The BAT on-board calculated location is RA, Dec 218.272, -35.197 which is
```
   RA(J2000)  =  14h 33m 05s
   Dec(J2000) = -35d 11' 46"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual for an image trigger (64-sec), there is nothing significant in the real-time TDRSS light curve.
Due to an observing constraint, Swift will not slew until T0+50.9 minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.nasa.gov). 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:     Wed 22 Jul 15 11:00:10 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     649916,   Seg_Num: 0
POINT_RA:        218.273d {+14h 33m 05s} (J2000)
POINT_DEC:       -35.189d {-35d 11' 19"} (J2000)
IMG_START_DATE:  17225 TJD;   203 DOY;   15/07/22
IMG_START_TIME:  39108.03 SOD {10:51:48.03} UT,   3234.9 [sec] since BAT Trigger Time
COUNTS:          1    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        0    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 22 Jul 15 11:02:11 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     649916,   Seg_Num: 0
POINT_RA:        218.273d {+14h 33m 05s} (J2000)
POINT_DEC:       -35.188d {-35d 11' 18"} (J2000)
POINT_ROLL:      283.250d
IMG_START_DATE:  17225 TJD;   203 DOY;   15/07/22
IMG_START_TIME:  39110.88 SOD {10:51:50.88} UT,   3237.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.286
N_STARS:         147
X_OFFSET:        434 [pixels]
Y_OFFSET:        493 [pixels]
X_MAX:           1393 [pixels]
Y_MAX:           1452 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    13
SL_URL:          sw00649916000msufc3237.fits
SUN_POSTN:       121.50d {+08h 05m 59s}  +20.29d {+20d 17' 09"}
SUN_DIST:        107.08 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.06d {+12h 40m 14s}   -3.53d {-03d 31' 55"}
MOON_DIST:        41.22 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      325.37, 23.22 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      227.23,-19.11 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 22 Jul 15 11:02:47 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     649916,   Seg_Num: 0
POINT_RA:        218.273d {+14h 33m 05s} (J2000)
POINT_DEC:       -35.188d {-35d 11' 18"} (J2000)
POINT_ROLL:      283.250d
IMG_START_DATE:  17225 TJD;   203 DOY;   15/07/22
IMG_START_TIME:  39110.88 SOD {10:51:50.88} UT,   3237.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.286
N_STARS:         147
X_OFFSET:        434 [pixels]
Y_OFFSET:        493 [pixels]
X_MAX:           1393 [pixels]
Y_MAX:           1452 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    13
SL_URL:          sw00649916000msufc3237.fits
SUN_POSTN:       121.50d {+08h 05m 59s}  +20.29d {+20d 17' 09"}
SUN_DIST:        107.08 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.06d {+12h 40m 15s}   -3.53d {-03d 32' 01"}
MOON_DIST:        41.22 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      325.37, 23.22 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      227.23,-19.11 [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:     Wed 22 Jul 15 11:03:31 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     649916,   Seg_Num: 0
POINT_RA:        218.273d {+14h 33m 05s} (J2000)
POINT_DEC:       -35.188d {-35d 11' 18"} (J2000)
ROLL:            283.250d
IMG_START_DATE:  17225 TJD;   203 DOY;   15/07/22
IMG_START_TIME:  39110.88 SOD {10:51:50.88} UT,   3237.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     459255125
X_OFFSET:        753 [pixels]
Y_OFFSET:        812 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       913
Y_GRB_POS:       972
BINNING_INDEX:   1
IM_URL:          sw00649916000msuni3252.fits
SUN_POSTN:       121.50d {+08h 06m 00s}  +20.29d {+20d 17' 08"}
SUN_DIST:        107.07 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.07d {+12h 40m 16s}   -3.54d {-03d 32' 08"}
MOON_DIST:        41.22 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      325.37, 23.22 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      227.23,-19.11 [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:     Wed 22 Jul 15 11:04:22 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     649916,   Seg_Num: 0
POINT_RA:        218.273d {+14h 33m 05s} (J2000)
POINT_DEC:       -35.188d {-35d 11' 18"} (J2000)
ROLL:            283.250d
IMG_START_DATE:  17225 TJD;   203 DOY;   15/07/22
IMG_START_TIME:  39110.88 SOD {10:51:50.88} UT,   3237.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     459255125
