//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17665 SUBJECT: GRB 150403A: Swift detection of a burst with an optical counterpart DATE: 15/04/03 22:17:05 GMT FROM: Scott Barthelmy at NASA/GSFC A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team: At 21:54:16 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150403A (trigger=637044). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 311.505, -62.702, which is RA(J2000) = 20h 46m 01s Dec(J2000) = -62d 42' 04" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows two overlapping peaks with a total duration of about 60 sec. The peak count rate was ~19,000 counts/sec (15-350 keV), at ~7 sec after the trigger. The XRT began observing the field at 21:55:31.5 UT, 74.7 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 311.5019, -62.7118 which is equivalent to: RA(J2000) = +20h 46m 0.46s Dec(J2000) = -62d 42' 42.5" with an uncertainty of 4.8 arcseconds (radius, 90% containment). This location is 35 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 6.34e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 84 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 20:46:01.14 = 311.50476 DEC(J2000) = -62:42:41.0 = -62.71138 with a 90%-confidence error radius of about 0.61 arc sec. This position is 5.0 arc sec. from the center of the XRT error circle. The estimated magnitude is 14.85 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.05. Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT 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: 17666 SUBJECT: GRB 150403A: Enhanced Swift-XRT position DATE: 15/04/04 09:28:12 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 3056 s of XRT Photon Counting mode data and 5 UVOT images for GRB 150403A, 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 = 311.50504, -62.71106 which is equivalent to: RA (J2000): 20h 46m 1.21s Dec (J2000): -62d 42' 39.8" with an uncertainty of 1.4 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: 17667 SUBJECT: GRB 150403A: Fermi-LAT detection DATE: 15/04/04 10:12:54 GMT FROM: Elisabetta Bissaldi at U.Innsbruk/IAPP F. Longo (University & INFN Trieste), E. Bissaldi (INFN Bari), M. Arimoto (Tokyo Tech) and S. Zhu (UMD, USA) report on behalf of the Fermi-LAT team: At 21:54:10.95 on April 03, 2015, Fermi-LAT detected high-energy emission from GRB 150403A, which was also detected by Fermi-GBM (trigger 449790853/150403913) and Swift (Lien at al, GCN 17665). The GBM location was initially inside the LAT field of view at an angle of ~55 degrees to the LAT boresight and triggered an autonomous repoint of the spacecraft. The best LAT on-ground location is found to be RA, Dec (J2000) 311.79, -62.76 with an error radius of 0.50 deg (95% containment, statistical error only) and consistent with the enhanced Swift/XRT location (Beardmore et al, GCN 17666). The data from the Fermi-LAT show a significant increase in the event rate within 12 degrees of the Swift/XRT location after the trigger. More than 30 photons above 100 MeV are observed within 2000 seconds. The highest-energy photon is a 5 GeV event which is observed 630 s after the GBM trigger. Using the LAT Low Energy (LLE) data selection, over 200 counts above background are detected within a 20 s interval coincident with the time of the GBM emission. The Fermi-LAT point of contact for this burst is Sylvia Zhu (sjzhu@umd.edu). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17668 SUBJECT: GRB 150403A: Swift-XRT refined Analysis DATE: 15/04/04 10:17:03 GMT FROM: Phil Evans at U of Leicester D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), A. Amaral-Rogers (U. Leicester), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB) and A.Y. Lien report on behalf of the Swift-XRT team: We have analysed 10 ks of XRT data for GRB 150403A (Lien et al. GCN Circ. 17665), from 64 s to 30.5 ks after the BAT trigger. The data comprise 3.5 ks in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 17666). The late-time light curve (from T0+5.1 ks) can be modelled with a series of power-law decays. The initial decay index is alpha=1.14 (+0.08, -0.15). At T+6776 s the decay steepens to an alpha of 8.0 (+0.0, -2.7) before breaking again at T+7063 s to a final decay with index alpha=1.42 (+0.14, -0.22). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.695 (+/-0.016). The best-fitting absorption column is 1.03 (+/-0.05) x 10^21 cm^-2, in excess of the Galactic value of 5.3 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.66 (+/-0.10) and a best-fitting absorption column of 1.1 (+/-0.3) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10^-11 (4.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.1 (+/-0.3) x 10^21 cm^-2 Galactic foreground: 5.3 x 10^20 cm^-2 Excess significance: 2.9 sigma Photon index: 1.66 (+/-0.10) If the light curve continues to decay with a power-law decay index of 1.42, the count rate at T+24 hours will be 0.16 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.7 x 10^-12 (7.7 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/00637044. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17672 SUBJECT: GRB 150403A: VLT/X-shooter redshift DATE: 15/04/04 12:06:05 GMT FROM: Dong Xu at DARK/NBI V. Pugliese (API/Uva), D. Xu (DARK/NBI), N. R. Tanvir, K. Wiersema (U. Leicester), J. P. U. Fynbo, B. Milvang-Jensen (DARK/NBI), V. D'Elia (ASI/ASDC and INAF/Roma) report on behalf of a larger collaboration: We observed the afterglow of GRB 150403A (Lien et al. GCN 17665; Longo et al. GCN 17667) with X-shooter at the Very Large Telescope (Paranal Observatory, Chile). Observations started at 08:44:48 UT on 2015-04-04 (i.e., 10.84 hr after the burst), and consisted of photometry in V-, r-, z-, and g- bands as well as spectroscopy of 4x600 s exposures covering the spectral range between 3000 and 25000 AA, equipped with UVB/VIS/NIR arms. The optical afterglow is well detected in each photometric image, and has m(R) ~ 19.1 mag at 10.85 hr post-burst, calibrated with nearby USNO B1 stars. For the spectroscopy, prominent absorption lines are detected in a continuum throughout the arms. In a preliminary reduction we detect absorption features of SII, SiIV, OI, SiII, SiII*, CII, CII*, CIV, AlII, NiII*, FeII, FeII*, MnI, MgII, MgI at a common redshift of z = 2.06, which is consistent with a broad Lya trough at the same redshift. We suggest this is the redshift of the GRB. We also detect an intervening system at z=1.76, identified with absorption lines of SiII, CIV, AlII, and so on. We acknowledge the excellent support provided by Paranal staff, and in particular Andrea Mehner, and Emanuela Pompei. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17673 SUBJECT: GRB 150403A: Swift/UVOT Detection DATE: 15/04/04 13:51:07 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150403A 85 s after the BAT trigger (Lien et al., GCN Circ. 17665). A source consistent with the XRT position (Beardmore et al. GCN Circ. 17666) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 20:46:01.15 = 311.50479 (deg.) Dec (J2000) = -62:42:41.0 = -62.71139 (deg.) with an estimated uncertainty of 0.42 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 85 235 147 14.89 +/- 0.02 v 627 647 20 16.49 +/- 0.13 b 553 573 20 16.65 +/- 0.08 u 298 547 246 16.14 +/- 0.03 w1 676 5286 294 19.68 +/- 0.21 m2 6317 23414 1178 >22.2 w2 5907 7536 387 >20.6 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17674 SUBJECT: GRB 150403A: Fermi GBM Detection DATE: 15/04/04 14:04:39 GMT FROM: Binbin Zhang at UAH Bin-Bin Zhang (UAH) reports on behalf of the Fermi GBM Team: "At 21:54:10.95 UT on 03 April 2015, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 150403A (trigger 449790853 / 150403913), which was also detected by the Swift (Lien et al. 2015, GCN 17665) and Fermi LAT (Longo et al. 2015, GCN 17667). The GBM on-ground location is consistent with the Swift position. The trigger resulted in an Autonomous Repoint Request (ARR) that was accepted and the spacecraft slewed to the GBM in-flight location. The initial angle from the Fermi LAT boresight is about 55 degrees. The GBM light curve shows a bright single pulse with a duration (T90) of about 22.3 s (50-300 keV). The time-averaged spectrum from T0+3.3 s to T0+25.6 s is best fit by a