Gamma-ray Burst 160910A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 10 Sep 16 17:20:03 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     495220783
GRB_RA:          229.333d {+15h 17m 20s} (J2000),
                 229.485d {+15h 17m 57s} (current),
                 228.878d {+15h 15m 31s} (1950)
GRB_DEC:         +41.200d {+41d 12' 00"} (J2000),
                 +41.140d {+41d 08' 22"} (current),
                 +41.382d {+41d 22' 56"} (1950)
GRB_ERROR:       21.67 [deg radius, statistical plus systematic]
GRB_INTEN:       136 [cnts/sec]
DATA_SIGNIF:     7.20 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        17641 TJD;   254 DOY;   16/09/10
GRB_TIME:        62379.15 SOD {17:19:39.15} UT
GRB_PHI:          17.00 [deg]
GRB_THETA:        65.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.92
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      96%  GRB
2nd_MOST_LIKELY:   1%  Generic Transient
DETECTORS:       1,1,1, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       169.35d {+11h 17m 25s}   +4.58d {+04d 34' 41"}
SUN_DIST:         64.76 [deg]   Sun_angle= -4.0 [hr] (East of Sun)
MOON_POSTN:      272.34d {+18h 09m 21s}  -18.43d {-18d 25' 47"}
MOON_DIST:        71.59 [deg]
MOON_ILLUM:      62 [%]
GAL_COORDS:       67.69, 57.02 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      208.08, 56.24 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2016/bn160910722/quicklook/glg_lc_medres34_bn160910722.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 43.53,-4.10 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the CALET_GBM event (trignum=1157563166).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 10 Sep 16 17:20:13 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      57
TRIGGER_NUM:     495220783
GRB_RA:          223.500d {+14h 54m 00s} (J2000),
                 223.661d {+14h 54m 39s} (current),
                 223.017d {+14h 52m 04s} (1950)
GRB_DEC:         +39.383d {+39d 22' 60"} (J2000),
                 +39.316d {+39d 18' 58"} (current),
                 +39.586d {+39d 35' 10"} (1950)
GRB_ERROR:       3.42 [deg radius, statistical plus systematic]
GRB_INTEN:       5326 [cnts/sec]
DATA_SIGNIF:     179.40 [sigma]
INTEG_TIME:      0.512 [sec]
GRB_DATE:        17641 TJD;   254 DOY;   16/09/10
GRB_TIME:        62379.15 SOD {17:19:39.15} UT
GRB_PHI:          15.98 [deg]
GRB_THETA:        70.00 [deg]
DATA_TIME_SCALE: 0.5120 [sec]
HARD_RATIO:      0.32
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      96%  GRB
2nd_MOST_LIKELY:   3%  Generic Transient
DETECTORS:       1,1,1, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       169.35d {+11h 17m 25s}   +4.58d {+04d 34' 41"}
SUN_DIST:         59.97 [deg]   Sun_angle= -3.6 [hr] (East of Sun)
MOON_POSTN:      272.34d {+18h 09m 21s}  -18.43d {-18d 25' 47"}
MOON_DIST:        73.48 [deg]
MOON_ILLUM:      62 [%]
GAL_COORDS:       66.51, 61.78 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      202.81, 52.54 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2016/bn160910722/quicklook/glg_lc_medres34_bn160910722.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 43.53,-4.10 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the CALET_GBM event (trignum=1157563166).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 10 Sep 16 17:20:16 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      56
TRIGGER_NUM:     495220783
GRB_RA:          212.780d {+14h 11m 07s} (J2000),
                 212.949d {+14h 11m 48s} (current),
                 212.272d {+14h 09m 05s} (1950)
GRB_DEC:         +41.440d {+41d 26' 24"} (J2000),
                 +41.362d {+41d 21' 43"} (current),
                 +41.675d {+41d 40' 29"} (1950)
GRB_ERROR:       3.11 [deg radius, statistical only]
DATA_SIGNIF:     29.10 [sigma]
DATA_INTERVAL:   1.024 [sec]
GRB_DATE:        17641 TJD;   254 DOY;   16/09/10
GRB_TIME:        62379.15 SOD {17:19:39.15} UT
GRB_PHI:           9.00 [deg]
GRB_THETA:        75.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4153 (Gnd S/W Version number)
SUN_POSTN:       169.35d {+11h 17m 25s}   +4.58d {+04d 34' 41"}
SUN_DIST:         53.52 [deg]   Sun_angle= -2.9 [hr] (East of Sun)
