//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7742 SUBJECT: GRB 080517: Swift detection of a burst DATE: 08/05/17 21:51:51 GMT FROM: David Burrows at PSU/Swift A. M. Parsons (GSFC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL) and E. Troja (U Leicester/INAF-IASFPA) report on behalf of the Swift Team: At 21:22:51 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080517 (trigger=311874). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 102.255, +50.731 which is RA(J2000) = 06h 49m 01s Dec(J2000) = +50d 43' 51" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 20 sec. The peak count rate was ~500 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 21:24:57.5 UT, 125.5 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 102.24274, 50.73512 which is equivalent to: RA(J2000) = 06h 48m 58.26s Dec(J2000) = +50d 44' 06.4" with an uncertainty of 2.7 arcseconds (radius, 90% containment). This location is 31 arcseconds from the BAT onboard position, within the BAT error circle. We note that a known, 18th magnitude optical source lies within our error circle; this is identified as a galaxy, EO0691-0008689, in the APM-North survey. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (8.12e+20 cm^-2, Kalberla et al. 2005), with an excess column of 2.5 (+1.70/-1.44) x 10^21 cm^-2 (90% confidence). The relation of Grupe et al. (2007) implies that this burst has a redshift z<4.8, although high redshift fits to the absorbed XRT spectrum are possible if paired with an anomalously large column. A summary of the promptly downlinked data is given at http://www.swift.ac.uk/sper/311874/. UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 130 seconds after the BAT trigger. A 400 second exposure with the V filter was taken starting 236 seconds after the BAT trigger. There is no evidence for an afterglow, however there is a known object within the XRT error circle visible in the UVOT images. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 18.5 mag in both images. No correction has been made for the expected extinction corresponding to E(B-V) of 0.11. Burst Advocate for this burst is A. M. Parsons (parsons AT milkyway.gsfc.nasa.gov). 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.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7743 SUBJECT: GRB080517: Liverpool Telescope Optical Observations DATE: 08/05/17 23:09:10 GMT FROM: James Smith at ARI,Liverpool John Moors U R.J. Smith (Liverpool JMU), A. Gomboc (Univ. of Ljubljana, Slovenia), A. Melandri, C. Guidorzi, M. Burgdorf, C.G. Mundell, I.A. Steele, D. Carter, A. Monfardini, C.J. Mottram, S. Kobayashi, D. Bersier (Liverpool JMU) report: The 2-m Liverpool Telescope started observing the field of GRB 080517 (Parsons et al. GCN 7742) at 3 min after the trigger time. No optical transient has been located in our images to the following magnitude limits: Filter t_mid (min from GRB) Exp (s) Lim ------------------------------------------------------------------ R 16.08 120 19.6 I 18.93 120 19.2 ------------------------------------------------------------------ Magnitudes were calibrated vs the USNOB1 catalogue. In particular, comparison with Digitized Sky Survey images shows no obvious additional optical source in the vicinity of the known, moderately bright object noted to be within the XRT error circle. Observations stopped one hour after the burst time. No further observations are currently planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7744 SUBJECT: GRB 080517: Enhanced Swift-XRT position DATE: 08/05/18 00:00:38 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 88 s of overlapping XRT Photon Counting mode and UVOT data for GRB 080517, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 102.24189, +50.73496 which is equivalent to: RA (J2000): 06h 48m 58.05s Dec (J2000): +50d 44' 05.8" with an uncertainty of 1.8 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method. This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7746 SUBJECT: GRB 080517: Swift-XRT refined analysis DATE: 08/05/18 07:39:17 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) and A.M. Parsons (GSFC) report on behalf of the Swift-XRT team: We have analysed the first two snapshots of Swift-XRT data obtained for GRB 080517 (Parsons et al, GCN Circ. 7742), comprising 3.3 ks in Photon Counting (PC) mode, starting 144 s after the BAT trigger. The UVOT-enhanced XRT position was given in Evans et al. (GCN Circ. 7744) The light curve can be described as a broken power-law, with an initial decay of 2.47 (+0.25/-0.23), with a break at T+~1100s to a slope of 0.57 (+0.25/-0.74). A spectrum obtained from all of the PC data can be modelled with an absorbed power-law, with gamma=1.91 (+0.36/-0.34) and an absorption column of 1.41 (+0.10/1.11) e21 cm^-2, in excess of the Galactic value of 8.12e20 cm^-2 (Kalberla et al. 2005). The observed (unabsorbed) flux in this spectrum is 6.07 (8.12) e-12 erg cm^-2 s^-1. The counts to observed flux conversion is 5.93e-11 erg cm^-2 count^-1. If the light-curve continues to decay at alpha=0.57 the count rate at 24 hours is predicted to be 1.6e-3 count s-1, corresponding to an observed (unabsorbed) flux of 7.10 (9.49) e-14 erg cm^-2 s^-1. This is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7748 SUBJECT: GRB 080517, Swift-BAT refined analysis DATE: 08/05/18 19:34:04 GMT FROM: Ann M. Parsons at NASA/GSFC/Swift C. Markwardt (GSFC/UMD), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/ UMBC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), K. McLean (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 080517 (trigger #311874) (Parsons, et al., GCN Circ. 7742). The BAT ground-calculated position is RA, Dec = 102.274, 50.741 deg which is RA(J2000) = 06h 49m 05.8s Dec(J2000) = +50d 44' 28.5" with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 50%. The mask-weighted lightcurve shows a single, FRED-like peak rising quickly to its maximum at ~T+4.4 sec with a roughly exponential decay down to background at ~T+60 sec. T90 (15-350 keV) is 64.6 +- 27.2 sec (estimated error including systematics). The time-averaged spectrum from T-0.9 to T+68.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.54 +- 0.33. The fluence in the 15-150 keV band is 5.6 +- 1.2 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+3.88 sec in the 15-150 keV band is 0.6 +- 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/311874/BA/ This burst satisfies Sakamoto/Ukwatta Swift-BAT possible high-z criteria (Ukwatta et al. arXiv:0802.3815). 1) PL photon index = 1.54 (PL photon index < 2) 2) 1-s peak photon flux = 0.627459 (1-s peak photon flux < 1.0 ph/cm2/s) 3) Light curve variance = 6.818773e-05 (Variance < 0.0001) 4) T90/(Peak photon flux) = 103.0 (T90/(Peak photon flux) > 100) Based on a limited sample of bursts, these criteria yield an 85% chance it has a redshift greater than 3.5. As noted in the initial Swift circular (Parsons, et al., GCN Circ. 7742), the observed X-ray absorption implies that the burst is most likely at z<4.8.