//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13510 SUBJECT: GRB 120724A: Swift detection of a burst DATE: 12/07/24 06:50:25 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo (INAF-OAB), W. H. Baumgartner (GSFC/UMBC), V. D'Elia (ASDC), H. A. Krimm (CRESST/GSFC/USRA), B. Sbarufatti (INAF-OAB/PSU) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift Team: At 06:39:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120724A (trigger=528443). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 245.190, +3.509 which is RA(J2000) = 16h 20m 46s Dec(J2000) = +03d 30' 33" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 40 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 06:40:52.0 UT, 109.1 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 245.18192, 3.50750 which is equivalent to: RA(J2000) = 16h 20m 43.66s Dec(J2000) = +03d 30' 27.0" with an uncertainty of 4.0 arcseconds (radius, 90% containment). This location is 29 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 consistent with the Galactic value of 4.29 x 10^20 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 5.14e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 117 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 19.6 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 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.05. Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT brera.inaf.it). 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: 13511 SUBJECT: GRB 120724A: FTN optical afterglow candidate DATE: 12/07/24 07:58:29 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), A. Melandri (INAF-OAB), J. Japelj (U. Ljubljana) on behalf of a large collaboration report: The 2-m Faulkes Telescope North automatically began observing GRB 120724A (D'Avanzo et al. GCN Circ. 13510) on July 24 2012, 06:42:31 UT corresponding to 209 seconds post burst trigger with BVRi' filters. Within the XRT error circle we found the following uncatalogued fading source, R.A. = 16:20:43.21 Dec = +03:30:29.3 (J2000) with an uncertainty of about 1" with a magnitude of 20.5 +/- 0.3 in the i band at 13.8 minutes, calibrated against nearby USNOB-1 stars. The source is also visible in stacked R-band frames. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13512 SUBJECT: GRB 120724A: Gemini-N tentative redshift DATE: 12/07/24 09:51:40 GMT FROM: Antonino Cucchiara at UCSC/UCO Lick A. Cucchiara (UCSC/UCO Lick), N.R. Tanvir (U. Leicester), D. Perley (Caltech), and A. J. Levan (U. Warwick) report on behalf of a larger collaboration: We observed the afterglow of GRB 120724A (Guidorzi et al. GCN 13511; D'Avanzo et al. GCN 13510) using the GMOS-N spectrograph on the Gemini-North telescope under very good seeing conditions (0.5"). Observations began at 2012-7-24 08:31 UT, about 2 hr post-burst. Two spectra of 900s each were acquired, covering the 6000-10000 Angstrom wavelength range. A preliminary analysis of some of the absorption features identified suggests that the GRB redshift is z = 1.48, based on identification of MgII2796,2803 doublet, MnII2606, FeII2600, and MnII2594. We thank the Gemini staff, in particular J. Holt and J. Kemp, for making these observations possible. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13514 SUBJECT: GRB 120724A: Swift-XRT refined Analysis DATE: 12/07/24 18:50:07 GMT FROM: Phil Evans at U of Leicester P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. Maselli (INAF-IASFPA), J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), and O.M. Littlejohns (U. Leicester) report on behalf of the Swift-XRT team: We have analysed 6.4 ks of XRT data for GRB 120724A (D'Avanzo et al. GCN Circ. 13510), from 115 s to 13.0 ks after the BAT trigger. The data comprise 40 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The best available XRT position (using the promptly downlinked event data, the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue) is RA, Dec = 245.1800, 3.5081 which is equivalent to: RA (J2000): 16 20 43.19 Dec(J2000): +03 30 29.0 with an uncertainty of 2.2 arcsec (radius, 90% confidence). The light curve can be modelled with an initial power-law decay with an index of alpha=2.78 (+/-0.22), followed by a break at T+851 s to an alpha of 0.48 (+0.18, -0.79). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.88 (+0.20, -0.09). The best-fitting absorption column is consistent with the Galactic value of 4.3 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.7 x 10^-11 (4.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Galactic foreground: 4.3 x 10^20 cm^-2 Intrinsic column: 0 (+9.3, -0) x 10^20 cm^-2 at z=1.48 Photon index: 1.88 (+0.20, -0.09) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00528443. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13515 SUBJECT: GRB 120724A: Enhanced Swift-XRT position DATE: 12/07/24 19:24:49 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 2299 s of XRT Photon Counting mode data and 4 UVOT images for GRB 120724A, 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 = 245.18020, +3.50793 which is equivalent to: RA (J2000): 16h 20m 43.25s Dec (J2000): +03d 30' 28.6" with an uncertainty of 1.5 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: 13516 SUBJECT: GRB 120724A: Swift/UVOT Detection of the Optical Afterglow DATE: 12/07/25 13:11:42 GMT FROM: Stephen Holland at STScI S. T. Holland (STScI) and P. D'Avanzo (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT observed the field of GRB 120724A starting 99 s after the BAT trigger (D'Avanzo et al., 2012, GCNC 13510). Settled observations started at 120 s. We detect a faint source with preliminary coordinates RA (J2000) 16:20:43.35 = 245.18062 (deg) Dec (J2000) +03:30:27.8 = +3.50772 (deg) and an