MOON_POSTN:      272.34d {+18h 09m 22s}  -18.43d {-18d 25' 47"}
MOON_DIST:        81.16 [deg]
MOON_ILLUM:      62 [%]
GAL_COORDS:       79.27, 68.29 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      189.82, 50.23 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2016/bn160910722/quicklook/glg_lc_medres34_bn160910722.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_495220783.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
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(2.0<100sec) coincident with the CALET_GBM event (trignum=1157563166).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 10 Sep 16 17:20:19 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      70
TRIGGER_NUM:     495220783
GRB_RA:          223.600d {+14h 54m 24s} (J2000),
                 223.761d {+14h 55m 03s} (current),
                 223.118d {+14h 52m 28s} (1950)
GRB_DEC:         +39.483d {+39d 28' 60"} (J2000),
                 +39.416d {+39d 24' 58"} (current),
                 +39.686d {+39d 41' 09"} (1950)
GRB_ERROR:       3.50 [deg radius, statistical plus systematic]
GRB_INTEN:       3857 [cnts/sec]
DATA_SIGNIF:     375.20 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        17641 TJD;   254 DOY;   16/09/10
GRB_TIME:        62379.15 SOD {17:19:39.15} UT
GRB_PHI:          15.98 [deg]
GRB_THETA:        70.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.54
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       1,1,1, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       169.35d {+11h 17m 25s}   +4.58d {+04d 34' 41"}
SUN_DIST:         60.07 [deg]   Sun_angle= -3.6 [hr] (East of Sun)
MOON_POSTN:      272.34d {+18h 09m 22s}  -18.43d {-18d 25' 47"}
MOON_DIST:        73.49 [deg]
MOON_ILLUM:      62 [%]
GAL_COORDS:       66.66, 61.68 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      202.84, 52.66 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2016/bn160910722/quicklook/glg_lc_medres34_bn160910722.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 43.53,-4.10 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the CALET_GBM event (trignum=1157563166).

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Sat 10 Sep 16 17:20:38 UT
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger 
TRIGGER_NUM:    7560,   Sub_Num: 0
GRB_INTEN:      9.70 [sigma]
GRB_TIME:       62381.14 SOD {17:19:41.14} UT
GRB_DATE:       17641 TJD;   254 DOY;   16/09/10
COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.
COMMENTS:       Time_Scale=0.8000 and Time_Error=0.4000.
COMMENTS:       
COMMENTS:       NOTE: This SPIACS event is temporally(2.0<100sec) coincident with the FERMI_GBM event (trignum=495220783).
COMMENTS:
COMMENTS:       The SPIACS lightcurve can be found at:
COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2016-09/2016-09-10T17-19-40.9917-07560-23440-0.lc

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 10 Sep 16 17:21:09 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      2
TRIGGER_NUM:     495220783
GRB_RA:          219.020d {+14h 36m 05s} (J2000),
                 219.184d {+14h 36m 44s} (current),
                 218.528d {+14h 34m 07s} (1950)
GRB_DEC:         +40.310d {+40d 18' 36"} (J2000),
                 +40.238d {+40d 14' 16"} (current),
                 +40.527d {+40d 31' 37"} (1950)
GRB_ERROR:       2.38 [deg radius, statistical only]
DATA_SIGNIF:     69.30 [sigma]
DATA_INTERVAL:   8.192 [sec]
GRB_DATE:        17641 TJD;   254 DOY;   16/09/10
GRB_TIME:        62379.15 SOD {17:19:39.15} UT
GRB_PHI:          13.00 [deg]
GRB_THETA:        72.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:       169.35d {+11h 17m 25s}   +4.58d {+04d 34' 40"}
SUN_DIST:         57.15 [deg]   Sun_angle= -3.3 [hr] (East of Sun)
MOON_POSTN:      272.35d {+18h 09m 23s}  -18.43d {-18d 25' 48"}
MOON_DIST:        76.70 [deg]
MOON_ILLUM:      62 [%]
GAL_COORDS:       71.04, 64.71 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      197.18, 51.68 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2016/bn160910722/quicklook/glg_lc_medres34_bn160910722.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_495220783.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This is likely a Long GRB.  