Band function with Epeak = 311 +/- 14 keV, alpha = -0.72 +/- 0.02, and beta = -1.85 +/- 0.03. The event fluence (10-1000 keV) in this time interval is (5.73 +/- 0.05)E-05 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+11.1 s in the 10-1000 keV band is 33.5 +/- 0.5 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." — Sent from Mailbox//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17675 SUBJECT: GRB 150403A: Swift-BAT refined analysis DATE: 15/04/04 18:40:14 GMT FROM: Amy Lien at GSFC T. Sakamoto (AGU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (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 150403A (trigger #637044) (Lien, et al., GCN Circ. 17665). The BAT ground-calculated position is RA, Dec = 311.505, -62.706 deg which is RA(J2000) = 20h 46m 01.1s Dec(J2000) = -62d 42' 20.5" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 40%. The mask-weighted light curve shows a single bright peak. The main structure starts at ~ T-10 s, peaks at ~ T+6 s, and ends at ~ T+35 s. There are some weaker emissions that starts at ~ T-170 s and lasts till ~ T+195 s. T90 (15-350 keV) is 40.90 +- 11.72 sec (estimated error including systematics). The time-averaged spectrum from T-83.15 to T+145.37 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.23 +- 0.04. The fluence in the 15-150 keV band is 1.7 +- 0.03 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+5.80 sec in the 15-150 keV band is 17.6 +- 0.6 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/637044/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17677 SUBJECT: Konus-Wind observation of GRB 150403A DATE: 15/04/05 12:02:58 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The long-duration, intense GRB 150403A (Swift-BAT trigger #637044: Lien et al., GCN 17665; Sakamoto et al., GCN 17675; Fermi-LAT detection: Longo et al., GCN 17667; Fermi-GBM detection: Zhang, GCN 17674) triggered Konus-Wind at T0=78852.693 s UT (21:54:12.693). The KW light curve shows a single bright pulse with a duration of ~26 s. The emission is visible up to ~10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB150403_T78852/ As observed by Konus-Wind, the burst had a fluence of 1.0(-0.1,+0.1)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+9.088 s, of 1.7(-0.1,+0.1)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum (measured from T0 to T0+27.136 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.93 (-0.07,+0.08), the high energy photon index beta = -2.06 (-0.12,+0.08), the peak energy Ep = 373 (-48,+58) keV, chi2 = 124/97 dof. The spectrum near the peak count rate (measured from T0+7.168 to T0+10.752 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.78 (-0.08,+0.10), the high energy photon index beta = -2.13 (-0.12,+0.09), the peak energy Ep = 430 (-57,+64) keV, chi2 = 117/97 dof. Assuming the redshift z=2.06 (Pugliese et al., GCN 17672) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, and Omega_Lambda = 0.73, we estimate the following rest-frame parameters: the isotropic energy release E_iso is ~1.0x10^54 erg, the peak luminosity L_iso is ~5.3x10^53 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,i, is ~1320 keV. All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17680 SUBJECT: GRB 150403A: MASTER-net optical observation DATE: 15/04/06 17:24:35 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov, Lomonosov Moscow State University, Sternberg Astronomical Institute D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka 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 SAAO was pointed to the GRB150403A (Lien et al. GCN 17665) 20418 sec after notice time and 20434 sec (5.7h) after trigger time at 2015-04-04 03:34:51 UT immediately after suitable weather condition came, in automatic mode. Observation lasted about 30 minutes, until the weather became bad again. We detect a faint OT on a Swift UVOT position (Kuin et al. GCN17673). The estimated unfiltered magnitude is: Date time_start T0-Tmid[s] Expt.[s] Mag Coadd 2015-04-04 03:34:51.49 20840 720 19.2 4 Our unfiltered band is well described by a parity 0.8R+0.2B (USNO B1). The message may be cited.