//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14897 SUBJECT: GRB 130615A: Swift detection of a burst DATE: 13/06/15 10:00:09 GMT FROM: Scott Barthelmy at NASA/GSFC E. Sonbas (NASA/GSFC/Adiyaman Univ.), S. D. Barthelmy (GSFC), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team: At 09:44:45 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130615A (trigger=558271). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 274.846, -68.166 which is RA(J2000) = 18h 19m 23s Dec(J2000) = -68d 09' 57" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is typical for image triggers, there is nothing obvious in the real-time TDRSS light curve. The XRT began observing the field at 09:47:39.3 UT, 174.1 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 274.82944, -68.16032 which is equivalent to: RA(J2000) = 18h 19m 19.07s Dec(J2000) = -68d 09' 37.2" with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 30 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (8.27 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 3 (+2.62/-2.27) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 2.11e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 250 seconds with the U filter starting 179 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.12. Burst Advocate for this burst is E. Sonbas (edasonbas AT yahoo.com). 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: 14898 SUBJECT: GRB 130615A: GROND afterglow candidate DATE: 13/06/15 12:44:37 GMT FROM: Sebastian Schmidl at TLS Tautenburg J. Elliott (MPE Garching), S. Schmidl (TLS Tautenburg), J.Greiner (MPE Garching), D. A. Kann (TLS Tautenburg), S. Ciceri and L. Mancini (both MPIA) report on behalf of the GROND team: We observed the field of GRB 130615A (Swift trigger 558271, Sonbas et al., GCN #14897) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla Observatory (Chile). Observations started on June 15, 2013, at 10:17:21 UT, 0.54 hrs after the GRB trigger. They were performed at an average seeing of 1".1 and at an average airmass of 1.9. We find a source inside the enhanced 2".1 SWIFT/XRT error circle (http://www.swift.ac.uk/sper/558271/) at RA (J2000.0) = 18:19:19.11 DEC (J2000.0) = -68:09:40.5 with an uncertainty of 0".5 in each coordinate. Based on a total exposure time of 263 s in g'r'i'z' and 240 s in JHK, at a midtime of 0.82 hrs after the burst, we measure the following preliminary AB magnitudes: g' = 21.3 +/- 0.1 mag, r' = 20.7 +/- 0.1 mag, i' = 20.6 +/- 0.1 mag, z' = 20.5 +/- 0.1 mag, J = 20.2 +/- 0.3 mag, H = 19.8 +/- 0.3 mag and K > 19.1 mag Considering the galactic foreground extinction, the fit to the spectral energy distribution indicates a redshift <~ 3. Given magnitudes are calibrated against GROND zeropoints as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.12 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14899 SUBJECT: GRB 130615A: Swift-BAT refined analysis DATE: 13/06/15 15:56:13 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), E. Sonbas (NASA/GSFC/Adiyaman Univ.), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 130615A (trigger #558271) (Sonbas, et al., GCN Circ. 14897). The BAT ground-calculated position is RA, Dec = 274.963, -68.161 deg, which is RA(J2000) = 18h 19m 51.2s Dec(J2000) = -68d 09' 39.7" with an uncertainty of 2.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 60%. The mask-weighted light curve shows two peaks both of which are nearly smooth. The first starts at ~T+10 sec and ends at ~T+150 se. The second peak goes from ~T+270 to T+450 sec. T90 (15-350 keV) is 304 +- 30 sec (estimated error including systematics). The time-averaged spectrum from T+25.57 to T+386.86 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.87 +- 0.92, and Epeak of 33.2 +- 8.6 keV (chi squared 61.91 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.1 +- 0.3 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+31.84 sec in the 15-150 keV band is 0.7 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.18 +- 0.16 (chi squared 70.23 for 57 d.o.f.). 