//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15128 SUBJECT: GRB 130828A: Fermi-LAT detection of a burst DATE: 13/08/29 03:25:30 GMT FROM: Giacomo Vianello at SLAC G.Vianello (Stanford), E.Sonbas (NASA/GSFC/Adiyaman Univ.) report on behalf of the Fermi-LAT team: At 07:20:00.15 on 2013-08-28 Fermi LAT detected high energy emission from GRB 130828A, which was also detected by Fermi-GBM (trigger 399367203). The best LAT on-ground location is found to be RA, DEC 259.83, +28.00 (J2000) with an error radius of 0.3 deg (68% containment, statistical error only), this was 40 deg from the LAT boresight at the time of the trigger, and triggered an autonomous repoint of the spacecraft. The data from the Fermi LAT show a significant increase (>> 5 sigma) in the event rate within 2.3 degree of the best HITL GBM location after the GBM trigger that is spatially and temporally correlated with the GBM emission with high significance. More than 30 photons above 100 MeV and 2 photons above 1 GeV are observed within 1000 seconds. The highest energy photon is a 1.5 GeV event which is observed 225 seconds after the GBM trigger. The Fermi LAT point of contact for this burst is Eda Sonbas (esonbas@slac.stanford.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: 15129 SUBJECT: GRB 130828A: Fermi GBM detection DATE: 13/08/29 03:32:12 GMT FROM: Andrew Collazzi at NASA/MSFC/ORAU Andrew C. Collazzi (NASA/ORAU) reports on behalf of the Fermi GBM Team: "At 07:20:00.15 UT on 28 August 2013, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 130828A (trigger 399367203 / 130828.306). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 258.14, Dec = +29.76 (J2000 degrees, equivalent to J2000 17h 12m, +29d 45' ), with a statistical uncertainty of 1.0 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 46 degrees. The burst was strong enough to trigger an Automatic Repointing Request (ARR) on the Fermi spacecraft. The GRB position was placed in the center of the LAT Field-of-view for 2.5 hours (subject to Earth angle constraints). The GBM light curve shows consists of several pulses, and is possibly on top of a particle event. We find a duration (T90) of about 159 +/- 23 s (50-300 keV). We find the 1.024s peak flux during this time to be (7.39 +/- 0.37) ph/s/cm^2. The time-averaged spectrum from T0-4.10 to T0+159.75 s is best fit by a Band function with Epeak = 320.7 +/- 21.0 keV, alpha = -0.90 +/- 0.03, and beta = -2.22 +/- 0.03. The fluence (10-1000 keV) in this time interval is (6.05 +/- 0.09)E-05 erg/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15130 SUBJECT: GRB 130828A Tiled Swift observations DATE: 13/08/29 12:26:26 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a series of observations, tiled on the sky, of the Fermi/LAT GRB 130828A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00018 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; and 2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15132 SUBJECT: IPN triangulation of GRB 130828A DATE: 13/08/29 18:34:05 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and J. Goldsten, on behalf of the MESSENGER NS GRB team, S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, D. Svinkin, and T. Cline, on behalf of the Konus-Wind team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, K. Yamaoka, M. Ohno, Y. Hanabata, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada, T. Murakami, and K. Makishima on behalf of the Suzaku WAM team, S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team, and V. Connaughton, M. S. Briggs, C. Meegan, and V. Pelassa, on behalf of the Fermi GBM team, report: GRB 130828A (GCN 15128, 15129, 15130) has been observed by Fermi, INTEGRAL (SPI-ACS), Konus-Wind, MESSENGER GRNS, Suzaku, and Swift (outside the coded field of view), so far. We have triangulated it to an annulus centered at RA(2000)=340.597 deg (22 h 42 m 23 s), Dec(2000)=-9.971 deg (-9 d 58 m 17 s), whose radius is 86.782 +/- 0.092 degrees (3 sigma). This annulus intersects the Fermi-LAT 1 sigma error circle (GCN 15128) to form an error box whose area (280 sq. arcmin.) is about 3.6 times smaller than that of the LAT error circle , and whose corners are RA(2000) Dec(2000) 259.541=17 h 18 m 09 s 27.843= 27 d 50 ' 34 " 259.649=17 h 18 m 35 s 28.254= 28 d 15 ' 13 " 259.722=17 h 18 m 53 s 27.716= 27 d 42 ' 56 " 259.875=17 h 19 m 30 s 28.297= 28 d 17 ' 50 " A map has been posted at ssl.berkeley.edu/ipn3/130828A. Some improvement in this triangulation is possible. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15133 SUBJECT: Correction to GCN 15132 - GRB 130828A DATE: 13/08/29 18:46:18 GMT FROM: Kevin Hurley at UCBerkeley/SSL The title of GCN 15132 should have been "IPN triangulation of GRB 130828A", rather than 130821A. I apologize for the confusion and thank Kim Page for catching this quickly. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15135 SUBJECT: GRB 130828A: Swift XRT and UVOT observations DATE: 13/08/30 01:53:41 GMT FROM: Dirk Grupe at PSU/Swift-XRT Dirk Grupe (PSU), Craig Swenson, and Mike Siegel report on behalf of the Swift team: Swift-XRT has observed the error circle of the Fermi/LAT GRB 130828A (Vianello & Sonbas, GCN Circ 15128) in a series of observations tiled on the sky. In 2.5 ks of data, beginning 105 ks after the Fermi/LAT trigger, we detect an uncatalogued X-ray source at RA, Dec = 259.73234, 27.99570 which is equivalent to: RA (J2000.0) = 17h 18m 55.76s Dec (J2000.0) = +27d 59' 44.5" with an uncertainty of 4.1 arcsec (radius, 90% confidence). This source is within the LAT error circle given in GCN circular 15128). At the present time we cannot determine whether the source is fading, therefore we cannot be certain whether this is the afterglow of GRB 130828A or a serendipitous source. The source was detected in observations with target ID 00020292. The results of the automated XRT processing of this source are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00018/20292/index_1.php The Swift UVOT observed this field for 2.5 ks in the u filter. There are two sources at the edge of the XRT error circle, one is a Seyfert 1.9 galaxy, SDSS J171855.44+275947.4, which may be the counter part of the X-ray source. However, the origin of the X-ray source is unclear at this point. This circular is an official product of the Swift team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15138 SUBJECT: IPN triangulation of GRB 130828A - error box DATE: 13/08/30 19:49:09 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and J. Goldsten, on behalf of the MESSENGER NS GRB team, S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, D. Svinkin, and T. Cline, on behalf of the Konus-Wind team, I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, K. Yamaoka, M. Ohno, Y. Hanabata, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada, T. Murakami, and K. Makishima on behalf of the Suzaku WAM team, S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team, and V. Connaughton, M. S. Briggs, C. Meegan, and V. Pelassa, on behalf of the Fermi GBM team, report: GRB 130828A (GCN 15128, 15129, 15130, 15132, 15133) was also observed by Mars Odyssey-HEND. We have triangulated this burst to the following 3 sigma error box, whose area is 28 square arcminutes: RA(2000) Dec(2000) 259.728=17 h 18 m 54 s 28.196= 28 o 11 ' 46 " 259.867=17 h 19 m 28 s 28.316= 28 o 18 ' 58 " 259.707=17 h 18 m 49 s 28.115= 28 o 06 ' 54 " 259.846=17 h 19 m 23 s 28.235= 28 o 14 ' 06 " The Swift XRT source (GCN 15135) lies outside this error box. A map has been posted at ssl.berkeley.edu/ipn3/130828A. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15206 SUBJECT: GRB 130828A: Further Swift XRT observations DATE: 13/09/09 21:13:13 GMT FROM: Dirk Grupe at PSU/Swift-XRT Dirk Grupe (PSU) reports on behalf of the Swift team: We report on two follow-up observations of the field of GRB 130828A which was discovered by the FERMI LAT as reported by Vianello & Sonbas (GCN circ 15128). The first Swift observation was performed on 2013-09-04 (obsID 20293) for 2.6ks and was centered on the X-ray source reported in Grupe et al. (GCN circ. 15135). This X-ray source is still present in the new observation suggesting that these X-rays are emitted from the Seyfert 1.9 galaxy SDSS J171855.44+275947.4 as suggested by Grupe et al. Support for this assumption comes from new IPN measurements by Hurley et al. (GCN circ. 15138) who published a new IPN error box. The X-ray source associated with SDSS J171855.44+275947.4 is significantly outside this error box. We re-examined the Swift observation of the field which contains the IPN error box (obsID 20289) and found enhanced X-ray emission within the IPN error box reported by Hurley et al. Applying the Bayesian statistics as described by Kraft et al. (1991, ApJ, 374, 344) suggesting a source detection at the 3sigma level of (2.4+4.2-2.1)e-3 counts/s. The position of this marginally detected source is: RA(hh mm ss.s) = 17h19m09.24s Dec(dd mm ss.s) = +28:13:14.05 with an uncertainty of 8". We re-observed the position of this source with Swift on 2013-09-07 for a total of 5157s (obsID 20295). No source was detected in this observation. The 3sigma upper limit at the position of the previously detected X-ray source within the IPN error box is 1.3e-3 counts/s. This may suggest that the X-ray source found within the IPN error box during observation 20289 is the X-ray afterglow of GRB 130828A. Note, however, that considering the 3sigma errors given above, this upper limit is non-conclusive. No further Swift observations are planned of this GRB. This circular is an official product of the Swift team.