Gamma-ray Burst 160726A

(All information courtesy of the instrument teams.)

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 26 Jul 16 01:38:12 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     706052,   Seg_Num: 0
GRB_RA:           98.821d {+06h 35m 17s} (J2000),
                  99.022d {+06h 36m 05s} (current),
                  98.212d {+06h 32m 51s} (1950)
GRB_DEC:          -6.644d {-06d 38' 39"} (J2000),
                  -6.659d {-06d 39' 31"} (current),
                  -6.603d {-06d 36' 11"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       323 [cnts]    Image_Peak=47 [image_cnts]
TRIGGER_DUR:     0.032 [sec] 
TRIGGER_INDEX:   10318     E_range: 25-100 keV
BKG_INTEN:       22473 [cnts]
BKG_TIME:        5631.38 SOD {01:33:51.38} UT
BKG_DUR:         8 [sec]
GRB_DATE:        17595 TJD;   208 DOY;   16/07/26
GRB_TIME:        5647.38 SOD {01:34:07.38} UT
GRB_PHI:         -26.06 [deg]
GRB_THETA:        38.10 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     24.28 [sigma]
IMAGE_SIGNIF:    7.60 [sigma]
MERIT_PARAMS:     +1  +0  +0  -5  +2  -2 -100  +1 -79  +0 
SUN_POSTN:       125.82d {+08h 23m 17s}  +19.37d {+19d 21' 59"}
SUN_DIST:         37.07 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:       21.29d {+01h 25m 09s}   +5.47d {+05d 28' 21"}
MOON_DIST:        78.52 [deg]
MOON_ILLUM:      60 [%]
GAL_COORDS:      217.04, -6.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      100.11,-29.77 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger integration interval;  
COMMENTS:        probably due to it occurring during a Malindi downlink session.  
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 = 74.57,12.00 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(0.0<100sec) coincident with the FERMI_GBM event (trignum=491189651).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 26 Jul 16 01:34:35 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     491189651
GRB_RA:          108.483d {+07h 13m 56s} (J2000),
                 108.661d {+07h 14m 39s} (current),
                 107.946d {+07h 11m 47s} (1950)
GRB_DEC:         -21.300d {-21d 18' 00"} (J2000),
                 -21.329d {-21d 19' 45"} (current),
                 -21.213d {-21d 12' 46"} (1950)
GRB_ERROR:       5.03 [deg radius, statistical plus systematic]
GRB_INTEN:       908 [cnts/sec]
DATA_SIGNIF:     25.90 [sigma]
INTEG_TIME:      0.256 [sec]
GRB_DATE:        17595 TJD;   208 DOY;   16/07/26
GRB_TIME:        5647.72 SOD {01:34:07.72} UT
GRB_PHI:          70.00 [deg]
GRB_THETA:        30.00 [deg]
DATA_TIME_SCALE: 0.2560 [sec]
HARD_RATIO:      0.63
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      96%  GRB
2nd_MOST_LIKELY:   3%  Generic Transient
DETECTORS:       1,1,1, 0,0,0, 0,0,0, 1,0,0, 0,0,
SUN_POSTN:       125.82d {+08h 23m 17s}  +19.37d {+19d 22' 01"}
SUN_DIST:         44.02 [deg]   Sun_angle= 1.1 [hr] (West of Sun)
MOON_POSTN:       21.25d {+01h 25m 00s}   +5.46d {+05d 27' 42"}
MOON_DIST:        89.58 [deg]
MOON_ILLUM:      60 [%]
GAL_COORDS:      234.42, -4.84 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      113.91,-43.22 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2016/bn160726065/quicklook/glg_lc_medres34_bn160726065.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 166.20,24.45 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the CALET_GBM event (trignum=1153531947).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 26 Jul 16 01:34:47 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     491189651
GRB_RA:          109.120d {+07h 16m 29s} (J2000),
                 109.307d {+07h 17m 14s} (current),
                 108.556d {+07h 14m 13s} (1950)
GRB_DEC:         -16.170d {-16d 10' 11"} (J2000),
                 -16.200d {-16d 12' 00"} (current),
                 -16.080d {-16d 04' 47"} (1950)
GRB_ERROR:       5.19 [deg radius, statistical only]
DATA_SIGNIF:     25.80 [sigma]
DATA_INTERVAL:   0.256 [sec]
GRB_DATE:        17595 TJD;   208 DOY;   16/07/26
GRB_TIME:        5647.72 SOD {01:34:07.72} UT
GRB_PHI:          60.00 [deg]
GRB_THETA:        31.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4153 (Gnd S/W Version number)
SUN_POSTN:       125.82d {+08h 23m 17s}  +19.37d {+19d 22' 01"}
SUN_DIST:         39.10 [deg]   Sun_angle= 1.1 [hr] (West of Sun)
MOON_POSTN:       21.25d {+01h 25m 01s}   +5.46d {+05d 27' 44"}
MOON_DIST:        89.66 [deg]
MOON_ILLUM:      60 [%]
GAL_COORDS:      230.14, -1.94 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      113.55,-38.06 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2016/bn160726065/quicklook/glg_lc_medres34_bn160726065.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_491189651.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the CALET_GBM event (trignum=1153531947).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 26 Jul 16 01:38:52 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     706052,   Seg_Num: 0
GRB_RA:           98.821d {+06h 35m 17s} (J2000),
                  99.022d {+06h 36m 05s} (current),
                  98.212d {+06h 32m 51s} (1950)
GRB_DEC:          -6.644d {-06d 38' 39"} (J2000),
                  -6.659d {-06d 39' 31"} (current),
                  -6.603d {-06d 36' 11"} (1950)
GRB_DATE:        17595 TJD;   208 DOY;   16/07/26
GRB_TIME:        5647.67 SOD {01:34:07.67} UT
TRIGGER_INDEX:   10318
GRB_PHI:         -26.06 [deg]
GRB_THETA:        38.10 [deg]
DELTA_TIME:      -27.00 [sec]
TRIGGER_DUR:     0.032 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     24.28 [sigma]
IMAGE_SIGNIF:    7.60 [sigma]
LC_URL:          sw00706052000msb.lc
SUN_POSTN:       125.82d {+08h 23m 17s}  +19.37d {+19d 21' 59"}
SUN_DIST:         37.07 [deg]   Sun_angle= 1.8 [hr] (West of Sun)
MOON_POSTN:       21.29d {+01h 25m 10s}   +5.47d {+05d 28' 28"}
MOON_DIST:        78.52 [deg]
MOON_ILLUM:      60 [%]
GAL_COORDS:      217.04, -6.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      100.11,-29.77 [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 = 74.57,12.00 [deg].

