//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14411 SUBJECT: GRB 130420B: Swift detection of a burst DATE: 13/04/20 13:14:19 GMT FROM: David Burrows at PSU/Swift S. R. Oates (UCL-MSSL), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC), S. T. Holland (STScI), N. P. M. Kuin (UCL-MSSL), C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC), M. H. Siegel (PSU) and E. Sonbas (NASA/GSFC/Adiyaman Univ.) report on behalf of the Swift Team: At 12:56:31 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130420B (trigger=553996). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 183.120, +54.386 which is RA(J2000) = 12h 12m 29s Dec(J2000) = +54d 23' 11" 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 10 sec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 12:57:25.6 UT, 54.5 seconds after the BAT trigger. No source was detected in the 2.5-s promptly available image. About 8 seconds of data were obtained in WT mode before Swift slewed away from the field, indicating a bright X-ray source in the field, but no position is available from the WT data. No XRT position will be available until data from the second orbit are processed. UVOT took a finding chart exposure of 8 seconds with the White filter starting 57 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. Results from the list of sources generated on-board are not available at this time. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02. Burst Advocate for this burst is S. R. Oates (samantha.oates AT 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: 14412 SUBJECT: GRB 130420B: MASTER-Net optical observations DATE: 13/04/20 13:51:33 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, D.Denisenko, A.Sankovich Sternberg Astronomical Institute, Moscow State University K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB130420B (Oates et. al GCN 14411) 44 sec s after notice time and 63 sec after GRB time at 2013-04-20 12:57:34.948 UT in two polarizations. On our first (10s exposure) set we haven`t found optical transient within SWIFT error-box (ra=12 12 28 dec=+54 23 24 r=0.050000). The 5-sigma upper limit has been about 16.0 mag. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14414 SUBJECT: GRB 130420B: Faulkes Telescope North observations DATE: 13/04/20 14:18:52 GMT FROM: Andrea Melandri at INAF-OAB A. Melandri (INAF-OAB), C. Guidorzi (U. Ferrara) and C. G. Mundell (Liverpool) report on behalf of a larger collaboration: The 2-m Faulkes Telescope North (FTN) automatically began observing GRB130420B (Oates et al., GCN 14411) on April 20, 12:59:50 UT corresponding to ~200 seconds after the burst event. We detect no new, uncatalogued source in the BAT error circle down to the following limiting magnitudes: Mid time from Exp Filter Mag limit trigger (min) (sec) --------------------------------------------------- 28.62 540 R > 20.5 32.75 520 I > 20.0 --------------------------------------------------- The magnitudes are calibrated against nearby USNO-B1.0 stars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14420 SUBJECT: GRB 130420B, Swift-BAT refined analysis DATE: 13/04/20 19:35:22 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift C. B. Markwardt (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), S. R. Oates (UCL-MSSL), D. M. Palmer (LANL), T. Sakamoto (AGU), 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-61 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130420B (trigger #553996) (Oates et al., GCN 14411). The BAT ground-calculated position is RA, Dec = 183.095, 54.376 deg which is RA(J2000) = 12h 12m 22.7s Dec(J2000) = +54d 22' 33.2" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a single gradual peak beginning at about T-5 seconds and detectable to T+12 seconds. T90 (15-350 keV) is 10.2 +- 5.4 sec (estimated error including systematics). The time-averaged spectrum from T-1.0 to T+16.0 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.28 +- 0.52, and Epeak of 71.3 +- 14.0 keV (chi squared 42.36 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 6.0 +- 0.5 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T+0.91 sec in the 15-150 keV band is 1.4 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.45 +- 0.10 (chi squared 61.94 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/553996/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14421 SUBJECT: GRB 130420B: Enhanced Swift-XRT position DATE: 13/04/20 19:47:34 GMT FROM: Kim Page at U.of Leicester K.L. Page, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team: Using 1436 s of XRT Photon Counting mode data and 3 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 = 183.12805, 54.39054 which is equivalent to: RA (J2000): 12 12 30.73 Dec (J2000): +54 23 25.9 with an uncertainty of 2.0 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: 14423 SUBJECT: GRB130420B: GMG optical upper limit DATE: 13/04/20 20:23:53 GMT FROM: Xiao-hong Zhao at Yunnan Obs X.-H. Zhao (YNAO and PSU), J. Mao (RIKEN and YNAO), J.-M. Bai (YNAO) report on behalf of a larger collaboration: We observed the field of GRB 130420B (Page et al., GCN 14421; Oates et al., GCN 14411) with 2.4m Gao-Mei-Gu (GMG) telescope. Observations started at 13:21:14 UT on 2013-04-20 (i.e., 0.4 hrs after the burst). The observations lasted for ~10min. The afterglow was not found at the XRT position, down to a upper limit of R>22.6. We thank the GMG staff, especially Yu-Xin Xin, Gui-Hua He and Jian-Duo He for performing these observations. [GCN OPS NOTE(20apr13): I hav removed their copy-paste double TITLE block.