Gamma-ray Burst 161015A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Sun 16 Oct 16 01:38:57 UT
  NOTICE_TYPE:     Fermi-LAT Offline Position
  TRIGGER_NUM:     498243790 
  GRB_RA:          269.150d {+17h 56m 36s} (J2000),
                   269.311d {+17h 57m 15s} (current),
                   268.671d {+17h 54m 41s} (1950)
  GRB_DEC:         +30.190d {+30d 11' 24"} (J2000),
                   +30.189d {+30d 11' 19"} (current),
                   +30.195d {+30d 11' 43"} (1950)
  GRB_ERROR:       12.59 [arcmin radius, 90% containment, statistical only]
  GRB_DATE:        17676 TJD;   289 DOY;   16/10/15
  GRB_TIME:        61387.03 SOD {17:03:07.03} UT
  TRIGGER_ID:      0x20000000
  MISC:            0x40000000
  SUN_POSTN:       201.40d {+13h 25m 36s}   -8.99d {-08d 59' 15"}
  SUN_DIST:         75.97 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
  MOON_POSTN:       20.93d {+01h 23m 42s}   +5.32d {+05d 19' 27"}
  MOON_DIST:       105.69 [deg] 
  MOON_ILLUM:      100 [%]
  GAL_COORDS:       55.80, 24.31 [deg] galactic lon,lat of the burst (or transient)       
  ECL_COORDS:      268.76, 53.63 [deg] ecliptic lon,lat of the burst (or transient)      
  COMMENTS:        Fermi LAT Offline position.
  COMMENTS:        This Notice was ground-generated -- not flight-generated.
  COMMENTS:        It is the result of human-in-the-loop processing.
  COMMENTS:        Fermi LAT Offline position.
  COMMENTS:        This Notice was ground-generated -- not flight-generated.
  COMMENTS:        It is the result of human-in-the-loop processing.
  COMMENTS:        This is a human generated position of a LAT ground detection.
  COMMENTS:        This source corresponds to GBM trigger.
  

• GCN Circular #20054
  Masanori Ohno (Hiroshima Univ.), E. Bissaldi (Politecnico & INFN Bari), J. E. McEnery (NASA/GSFC), M. Arimoto (Tokyo Tech) and G. Vianello (Stanford) report on behalf of the Fermi-LAT team:
  At 17:03:07.04 on October, 15, 2016 Fermi-LAT detected high-energy emission from GRB 161015A, which was also detected by Fermi-GBM (trigger 498243790 / 161015710).
  The best LAT on-ground location is found to be
  RA, Dec = 269.15, 30.19 (J2000)
  with an error radius of 0.21 deg (90 % containment, statistical error only). This was 50 deg from the LAT boresight at the time of the trigger and triggered an autonomous repoint of the spacecraft. The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the trigger with high significance. The highest-energy photon is a 1.5 GeV event which is observed 72 seconds after the GBM trigger. A Swift ToO has been requested for this burst. The Fermi-LAT point of contact for this burst is Masanori Ohno ( ohno@hep01.hepl.hiroshima-u.ac.jp)
  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 #20055
  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 161015A. 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 #20056
  M Stanbro (UAH) and C Meegan (UAH) report on behalf of the Fermi GBM Team:
  "At 17:03:07.03 UT on 15 October 2016, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 161015A (trigger 498243791 / 161015710), which was also detected by the Fermi-LAT (Masanori Ohno et al. 2016, GCN 20054) The GBM on-ground location is consistent with the Fermi-LAT position.
  The GBM light curve consists of 3 episodes with a duration (T90) of about 15 s (50-300 keV). The time-averaged spectrum from T0-0.003 s to T0+16.384 s is best fit by a Band function with Epeak = 151 +/- 9 keV, alpha = -0.82 +/- 0.05, and beta = -2.32 +/- 0.11.
  The event fluence (10-1000 keV) in this time interval is (1.17 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.24 s in the 10-1000 keV band is 10.58 +/- 0.30 ph/s/cm^2.
  A power law function with an exponential high-energy cutoff fits the spectrum equally well with Epeak= 183 +/- 7 keV, alpha = -0.93 +/- 0.03.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
• GCN Circular #20057
  P. D'Avanzo, A. Melandri (INAF-OAB), P. A. Evans (U. Leicester), report on behalf of the Swift-XRT team:
  Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 161016A (Masanori Ohno et al., GCN 20054; Stanbro & Meegan, GCN Circ. 20056) in a series of observations tiled on the sky. The total exposure time is 5 ks, distributed over 4 tiles. The data were collected between T0+38.2 ks and T0+45.8 ks, and are entirely in Photon Counting (PC) mode.
  An uncatalogued X-ray source is detected within the Fermi/LAT error circle. The position of this source is RA, Dec=269.2518, +30.37356 which is equivalent to:

