//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9044 SUBJECT: Fermi LAT and GBM detections of GRB090328 DATE: 09/03/28 23:18:16 GMT FROM: Julie McEnery at UMBC/GSFC Julie McEnery (NASA/GSFC), Sara Cutini (ASDC), Masanori Ohno (ISAS/JAXA) and Elmar Koerding (AIM/Saclay) report on behalf of the Fermi LAT collaboration and Valerie Connaughton (UAH) reports on behalf of the Fermi GBM collaboration At 09:36.46 UT on 28 March 2009, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 090328 (trigger 259925808 / GRB090328401). The GBM lightcurve shows a multi-peaked event, with the brightest set of peaks occurring within 50 sec and a further peak at 60 sec tailing off beyond 100 sec post-trigger. The burst is detected at least to 1 MeV. The Fermi Large Area Telescope (LAT) has significantly detected this GRB. Emission was observed in the LAT up to a few GeV with a detection significance of more than 5 sigma. The current best LAT on-ground localization is found to be (RA,Dec=90.87, -41.95) with a 68% containment radius of 0.11 deg, and a systematic error less than 0.1 deg. The GBM on-ground localization is consistent with this LAT localization within statistical and systematic uncertainties. We further report that the Fermi Observatory executed a maneuver following this trigger and tracked the burst location for the next 5 hours, subject to Earth-angle constraints. Swift TOO observations have been requested at the LAT measured position. Further analysis is ongoing. The points of contact for this burst are Julie McEnery (LAT, julie.mcenery@nasa.gov) and Valerie Connaughton (GBM, valerie@nasa.gov). 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. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9045 SUBJECT: GRB 090328: Possible Swift/XRT detection DATE: 09/03/29 04:27:22 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT J. Kennea (PSU) reports on behalf of the Swift/XRT Team: Swift began a TOO observation observation of the LAT error circle of GRB 090328 (McEnery et al, GCN #9044) at 01:26UT March 29th, 2009. Preliminary analysis of the downlinked XRT data finds an uncatalogued X-ray source approximately 10 arcminutes from the centre of the LAT error circle, at the following location: RA, Dec = 90.66485, -41.88421 which is equivalent to: RA(J2000) = 06h 02m 39.6s Dec(J2000)= -41d 53m 03.2s with an estimated uncertainty of 6 arcseconds radius (90% confidence). We cannot confirm at this time if the afterglow candidate is fading. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9046 SUBJECT: GRB 090328: Updated position/optical afterglow candidate DATE: 09/03/29 05:46:10 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT J. Kennea (PSU), P. Evans and M. Goad (U Leicester) report on behalf of the Swift/XRT Team: Further analysis of the candidate afterglow of GRB 090328 has been performed utilizing downlinked Swift XRT and UVOT data. Using 1329 s of XRT Photon Counting mode data and 2 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 = 90.66494, -41.88265 which is equivalent to: RA (J2000): 06 02 39.58 Dec (J2000): -41 52 57.5 with an uncertainty of 2.0 arcsec (radius, 90% confidence). Position enhancement is described by Goad et al. (2007, A&A, 476, 1401 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method. Swift/UVOT detects a point source at a location consistant with the XRT error circle, detected in the U and White filters. A catalogue search does not reveal any known source at the location of this source. We tentatively suggest that this UVOT source may be the optical afterglow of GRB 090328, although this cannot be confirmed until either the optical or X-ray afterglow candidates are seen to fade. