//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7525 SUBJECT: GRB 080328: Swift detection of a burst with an optical counterpart DATE: 08/03/28 08:28:44 GMT FROM: David Palmer at LANL M. Perri (ASDC), D. N. Burrows (PSU), S. Campana (INAF-OAB), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), C. Guidorzi (INAF-OAB), C. B. Markwardt (CRESST/GSFC/UMD), K. L. Page (U Leicester), D. M. Palmer (LANL), D. Perez (U Leicester), P. Romano (INAF-IASFPA), R. L. C. Starling (U Leicester), G. Stratta (ASDC), D. E. Vanden Berk (PSU), P. A. Ward (MSSL-UCL) and H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team: At 08:03:04 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080328 (trigger=307931). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 80.479, +47.524 which is RA(J2000) = 05h 21m 55s Dec(J2000) = +47d 31' 26" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 110 sec. The peak count rate was ~9500 counts/sec (15-350 keV), at ~10 sec after the trigger. The XRT began observing the field at 08:04:44.0 UT, 99.4 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 80.48189, 47.51035 which is equivalent to: RA(J2000) = 05h 21m 55.65s Dec(J2000) = +47d 30' 37.3" with an uncertainty of 2.6 arcseconds (radius, 90% containment). This location is 49 arcseconds from the BAT onboard position, within the BAT error circle. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 3.38e+21 cm^-2 (Kalberla et al. 2005), so we cannot constrain the redshift at this time using the relation from Grupe et al. (2007). A summary of the promptly downlinked data is given at http://www.swift.ac.uk/sper/307931/. The initial flux in the 2.5 s image was 1.08e-08 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of nominal 400 seconds with the V filter starting 216 seconds after the BAT trigger. There is a candidate afterglow in the list of sources generated on-board at RA(J2000) = 05:21:55.85 = 80.4827 DEC(J2000) = +47:30:39.2 = 47.5109 with a 1-sigma error radius of about 0.6 arc sec. This position is 2.8 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.7 with a 1-sigma error of about 0.5 mag. No correction has been made for the expected extinction of about 1.9 magnitudes. Burst Advocate for this burst is M. Perri (perri AT asdc.asi.it). 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: 7526 SUBJECT: GRB080328: Faulkes Telescope North observations DATE: 08/03/28 09:39:11 GMT FROM: Cristiano Guidorzi at INAF-OAB C. Guidorzi (INAF-OAB),, A. Gomboc (U. Ljubljana), D. Bersier, C.G. Mundell, I.A. Steele, R.J. Smith, D. Carter, S. Kobayashi, M. Bode (Liverpool JMU), P. O'Brien, N. Bannister, N. Tanvir (U. Leicester) report: The 2-m Faulkes North Telescope (Hawaii) automatically reacted to the Swift burst GRB080328 (trigger=307931, Perri et al. GCN 7525). Observations started about 167 s after the trigger time. We confirm the detection of the optical counterpart by UVOT. From the first 3x10 s exposure frames in R, we estimate a temporal decay index between 167 and 240 s after the trigger time of alpha = 1.4 +/- 0.2. Filter Tstart(s) Exposure(s) Mag ----------------------------------------------- R 167 10 16.96 +/- 0.02 R 198 10 17.26 +/- 0.02 R 230 10 17.44 +/- 0.02 ----------------------------------------------- Magnitudes are calibrated with respect to USNOB1 R2 in the R filter. A systematic error on absolute magnitudes of ~0.3 must be included. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7527 SUBJECT: GRB 080328: Enhanced Swift-XRT position DATE: 08/03/28 11:00:29 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 855 s of overlapping XRT Photon Counting mode and UVOT data for GRB 080328, 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 = 80.48231, +47.51063 which is equivalent to: RA (J2000): 05h 21m 55.75s Dec (J2000): +47d 30' 38.3" with an uncertainty of 1.7 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 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method. This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7530 SUBJECT: Swift/UVOT observations of GRB080328 DATE: 08/03/28 17:49:09 GMT FROM: Paul Ward at MSSL P. Ward (MSSL-UCL), P. Schady (MSSL-UCL) and M. Perri (ASDC) report on behalf of the Swift-UVOT team The Swift/UVOT observed the field of GRB 080328 starting 110s after the BAT trigger (Perri et al., GCN 7525). The afterglow is detected at RA: 05h 21m 55.87s DEC: +47d 30' 