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(2.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=7560).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 10 Sep 16 17:21:13 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      3
TRIGGER_NUM:     495220783
GRB_RA:          221.560d {+14h 46m 14s} (J2000),
                 221.723d {+14h 46m 54s} (current),
                 221.071d {+14h 44m 17s} (1950)
GRB_DEC:         +39.420d {+39d 25' 12"} (J2000),
                 +39.351d {+39d 21' 02"} (current),
                 +39.629d {+39d 37' 45"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
DATA_SIGNIF:     160.90 [sigma]
DATA_INTERVAL:   9.216 [sec]
GRB_DATE:        17641 TJD;   254 DOY;   16/09/10
GRB_TIME:        62379.15 SOD {17:19:39.15} UT
GRB_PHI:          15.00 [deg]
GRB_THETA:        71.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:       169.36d {+11h 17m 25s}   +4.58d {+04d 34' 40"}
SUN_DIST:         58.58 [deg]   Sun_angle= -3.5 [hr] (East of Sun)
MOON_POSTN:      272.35d {+18h 09m 24s}  -18.43d {-18d 25' 48"}
MOON_DIST:        74.64 [deg]
MOON_ILLUM:      62 [%]
GAL_COORDS:       67.56, 63.20 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      200.63, 51.86 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2016/bn160910722/quicklook/glg_lc_medres34_bn160910722.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_495220783.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This is likely a Long GRB.  
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(2.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=7560).

GCN Circular #19901
P Veres (UAH) and C Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 17:19:39.15 UT on 10 September 2016, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 160910A (trigger 495220783 / 160910722).
The on-ground calculated location, using the GBM trigger data, is RA = 221.8, DEC = 39.6 (J2000 degrees, equivalent to 14 h 47 m, 39 d 38 '), with an uncertainty of 1 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).
The trigger resulted in an Autonomous Repoint Request (ARR) by the GBM Flight Software owing to the high peak flux of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight location. The initial angle from the Fermi LAT boresight to the GBM ground location is 71 degrees.
The GBM light curve shows a single pulse with a duration (T90) of about 24.3 s (50-300 keV). The time-averaged spectrum from T0 to T0+32.3 s is best fit by a Band function with Epeak = 347 +/- 9 keV, alpha = -0.78 +/- 0.01, and beta = -2.23 +/- 0.04.
The event fluence (10-1000 keV) in this time interval is (8.41 +/- 0.06)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+8.2 s in the 10-1000 keV band is 76.5 +/- 0.5 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #19902
J. L. Racusin (NASA/GSFC) and D. Kocevski (NASA/GSFC) report on behalf of the Fermi-LAT team:
At 17:19:39 on September 10, 2016 Fermi-LAT detected high-energy emission from GRB 160910A, which was also detected by Fermi-GBM (trigger 495220782/160910722; Veres et al. GCN #19901).
The best LAT on-ground location is found to be
RA, Dec = 221.26, 38.76 (J2000)
with an error radius of 0.35 deg (90 % containment, statistical error only).
The GBM location was initially at the edge of the LAT field of view at an angle of 71 degrees to the LAT boresight and triggered an autonomous repoint of the spacecraft. The highest-energy photon is a 500 MeV event which is observed 9 ks after the GBM trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is Dan Kocevski (daniel.kocevski@nasa.gov).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
GCN Circular #19904
A. D'A=EF=BF=BD (INAF-IASFPA), V. D'Elia (ISDC), J. Cummings (GSFC/UMBC), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), T.G.R. Roegiers (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Fermi/GBM (Veres et al., GCN Circ. 19901) and Fermi/LAT (Racusin et al., GCN Circ. 19902) detected burst GRB 160910A in a series of 4 observations tiled on the sky. The total exposure time is 5 ks, distributed over 4 tiles. The data were collected between T0+35 ks and T0+47 ks, and are entirely in Photon Counting (PC) mode.
An uncatalogued X-ray source is detected and is above the RASS limit, and is therefore likely the GRB afterglow. The position of this source is RA, Dec.=3D221.4423, 39.0668 which is equivalent to:
```
RA (J2000)   =3D 14h45m46.16s
Dec (J2000) =3D +39:04:00.64
```
with an uncertainty of 4.3 arcsec (radius, 90% confidence). This position is 0.34 deg from the Fermi/LAT position and 0.6 deg from the GBM position. The light curve built with the data collected so far is consistent with a constant source of mean count rate (1.0 +/- 0.1)e-01 ct/sec. More data are required to search for a fading behaviour.