  RA (J2000): 17:57:00.43
  Dec(J2000): +30:22:24.8
  

  with an uncertainty of 2.7 arcsec (radius, 90% confidence). This position is 12.2 arcmin from the Fermi/LAT position. The source has a 0.3-10 keV count rate of about 0.03 ct/sec. We cannot determine fading at this time.
• GCN Circular #20060
  V. Kumar, V. Sharma, D. Bhattacharya and V. Bhalerao (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
  Analysis of AstroSat CZTI data showed clear detection of a bright GRB161015A (Fermi LAT detection: Masanori Ohno et al., GCN Circ. 20054) in the 40-200 keV energy range. The light curve shows a complex structure with peak at 17:03:08.04 UT after 1 second of the Fermi Trigger at 17:03:07.04 UT. The measured peak count rate is 660.0 counts/sec above the background in combined data of four quadrants, with a total of 2942.0 counts. The local mean background count rate was 320.0 counts/sec. Using cumulative rates, we measure a T90 of 22.0 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 #20062
  D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report:
  The long-duration GRB 161015A (Fermi-LAT detection: Masanori Ohno et al., GCN Circ. 20054; Fermi-GBM detection: Stanbro and Meegan, GCN Circ. 20056; AstroSat-CZTI detection: Kumar et al., GCN Circ. 20060) triggered Konus-Wind at T0=61386.899 s UT (17:03:06.899).
  The burst light curve shows multipeaked structure starting at ~T0-0.5 s and having a total duration of ~16 s. The emission is seen up to 3 MeV.
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB161015_T61386/
  As observed by Konus-Wind, the burst had a fluence of 1.11(-0.08,+0.09)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+1.888 s, of 4.01(-0.84,+0.85)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
  The time-averaged spectrum of the burst (measured from T0 to T0+16.640 s) is best fit in the 20 keV - 4 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.12(-0.12,+0.13) and Ep = 215(-26,+34) keV (chi2 = 60/73 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.6 (chi2 = 60/72 dof)
  The spectrum near the maximum count rate (measured from T0+0.256 to T0+8.448 s) is best fit in the 20 keV - 4 MeV range by a power law with exponential cutoff model: with alpha = -0.68(-0.14,+0.16) and Ep = 256(-26,+32) keV (chi2 = 73/73 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.2 (chi2 = 73/72 dof)
  All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
• GCN Circular #20065
  M. De Pasquale (MSSL-UCL) and J. Cannizzo (NASA/UMBC) report on behalf of the Swift/UVOT team:
  The Swift/UVOT report started to observe the field of the putative X-ray afterglow of GRB 161015A, the Fermi/LAT burst (Ohno et al. GCN Circ. 20054, D'Avanzo et al. GCN Circ. 20057), 38 ks after the LAT trigger.
  No optical counterpart to this source is found. The 3 sigma upper limit is given in the table below.

    T_start (s)  T_end (s)  Exposure Time (s)  filter   3s UL
  
     37991        45608         1210             u      >20.35
  

  The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998).
• GCN Circular #20085
  A. Melandri, P. D'Avanzo (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU) and J. Cannizzo (NASA/UMBC) report on behalf of the Swift team:
  Swift-XRT carried out further observations of the field of the Fermi GRB 161015A (Ohno et al., GCN Circ. 20054; Stanbro & Meegan, GCN 20056) between T0+371.3 ks and T0+395.9 ks. The total exposure time is 5.0 ks, entirely in Photon Counting (PC) mode.
  The source reported in D'Avanzo et al. (GCN Circ. 20057) as an X-ray afterglow candidate is no longer detected. The 3sigma u.l. is about 3.4e-3 ct/sec (corresponding to a 0.3-10 keV observed flux of 1.7e-13 erg cm^-2 s^-1, assuming a typical GRB spectrum). We thus confirm it as the X-ray afterglow associated with GRB 161015A.
  This is an official product of the Swift-XRT team.
• GCN Circular #20116
  K. P. Mooley (Hintze Fellow, Oxford), 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 161015A (Ohno et al., GCN 20054) with the AMI Large Array at 15 GHz on 2016 Oct 17.75, Oct 18.73, Oct 20.70, and Oct 24.65 (UT) as part of the 4pisky program. We do not detect any radio source at the XRT location (D'Avanzo et al., GCN 20057), with 3sigma upper limits of 105 uJy, 96 uJy, 147 uJy, and 78 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/.