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9048 SUBJECT: GRB 090328: Swift UVOT observations DATE: 09/03/29 15:11:20 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) reports on behalf of the Swift/UVOT team: The Swift/UVOT began observing the field of GRB 090328 16 hrs after the Fermi LAT trigger (McEnery et al., GCN 9044). We detect a candidate optical afterglow in the u and white filters at: RA(J2000.0) = 06:02:39.67 DEC(J2000.0) = -41:52:54.5 with an estimated uncertainty of 0.6 arcsec (radius, 90% confidence). At the moment we are unable to tell if the source is fading, further observations have been performed, but due to a data gap, the data is currently unavaliable. Preliminary magnitudes for the white and u filters are: Filter T_mid (hrs) Exposure(s) Mag Err ------------------------------------------------------------ u 16.0 793 19.04 +/- 0.13 white 16.1 173 19.56 +/- 0.14 The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.06 mag (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT flight system described in Poole et al. (2008, MNRAS, 383,627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9049 SUBJECT: GRB 090328: IPN Triangulation DATE: 09/03/29 18:06:02 GMT FROM: Valerie Connaughton at MSFC S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T.Cline on behalf of the Konus-Wind team, A. von Kienlin, G. Lichti, A. Rau, and K. Hurley on behalf of the INTEGRAL SPI-ACS GRB team, and V. Connaughton, M. Briggs, and C. Meegan, on behalf of the Fermi GBM team, report: Konus-Wind and INTEGRAL (SPI-ACS) have so far observed the long bright GRB 090328 (McEnery et al. GCN 9044). We have triangulated this burst to a Konus-SPI-ACS annulus centered at RA(2000), Dec(2000) =26.911, +1.465, whose radius is 72.339 +/- 0.671 degrees (3 sigma). This annulus intersects the GBM localization, and the LAT localization lies 0.357 degrees from the center line of this annulus. A map is posted at http://www.ioffe.ru/LEA/GRBs/GRB090328_T34609/IPN/ showing the GBM contours (statistical) and best-fit position (diamond), the IPN annulus (solid line), and the LAT best-fit position (diamond) and error circle (68% CL, statistical). This map will also be posted at http://ssl.berkeley.edu/ipn3/090328 . The IPN localization may be improved. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9050 SUBJECT: Konus-Wind observation of GRB 090328 DATE: 09/03/29 18:18:18 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The long bright GRB 090328 (Fermi-GBM trigger trigger 259925808 / GRB090328401) localized by Fermi-LAT (McEnery et al., GCN 9044; the LAT localization was confirmed by the IPN triangulation: Golenetskii et al., GCN 9049) triggered Konus-Wind at T0=34609.486 s UT (09:36:49.486). The burst light curve shows a multipeaked structure with a duration of ~80 s. There is a hint of an extended soft emission. As observed by Konus-Wind the burst had a fluence of 9.25(-1.98, +1.63)x10^-5 erg/cm2, and a 64-ms peak flux measured from T0+20.064 s of 1.22(-0.26, +0.25)x10^-5 erg/cm2/s (both in the 20 keV - 8 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+72.960 s) is well fitted (in the 20 keV - 8 MeV range) by GRB (Band) model for which: the low-energy photon index alpha = -1.04(-0.10, +0.11), the high energy photon index beta = -2.05(-0.90, +0.22), the peak energy Ep = 592(-141, +237) keV (chi2 = 78.4/81 dof). The spectrum of the most intense part (from T0 to T0+23.808 s) is well fitted (in the 20 keV - 8 MeV range) by GRB (Band) model for which: the low-energy photon index alpha = -0.94 +/- 0.08, the high energy photon index beta = -2.07(-0.36, +0.16), the peak energy Ep = 600(-100, +147) keV (chi2 = 81.1/81 dof). The fluence of this part is 7.48(-0.93, +0.83)x10^-5 erg/cm2 (in the 20 keV - 8 MeV energy range). All the quoted errors are at the 90% confidence level. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB090328_T34609/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9052 SUBJECT: GRB 090328: Swift XRT refined analysis DATE: 09/03/29 20:39:01 GMT FROM: Antonia Rowlinson at U.of Leicester A. Rowlinson and K. Page (U. Leicester) report on behalf of the Swift/XRT Team: We have analysed 3.4 ks of XRT data for the Fermi GBM and LAT detected GRB 090328 (McEnery et al. GCN Circ. 9044, Kennea et al. GCN Circ. 9045), from 57.1 ks to 94.3 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=2.60 (+/-0.28). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.9 (+0.3, -0.4). The best-fitting absorption column is 1.9 (+1.4, -1.1) x 10^21 cm^-2, in excess of the Galactic value of 5.0 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 4.9 x 10^-11 (6.6 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 2.60, the count rate at T+48 hours will be 0.004 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.96 x 10^-13(2.64 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00031387. This circular is an official product of the Swift-XRT team //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9053 SUBJECT: GRB 090328: Gemini South Redshift DATE: 09/03/30 02:50:53 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko, J. S. Bloom, A. N. Morgan, and D. A. Perley (UC Berkeley) report on behalf of a larger collaboration: We have obtained optical spectra of the candidate UVOT afterglow (GCN 9046, 9048) of the Fermi GRB090328 (GCN 9044) with the Gemini Multi-Object Spectrograph mounted on the Gemini South Telescope. Observations began at 00:05 UT on 2009 March 29. Our first 1500 second spectrum uses the R400 grating and covers the approximate wavelength range from 4000-8000 A. We find a single bright emission line at observed wavelength ~ 6470 A that we identify as [OII] 3727 at z = 0.736, along with an absorption doublet consistent with Mg II 2796/2803 at the same redshift. We therefore suggest that this is the redshift of GRB090328. Further observations are in progress. We wish to thank the entire staff at Gemini observatory, in particular M. Edwards and J. Blakeslee, for the prompt execution of our observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9054 SUBJECT: GRB 090328: GROND Detection of the Optical/NIR Afterglow DATE: 09/03/30 03:36:16 GMT FROM: Adria C. Updike at Clemson U Adria Updike (Clemson University), Sylvio Klose (Tautenburg Obs.), Christian Clemens and Jochen Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 090328 (Fermi trigger 259925808; McEnergy et al., GCN 9044) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile). Observations started at 23:24 UT on date, about 1.6 days after the GRB trigger, and are continuing. They were performed at an average seeing of 1.8" and at an average airmass of 1.06. We detect the afterglow reported by Kennea et al. (GCN 9045) in all bands. Based on the first 8 min of total exposures in g'r'i'z' JHK, we estimate preliminary magnitudes (all in AB system) of g' = 20.97 +/- 0.05 mag, r' = 20.23 +/- 0.03 mag, i' = 19.89 +/- 0.04 mag, z' = 19.54 +/- 0.03 mag, J = 19.54 +/- 0.06 mag, H = 19.02 +/- 0.06 mag and K = 18.52 +/- 0.08 mag Given magnitudes are calibrated against USNO as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V) = 0.06 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9056 SUBJECT: GRB 090328B: Fermi GBM Detection DATE: 09/03/30 18:06:00 GMT FROM: Adam Goldstein at Fermi-GBM/UAH A. Goldstein (UAH) reports on behalf of the Fermi GBM Team: "At 17:07:04.94 UT on 28 March 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090328B (trigger 259952826 / 090328713). The Fermi Observatory executed a maneuver following this trigger and tracked the burst location for the next 5 hours, subject to Earth-angle constraints. The on-ground calculated location, using the GBM trigger data, is RA = 155.72, DEC = +33.40 (J2000 degrees, equivalent to 10h 23m, 33d 24'), with an uncertainty of 7.94 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 74 degrees. The GBM light curve consists of a single bright peak with a duration (T90) of