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/558271/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14900 SUBJECT: GRB 130615A: Enhanced Swift-XRT position DATE: 13/06/15 16:33:43 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 1436 s of XRT Photon Counting mode data and 1 UVOT images for GRB 130615A, 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 = 274.82896, -68.16092 which is equivalent to: RA (J2000): 18h 19m 18.95s Dec (J2000): -68d 09' 39.3" with an uncertainty of 2.3 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) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14901 SUBJECT: GRB 130615A: Skynet/PROMPT Observations DATE: 13/06/15 17:58:55 GMT FROM: Nathan Frank at U.North Carolina N. Frank, A. Trotter, J. Haislip, D. Reichart, A. LaCluyze, T. Berger, M. Carroll, H. T. Cromartie, R. Egger, A. Foster, C. Foster, K. Ivarsen, D. James, M. Maples, J. Moore, M. Nysewander, E. Speckhard, P. Taylor and J. A. Crain report Skynet observed the Swift/XRT localization of the field of GRB 130615A (Sonbas et al., GCN 14897, Swift trigger #558271), starting at 2013-06-15, 09:46:37 UT (t=1.86m post-trigger), with four 16" telescopes of the PROMPT array at CTIO, Chile. We detect an uncataloged optical source in B, V, R and I bands at: RA = 18:19:19.08, Dec = -68:09:41.02 (J2000.0), consistent with the GROND (Elliott et al., GCN 14898) and enhanced Swift/XRT positions (Evans et al., GCN 14900). Calibrating to 6 APASS stars in the field we find an average magnitude of R~20.4 over the time period between t~8m and t~46m. The time range and sensitivity of these observations is not sufficient to determine if the source is fading with time. A preliminary light curve is at: http://skynet.unc.edu/grb/grb130615a.png Skynet observations are scheduled to determine if the source is indeed fading. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14902 SUBJECT: GRB 130615A: Swift/UVOT Upper Limits DATE: 13/06/15 19:21:11 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) and E. Sonbas (NASA/GSFC/Adiyaman Univ.) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130615A 180 s after the BAT trigger (Sonbas et al., GCN Circ. 14897). No optical afterglow consistent with the optical position (Elliott et al. GCN Circ. 14898) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u_FC 180 430 246 >20.1 v 463 7314 580 >20.1 u 180 12850 1827 >21.3 w1 512 11936 1434 >20.9 m2 488 7445 672 >20.3 w2 439 13208 933 >20.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.12 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14904 SUBJECT: GRB 130615A: Swift-XRT refined Analysis DATE: 13/06/15 22:00:05 GMT FROM: Phil Evans at U of Leicester P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), J.A. Kennea (PSU), M.C. Stroh (PSU), B.P. Gompertz (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), V. D'Elia (ASDC), A. Maselli (INAF-IASFPA) and E. Sonbas report on behalf of the Swift-XRT team: We have analysed 10 ks of XRT data for GRB 130615A (Sonbas et al. GCN Circ. 14897), from 180 s to 28.9 ks after the BAT trigger. The data comprise 459 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 14900). The late-time light curve (from T0+5.3 ks) can be modelled with a power-law decay with a decay index of alpha=0.5 (+/-0.3). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.05 (+/-0.03). The best-fitting absorption column is 1.93 (+/-0.09) x 10^21 cm^-2, in excess of the Galactic value of 8.3 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.06 (+0.27, -0.09) and a best-fitting absorption column consistent with the Galactic value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (4.4 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 0 (+4.4, -0) x 10^20 cm^-2 Galactic foreground: 8.3 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 2.06 (+0.27, -0.09) If the light curve continues to decay with a power-law decay index of 0.5, the count rate at T+24 hours will be 4.9 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x 10^-13 (2.2 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00558271. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14905 SUBJECT: GRB 130615A: TAROT La Silla observatory optical observations DATE: 13/06/15 22:01:29 GMT FROM: Alain Klotz at IRAP-CNRS-OMP Klotz A. (IRAP-CNRS-OMP), Gendre B. (IRAP-CNRS-OMP), Boer M., Siellez K., Dereli H., Bardho O. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report: We imaged the field of GRB 130615A detected by SWIFT (trigger 558271) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile. The observations started 91.8s after the GRB trigger (14.2s after the notice). The elevation of the field decreased from 36 degrees above horizon and weather conditions were good. The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We do not detect the afterglow candidate mentioned by Elliott et al. (GCNC 14898) with a limiting magnitude of: t0+91.8s to t0+151.8s : Rlim = 16.4 The second image is 30.0s exposure in tracking mode, the afterglow is not seen: t0+165.4s to t0+195.4s : Rlim = 18.0 We co-added a series of exposures, the afterglow is not seen: t0+479s to t0+992s : Rlim = 19.3 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14906 SUBJECT: GRB 130615A: Zadko observatory - Gingin optical observations DATE: 13/06/15 22:02:27 GMT FROM: Alain Klotz at IRAP-CNRS-OMP A. Klotz (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. Coward (UWA), B. Gendre (IRAP-CNRS-OMP), M. Boer, K. Siellez, H. Dereli , O. Bardho (UNS-CNRS-OCA), A. Williams (PO-UWA), R. Martin (PO-UWA) report: We imaged the field of GRB 130615A detected by SWIFT (trigger 558271) with the Zadko robotic telescope (D=100cm) located at the observatory - Gingin, Australia. The observations started 1.58h after the GRB trigger just after the beginning of the night. The elevation of the field increased from 30 degrees above horizon and weather conditions were good. We detect the afterglow candidate discovered by Elliott et al. (GCNC 14898). However, as mentioned by Frank et al. (GCNC 14901) the stellar object stays at a constant magnitude of R = 20.7 from 1.6h to 4.8h after the trigger. Due to the absence of fading of its brightness, we are not sure that the stellar object mentioned by Elliott et al. (GCNC 14898) is the GRB afterglow. Magnitudes were estimated with the nearby star NOMAD-1 0218-0667138 (R.A.=274.8458361 Dec=-68.1621056 J2000) R=17.840. Magnitudes are not corrected for galactic dust extinction. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14909 SUBJECT: GRB 130615A: Continued Skynet/PROMPT Observations DATE: 13/06/16 22:03:11 GMT FROM: Nathan Frank at U.North Carolina N. Frank, A. Trotter, J. Haislip, D. Reichart, A. LaCluyze, T. Berger, M. Carroll, H. T. Cromartie, R. Egger, A. Foster, C. Foster, K. Ivarsen, D. James, M. Maples, J. Moore, M. Nysewander, E. Speckhard, P. Taylor and J. A. Crain report Skynet continued observing the field of GRB 130615A (Sonbas et al., GCN 14897, Swift trigger #558271) with four 16" telescopes of the PROMPT array at CTIO, Chile, starting at 2013-06-16, 04:10 UT, and continuing until 10:11 UT (t=18.4h-24.4h post-trigger). In Frank et al. (GCN 14901) we reported detection of an uncatalogued optical source at the position reported by Elliott et al. (GCN 14898) and Evans et al. (GCN 14900). We could not determine from our data whether the source was fading. We took ~300 60s exposures in each of the B, V, R and I bands, with a mean time t~0.9d. We do not detect the optical source in the B, R or I bands in stacks of all the exposures; there is a questionable (3-sigma) detection in the V-band stack. The 3-sigma limiting magnitudes of our stacked images are: Filter B V R I Mag >21.83 >21.95 >22.09 >21.17 A light curve of both the first and second nights' data is at: http://skynet.unc.edu/grb/grb130615a_2.png Photometry is calibrated to 6 APASS stars in the field and magnitudes are in the Vega system. No correction has been applied for the expected line-of-sight Milky Way extinction of E(B-V)=0.12 (Schlegel et al. 1998). These observations are consistent with a fading afterglow with alpha <~ -0.4. No further Skynet observations are scheduled.