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14425 SUBJECT: GRB 130420B: Swift/UVOT Upper Limits DATE: 13/04/20 21:28:15 GMT FROM: Massimiliano de Pasquale at MSSL-UCL M. De Pasquale, S. R. Oates (MSSL-UCL) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130420B 57 s after the BAT trigger (Oates et al., GCN Circ. 14411). No optical afterglow consistent with the XRT position (Page et al., GCN circ. 14421) is detected in the initial and summed UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) are: Filter T_start(s) T_stop(s) Exp(s) Mag white 57 5841 460 >21.7 v 4707 4907 197 >19.6 b 4091 5727 393 >20.9 u 3886 5521 393 >20.6 w1 5117 5317 197 >20.1 m2 4912 5111 197 >19.8 w2 4502 4702 197 >20.1 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14426 SUBJECT: GRB 130420B: Weihai optical upper limit DATE: 13/04/20 22:06:40 GMT FROM: Dong Xu at DARK/NBI Dong Xu (DARK/NBI), Chen Cao, Shaoming Hu, Dayong Ren (SDU) report: We observed the field of GRB 130420B (Oates et al., GCN 14411) using the 1m telescope located in Weihai, Shandong Province, China. We obtained 12x300s I-band frames with a mean time of 2.973 hr after the BAT trigger. No optical source is detected within the enhanced XRT error circle (Page et al., GCN 14421) in the stacked image, down to a limiting magnitude of I>21.2 mag. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14430 SUBJECT: GRB 130420B: Swift-XRT refined Analysis DATE: 13/04/21 05:10:08 GMT FROM: Kim Page at U.of Leicester K.L. Page (U. Leicester) and S. R. Oates (UCL-MSSL) report on behalf of the Swift-XRT team: We have analysed 6.4 ks of XRT data for GRB 130420B (Oates et al. GCN Circ. 14411), from 39 s to 39.9 ks after the BAT trigger. The data comprise 18 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. Using 2638 s of PC mode data and 4 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 183.12838, +54.39054 which is equivalent to: RA (J2000): 12h 12m 30.81s Dec(J2000): +54d 23' 26.0" with an uncertainty of 1.8 arcsec (radius, 90% confidence). The light curve can be modelled with a power-law decay with a decay index of alpha=1.11 (+0.09, -0.14). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.0 (+/-0.4). The best-fitting absorption column is 6.8 (+9.6, -5.4) x 10^20 cm^-2, consistent with the Galactic value of 1.4 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 3.5 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 6.8 (+9.6, -5.4) x 10^20 cm^-2 Galactic foreground: 1.4 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 2.0 (+/-0.4) If the light curve continues to decay with a power-law decay index of 1.11, the count rate at T+24 hours will be 2.0 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.1 x 10^-14 (8.5 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00553996. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14432 SUBJECT: GRB 130420B: RATIR Optical and NIR Observations DATE: 13/04/21 17:24:52 GMT FROM: Nat Butler at Az State U Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We observed the field of GRB 130420B (Oates et al., GCN 14411) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2013/04 21.15 to 2013/04 21.29 UTC (14.54 to 18.10 hours after the BAT trigger), obtaining a total of 1.32 hours exposure in the r' and i' bands and 0.55 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-XRT error circle (Page et al., GCN 14430), in comparison with SDSS DR8 and 2MASS, we obtain the following upper limits (3-sigma) in the AB magnitude system: r'> 23.19 i'> 22.99 Z > 21.87 Y > 21.39 J > 21.20 H > 20.53 These magnitudes are not corrected for Galactic extinction in the direction of the GRB. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14435 SUBJECT: GRB 130420B: Fermi GBM observation DATE: 13/04/22 11:29:13 GMT FROM: Arne Rau at MPE Arne Rau (MPE) reports on behalf of the Fermi GBM Team: "At 12:56:32.99 UT on 20 April 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 130420B (trigger 388155395 / 130420539), which was also detected by Swift/BAT (Oates et al., GCN 14411). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is about 50 degrees. The GBM light curve shows a single pulse with a duration (T90) of about 16 s (50-300 keV). The time-averaged spectrum from T0-4 s to T0+4 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is 0.24 +/- 0.25 and the cutoff energy, parameterized as Epeak, is 91 +/- 9 keV. The event fluence (10-1000 keV) in this time interval is (1.04 +/- 0.08)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.0 s in the 10-1000 keV band is 2.6 +/- 0.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14444 SUBJECT: GRB 130420B: CARMA and VLA radio observations DATE: 13/04/25 20:44:52 GMT FROM: Ashley Zauderer at CfA B. A. Zauderer and E. Berger (Harvard) report on behalf of the CARMA Key Project "A Millimeter View of the Transient Universe" and a larger collaboration: "We observed the position of GRB 130420B (Oates et al.; GCN 14411) beginning 2013 Apr 23.29 UT (dt = 2.75 d) with the Very Large Array (VLA) and beginning 2013 Apr 22.91 (dt = 2.37 d) with the Combined Array for Research at Millimeter Astronomy (CARMA). We do not find any significant radio emission at the position of the enhanced Swift-XRT position (Page et al.; GCN 14421) at a mean frequency of 5.8 GHz (VLA) to a 3-sigma limit of 32 uJy, at 21.8 GHz (VLA) to a 3-sigma limit of 47 uJy, or at 85 GHz (CARMA) to a 3-sigma limit of 0.78 mJy. We thank the VLA and CARMA observatories for their support of these observations."