//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9746 SUBJECT: GRB 090807: Swift detection of a burst DATE: 09/08/07 15:18:32 GMT FROM: Scott Barthelmy at NASA/GSFC J. K. Cannizzo (NASA/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), P.A. Curran (MSSL-UCL), A. de Ugarte Postigo (INAF-OAB), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), C. Guidorzi (U Ferrara), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (MSSL), J. Mao (INAF-OAB), R. Margutti (Univ Bicocca&OAB), K. L. Page (U Leicester), T. Sakamoto (NASA/UMBC), M. H. Siegel (PSU), M. Stamatikos (NASA/ORAU), T. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the Swift Team: At 15:00:27 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090807 (trigger=359378). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 273.744, +10.281 which is RA(J2000) = 18h 14m 59s Dec(J2000) = +10d 16' 51" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT TDRSS light curve does not show anything as is typical for image triggers. The XRT began observing the field at 15:03:00.5 UT, 153.5 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 273.7438, 10.2665 which is equivalent to: RA(J2000) = 18h 14m 58.51s Dec(J2000) = +10d 15' 59.3" with an uncertainty of 2.4 arcseconds (radius, 90% containment). This location is 52 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (8.6e+20 cm^-2, Kalberla et al. 2005), with an excess column of 2 (+1.68/-1.50) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 8.55e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of nominal 150 seconds with the White filter starting 163 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The 3-sigma upper limit is about 19.2 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.18. Burst Advocate for this burst is J. K. Cannizzo (cannizzo AT milkyway.gsfc.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: 9747 SUBJECT: GRB 090807, RIMOTS optical upper limits DATE: 09/08/07 16:43:17 GMT FROM: Kenta Kono at Miyazaki U K.Kono, K.Noda, E.Sonoda, N.Ohmori, H.hayasi, A.Daikyuji, Y.Nisioka, M.Yamauchi (University of Miyazaki) We have observed the field covering the error circle of GRB 090807 (Swift trigger 359378, GCN 9746, J. K. Cannizzo et al.) with the unfiltered CCD camera on the 30-cm telescope at University of Miyazaki. The observation was started 15:04:25 UT, about 2.2 min 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. (GCN 9746, J. K. Cannizzo et al.) the upper limits are as follows: -------------------------------------------------------------- Start(UT) End(UT) 　　Num. of frames 　Limit (mag.) -------------------------------------------------------------- 15:04:25 15:04:55 1 12.6 15:04:25 15:30:26 19 18.5 --------------------------------------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9748 SUBJECT: GRB 090807: Enhanced Swift-XRT position DATE: 09/08/07 19:10:10 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 1531 s of XRT Photon Counting mode data and 2 UVOT images for GRB 090807, 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 = 273.74377, +10.26583 which is equivalent to: RA (J2000): 18h 14m 58.50s Dec (J2000): +10d 15' 57.0" with an uncertainty of 1.8 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, arXiv:0812.3662). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9749 SUBJECT: GRB 090807, Swift-BAT refined analysis DATE: 09/08/07 20:06:11 GMT FROM: Hans Krimm at NASA-GSFC T. N. Ukwatta (GWU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. K. Cannizzo (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), (i.e. the Swift-BAT team): Using the data set from T-239 to T+423 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090807 (trigger #359378) (Cannizzo, et al., GCN Circ. 9746). The BAT ground-calculated position is RA, Dec = 273.741, 10.279 deg which is RA(J2000) = 18h 14m 57.8s Dec(J2000) = +10d 16' 45.9" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 64%. The mask-weighted light curve shows a complex structure lasting from T-5 to T+150 seconds with at least five peaks superimposed on a broad, soft and slowly varying background. There is an additional peak at T+185 sec which corresponds to a large flare seen in the Swift/XRT. There is also possible precursor activity from T-200 to T-80 sec. T90 (15-350 keV) is 140.8 +- 13.1 sec (estimated error including systematics). The time-averaged spectrum from T-9.5 to T+151.5 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.25 +- 0.14. The fluence in the 15-150 keV band is 2.2 +- 0.2 x 10-6 erg/cm2. The 1-sec peak photon flux measured from T+41.96 sec in the 15-150 keV band is 0.7 +- 0.2 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/359378/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9750 SUBJECT: GRB 090807: Swift-XRT refined analysis DATE: 09/08/07 22:37:04 GMT FROM: Raffaella Margutti at U. di Milano Bicocca R. Margutti (Univ. Bicocca & INAF-OAB), J. Mao (INAF-OAB), A. de Ugarte Postigo (INAF-OAB) and J. K. Cannizzo (NASA/UMBC) report on behalf of the Swift-XRT team: We have analysed the first orbit of Swift-XRT data obtained for GRB 090807 (Cannizzo et al. GCN Circ. 9746), covering 149 s of Windowed Timing (WT) and 1.5 ks of Photon Counting (PC) mode data, respectively, between 154 s and 1.9 ks after the trigger. The UVOT-enhanced XRT position was given by Beardmore et al. in GCN Circ. 9748. The light curve shows a large flare peaking around 185 s which was also detected in the 15-150 keV energy range by Swift/BAT (Ukwatta et al. GCN Circ. 9749). The underlying light curve decays with a power-law index of 5.0 +/- 0.5. Around T+580 s the decay flattens, to a slope of 0.87 +/- 0.42. The spectrum extracted from WT data can be modelled with an absorbed simple power-law, with Gamma = 2.2 +/- 0.1 and NH = (3.0+/-0.2)x10^21 cm^-2 in excess of the Galactic column in this direction which is 8.6x10^20 cm^-2 (Kalberla et al. 2005). A spectrum extracted from PC data in the time interval T+310 s - T+1840 s has a best-fitting photon index of 2.6 +/- 0.4 and a best-fitting absorption column of NH = (3.3+/-0.1)x10^21 cm^-2 in excess of the Galactic value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.1 x 10^-11 (8.4 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 0.9, the count rate at T+24 hours will be 0.002 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.2 x 10^-14 (1.7 x 10^-13) erg cm^-2 s^-1. However, the light-curve is possible to break before this time, making this prediction unreliable. