//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13454 SUBJECT: GRB 120712A: Swift detection of a burst with optical afterglow DATE: 12/07/12 13:52:34 GMT FROM: Scott Barthelmy at NASA/GSFC M. J. Page (UCL-MSSL), A. A. Breeveld (UCL-MSSL), D. N. Burrows (PSU), V. D'Elia (ASDC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), N. P. M. Kuin (UCL-MSSL), O. M. Littlejohns (U Leicester), F. E. Marshall (NASA/GSFC), S. R. Oates (UCL-MSSL), K. L. Page (U Leicester), D. M. Palmer (LANL) and V. N. Yershov (UCL-MSSL) report on behalf of the Swift Team: At 13:42:27 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120712A (trigger=526351). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 169.605, -20.061 which is RA(J2000) = 11h 18m 25s Dec(J2000) = -20d 03' 38" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a couple of overlapping peaks with a total duration of about 25 sec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~8 sec after the trigger. The XRT began observing the field at 13:43:58.2 UT, 90.9 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 169.59034, -20.03336 which is equivalent to: RA(J2000) = 11h 18m 21.68s Dec(J2000) = -20d 02' 00.1" with an uncertainty of 4.1 arcseconds (radius, 90% containment). This location is 111 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 (3.60 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 3 (+2.23/-1.94) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 95 seconds after the BAT trigger. There is a candidate afterglow in the list of sources generated on-board at RA(J2000) = 11:18:21.23 = 169.58847 DEC(J2000) = -20:02:01.8 = -20.03383 with a 90%-confidence error radius of about 1.10 arc sec. This position is 6.5 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.10. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04. Burst Advocate for this burst is M. J. Page (mjp AT mssl.ucl.ac.uk). 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: 13455 SUBJECT: GRB 120712A: Swift-BAT refined analysis DATE: 12/07/12 20:14:07 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), M. J. Page (UCL-MSSL), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-120 to T+254 sec from recent telemetry downlinks, we report further analysis of BAT GRB 120712A (trigger #526351) (Page, et al., GCN Circ. 13454). The BAT ground-calculated position is RA, Dec = 169.598, -20.051 deg, which is RA(J2000) = 11h 18m 23.6s Dec(J2000) = -20d 03' 02.9" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 55%. The mask-weighted light curve shows two main overlapping peaks starting at ~T-5 sec, peaking at ~T+0 and ~T+8 sec, and ending at ~T+20 sec. T90 (15-350 keV) is 14.7 +- 3.3 sec (estimated error including systematics). The time-averaged spectrum from T-4.57 to T+16.53 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.36 +- 0.08. The fluence in the 15-150 keV band is 1.8 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+7.51 sec in the 15-150 keV band is 2.4 +- 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/526351/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13456 SUBJECT: GRB 120712A: Enhanced Swift-XRT position DATE: 12/07/12 22:28:43 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 5145 s of XRT Photon Counting mode data and 8 UVOT images for GRB 120712A, 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 = 169.58851, -20.03397 which is equivalent to: RA (J2000): 11h 18m 21.24s Dec (J2000): -20d 02' 02.3" 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: 13457 SUBJECT: GRB 120712A: GROND Detection of the Optical/NIR Afterglow Candidate and photo-z DATE: 12/07/13 01:17:11 GMT FROM: Jonny Elliott at MPE/GROND J. Elliott, P. Schady (MPE Garching), D. A. Kann (TLS Tautenburg) and J. Greiner (MPE Garching), report on behalf of the GROND team: We observed the field of GRB 120712A (Swift trigger 526351; Page et al., GCN #13454) 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 at 22:57 UT on 2012-07-12, 9.24 hours after the GRB trigger, and are continuing. They were performed at an average seeing of 1".12 and at an average airmass of 1.27. We found a single point source within the 1".5 enhanced Swift-XRT error circle reported by Osborne et al. (GCN #13456) at RA (J2000.0) = 11:18:21.24 DEC (J2000.0) = -20:02:01.4 with an uncertainty of 0".5 in each coordinate. Based on images of 7.66 min of total exposures in g'r'i'z' and 8 min in JHK, 9.5 hours post-burst, we estimate preliminary magnitudes (all in AB) of g' = 23.1 +/- 0.1, r' = 21.3 +/- 0.1, i' = 20.6 +/- 0.1, z' = 20.5 +/- 0.1, J = 20.0 +/- 0.1, H = 19.8 +/- 0.2 and, K > 19.1. Assuming no dust the SED is well fit with a spectral index of beta=1.1 +/- 0.1 at a redshift of z=4.0 +/- 0.2. Including host galaxy dust decreases the redshift, although both solutions remain consistent within 1-sigma. 