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.7 (+0.6, -0.6). The best-fitting absorption column is 1.3 (+1.7, -1.3) x 10^21 cm^-2, consistent with the Galactic value of 1.0 x 10^20 cm^-2 (Willingale et al. 2013). The [absorbed] unabsorbed 0.3-10 keV flux is 5.1 (+1.6, -1.0)e^-10 erg cm^-2 s^-1 [4.7 (+2.1, -1.3) e-10 erg cm^-2 s^-1].
This circular is an official product of the Swift-XRT team.

GCN NOTICE

TITLE:          GCN/GRB_COUNTERPART POSITION NOTICE
NOTICE_DATE:    Sun 11 Sep 16 16:26:40 UT
NOTICE_TYPE:    Other
TRIGGER_NUM:    20695
CNTRPART_RA:    221.4422d {+14h 45m 46.1s} (J2000),
                221.6061d {+14h 46m 25.4s} (current),
                220.9511d {+14h 43m 48.2s} (1950)
CNTRPART_DEC:   +39.0669d {+39d 04' 00.8"} (J2000),
                +38.9973d {+38d 59' 50.3"} (current),
                +39.2764d {+39d 16' 34.9"} (1950)
CNTRPART_ERROR: 2.5 [arcsec, radius]
GRB_DATE:       17641 TJD;   254 DOY;   16/09/10
GRB_TIME:       62379.00 SOD {17:19:39.00} UT
OBS_DATE:       17642 TJD;   255 DOY;   16/09/11
OBS_TIME:       11144.0 SOD {03:05:44.00} UT
OBS_DUR:        791.0 [sec]
INTENSITY:      6.90e-12 +/- 1.60e-12 [erg/cm2/sec]
ENERGY:         0.3-10 [keV]
TELESCOPE:      Swift-XRT
SUBMITTER:      Phil_Evans
SUN_POSTN:      170.22d {+11h 20m 52s}   +4.21d {+04d 12' 41"}
SUN_DIST:        58.00 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:     285.00d {+18h 59m 59s}  -18.20d {-18d 11' 43"}
MOON_DIST:       82.29 [deg]
MOON_ILLUM:     71 [%]
GAL_COORDS:      66.87, 63.40 [deg] galactic lon,lat of the counterpart
ECL_COORDS:     200.77, 51.50 [deg] ecliptic lon,lat of the counterpart
COMMENTS:       GRB COUNTERPART Coordinates.
COMMENTS:       Swift is performing multiple tiled observations of this GRB.
COMMENTS:       This object is uncatalogued.
COMMENTS:       The INTENSITY is the OBSERVED flux.
COMMENTS:       See http://www.swift.ac.uk/xrt_products/TILED_GRB00058/index_1.php for more details.
COMMENTS:       This is probably the GRB afterglow
COMMENTS:       The source peak brightness is above the RASS limit

GCN Circular #19906
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a series of observations, tiled on the sky, of the Fermi/LAT GRB 160910B. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00059
Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular #19907
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), L. Izzo (IAA-CSIC),=20 D.A. Kann (TLS Tautenburg), V. Casanova (IAA-CSIC) report on=20 behalf of a larger collaboration:
We have observed the field of GRB 160910A (Veres et al. GCN 19901,=20 Racusin et al. GCN 19902, D=E2=80=99A=C3=AC et al. GCN 19904) with the 1.5m OSN telescope in Granada (Spain). The observation consisted of I-band=20 imaging and started at 20:15:07 (26.92 hr after the burst). On the first 300 s image we detect an object within the XRT error box at I(AB) ~ 19.3 mag,=20 not present in the SDSS images, which we identify as the counterpart of=20 GRB 160910A
We encourage further follow-up and spectroscopy of this bright afterglow.
GCN Circular #19908
D. Malesani (DARK/NBI and DTU Space), D. Xu (NAOC/CAS), A. de Ugarte Postigo (IAA-CSIC and DARK/NBI), R. Tronsgaard Rasmussen (NOT), P. Blay (NOT/IAC), report on behalf of a larger collaboration.
