//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14551 SUBJECT: Trigger 555096: Swift detection of a possible burst DATE: 13/05/04 02:29:39 GMT FROM: David Palmer at LANL J. R. Cummings (NASA/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU), E. Troja (NASA/GSFC/UMCP) and T. N. Ukwatta (MSU) report on behalf of the Swift Team: At 02:05:34 UT, the Swift Burst Alert Telescope (BAT) triggered and located trigger=555096. Swift slewed immediately to the transient. The BAT on-board calculated location is RA, Dec 272.365, -16.344 which is RA(J2000) = 18h 09m 27s Dec(J2000) = -16d 20' 38" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed two FRED peaks with a duration of about 25 sec. The peak count rate was ~1617 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 02:07:00.2 UT, 85.9 seconds after the BAT trigger. No source was detected in 1.1 ks of promptly downlinked data. We are waiting for the full dataset to detect and localise the XRT counterpart. UVOT took a finding chart exposure of 150 seconds with the White filter starting 88 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 25% of the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the BAT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the large, but uncertain extinction expected. The event is unusual in that it is a long burst in BAT with no detected X-ray counterpart after an immediate slew. We also note that this location is in the Galactic bulge near the plane (lon = 13.65, lat=1.56). Ground analysis of the detector plane histogram finds only a marginal image detection (5.9 sigma). For these reasons, we will not be able to determine the reality or nature of this event until ground-linked data is available. Burst Advocate for this burst is J. R. Cummings (jayc 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: 14553 SUBJECT: Swift-XRT X-ray afterglow candidate for GRB 130504A (BAT trigger 555096) DATE: 13/05/04 09:28:24 GMT FROM: Phil Evans at U of Leicester P. D'Avanzo (INAF-OAB), A. Melandri (INAF-OAB), K.L. Page (U. Leicester), P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: We have analysed 654 s of XRT data for GRB 130504A, from 99 s to 754 s after the BAT trigger. The data are entirely in Photon Counting (PC) mode. No X-ray afterglow is detected within the BAT error circle (Cummings et al. GCN 14551). We note however the presence of a bright, uncatalogued, fading X-ray source at the following refined position RA, Dec = 272.45484, -16.31423 which is equivalent to: RA (J2000): 18 09 49.16 Dec(J2000): -16 18 51.2 with an uncertainty of 3.5 arcsec (radius, 90% confidence). This position is about 5.5 arc min away from the BAT position. Given its fading nature, we propose it as the X-ray afterglow of GRB 130504A. The light curve can be modelled with a power-law decay with a decay index of alpha=0.79 (+/-0.19). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.7 (+/-0.4). The best-fitting absorption column is 1.6 (+0.5, -0.4) x 10^22 cm^-2, in excess of the Galactic value of 8.1 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 7.4 x 10^-11 (1.3 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.6 (+0.5, -0.4) x 10^22 cm^-2 Galactic foreground: 8.1 x 10^21 cm^-2 Excess significance: 2.8 sigma Photon index: 1.7 (+/-0.4) If the light curve continues to decay with a power-law decay index of 0.79, the count rate at T+24 hours will be 0.021 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.5 x 10^-12 (2.8 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00555096. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14554 SUBJECT: GRB 130504A, Swift-BAT refined analysis DATE: 13/05/04 11:08:22 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift D. M. Palmer (LANL), 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), T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) Using the data set from T-61 to T+242 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130504A (trigger #555096) (Cummings, et al., GCN Circ. 14551). The BAT ground-calculated position is RA, Dec = 272.459, -16.320 deg which is RA(J2000) = 18h 09m 50.1s Dec(J2000) = -16d 19' 13.1" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. This position is 5.3 arcmin away from the automated flight position reported in GCN circular# 14551. The imaging interval selected onboard was not optimum. The refined error circle includes the position of the XRT afterglow candidate reported by D'Avanzo et al. in GCN circular# 14553, hence we believe that fading x-ray source to be the correctly identified afterglow of GRB 130504A. The