GCN Circular #19731
R. L. C. Starling (U Leicester), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester) and T. Sakamoto (AGU) report on behalf of the Swift Team:
At 01:34:07 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 160726A (trigger=706052). Swift did not slew immediately due to an observational constraint. The BAT on-board calculated location is RA, Dec 98.821, -6.644 which is
```
   RA(J2000) = 06h 35m 17s
   Dec(J2000) = -06d 38' 39"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 1 sec. The peak count rate was ~14000 counts/sec (15-350 keV), at ~0.7 sec after the trigger.
Due to a Sun observing constraint, Swift cannot slew to the BAT position until 12:53 UT on 2016 August 10. There will thus be no XRT or UVOT data for this trigger before this time.
Burst Advocate for this burst is R. L. C. Starling (rlcs1 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 Circular #19732
R. Hamburg (UAH), E. Burns (UAH), and E. Bissaldi (Politecnico & INFN Bari) report on behalf of the Fermi GBM Team:
"At 01:34:07.72 UT on 26 July 2016, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 160726A (trigger 491189651 / 160726065), which was also detected by the Swift/BAT (Starling et al. 2016, GCN 19731). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi-LAT boresight at the GBM trigger time is 50 degrees.
The GBM light curve consists of two short peaks with a duration (T90) of about 0.7 s (50-300 keV). The time-averaged spectrum from T0-0.06 s to T0+0.77 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.0 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 540 +/- 100 keV.
The event fluence (10-1000 keV) in this time interval is (1.01 +/- 0.05)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.06 s in the 10-1000 keV band is 5.5 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #19733
D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report:
The short GRB 160726A (Swift/BAT detection: Starling et al., GCN 19731; Fermi GBM observation: Hamburg et al., GCN 19732) triggered Konus-Wind at T0=3D5645.315 s UT (01:34:05.315).
The light curve shows a short pulse with a total duration is ~0.2 s. The emission is seen up to ~2 MeV.
As observed by Konus-Wind, the burst had a fluence of (1.5 =B1 0.5)x10^-6 erg/cm2 and a 16-ms peak energy flux, measured from T0+0.016, of (1.1 =B1 0.3)x10^-5 erg/cm2 (both in the 20 keV - 10 MeV energy range).
The spectrum of the burst (measured from T0 to T0+0.128 s) is best fit in the 20 keV - 2 MeV range by a cutoff power-law (CPL) function with the following model parameters: the photon index alpha =3D -0.65(-0.47,+0.71), and the peak energy Ep =3D 424(-163,+389) keV, chi2 =3D 19.5/20 dof. Fitting this spectrum with the GRB (Band) function yields the same alpha and Ep with only an upper limit on beta of -1.8, chi2 =3D 19.5/19 dof.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB160726_T05645/
All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.
GCN Circular #19734
S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), J. P. Norris (BSU), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), R. L. C. Starling (U Leicester), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 160726A (trigger #706052) (Starling et al., GCN Circ. 19731). The BAT ground-calculated position is RA, Dec = 98.809, -6.617 deg which is
```
  RA(J2000)  =  06h 35m 14.2s
  Dec(J2000) = -06d 37' 03.0"
```
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 58%.
The mask-weighted light curve shows a double-peaked structure that starts at ~T0 and ends at ~T+0.8 s, with the two peaks at ~ T0 and ~T+0.6 s, respectively. T90 (15-350 keV) is 0.7 +- 0.04 sec (estimated error including systematics).
The time-averaged spectrum from T+0.0 to T+0.8 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.26 +- 0.13. The fluence in the 15-150 keV band is 2.6 +- 0.2 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.11 sec in the 15-150 keV band is 3.2 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
Using a 4-ms binned light curve, the lag analysis finds a lag of is -3.5 +/- 3 ms for the 100-350 keV to 25-50 keV, and -5 +/- 6 ms for the 50-100 keV to 15-25 keV band. These numbers are consistent with those of a short GRB.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/706052/BA/
GCN Circular #19751
Y. Shimizu (Kanagawa U), A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena) and the CALET collaboration:
The short-duration GRB 160726A (Starling, et al., GCN circ. 19731; Hamburg, et al., GCN circ. 19732; Frederiks, et al. GCN circ. 19733) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 01:34:08.25 on 26 July 2016. The burst signal was seen by all CGBM instruments.
The light curve of the SGM shows two peaks. The first weak episode peaks at T-0.55 s. The second peak starts at T-0.1 s, peaks at T+0.1 s and ends at T+0.3 s. The T90 duration measured by the SGM data is 0.83 +- 0.09 sec (40-1000 keV).
The light curve is available at
http://cgbm.calet.jp/cgbm_trigger/flight/1153531947/
The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.

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Jochen Greiner, last update: 01-Aug-2016 [Disclaimer]