We observed the field of the Fermi GRB 160910A (Veres & Meegan, GCN 19901; Racusin & Kocevski, GCN 19902) with the Nordic Optical Telescope (NOT) equipped with the AlFOSC imaging camera.
Observations started on 2016 Sep 11.847 UT, and consisted of 3x300 s in the SDSS r filter. We detect the afterglow reported by de Ugarte Postigo et al. (GCN 19907), and we provide coordinates (J2000):
```
RA = 14:45:46.04
Dec = +39:04:00.2
```
The expected uncertainty is <0.5". Comparing with nearby SDSS stars, we measure for the afterglow a magnitude r = 19.65 +- 0.01 (AB) at a mean time of Sep 11.8487 UT (27.04 hr after the GRB trigger).
GCN Circular #19909
Y. Kawakubo, A. Yoshida, T. Sakamoto, M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, 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 long-duration GRB 160910A (Veres et al., GCN Circ. 19901; Racusin et al., GCN Circ. 19902; INTEGRAL-SPI/ACS trigger #7560) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 17:19:41.25 on 10 September 2016. The burst signal was seen by all CGBM instruments.
The light curve of the SGM shows an initial weak peak followed by a main bright peak. The weak initial peak starts at T0, peaks at T+3 sec and ends at T+4 sec. The main bright peak starts at T+4 sec, peaks at T+6 sec and ends at T+20 sec. Several overlapping pulses are evident in the main peak. The T90 duration measured by the SGM data is 20.7 +- 1.5 sec (40-1000 keV).
The light curve is available at
http://cgbm.calet.jp/cgbm_trigger/flight/1157563166/
The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.
GCN Circular #19910
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Due to technical issues, GCN 19905 was issues with an incorrect encoding and GCN 19906 was contained the wrong name and URL.
Swift-XRT observed the field of GRB 160910A and discovered an afterglow as reported by D'Ai et al (GCN Circ. 19904). As the afterglow has been detected, the full XRT results for the GRB are available at http://www.swift.ac.uk/xrt_products/00020695
Analysis of the entire tiled campaign is at http://www.swift.ac.uk/xrt_products/TILED_GRB00058/
GCN Circular #19911
A. D'A=EF=BF=BD reports on behalf of the Swift/XRT team: the reported absorbed/unabsorbed fluxes in GCN 19904 have been incorrectly reported. The correct information is:
"The [absorbed] unabsorbed 0.3-10 keV flux is 5.6 (+1.4, -1.2) x 10^-12 erg cm^-2 s^-1 [4.9 (+1.9, -1.4) x 10^-12 erg cm^-2 s^-1]."
We thank M. De Pasquale for spotting the mistake. We apologize for any confusion.
GCN Circular #19913
A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline on behalf of the Konus-Wind team, report:
The long-duration, very intense GRB 160910A (Fermi GBM observation: Veres & Meegan, GCN 19901; Fermi-LAT detection: Racusin & Kocevski, GCN 19902; CALET Gamma-Ray Burst Monitor detection: Kawakubo et al., GCN 19909) triggered Konus-Wind at T0=62379.089 s UT (17:19:39.089).
The burst light curve starts with an initial weaker emission followed by a main bright peak with a duration of ~50 s. The main pulse is followed by a long weak tail seen up to ~T0+150 s. The emission is seen up to ~10 MeV.
As observed by Konus-Wind, the burst had a fluence of 1.36(-0.09,+0.10)x10^-4 erg/cm2, and a 64-ms peak energy flux, measured from T0+5.120 s, of 3.51(-0.32,+0.32)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum of the burst (measured from T0 to T0+47.872 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.81(-0.06,+0.07), the high energy photon index beta = -2.16(-0.12,+0.09), the peak energy Ep = 315(-29,+31) keV, chi2 = 97/98 dof.
