Gamma-ray Burst 170724A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 24 Jul 17 00:50:00 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     764204,   Seg_Num: 0
GRB_RA:          150.081d {+10h 00m 20s} (J2000),
                 150.305d {+10h 01m 13s} (current),
                 149.443d {+09h 57m 46s} (1950)
GRB_DEC:          -1.048d {-01d 02' 50"} (J2000),
                  -1.132d {-01d 07' 55"} (current),
                  -0.807d {-00d 48' 24"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1335 [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:        17958 TJD;   205 DOY;   17/07/24
GRB_TIME:        2924.58 SOD {00:48:44.58} UT
GRB_PHI:         -69.86 [deg]
GRB_THETA:        25.13 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    8.43 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  -1 -100  +0 -83  +0 
SUN_POSTN:       123.57d {+08h 14m 18s}  +19.86d {+19d 51' 30"}
SUN_DIST:         33.58 [deg]   Sun_angle= -1.8 [hr] (East of Sun)
MOON_POSTN:      131.94d {+08h 47m 45s}  +16.56d {+16d 33' 29"}
MOON_DIST:        25.33 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      240.26, 40.15 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      152.54,-12.42 [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 = 147.48,-14.79 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 24 Jul 17 00:52:36 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     764204,   Seg_Num: 0
GRB_RA:          150.081d {+10h 00m 20s} (J2000),
                 150.305d {+10h 01m 13s} (current),
                 149.443d {+09h 57m 46s} (1950)
GRB_DEC:          -1.048d {-01d 02' 50"} (J2000),
                  -1.132d {-01d 07' 55"} (current),
                  -0.807d {-00d 48' 24"} (1950)
GRB_DATE:        17958 TJD;   205 DOY;   17/07/24
GRB_TIME:        2924.58 SOD {00:48:44.58} UT
TRIGGER_INDEX:   20000
GRB_PHI:         -69.86 [deg]
GRB_THETA:        25.13 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     64.000 [sec] 
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    8.43 [sigma]
LC_URL:          sw00764204000msb.lc
SUN_POSTN:       123.58d {+08h 14m 18s}  +19.86d {+19d 51' 29"}
SUN_DIST:         33.58 [deg]   Sun_angle= -1.8 [hr] (East of Sun)
MOON_POSTN:      131.96d {+08h 47m 51s}  +16.55d {+16d 33' 12"}
MOON_DIST:        25.30 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      240.26, 40.15 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      152.54,-12.42 [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 = 147.48,-14.79 [deg].

GCN Circular #21364
T. N. Ukwatta (LANL), A. Cholden-Brown (PSU), C. Gronwall (PSU), J. A. Kennea (PSU), A. Melandri (INAF-OAB) and D. M. Palmer (LANL) report on behalf of the Swift Team:
At 00:48:44 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170724A (trigger=764204). Due to a Sun constraint, Swift did not slew to the burst location. The BAT on-board calculated location is RA, Dec 150.081, -1.048 which is
```
   RA(J2000) = 10h 00m 20s
   Dec(J2000) = -01d 02' 50"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is typical for an image trigger, the immediately-available lightcurve show no obvious variation.
Due to a Sun observing constraint, Swift cannot slew to the BAT position until 09:13 UT on 2017 October 11. There will thus be no XRT or UVOT data for this trigger before this time.
Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta AT gmail.com). 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 #21365
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. Stamatikos (OSU), 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 170724A (trigger #764204) (Ukwatta et al., GCN Circ. 21364). The BAT ground-calculated position is RA, Dec = 150.057, -1.025 deg which is
```
  RA(J2000)  =  10h 00m 13.7s
  Dec(J2000) = -01d 01' 31.0"
```
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 58%.
The mask-weighted light curve shows a weak complex structure that starts at ~T-50 s and ends at ~T+80 s. T90 (15-350 keV) is 98.0 +- 26.1 sec (estimated error including systematics).
The time-averaged spectrum from T-45.6 to T+63.6 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.46 +- 0.23. The fluence in the 15-150 keV band is 1.1 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+35.92 sec in the 15-150 keV band is 0.5 +- 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/764204/BA/
GCN Circular #21425
A.Kozlova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, and T. Cline on behalf of the Konus-Wind team, report:
The long GRB 170724A (Swift-BAT trigger #764204: Ukwatta et al., GCN 21364; Sakamoto et al., GCN 21365) was detected by Konus-Wind (KW) in the waiting mode.
The burst light curve shows two emission episodes. The first started at at ~T0(BAT)-508.6 s with a duration of ~247 s and the second weaker episode, which corresponds to the BAT trigger, started at ~T0(BAT)-20 s with a duration of ~91 s.
As observed by Konus-Wind, the first episode had a fluence of 5.49(-0.24,+0.26)x10^-5 erg/cm2 and a 2.944-s peak flux, measured from ~T0(BAT)-408.5 s, of 1.33(-0.16,+0.16)x10^-6 erg/cm2/s. The second episode had a fluence of ~ 0.4 x10^-5 erg/cm2 (all in the 20 - 1000 keV energy range).
Modeling the KW 3-channel time-integrated spectrum of the first episode (from ~T0(BAT)-508.6 s to ~T0(BAT)-261.3 s) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -1.36 (-0.78,+0.82), and Ep = 340 (-49,+77) keV.
Modeling the KW 3-channel time-integrated spectrum of the second episode (from ~T0(BAT)-20 s to ~T0(BAT)+71.4 s) by a simple power-law model yields a power law index of -2.06(-0.13,+0.24), chi2=0.9/1 dof.
The KW light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB170724A/
All the quoted errors are estimated at the 1 sigma confidence level. All the presented results are preliminary.

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Jochen Greiner, last update: 08-Aug-2017 [Disclaimer]