about 0.32 s (8-1000 keV). The time-averaged spectrum from T0-0.13 s to T0+0.13 s is well fit by a Band function with Epeak = 1967.0 +/- 701.0 keV, alpha = -0.92 +/- 0.06, and beta = -2.48 +/- 0.66 (chi squared 452.6 for 482 d.o.f.). The event fluence (8-1000 keV) in this time interval is (9.61 +/- 0.31)E-07 erg/cm^2. The 0.064-sec peak photon flux measured starting from T0+0.0 s in the 8-1000 keV band is 29.83 +/- 2.38 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: 9057 SUBJECT: GRB 090328: Fermi GBM Spectral Analysis DATE: 09/03/30 20:10:37 GMT FROM: Arne Rau at MPE Arne Rau (MPE), Valerie Connaughton (UAH) and Michael Briggs (UAH) report on behalf of the Fermi GBM team: "We have performed spectral analysis of the GBM data for GRB 090328 (GCN 9044). The spectrum from T0+3.1s to T0+29.7s is best fit by a Band function with indices alpha=-0.93 +/- 0.02 and beta=-2.2 +/- 0.1, and peak energy of Epeak=653 +/- 45 keV (chi squared 365 for 311 d.o.f.). At a redshift of 0.736 (GCN 9053), the Epeak in the GRB rest frame, Epeak_rest, is 1133 +/- 0.078 MeV. The event fluence in this time interval is (8.09 +/- 0.10)E-5 erg/cm^2 in the 8-1000 keV band and (9.5 +/- 1.0)E-5 erg/cm^2 in the 8keV-40MeV band. Using standard cosmology (Omega_matter = 0.27, Omega_lambda = 0.73, H0=71) the isotropic equivalent energy in the 8keV-40MeV band is E_iso = (2.3 +/- 0.2)E+53 ergs. The 1-sec peak photon flux measured starting from T0+23.5 s in the 8-1000 keV band is 18.5 +/- 0.5 ph/s/cm^2. This time interval consists of three main emission peaks, from T0+3.1s to T0+8.2s, from T0+13.3s to T0+19.5s, and from T0+23.6 to T0+25.6s. All of these shorter intervals are also best fit by a Band function. For the first interval the power-law indices are alpha=-0.79 +/- 0.04 and beta=-2.3 +/- 0.2, Epeak is 648 +/- 68 keV, Epeak_rest is 1125 +/- 118 keV, and the fluence (8-1000 keV) is (3.80 +/- 0.08)E-06. For the second interval the power-law indices are alpha=-0.86 +/- 0.03, beta=-2.3 +/- 0.2, Epeak is 676 +/- 62 keV, Epeak_rest is 1174 +/- 108 keV, and the fluence (8-1000 keV) is (4.35 +/- 0.07)E-6. For the third interval the power-law indices are alpha=-0.94 +/- 0.05, beta=-2.4 +/- 0.3, Epeak is 481 +/- 60 keV, Epeak_rest is 835 +/- 104 keV, and the fluence (8-1000 keV) is (4.3 +/- 0.1)E-6. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9058 SUBJECT: GRB 090328: BOOTES-3 optical observations DATE: 09/03/30 23:58:43 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia Bill Allen (Vintage Lane Obs., Blenheim, New Zealand), Phil Yock (Auckland Univ., NZ), A. de Ugarte Postigo (ESO Santiago), Ian Bond (Massey Univ., NZ), John Hearnshaw (Univ. of Canterbury, NZ), Grant Christie (Stardome Obs., NZ), Petr Kubánek (GACE, Univ. of Valencia), S. Castillo (Univ. de Málaga), J. M. Castro Cerón (ESAC Madrid), T. Mateo Sanguino (Univ. de Huelva), D. Pérez-Ramírez (Univ. de Jaén), M. Cerviño, A. Claret, J. M. García Pelayo, J. Gorosabel, S. Guziy, M. Jelínek, S. Martín Ruiz and A. J. Castro-Tirado (IAA-CSIC Granada), report: "Following the detection by Fermi LAT and GBM of GRB 090328 (McEnery et al. GCNC 9044), follow-up observations were performed by the 0.6-m Yock-Allen robotic telescope at the new BOOTES-3 astronomical station in Blenheim (New Zealand). A co-added 1500s unfiltered image, obtained on 29 Mar (10:12-10:41 UT, i.e. 24.8 hr after the onset of the event) shows a rather bright optical afterglow at the UVOT position reported by Kennea et al. (GCNC 9046). We measure R~19.7+/-0.3 (clear filter), calibrated against USNO-B1.0 stars. Additional observations are encouraged." This message can be quoted. [GCN OPS NOTE(31mar09): Per author's request, the numerical values of the times (which were local time) were converted to true UT time values; the "36.8 hrs" was changed to "24.8"; and Cervino was added to the author list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9060 