X_OFFSET:        753 [pixels]
Y_OFFSET:        812 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       913
Y_GRB_POS:       972
BINNING_INDEX:   1
IM_URL:          sw00649916000msuni3252.fits
SUN_POSTN:       121.50d {+08h 06m 00s}  +20.29d {+20d 17' 08"}
SUN_DIST:        107.07 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.07d {+12h 40m 18s}   -3.54d {-03d 32' 15"}
MOON_DIST:        41.21 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      325.37, 23.22 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      227.23,-19.11 [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:     Wed 22 Jul 15 11:06:13 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     649916,   Seg_Num: 0
GRB_RA:          218.2771d {+14h 33m 06.50s} (J2000),
                 218.5144d {+14h 34m 03.44s} (current),
                 217.5165d {+14h 30m 03.94s} (1950)
GRB_DEC:         -35.1965d {-35d 11' 47.4"} (J2000),
                 -35.2644d {-35d 15' 51.7"} (current),
                 -34.9768d {-34d 58' 36.4"} (1950)
GRB_ERROR:       3.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17225 TJD;   203 DOY;   15/07/22
IMG_START_TIME:  39118.00 SOD {10:51:58.00} UT,   3244.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       121.50d {+08h 06m 00s}  +20.29d {+20d 17' 07"}
SUN_DIST:        107.08 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.09d {+12h 40m 21s}   -3.54d {-03d 32' 32"}
MOON_DIST:        41.21 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      325.37, 23.21 [deg] galactic lon,lat of the burst
ECL_COORDS:      227.24,-19.11 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 1.1% < P(seren) < 2.8%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 22 Jul 15 12:06:14 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     649916,   Seg_Num: 0
GRB_RA:          218.2777d {+14h 33m 06.64s} (J2000),
                 218.5150d {+14h 34m 03.59s} (current),
                 217.5171d {+14h 30m 04.09s} (1950)
GRB_DEC:         -35.1963d {-35d 11' 46.6"} (J2000),
                 -35.2642d {-35d 15' 50.9"} (current),
                 -34.9766d {-34d 58' 35.7"} (1950)
GRB_ERROR:       3.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17225 TJD;   203 DOY;   15/07/22
IMG_START_TIME:  39118.00 SOD {10:51:58.00} UT,   3244.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       121.54d {+08h 06m 10s}  +20.28d {+20d 16' 37"}
SUN_DIST:        107.04 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.56d {+12h 42m 14s}   -3.69d {-03d 41' 41"}
MOON_DIST:        40.81 [deg]
MOON_ILLUM:      34 [%]
GAL_COORDS:      325.37, 23.21 [deg] galactic lon,lat of the burst
ECL_COORDS:      227.24,-19.11 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 1.1% < P(seren) < 2.8%.

GCN Circular #18043
S. Campana (INAF-OAB), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU) and G. Tagliaferri (INAF-OAB) report on behalf of the Swift-XRT team:
The XRT began observing the field of GRB 150722A at 10:51:48.0 UT, 3234.9 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 218.27775, -35.19644 which is equivalent to:
```
   RA(J2000)  = 14h 33m 06.66s
   Dec(J2000) = -35d 11' 47.2"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 17 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 5.92 x 10^20 cm^-2 (Willingale et al. 2013).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 22 Jul 15 12:37:09 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     649916,   Seg_Num: 0
GRB_RA:          218.2777d {+14h 33m 06.64s} (J2000),
                 218.5150d {+14h 34m 03.59s} (current),
                 217.5171d {+14h 30m 04.09s} (1950)
GRB_DEC:         -35.1963d {-35d 11' 46.6"} (J2000),
                 -35.2642d {-35d 15' 50.9"} (current),
                 -34.9766d {-34d 58' 35.7"} (1950)
GRB_ERROR:       3.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17225 TJD;   203 DOY;   15/07/22
IMG_START_TIME:  39118.00 SOD {10:51:58.00} UT,   3244.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       121.56d {+08h 06m 15s}  +20.27d {+20d 16' 22"}
SUN_DIST:        107.02 [deg]   Sun_angle= -6.5 [hr] (East of Sun)
MOON_POSTN:      190.80d {+12h 43m 12s}   -3.77d {-03d 46' 23"}
MOON_DIST:        40.60 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      325.37, 23.21 [deg] galactic lon,lat of the burst
ECL_COORDS:      227.24,-19.11 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 1.1% < P(seren) < 2.8%.