39.4" only in the white and v filters, with an error radius of 0.6 arcsec (90% confidence). The afterglow is seen to decay in both these filters, and has the following magnitudes and 3-sigma upper limits (in the UVOT photometric system, Poole et al. (2008, MNRAS, 383, 627)). Filter Tstart(s) Exp(s) Magnitude white 110 99.8 17.84 +/- 0.05 white 867 99.8 20.43 +/- 0.27 white 5611 399.8 > 21.60 v 217 399.8 17.90 +/- 0.08 v 973 399.8 19.25 +/- 0.20 v 6023 399.8 > 20.00 The afterglow is not detected in any other filters, perhaps due to the high Galactic extinction value of E(B-V) = 0.58 mag. The following are the 3-sigma upper limits for these filters. Filter Tstart(s) Exp(s) Magnitude b 851 493.6 > 20.96 u 673 338.5 > 20.59 uvw1 648 362.8 > 20.54 uvm2 623 393.2 > 20.38 uvw2 728 498.5 > 20.88 The values quoted above are not corrected for Galactic extinction corresponding to a reddening of E(B-V) = 0.58 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7532 SUBJECT: GRB 080328: Swift XRT refined analysis DATE: 08/03/28 19:06:57 GMT FROM: Matteo Perri at ISAC/ASDC M. Perri and G. Stratta (ASDC) report on behalf of the Swift XRT team: We have analysed the first 3 orbits of Swift XRT data of the BAT GRB 080328 (Perri et al., GCN Circ. 7525). The data consist of 151 s in Windowed Timing (WT) mode, from T+108s to T+259s, and of 6.9 ks in Photon Counting (PC) mode thereafter. The best XRT position is the UVOT-enhanced position reported by Beardmore et al. (GCN Circ. 7527). The early 0.3-10 keV X-ray light curve in WT mode shows a rapid decay. Starting from T+260s up to T+13.7ks the curve is well fit by a broken power-law model with decay indices alpha1=-0.57 (+0.09) (-0.06), alpha2=-1.10 (+/-0.05) and a temporal break at (1.7+/-0.3) ks. The WT X-ray spectrum is well fit by an absorbed power-law model with a photon index of 2.1 (+/-0.1), a column density of (4.2+/-0.4)e21 cm**-2 and an average observed 0.3-10 keV flux of 9.3e-10 erg/cm**2/s. The PC X-ray spectrum during the first orbit, from T+260s to T+2106s, is also well fit by an absorbed power-law model with a photon index of 2.2 (+/-0.1) and a column density of (5.0+/-0.6)e21 cm**-2. The observed 0.3-10 keV flux for this spectrum is 1.5e-10 erg/cm**2/s. We note the Galactic column density in the direction of the source is 3.4e21 cm**-2. Assuming the X-ray emission continues to decline at the same rate, we predict a 0.3-10 keV XRT count rate of 0.03 count/s at T+24hr, which corresponds to an observed 0.3-10 keV flux of about 1.4e-12 erg/cm**2/s. This circular is an official product of the Swift XRT Team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7533 SUBJECT: GRB 080328, Swift-BAT refined analysis DATE: 08/03/28 21:11:42 GMT FROM: Craig Markwardt at NASA/GSFC/UMD H. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), M. Perri (ASDC), T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-120 to T+183 sec from the recent telemetry downlink, we report further analysis of BAT GRB 080328 (trigger #307931) (Perri, et al., GCN Circ. 7525). The BAT ground-calculated position is RA, Dec = 80.490, 47.523 deg which is RA(J2000) = 05h 21m 57.7s Dec(J2000) = +47d 31' 23.8" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 37%. The mask-weighted light curve consists of about about ten major pulses spread over ~100 sec. T90 (15-350 keV) is 90.6 +- 1.5 sec (estimated error including systematics). The time-averaged spectrum from T-2.2 to T+117.5 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.52 +- 0.04. The fluence in the 15-150 keV band is 9.4 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+9.3 sec in the 15-150 keV band is 5.5 +- 0.3 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/307931/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7534 SUBJECT: GRB 080328: BTA optical imaging and spectroscopy DATE: 08/03/29 00:10:31 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia T. A. Fatkhullin, A. S. Moskvitin, V. V. Sokolov (SAO-RAS, Nizhnij Arkhyz), A. S. Pozanenko (IKI, Moscow), A. de Ugarte Postigo (ESO, Santiago), M. Jelínek, J. Gorosabel and A. J. Castro-Tirado (IAA-CSIC Granada), on behalf of a larger collaboration, report: "Following the detection of GRB 080328 by Swift (Perri et al. GCNC 7525), we have obtained BVRI imaging and spectroscopy (3800-7500 A) with the 6.0m BTA SAO-RAS telescope starting on Mar 28.76 UT (i.e. 12.4 hr after the onset of the