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)=0.04 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13458 SUBJECT: GRB 120712A Gemini-S redshift DATE: 12/07/13 01:17:34 GMT FROM: Nial Tanvir at U.Leicester N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick) and D. Krogsrud (Gemini) report on behalf of a larger collaboration: We observed the afterglow of GRB 120712A (Page et al. GCN 12454; using the GMOS-S spectrograph on Gemini-South in good conditions. Observations began at 2012-7-12 23:43 UT, about 10 hr post-burst. The spectrum reveals a clear Ly-a break, and many other absorption features. A provisional reduction gives a redshift of z=4.15, although this figure will be refined with better calibration. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13459 SUBJECT: GRB 120712A: Swift-XRT refined Analysis DATE: 12/07/13 01:52:07 GMT FROM: Phil Evans at U of Leicester K.L. Page (U. Leicester), C. Pagani (U. Leicester), B. Sbarufatti (INAF-OAB/PSU), G. Stratta (ASDC), P. D'Avanzo (INAF-OAB), M.C. Stroh (PSU), D.N. Burrows (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester) and M.J. Page report on behalf of the Swift-XRT team: We have analysed 6.2 ks of XRT data for GRB 120712A (Page et al. GCN Circ. 13454), from 94 s to 12.9 ks after the BAT trigger. The data comprise 90 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN. Circ 13456). The light curve can be modelled with an initial power-law decay with an index of alpha=0.87 (+/-0.06), followed by a break at T+3706 s to an alpha of 1.80 (+0.33, -0.29). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.16 (+0.17, -0.14). The best-fitting absorption column is 5.0 (+3.1, -1.4) x 10^20 cm^-2, consistent with the Galactic value of 3.6 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 3.3 x 10^-11 (4.0 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 5.0 (+3.1, -1.4) x 10^20 cm^-2 Galactic foreground: 3.6 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 2.16 (+0.17, -0.14) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00526351. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13460 SUBJECT: GRB 120712A: VLT/Xshooter redshift DATE: 12/07/13 03:07:57 GMT FROM: Dong Xu at Weizmann Inst D. Xu (WIS), J. P. U. Fynbo (DARK/NBI), V. D'Elia (ASDC, INAF), N. R. Tanvir (U. Leicester) report on behalf of the X-shooter GRB GTO collaboration: We observed the field of GRB 120712A (Page et al., GCN 13454) with the ESO VLT equipped with the X-shooter spectrograph. Observations started at 00:06 UT on 2012-07-13 (10.4 hr after the BAT trigger), for a total exposure time of ~60 min in each of the UVB, VIS, and NIR arms, covering the wavelength range 3000-25000A. The spectrum exhibits a relatively broad trough (centered at ~6292A) which we interpreted as Lyman-alpha break. Redward of this feature the spectrum shows metals lines such as Mg II, Si II, and Fe II, all at a common redshift z=4.1745. We also measured the HI column density, logN(HI)~20.3, from the Lyman-alpha feature. We acknowledge the excellent support of the ESO observing staff, in particular Fernando J. Selman. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13461 SUBJECT: GRB 120712A: Swift/UVOT Detection DATE: 12/07/13 12:15:47 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) and M. J. Page (MSSL-UCL) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120712A 95 s after the BAT trigger (Page et al., GCN Circ. 13454). A source consistent with the XRT position (Osborne et al., GCN Circ. 13456) and the optical position reported by GROND (Elliott et al., GCN Circ. 13457) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 11:18:21.25 = 169.58854 (deg.) Dec (J2000) = -20:02:01.7 = -20.03380 (deg.) with an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white (FC) 95 245 147 16.95 +/- 0.03 white 861 1010 150 18.93 +/- 0.09 v 637 657 19 16.79 +/- 0.15 b 563 18691 1160 >21.8 u 308 35517 2569 >22.1 w1 686 35216 3108 >22.0 m2 4818 41481 3296 >22.1 w2 613 40167 2931 >22.1 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13469 SUBJECT: GRB 120712A: Fermi GBM observation DATE: 12/07/14 17:45:22 GMT FROM: David Gruber at MPE David Gruber (MPE) reports on behalf of the Fermi GBM Team: "At 13:42:25.61 UT on 12 July 2012, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 120712A (trigger 363793348 / 120712571). which was also detected by the Swift/BAT (Page et al. 2012, GCN 13454). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 42 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve consists of two overlapping peaks with a duration (T90) of about 23 s (50-300 keV). The time-averaged spectrum from T0-3 s to T0+16 s is well fit by a Band function with Epeak = 124 +/- 26 keV, alpha = -0.6 +/- 0.2, and beta = -1.80 +/- 0.02. The event fluence (10-1000 keV) in this time interval is (4.43 +/- 0.05)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+9.3 s in the 10-1000 keV band is 3.5 +/- 0.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."