GCN Circular #18044
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 2194 s of XRT Photon Counting mode data and 6 UVOT images for GRB 150722A, 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 = 218.27800, -35.19588 which is equivalent to:
```
RA (J2000): 14h 33m 6.72s
Dec (J2000): -35d 11' 45.2"
```
with an uncertainty of 1.7 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, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #18046
N. P. M. Kuin (UCL-MSSL) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 150722A 3238 s after the BAT trigger (Marshall et al., GCN Circ. 18042). No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. No. 18044) 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          3238         3388          147         >20.6
white             3238         5442          541         >21.6
v                 4217         5791          333         >20.0
b                 3602         5237          393         >21.0
u                 3396         5031          393         >20.6
w1                4627         4827          197         >20.1
m2                4422         4622          197         >20.3
w2                4012         5647          393         >21.4
```
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 #18047
D.N. Burrows (PSU), T.G.R. Roegiers (PSU), B.P. Gompertz (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), L.M. McCauley (PSU), A. Amaral-Rogers (U. Leicester) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift-XRT team:
We have analysed 5.7 ks of XRT data for GRB 150722A (Marshall et al. GCN Circ. 18042), from 3.2 ks to 17.3 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 18044).
The light curve can be modelled with a power-law decay with a decay index of alpha=0.90 (+0.14, -0.13).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.08 (+/-0.13). The best-fitting absorption column is 1.4 (+0.4, -0.3) x 10^21 cm^-2, in excess of the Galactic value of 5.9 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.2 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.4 (+0.4, -0.3) x 10^21 cm^-2
Galactic foreground: 5.9 x 10^20 cm^-2
Excess significance: 3.6 sigma
Photon index:	     2.08 (+/-0.13)
```
If the light curve continues to decay with a power-law decay index of 0.90, the count rate at T+24 hours will be 0.013 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.2 x 10^-13 (5.6 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/00649916.
This circular is an official product of the Swift-XRT team.
GCN Circular #18048
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 150722A (trigger #649916) (Marshall, et al., GCN Circ. 18042). The BAT ground-calculated position is RA, Dec = 218.297, -35.196 deg which is
```
    RA(J2000)  =  14h 33m 11.3s
    Dec(J2000) = -35d 11' 45.1"
```
with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 94%.
The mask-weighted light curve shows weak, variable emission from prior to T-200 to about T+55 seconds. T90 (15-350 keV) is 67 +- 12 sec (estimated error including systematics).
The time-averaged spectrum from T-26.00 to T+48.00 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.79 +- 0.26. The fluence in the 15-150 keV band is 6.1 +- 0.9 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+15.00 sec in the 15-150 keV band is 0.4 +- 0.1 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/649916/BA/
GCN Circular #18049
S. Dichiara, C. Guidorzi (U. Ferrara), D. Kopac (LJMU), on behalf of a large collaboration report:
One of the LCOGT 1-m telescopes in Sutherland (South Africa) began observing GRB 150722A (Marshall et al. GCN 18042) on July 22 at 17:01:14 UT, i.e. ~7 hours after the BAT trigger with the r' and i' filters.
Within the XRT error circle (Evans et al. GCN 18044) we found no new source down to the following limit:
```
Mid time from  Total Exp   Filter    Magnitude
trigger (hr)   (s)
-------------------------------------------------
7.46           120x15        r'        > 20.0
7.90           120x6         i'        > 18.8
-------------------------------------------------
```
Values have been calibrated against nearby USNOB-1 stars (R2 and I).

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Jochen Greiner, last update: 23-Jul-2015 [Disclaimer]