estimated uncertainty of 0.77 arcsec (radius, 90% confidence, statistical + systematic). This position is consistent with the optical source discovered by Guidorzi et al. (2012, GCNC 13511) and is slightly outside the UVOT-enhanced XRT position (D'Avanzo et al., 2012, GCNC 13514). Preliminary magnitiudes for this source, and 3-sigma upper limits for the finding charts (FC) and the co-added images, are Filter TSTART TSTOP EXPOSURE Mag Err Sigma ---------------------------------------------------------------- white (FC) 117 267 147 >21.3 u (FC) 330 580 246 >20.5 white (FC) 609 629 20 >19.8 ---------------------------------------------------------------- v 832 1404 72 >19.2 b 585 1331 58 20.01 0.41 2.7 u 330 1461 288 20.50 0.37 3.0 uvw1 1088 1453 59 >19.2 uvm2 1237 1429 39 >18.4 uvw2 635 1380 78 >19.5 white 117 1355 199 21.54 0.45 2.5 ---------------------------------------------------------------- The quoted magnitudes and upper limits have not been corrected for the Galactic extinction along the line of sight to this burst of E_{B-V} = 0.05 mag (Schlafly et al. 2011, ApJS, 737, 103). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13517 SUBJECT: GRB 120724A, Swift-BAT refined analysis DATE: 12/07/25 18:14:34 GMT FROM: Hans Krimm at NASA-GSFC H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), P. D'Avanzo (INAF-OAB), E. E. Fenimore (LANL), N. Gehrels (GSFC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), 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 the recent telemetry downlink, we report further analysis of BAT GRB 120724A (trigger #528443) (D'Avanzo, et al., GCN Circ. 13510). The BAT ground-calculated position is RA, Dec = 245.193, 3.535 deg which is RA(J2000) = 16h 20m 46.3s Dec(J2000) = +03d 32' 07.2" with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 50%. The mask-weighted light curve shows a single broad peak starting at roughly T0-30 seconds, peaking at T0 and extending until T0+100 seconds. T90 (15-350 keV) is 72.8 +- 16.4 sec (estimated error including systematics). The time-averaged spectrum from -21.3 to 64.5 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.53 +- 1.53, and Epeak of 27.6 +- 7.5 keV (chi squared 43.55 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 6.8 +- 1.1 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T+7.51 sec in the 15-150 keV band is 0.6 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.45 +- 0.26 (chi squared 50.75 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/528443/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13519 SUBJECT: GRB 120724A: JCMT SCUBA-2 sub-mm observation DATE: 12/07/25 20:30:50 GMT FROM: Ian Smith at Rice U I.A. Smith (Rice U.), R.P.J. Tilanus (JAC), N.R. Tanvir (U. of Leicester), D.A. Frail (NRAO) report: We observed the location of GRB 120724A (D'Avanzo et al., GCN Circ. 13510) using the SCUBA-2 sub-millimeter continuum camera on the James Clerk Maxwell Telescope. The observation started at 07:48 UT on 2012-07-24, corresponding to 69 minutes after the burst trigger. Exposures totaling 1.7 hours were made in reasonable weather conditions. No source was detected, with a preliminary RMS of 3.3 mJy/beam at 850 microns. We thank Jeff Cox and Antonio Chrysostomou for their prompt support of these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13520 SUBJECT: GRB 120724A: optical observation in Maidanak observatory DATE: 12/07/26 19:48:38 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), A. Sergeev (Institute of Radio Astronomy of NASU), A. Volnova (SAI MSU), O. Burhonov (UBAI), I. Molotov (KIAM) report on behalf GRB follow-up collaboration: We observed the field of Swift GRB 120724A (D'Avanzo et al., GCN 13510) with AZT-22 telescope of Maidanak observatory starting on Jul. 24 (UT) 15:55:51 under mean seeing (FWHM) of about 1.1 arcsec. Totally we obtained 4 images of 600 s exposure in R filter. At the edge of the enhanced XRT position (Goad et al., GCN 13515) we detected the object with coordinates (J2000) 16 20 43.28 +03 30 27.1 (uncertainty of 0.12 arcsec in both coordinates), which is slightly apart from coordinates of the OT reported earlier (Guidorzi et al., GCN 13511; Holland et al., GCN 13516). Since the object is also visible in stacked DSS images (R+I) we suggest it is a possible host galaxy of GRB 120724A. A preliminary photometry of the object is based on USNO-B1.0 nearby stars: T0+ Filter, Exposure, OT (mid, d) (s) 0.42252 R 3x600 20.97 +/- 0.09 A finding chart can be found at http://grb.rssi.ru/GRB120724A/GRB120724A_AZT22&DSS.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18183 SUBJECT: KAIT Optical Upper Limits for GRB 120422A, 120724A, 120803B, 120911A, and 120923A DATE: 15/08/20 18:55:59 GMT FROM: Xiang-Gao Wang at GuangXi U Xianggao Wang (UC Berkeley, GXU, UNLV), WeiKang Zheng, Alexei V. Filippenko (UC Berkeley), and S. Bradley Cenko (GSFC) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to Swift GRBs 120422A (Troja et al., GCN 13243), 120724A (D'Avanzo et al., GCN 13510), 120803B (Racusin et al. GCN 13566), 120911A (Cannizzo et al., GCN 13744), and 120923A (Yershov et al., GCN 13796) at 510 s, 202 s, 196 s, 147 s, and 236 s after the burst, respectively. Observations were performed with an automatic sequence in the clear (roughly R), V, and I filters, and the exposure time was 20 s per image. We do not detect any new sources within the XRT error circles. We estimate the following upper limits (magnitudes) in clear-band images for each GRB calibrated to USNO B1.0: GRB Start-Time Coadd-Images Mid-time Upper-Limit (3 sigma) 120422A 510 s 20 s x 6 758 s 20.6 120724A 202 s 20 s x 10 647 s 20.7 120803B 196 s 20 s x 10 644 s 21.7 120911A 147 s 20 s x 6 501 s 20.9 120923A 236 s 20 s x 6 563 s 21.0