The spectrum near the peak count rate (measured from T0+4.864 to T0+6.400 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.15(-0.10,+0.10), the high energy photon index beta = -2.27(-0.09,+0.07), the peak energy Ep = 266(-19,+21) keV, chi2 = 100/69 dof.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB160910_T62379/
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #19914
V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov Lomonosov Moscow State University, Sternberg Astronomical Institute
D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory
R. Rebolo, M. Serra Ricart, N. Lodieu, G. Israelian The Instituto de Astrofisica de Canarias
K.Ivanov, O.Gres, N.M.Budnev, S.Yazev, Irkutsk State University
A. Tlatov, V.Senik, D. Dormidontov, A.Parkhomenko Kislovodsk Solar Station of the Pulkovo Observatory
V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk
Hugo Levato, Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA)
MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in SAAO was pointed to the FERMI GBM GRB160910.72 15 sec after notice time and 65 sec after trigger time at 2016-09-10 17:20:45 UT.
On our first (20s exposure started 75 sec after GBM trigger) set we do not found optical transient within FERMI error-box (ra=14 54 00 dec=+39 23 00 r=3.41, trigger 495220783 / 160910722 (Veres and C.Meegan, GCN 19901)) because very low altitude on horizont ~3 degrees (one tube was under the roof).
Fortunatelly, we saw OT by one of two MASTER Very Wide Field Cameras (5 sec expositon, 0.25 sec readout) . On MASTER-SAAO VWF Camera we see OT at 3 sigma confidence level with magnitude 11.6 +- 0.5 mag on a co-added images with total exposure 95 seconds (19 x 5 sec) starting at 17:20:45 i.e. 65 sec after trigger time. Mean time is 113 sec after trigger.
On our second MASTER-SAAO (30s exposure) set started at 2016-09-10 17:22:26 (167 sec after trigger time) we found OT within FERMI error-box with unfileterd magnitide m = 11.6+-0.1 . The second exposition was making after receiving new Fermi GBM coordinates.
Ra, Dec = 14h 45m 46.03s +39d 04m 00.52s err = +-0.5 arcsec
(cf. A. D'A. et al., GCN 19904; A. de Ugarte Postigo et al., 19907; Malesani et al., GCN 19908 )
MASTER-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in IAC was starting survey on the FERMI GBM GRB160910.72 error-box (ra=14 46 14 dec=+39 25 10 r=1.0) 11142 sec after notice time and 11239 sec after trigger time at 2016-09-10 20:26:58 UT. The 5-sigma upper limit on our first (60s exposure) set is about 18.3 mag . The OT unfiltered magnitude is 17.4+-0.4 .
The light curve is available at http://master.sai.msu.ru/static/GRB160910A.png
The MASTER-SAAO power law index alpha = 1.30+-0.07 ( I ~ t^-alpha) in agreement with MASTER-IAC and some contradiction with late point (Malesani et al., GCN 19908 )
The MASTER-SAAO and NOT combined power law index alpha = 1.17+-0.02 .
All MASTER observations was done before LAT alert.
The message may be cited.
GCN Circular #19919
E. Mazaeva (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI), I. Korobtsev (ISTP) report on behalf of larger GRB follow-up collaboration:
We observed the field of the GRB 160910A (Veres et al., GCN 19901; Racusin et al., GCN 19902) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Sep., 12 (UT) 14:02:46. We obtained several images in R-filter. We clearly detected optical afterglow (Ugarte Postigo et al., GCN 19907; Malesani et al., GCN 19908; Lipunov et al., GCN 19914). Preliminary photometry of the afterglow is following
```
Date        UT start   t-T0      Filter Exp.   OT        UpLim (3 sigma)
                        (mid, days)       (s)

2016-09-12  14:02:46   1.87506    R      32*60 19.92+/-0.05  22.2
```
Photometry is based on nearby SDSS-DR9 stars
```
SDSS-DR9_id    R(Lupton transformation)
J144549.10+390403.4    16.86
J144552.78+390234.9    17.32
J144538.58+390535.0    18.34
J144541.35+390128.0    17.15 
```
GCN Circular #19923
L. M. Z. Hagen (PSU) and J. R. Cummings (GSFC/UMBC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160910A 196954 s after the Fermi/GBM (Veres et al., GCN Circ. 19901) and Fermi/LAT (Racusin et al., GCN Circ. 19902) triggers. We detect a fading source consistent with the XRT position (D'Ai et al., GCN Circ. 19904) and optical detections (de Ugarte Postigo et al., GCN Circ. 19907; Malesani et al., GCN Circ. 19908; Lipunov et al., GCN Circ. 19914; Mazaeva et al., GCN Circ. 19919).
