//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10810 SUBJECT: GRB 100528A: SuperAGILE Localization of a Long GRB DATE: 10/05/28 08:23:17 GMT FROM: Marco Feroci at IASF/INAF E. Del Monte, I. Donnarumma, Y. Evangelista, M. Feroci, F. Lazzarotto, L. Pacciani, P. Soffitta, E. Costa, I. Lapshov, M. Rapisarda (INAF/IASF Rome), G. Barbiellini, F. Longo, E. Moretti (INFN Trieste), A. Bulgarelli, F. Gianotti, M. Trifoglio, G. Di Cocco, C. Labanti, F. Fuschino, M. Marisaldi, M. Galli (INAF/IASF Bologna), A. Giuliani, A. Chen, S. Mereghetti, F. Perotti, P. Caraveo (INAF/IASF Milan), M. Tavani, G. Pucella, V. Vittorini, A. Argan, A. Trois, G. Piano, S. Sabatini (INAF/IASF Rome), A. Pellizzoni, M. Pilia (INAF/OA Cagliari), S. Vercellone, F. D'Ammando (INAF/IASF Palermo), P. W. Cattaneo, A. Rappoldi (INFN Pavia), P. Picozza, A. Morselli, E. Striani, (INFN Roma-2), M. Prest, E. Vallazza (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), P. Giommi, C. Pittori, F. Lucarelli, P. Santolamazza, F. Verrecchia (ASDC) and L. Salotti (ASI), on behalf of the AGILE Team, report: "SuperAGILE detected a gamma ray burst on 28 May 2010, at 01:48:05 UT. The event had a duration of about 20 s in the 20-60 keV energy range, with a single peak structure. Due to the AGILE spinning operative mode, the measured duration may be a lower limit. The burst position was reconstructed as (RA, Dec) (311.119, 27.810) deg, which is: RA(J2000) = 20h 44m 28.52s Dec(J2000) = 27d 48' 35.80" with an uncertainty of 5' radius. The given uncertainty accounts for both the statistical and systematic errors. AGILE MCAL reports significant detection above 1.4 MeV. An analysis of the AGILE Gamma Ray Imager (GRID) data is in progress." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10811 SUBJECT: GRB 100528A: Fermi GBM observation DATE: 10/05/28 09:07:46 GMT FROM: Arne Rau at MPE Arne Rau (MPE) and Alexander van der Horst (UAH) report on behalf of the Fermi GBM Team: "At 01:48:01.11 UT on 28 May 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100528A (trigger 296704083 / 100528075) which was also detected by the SuperAGILE (Del Monte et al. 2010, GCN 10810). The GBM on-ground location is consistent with the SuperAGILE position. The angle from the Fermi LAT boresight is 53 degrees. The GBM light curve shows a main peak followed by a fainter second pulse with a duration (T90) of about 24.6 +/- 0.5s (50-300 keV). The time-averaged spectrum from T0+0.003 s to T0+24.576 s is best fit by a Band function with Epeak = 316.5 +/- 17.8 keV, alpha = -1.16 +/- 0.02, and beta = -1.99 +/- 0.06 (CSTAT 1868.5 for 657 d.o.f.). The event fluence (10-1000 keV) in this time interval is (2.77 +/- 0.02) E-05 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+8.576 s in the 10-1000 keV band is 14.76 +/- 0.21 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: 10813 SUBJECT: Swift UVOT and UVOT-enhanced XRT position for GRB 100528A DATE: 10/05/28 22:03:49 GMT FROM: Dirk Grupe at PSU/Swift-XRT D. Grupe (PSU), M. Siegel (PSU), J. Gelbord (PSU), P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift team: We report of the Swift UVOT and XRT detections of a bright source within the 5' error radius of the SuperAGILE detected GRB 100528A (Del Monte et al., GCN Circ 10810) at a level of 2e-12 ergs/s/cm2 in the 0.3-10 keV band. Swift started observing the field of GRB 100528A 42.5 ks after the AGILE detection and has observed it so far for 5 ks (two orbits). At this point it is not obvious if the X-ray source is fading. However, this X-ray source was not present during the ROSAT All-Sky Survey. There is also an archival XMM data set that covers this position (OBSID 0037990101, a 17ks exposure taken 2002-11-21). There is no source detected at the position of the counter part. Measuring the flux within a 30" radius of this position, the 4-sigma upper limit of 5e-14 ergs/s/cm2 in the 0.2-12 keV band. Most likely the X-ray source found by the XRT is the X-ray afterglow of GRB 100528A. Using 2497 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 = 311.14130, 27.80660 which is equivalent to: RA (J2000): 20 44 33.92 Dec (J2000): +27 48 23.8 with an uncertainty of 2.1 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). Using 4985 s of UVOT data take in the u, v and White filters, we identify a faint uncataloged source within the XRT error circle at a position in the white images of RA,DEC=311.14130, 27.80660 which is equivalent to: RA (J2000): 20 44 33.92 Dec (J2000): +27 48 23.8 with a 90%-confidence interval of about 0.60 arc sec. Preliminary magnitudes using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) are: FILTER T_start(s) T_stop Exposure Mag ========================================================= white 43296 49881 1632 20.96+-0.13 v 44124 50777 1721 20.01+-0.35 u 42469 49036 1632 20.63+-0.24 ========================================================= The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.29 (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). This circular is an official product of the Swift team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10814 