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00359378. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9751 SUBJECT: GRB 090807: Swift/UVOT Upper Limits DATE: 09/08/07 23:57:25 GMT FROM: Craig Swenson at PSU/Swift C. A. Swenson (PSU) and Cannizzo (NASA/UMBC)report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 090807 164 s after the BAT trigger (Cannizzo et al., GCN Circ. 9746). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ. 9748) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 164 313 147 >21.2 u_FC 322 571 246 >20.1 white 164 1026 295 >21.1 u 322 571 246 >20.1 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.18 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9752 SUBJECT: GRB 090807: MITSuME optical upper limit DATE: 09/08/08 07:58:00 GMT FROM: Michitoshi Yoshida at Okayama Astrophysical Obs M. Yoshida, D. Kuroda, K. Yanagisawa, Y. Shimizu, S. Nagayama, H. Toda (OAO, NAOJ) and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 090807 (Cannizzo et al. GCN 9746) with optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2009-08-07 15:03:35 UT (3m 8s after the burst). We did not find any point source in the error circle of the XRT position reported by Beardmore et al. (GCN 9748) in all the three bands. Three sigma upper limits of the OT are listed below. We used USNO B1 catalog for flux calibration. PDAY MID-UT T-EXP g' Rc Ic --------------------------------------------------- 0.00589 15:08:56 540.0 >18.3 >18.5 >18.2 0.04169 16:00:30 4860.0 >18.9 >19.1 >18.7 --------------------------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9753 SUBJECT: GRB 090807: Liverpool Telescope observations DATE: 09/08/08 11:31:45 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), A. Gomboc (U. Ljubljana), R.J. Smith, C.G. Mundell, I.A. Steele, A. Melandri, S. Kobayashi, C.J. Mottram, D.F. Bersier, Z. Cano (Liverpool JMU), N.R. Tanvir, P. O'Brien (U. Leicester) report on behalf of a large collaboration: On 2009 August 07 at 23:45:24 UT we observed the Swift GRB 090807 (Cannizzo et al., GCN Circ. 9746) with the 2-m Liverpool Telescope. Observations started 8.75 hours after the BAT trigger time and were performed using the r' and i' filters. We could not find any uncatalogued object inside the UVOT-enhanced XRT error circle (Beardmore et al. GCN Circ. 9748) down to the following limiting magnitudes: Time Interval Total Exp Filter Limit (hours from GRB) (s) (mag) ---------------------------------------------- 8.75-9.27 6x300 R > 22.1 9.29-9.90 6x300 I > 22.0 ---------------------------------------------- Magnitudes have been calibrated against the nearby USNOB-1 star RA=18:15:00.349, Dec=+10:15:45.21, using R2=16.19, I=15.82. We note the presence of an uncatalogued source lying outside the XRT error circle at 4.2" from the XRT centroid, at RA=18:14:58.24, Dec=+10:15:58.4 with estimated magnitudes R=22.4 +/- 0.2, I=21.6 +/- 0.2: http://www.fe.infn.it/u/guidorzi/090807_LT_ri.png At the moment we cannot assess whether this source is fading. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9767 SUBJECT: GRB 090807B: Fermi GBM detection DATE: 09/08/11 22:36:36 GMT FROM: Bill Paciesas at UAH W. Paciesas (UAHuntsville) reporta on behalf of the Fermi GBM Team: "At 19:57:59.02 UT on 7 August 2009, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 090807B (trigger 271367881 / 090807.832). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 326.9, Dec = +7.2 (J2000 degrees, equivalent to J2000 21h 48m, +7d 12'), with a statistical uncertainty of 2.6 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 45 degrees. The GBM light curve consists of a single structured pulse with a duration of about 3 s (8-1000 keV). The time-averaged spectrum from T0-0.640 to T0+1.408 s is best fit by a Band function with Epeak = 37 +/- 5 keV, alpha = -0.6 +/- 0.4, and beta = -2.4 +/- 0.1 (chi^2 387 for 357 d.o.f.). The fluence (8-1000 keV) in this time interval is (1.02 +/- 0.07)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.512 s in the 8-1000 keV band is 10.9 +/- 0.5 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: 9924 SUBJECT: GRB 090807: Skynet/DSO Observations DATE: 09/09/18 06:01:13 GMT FROM: Josh Haislip at U.North Carolina J. Haislip, D. Reichart, A. Smith, D. Caton, L. Hawkins, K. Ivarsen, M. Schubel, A. LaCluyze, A. Foster, J. Moore, A. Oza, M. Schubel, J. Styblova, A. Trotter, J. A. Crain, and M. Nysewander report: Skynet observed the Swift/BAT localization of GRB 090807 (Cannizzo et al., GCN 9746) with the 14" Dark Sky Observatory telescope in North Carolina beginning 10.4 hours after the trigger in I. We do not detect the afterglow (Cannizzo et al., GCN 9746). Stacking only images that increase the limiting magnitude yields: mean 1-sig. 1-sig. time 3-sig. sys. stat. since lim. cal. cal. cal. trig. tel. exp. fil. mag. stars unc. unc. (h) (# x s) (mag) (mag) 10.7 DSO-14 10 x 160 I 18.9 807 USNO B1 0.489 0.000