Preliminary detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white           196954       267060         1620          20.61+-0.14
white           267064       318724         2326          20.95+-0.14
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #19925
E. Mazaeva (IKI), A. Pozanenko (IKI), B. Hafizov (UBAI). A. Volnova (IKI), O. Burhonov (UBAI) report on behalf of larger GRB follow-up collaboration:
We observed the GRB 160910A (Veres et al., GCN 19901; Racusin et al., GCN 19902) with AZT-22 telescope of Maidanak observatory equipped with SNUCAM in R filter. We clearly detected optical afterglow (de Ugarte Postigo et al., GCN 19907; Malesani et al., GCN 19908; Lipunov et al., GCN 19914; Mazaeva et al., GCN 19919; Hagen et al., GCN 19923). Preliminary photometry of the afterglow is following
Preliminary photometry of the afterglow is following
```
Date         UT start   t-T0    Filter   Exp.     OT     Err.   UL
                        (mid, days)        (s)

2016-09-14   14:40:40  3.89933  R        15*120   21.40  0.14   22.2
```
Photometry is based on nearby SDSS-DR9 stars
```
SDSS-DR9_id    R(Lupton transformation)
J144549.10+390403.4    16.86
J144552.78+390234.9    17.32
J144538.58+390535.0    18.34
J144541.35+390128.0    17.15
```
GCN Circular #19935
E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), I. Reva (Fesenkov Astrophysical Institute), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the GRB 160910A (Veres et al., GCN 19901; Racusin et al., GCN 19902) with Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory. We obtained several images in R filter starting on Sep., 12 and Sep., 15. We clearly detected optical afterglow (Ugarte Postigo et al., GCN 19907; Malesani et al., GCN 19908; Lipunov et al., GCN 19914). Preliminary photometry of the afterglow is following
```
Date UT start t-T0 Filter Exp. OT UpLim (3 sigma)
                          (mid, days) (s)
2016-09-12 14:43:02 1.92176 R 27*120 19.96 +/- 0.08 21.7
2016-09-15 14:31:13 4.91356 R 27*120 21.70 +/- 0.30 21.7
```
Photometry is based on nearby SDSS-DR9 stars used in GCN 19919 (Mazaeva et al.).
GCN Circular #19937
K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)
We observed the Fermi/LAT GRB 160910A (Racusin et al., GCN 19902) with the AMI Large Array at 15 GHz on 2016 Sep 12.65, Sep 13.68, Sep 15.67, and Sep 20.68 (UT) as part of the 4pisky program. We detect the radio afterglow at the NOT location (Malesani et al., GCN 19908) at flux densities of 791+/-55 uJy, 1151+/-82 uJy, 840+/-146 uJy, and 462+/-39 uJy respectively.
We thank the AMI staff for scheduling these observations. The AMI-GRB database is a log of all GRB follow up observations with the AMI, and is available at http://4pisky.org/ami-grb/.
GCN Circular #19949
V. Bhalerao (IUCAA), V. Kumar (IUCAA), D. Bhattacharya (IUCAA), A. R. Rao (TIFR), S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:
Analysis of Astrosat data showed the CZTI detection of a very bright GRB160910A (Fermi-GBM detection: P. Veres et al., GCN Circ. 19901).
The source was clearly detected in the 40-200 keV energy range. The light curve shows a single peak at 17:19:47.15 UT, 8 seconds after Fermi Trigger at 17:19:39.15 UT and a peak count rate of 1738 counts/sec above the background (four quadrants summed together), with a total of 7184 counts. The local mean background count rate was 343 counts/sec. Using cumulative rates, we measure a T90 of 9.44 secs.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb . CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN Circular #19966
A.J Nayana (NCRA-TIFR) and Poonam Chandra (NCRA-TIFR) report:
We carried out Giant Metrewave Radio Telescope (GMRT) observations of GRB 160910A (Veres et al. 2016., GCN Circ. 19901. , Racusin et al. 2016., GCN Circ. 19902) at 1390 MHz band on 2016 Sep 27.21 UT. We detect a 4-sigma source within the XRT error circle (D'Ai et al. 2016., GCN Circ. 19904) with a flux density of 185+/-69 uJy. This is likely to be the radio afterglow of GRB 160910A. Map rms is 35 uJy.
We thank GMRT staff for making these observations possible.

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Jochen Greiner, last update: 29-Sep-2016 [Disclaimer]