SUBJECT: GRB 100528A: NOT optical observation DATE: 10/05/29 16:30:12 GMT FROM: Dong Xu at DARK,NBI D. Xu (Weizmann Inst.), P. Jakobsson (Univ. Iceland), A. Irrgang (Karl Remeis Observatory & ECAP) report on behalf of a larger collaboration: We observed the field of GRB 100528A (Del Monte et al., GCN 10810; Grupe et al., GCN 10813) with the NOT equipped with ALFOSC in the B, V, R, and i filters. Observations started on May 29 at 04:08 UT (26.34 hrs after the GRB). We obtained 3x180 s frames in each filter. An optical source is found at the UVOT position (Grupe et al., GCN 10813) and is clearly detected in the stacked frame in each filter. Preliminary analysis shows the following Vega magnitudes: m(B)=21.71+/-0.06 (mid_time=26.4417 hr) m(V)=20.95+/-0.03 (mid_time=26.6751 hr) m(R)=20.48+/-0.02 (mid_time=26.9090 hr) m(i)= 20.02+-0.02 (mid_time= 27.1415 hr), which are mainly calibrated against the #1178-0655113 star in the USNO B1 catalog and the Galactic extinction is not taken into account. The source is very likely the afterglow of GRB 100528A as there exists decay in the V filter compared with the measurement in Grupe et al. (GCN 10813). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10815 SUBJECT: GRB 100528A: GROND detection in all bands DATE: 10/05/30 14:09:01 GMT FROM: Andrea Rossi at TLS Tautenburg P. Afonso (MPE Garching), A. Nicuesa, A. Rossi, S. Klose (TLS Tautenburg), T. Kruehler, A. Yoldas and J. Greiner (MPE Garching), report on behalf of the GROND team: We observed the field of GRB 100528A discovered by SuperAGILE (Del Monte et al., GCN #10810) and observed also by Fermi/GBM (Rau & van der Horst, GCN #10811), simultaneously in g'r'i'z'JHK with GROND (Greiner et al.2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La Silla Observatory (Chile). Observations started at 07:49 UT on March 30, 54 hours after the GRB trigger. At the position of the UVOT detection (Grupe et al., GCN #10813) we detect and confirm the afterglow mentioned also by Xu et al. (GCN #10814). Based on stacked images with a total integration time of 40 minutes in JHK and 50 minutes in g'r'i'z' we estimate the following preliminary magnitudes (all in the AB system): g' = 21.93+-0.08 r' = 21.56+-0.04 i' = 21.27+-0.05 z' = 21.36+-0.07 J = 20.49+-0.10 H = 20.25+-0.12 K = 20.46+-0.21 All magnitudes given above are calibrated against SDSS and 2MASS field stars. No correction has been applied for the large, uncertain Galactic foreground extinction corresponding to a reddening of E(B-V)~ 0.22 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10816 SUBJECT: GRB 100528A: Faulkes Telescope North Detection DATE: 10/05/31 10:32:49 GMT FROM: Zach Cano at ARI/John Moores Liverpool Z. Cano (Liverpool JMU) & D. Kopac (U. Ljubljana) report on behalf of a larger collaboration: On 2010 May 27 at 13:07:01 UT the 2-m Faulkes Telescope North (Hawaii) began observing in the R and i' filters the SuperAGILE GRB 100528A (Del Monte et al., GCN Circ. 10810), which was also detected by Fermi/GBM (Rau & Van der Horst, GCN Circ. 10811). We clearly detect the optical afterglow at the UVOT position (Grupe et al., GCN Circ. 10813; Xu et al., GCN Circ. 10814; Afonso et al., GCN Circ. 10815) with the following magnitudes: --------------------------------------------------------------------- T-To (days) Filter magnitude magnitude error --------------------------------------------------------------------- 1.51 r' 20.98 0.06 1.48 i' 20.88 0.08 --------------------------------------------------------------------- Photometry is calibrated and quoted with respect to SDSS stars in the field. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10817 SUBJECT: Konus-Wind observation of GRB 100528A DATE: 10/05/31 15:33:58 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 GRB 100528A localized by SuperAGILE (Del Monte et al., GCN 10810) triggered Konus-Wind at T0=6483.610 s UT (01:48:03.610). The burst light curve shows a main pulse with a duration of ~30 s followed by a much weaker and softer pulse at ~T0+44 s with a duration of ~15 s. As observed by Konus-Wind the burst had a fluence of 2.85(-0.19, +0.21)x10^-5 erg/cm2, and a 256-ms peak flux measured from T0+6.688 s of 3.99(-0.58, +0.59)x10^-6 erg/cm2/s (both in the 20 keV - 2 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+23.296 s) is well fitted (in the 20 keV - 2 MeV range) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), with alpha = -1.28(-0.06, +0.07), and Ep = 382(-52, +69) keV (chi2 = 55.0/61 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and only an upper limit on the high energy photon index: beta < -2.28 (chi2 = 55.0/60 dof). The spectrum accumulated over the burst maximum (from T0 to T0+6.912 s) is well fitted (in the 20 keV - 2 MeV range) by a power law with exponential cutoff model with alpha = -1.18 +/- 0.07, and Ep = 558(-85, +115) keV (chi2 = 71.4/61 dof). Fitting by GRB (Band) model yields the same alpha and Ep, and only an upper limit on the high energy photon index: beta < -2.43 (chi2 = 71.4/60 dof). 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/GRB100528_T06483/