Gamma-ray Burst 171010B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #21995
  D. M. Palmer (LANL) and A. Y. Lien (GSFC/UMBC), report on behalf of the Swift team:
  At 20:59:24.168 UT on 2017-10-10, the Swift Burst Alert Telescope (BAT) triggered on GRB 171010B (trigger=778019). However, on-board analysis was truncated by a pre-planned slew to a scheduled target. Subsequent ground analysis using data from T+1 to T+11 s finds the source at a location of RA, Dec = 34.123, -54.410 deg which is

    RA(J2000)  =  02h 16m 29.6s 
    Dec(J2000) = -54d -24' -36.7" 
  

  with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 71%.
  The BAT light curve shows a single-peaked structure that starts and peaks at ~T0, and ends at ~ T+30 s. Because the burst was not identified on board, the event data available (~T+1 to ~T+11) do not cover the entire burst duration. T90 estimated from the BAT raw light curve (15-350 keV) is about 30.4 s.
  The time-averaged spectrum from T+1.0 to T+11.1 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.41 +- 0.18. The fluence in the 15-150 keV band is 3.9 +- 0.5 x 10^-7 erg/cm2. All the quoted errors are at the 90% confidence level.
  This event was also detected by Fermi/GBM (trigger 529361971).
  A Swift Target of Opportunity observation has been requested.
  The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/778019/BA/
• GCN Circular #21997
  P. A. Evans (U. Leicester) reports on behalf of the Swift team:
  Swift has initiated a ToO observation of the Swift/BAT GRB 171010B. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/ToO_GRBs/00020780
  Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Swift/BAT event. 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 #21999
  S. Poolakkil and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
  "At 20:59:26.48 UT on 10 October 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 171010B (trigger 529361971/ 171010875) which was also detected by Swift-BAT (D. M. Palmer et al,GCN 21995). 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 several episodes with a duration (T90) of about 25s (50-300 keV). The time-averaged spectrum from T0-2.05 s to T0+6.14 s is best fit by by a simple power law function with index -1.66 +/- 0.07.
  The event fluence (10-1000 keV) in this time interval is (8.073 +/- 1.802)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0-1.85 s in the 10-1000 keV band is 1.41 +/- 0.15 ph/s/cm^2.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
• GCN Circular #22009
  B. Sbarufatti (PSU), J. D. Gropp (PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
  Swift-XRT has performed follow-up observations of the Swift/BAT-detected burst GRB 171010B (Palmer et al. GCN Circ. 21995), collecting 4.8 ks of Photon Counting (PC) mode data between T0+91.1 ks and T0+120.1 ks.
  One uncatalogued X-ray source has been detected consistent with being within 96 arcsec of the Swift/BAT position, however it is not above the RASS limit and does not show definitive signs of fading. Therefore, at the present time we cannot confirm if it is the afterglow. Details of the source are given below:
  Source 2:

    RA (J2000.0):  34.1342  =  02:16:32.20
    Dec (J2000.0): -54.3915  =  -54:23:29.2
    Error: 5.6 arcsec (radius, 90% conf.)
    Count-rate: (6.9 [+1.5, -1.4])e-3 ct s^-1   
    Distance: 71 arcsec from Swift/BAT position.
    Flux: (3.35 [+0.74, -0.68])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
  

  Six uncatalogued sources were also detected too far from the GRB position to be likely afterglow candidates.
  The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/ToO_GRBs/00020780.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #22023
  A. Melandri (INAF-OAB), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
  Swift-XRT has conducted further observations of the field of the Swift/BAT-detected burst GRB 171010B (Palmer et al. GCN Circ. 21995). The observations now extend from T0+91.1 ks to T0+614.5 ks.
  Of the sources reported by Sbarufatti et al. (GCN Circ. 22009), "Source 2" is believed to be the afterglow. The position of this source is RA, Dec=34.1342, -54.3915 which is equivalent to:

  RA (J2000): 02:16:32.20
  Dec(J2000): -54:23:29.2
  

  with an uncertainty of 5.6 arcsec (radius, 90% confidence). This position is 71 arcsec from the Swift/BAT position.
  The light curve can be modelled with a power-law decay with a decay index of alpha=0.8 (+0.6, -0.4).
  The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020780. The results of the full analysis of the XRT observations are available at http://www.swift.ac.uk/ToO_GRBs/00020780.
  This circular is an official product of the Swift-XRT team.