SUBJECT: GRB 090328: Radio afterglow detection DATE: 09/03/31 13:04:13 GMT FROM: Dale A. Frail at NRAO D. A. Frail (NRAO), P. Chandra (RMC), and B. Cenko (UC Berkeley) report on behalf of a larger collaboration: "We observed a field toward the optical afterglow (GCN Circ. 9046, GCN Circ. 9048) of the Fermi GBM/LAT GRB 090328 (GCN Circ. 9044, GCN Circ. 9057) on March 30.99 UT using the Very Large Array (VLA) at a frequency of 8.46 GHz. We detect an unresolved radio source at the GRB afterglow position with a flux density of 337+/-60 uJy at a (J2000) position of: RA = 06h 02m 39.67s DEC = -41d 52' 53.8" with a conservative error of 0.25" The source was not detected (<180 uJy) in observations taken 24 hours earlier. Further observations are planned. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9065 SUBJECT: GRB 090328B: MASTER-Irkutsk prompt optical short burst observations DATE: 09/04/01 08:47:35 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs K.Ivanov, S.Yazev, Irkutsk State University E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina, D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinski, I.Zalognikh, T.Kopytova Ural State University, Kourovka There are 6 MASTER Very Wide Field cameras located at Kislovodsk and Irkutsk with common FOW = 6000 square degrees (http://observ.pereplet.ru/). One of the two MASTER Very Wide Field Cameras located at Irkutsk (D=50 mm, 2x1000 square degrees, 11 Mpx) has observed ~20% 1-sigma Fermi error box (A. Goldstein, GCN 9056) with 1s exposure during all night: befoure, during and after GRB Time without time gap between images. Our unfiltered images are calibrated relative to Tycho stars (V). The magnitude limit of the each emage is ~9.1 m at the edge of FOW (some ising was attend at this night). We do not detect OT inside 20% part of the error box. We conclude (in the case that GRB inside our FOW ): 1). the optical fluence during the short 0.3 s GRBurst is limited by ~<= 3 x 10E-9 erg/cm_2 excluding possible host galaxy absorbtion. The event fluence (8-1000 keV) in this time interval is (9.61 +/- 0.31)E-07 erg/cm^2 (A. Goldstein, GCN 9056). So: 2). Optical-Fluence/Gamma-Fluence(8-1000 keV) ~ < 1/300 The same ratio for long GRB080319B is Optical-Fluence/Gamma-Fluence(8 - 1000 keV) ~ 1/140 (Naked Eye GRB, Racusin, Karpov et al., Nature, vol.455, 183, 2008). The film of our observations is available at http://observ.pereplet.ru/images/GRB090320B/GRB090328B.gif Black circles are the 1-sigma and 3-sigma error boxes (A. Goldstein, GCN 9056). The reduction is continued. The message may be cited. mailto: lipunov@sai.msu.ru //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9077 SUBJECT: GRB 090328: Fermi-LAT refined analysis DATE: 09/04/01 19:30:09 GMT FROM: Sara Cutini at ASDC Sara Cutini (ASDC), V. Vasileiou (NASA/GSFC, UMBC) and Jim Chiang (SLAC/KIPAC) report on behalf of the Fermi LAT team. We report further analysis with the LAT data on GRB 090328 (McEnery et al. GCN Circ. 9044, Kennea et al. GCN Circ. 9045). The emission in the LAT lasts up around 900s after the trigger, we did not find evidence for further high-energy delayed emission beyond 900s. Considering the rate of events passing the on board event filters for gamma-rays, the light curve shows a single pulse peaking at 25s which corresponds to the third spike of GBM light curve (A. Rau at al. GCN Circ. 9057). The highest energy events detected by the LAT which are spatially coincident with the burst position arrived hundreds of seconds after the GRB trigger time. In a preliminary time resolved spectral analysis we find no evidence of a change in spectral index during the whole duration of the burst. The points of contact for this burst are Julie McEnery (LAT, julie.mcenery@nasa.gov) and Arne Rau (GBM, arau@mpe.mpg.de). 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.