mask-weighted light curve shows multiple weak peaks. T90 (15-350 keV) is 50 +- 10 sec (estimated error including systematics). The time-averaged spectrum from T-31.07 to T+36.84 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.52 +- 0.68, and Epeak of 84.5 +- 47.6 keV (chi squared 82.16 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T-0.06 sec in the 15-150 keV band is 0.9 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.41 +- 0.15 (chi squared 88.43 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/555096/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14556 SUBJECT: GRB 130504A: Swift/UVOT Upper Limits DATE: 13/05/04 13:46:27 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (MSSL-UCL) and J. R. Cummings (GSFC/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130504A 89s after the BAT trigger (Cummings et al., GCN Circ. 14551), but the GRB position is outside the field of view for several exposures. No optical afterglow consistent with the XRT position (D'Avanzo et al. GCN Circ. 14553) 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 u filter finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u_FC 301 551 246 >19.8 white 858 1008 147 >20.5 w1 680 6058 333 >20.2 m2 655 7093 356 >20.4 w2 606 6878 549 >20.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 3.22 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14558 SUBJECT: GRB 130504A: Enhanced XRT position DATE: 13/05/04 16:47:01 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo (INAF-OAB), P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team: Using 3463 s of XRT Photon Counting mode data and 5 UVOT images, 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 = 272.45604, -16.31339 which is equivalent to: RA (J2000): 18 09 49.45 Dec (J2000): -16 18 48.2 with an uncertainty of 1.7 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 is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14559 SUBJECT: GRB 130504A: Bassano Bresciano Observatory optical upper limit DATE: 13/05/04 17:23:59 GMT FROM: Ulisse Quadri at Bassano Bresciano Obs U.Quadri, L.Strabla, R.Girelli and A.Quadri report: We imaged the field of GRB 130504A detected by SWIFT(trigger 555096) with the robotic telescopes of (IAU station 565) Bassano Bresciano Observatory, Italy. The observations started automatically 2 min 42 sec after the GRB trigger, with our schmidt telescope D=400 mm F/D=3 and our Newton telescope D=250mm F/D=5.5. Weather conditions were good. We co-added 2 series of 10 unfiltered CCD exposures of 120s each. We did not found any optical counterpart in the error box of the XRTcandidate (Cummings et al. GCN 14551) and in error box of X-ray afterglow candidate (P. D'Avanzo (INAF-OAB), A. Melandri (INAF-OAB) et al. GCN 14553) at our following limiting magnitude: . Start End Vlim 2.7min 52min 18.0 Magnitudes were estimated with the USNO-B1 cat. and are not corrected for galactic dust extinction. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14562 SUBJECT: GRB 130504A: MITSuME Okayama upper limits DATE: 13/05/05 02:16:31 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 130504A (Cummings et al., GCNC 14551) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2013-05-04 15:09:24 UT (~13.1 h after the burst). We did not find any new point source within the enhanced XRT circle (D'Avanzo et al., GCNC 14558) in all the three bands. Photometric results of the OT are listed below. We used GSC2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Ic ----------------------------------------------------- 0.58630 16:09:50 6360.0 >19.9 >19.7 >18.6 ----------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14564 SUBJECT: GRB 130504A: IAC80 optical candidate DATE: 13/05/05 08:38:59 GMT FROM: Javier Gorosabel at IAA-CSIC J. Gorosabel (IAA-CSIC/UPV-EHU), A. de Ugarte Postigo (IAA-CSIC/DARK-NBI), J.C. Tello (IAA-CSIC), A.J. Castro-Tirado (IAA-CSIC), J. Cepa (IAC), D. Jimenez-Mejias (IAC), J.L. Doreste Caballero (HGT), D. Hernandez Ojados (SECAT), R. Sanchez-Ramirez (IAA-CSIC), report on behalf of a larger collaboration: We observed the GRB 130504A field (BAT trigger 555096; Cummings et al. GCN 14551) with the 0.82m IAC80 telescope. The data were acquired in the I-band. The observations started at 02:22:30.6 UT (~17 min post burst) and lasted ~1.5 hours. An object, coincident with the enhanced XRT position (D'Avanzo et al. 14558), shows a clear fading in our images. The optical candidate is placed at RA(J2000)=18:09:49.44, DEC(J2000)=-16:18:48.0 with a Vega magnitude of I=18.1 (against USNO B1.0) in our first images.