event). A faint optical source (with R about 22.5) consistent with the UVOT position (Ward et al. GCNC 7530) is detected in all frames, thus implying an upper limit of about 2.5 for the GRB 080328 redshift. Its brightness is not consistent with the extrapolation of the early decay reported by Guidorzi et al. (GCNC 7526) indicating significant contribution of the reverse shock emission in the FTN data. Our BTA spectrum (2 x 900s) shows only a faint continuum and nothing conclusive can be reported (except the non-existence of strong emission lines arising from an underlying host galaxy)." This message can be quoted. [GCN OPS NOTE(29mar08): Per author's request, 3 typos were fixed in the Fatkhullin, Moskvitin and Pozanenko names.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7548 SUBJECT: Konus-Wind observation of GRB 080328 DATE: 08/03/30 15:58:08 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team report: The long GRB 080328 (Swift-BAT trigger #307931: Perri et al., GCN 7525, Krimm et al., GCN 7533) triggered Konus-Wind at T0=28982.306 s UT (08:03:02.306). The burst light curve shows a multipeaked structure with a total duration of ~90 s. As observed by Konus-Wind the burst had a fluence of 2.23(-0.22, +0.23)x10^-5 erg/cm2, and a 256-ms peak flux measured from T0+10.512 s of (2.51 +/- 0.41)x10^-6 erg/cm2/s (both in the 20 keV - 1 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+90.368 s) is well fitted (in the 20 keV-1 MeV range) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.13(-0.20, +0.17), and Ep = 289(-57, +93) keV (chi2 = 62.8/56 dof). The spectrum of the most intense part (from T0+8.448 to T0+16.640 s) is well fitted (in the same range) by a power law with exponential cutoff model with alpha = -0.59(-0.19, +0.17) and Ep = 338(-40, +51) keV (chi2 = 60.8/56 dof). The fluence of this part is (8.79 +/- 0.68)x10^-6 erg/cm2. All the quoted errors are at the 90% confidence level. The Konus-Wind light curve of this GRB is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB080328_T28982/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7551 SUBJECT: GRB 080328: Suzaku WAM observation of the prompt emission DATE: 08/03/30 23:10:38 GMT FROM: Makoto Tashiro at Saitama U/Swift N. Kodaka, M. Tashiro, Y. Terada, Y. Urata, A. Endo, K. Onda, M. Suzuki, K. Morigami (Saitama U.), K. Yamaoka, Y. E. Nakagawa, S. Sugita (Aoyama Gakuin U.), M. Ohno, T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima U.), T. Tamagawa (RIKEN), T. Enoto, R. Miyawaki, K. Nakazawa, K. Makishima (Univ. of Tokyo), E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara (Univ. of Miyazaki), M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report: The long GRB 080328 (Swift/BAT trigger #307931 ; Perri et al., GCN 7525) was detected by the the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 2008-03-28 08:03:14 UT (=T0). The observed light curve shows a multi-peaked structure starting at T0+0s, ending at T0+100 with a duration (T90) of about 85 seconds. The fluence in 100 - 1000 keV was 1.61 (-0.40,+0.37) * 10^-5 erg/cm^2. The 1-s peak flux measured from T0+0s was 6.4 (-0.39,+0.39) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-0s to T0+100s is well fitted by a single power-law with a photon index of 1.72 (-0.26, +0.38) (chi^2/d.o.f = 11.9/15). All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included. The light curves for this burst are available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7557 SUBJECT: GRB080328, RIMOTS optical upper limit DATE: 08/04/01 09:54:59 GMT FROM: Hiroki Tanaka at U of Miyazaki H.Tanaka, K.Kono, R.Hara, N.Ohmori, H.hayasi, M.Yamauchi, E.Sonoda (University of Miyazaki) We have observed the field covering the error circle of GRB080328 (GCN 7527, A.P. Beardmore et al.) with the unfiltered CCD camera on the 30-cm telescope at University of Miyazaki. The observation was started 11:09:32 UT; about 186 minutes after the Swift trigger time. We have compared our data of 30 sec exposures with the USNO-A2.0 catalog, there is no new source at the reported position. the upper limits are as follows: -------------------------------------------------------------- Start(UT) End(UT) Num. of frames Limit (mag.) -------------------------------------------------------------- 11:10:49 11:11:07 1 ~15.74 11:10:59 12:58:24 65 ~17.70 ---------------------------------------------------------------