Gamma-ray Burst 140909A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #16808
  David Palmer reports on behalf of the Swift Team:
  In two successive 64-second images, beginning at 06:56:51, BAT detected a source at a consistent location. Although the individual images were below threshold, the combined detection is highly significant, in excess of 8 sigma. A 320 s image that includes the data from both 64 s images indicates additional flux outside of the 128 s time interval.
  The BAT on-board calculated location is RA,dec =3D 193.638,63.494 (J2000), which is

    RA(J2000) =  12h 54m 33s
    Dec(J2000) = +63d 29 38
  

  As is usual for image triggers, there is no obvious variation in the BAT lightcurve.
  Because the individual images were below threshold, Swift did not automatically slew to the location. However, a ToO has been requested.
• GCN Circular #16811
  C. Pagani, K.L. Page and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
  We have analysed 5.0 ks of XRT data for the Swift/BAT-detected burst: GRB 140909A, from 44.0 ks to 56.5 ks after the Swift/BAT trigger. The data are entirely in Photon Counting (PC) mode. An X-ray source is detected within the Swift/BAT error circle. Using 1945 s of PC mode data and 1 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 193.61156, +63.51677 which is equivalent to:

  RA (J2000): 12h 54m 26.78s
  Dec(J2000): +63d 31' 00.4"
  

  with an uncertainty of 7.2 arcsec (radius, 90% confidence). This position is 92 arcsec from the Swift/BAT position. The source has a mean count rate of 6.9e-03 ct/sec; we cannot determine at the present time whether it is fading.
  The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020417.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #16812
  GRB 140909A: Swift/UVOT Upper Limits
  M. H. Siegel (PSU) and E. Sonbas (Adiyaman Univ.) report on behalf of the Swift/UVOT team:
  The Swift/UVOT began settled observations of the field of GRB 140909A 44028 s after the BAT trigger (Palmer et al., GCN Circ. 16808). No optical afterglow consistent with the XRT position (Pagani et al. GCN Circ. 16811) is detected in the initial UVOT exposure. The preliminary 3-sigma upper limit using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposure is:

  Filter         T_start(s)   T_stop(s)      Exp(s)         Mag
  
  white            44028        56310         3213         >22.0
  

  The magnitude is not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.015 in the direction of the burst (Schlegel et al. 1998).
• GCN Circular #16816
  C. Pagani (U. Leicester) and E. Sonbas (Adiyaman U.) report on behalf of the Swift team:
  A second epoch of XRT data was collected on the field of the Swift/BAT ground detected GRB 140909A (Palmer, GCN Circ. 16808), from 148 ks to 252 ks after the Swift/BAT trigger.
  The X-ray source reported in GCN Circ. 16811, Pagani et al., at a mean count rate of 6.9e-03 ct/sec, is now no longer detected, having faded below a 3-sigma upper limit of 2.3 x 10^-3 count s^-1 (0.3-10 keV). We therefore confirm that this is the X-ray afterglow of GRB 140909A
  This circular is an official product of the Swift-XRT team.