//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9491 SUBJECT: GRB 090607: Swift detection of a burst DATE: 09/06/07 06:11:45 GMT FROM: Scott Barthelmy at NASA/GSFC F. E. Marshall (NASA/GSFC), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), M. M. Chester (PSU), C. Guidorzi (U Ferrara), H. A. Krimm (CRESST/GSFC/USRA), K. L. Page (U Leicester), D. M. Palmer (LANL), T. N. Ukwatta (GSFC/GWU) and H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team: At 05:30:17 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090607 (trigger=354299). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 191.209, +44.130 which is RA(J2000) = 12h 44m 50s Dec(J2000) = +44d 07' 47" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows several spikes with a duration of about 5 sec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 05:31:27 UT, 70 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 191.16903, 44.10541 which is equivalent to: RA(J2000) = 12h 44m 40.57s Dec(J2000) = +44d 06' 19.5" with an uncertainty of 3.9 arcseconds (radius, 90% containment). This location is 136 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 (1.84e+20 cm^-2, Kalberla et al. 2005), with an excess column of 4.1 (+2.44/-2.19) x 10^21 cm^-2 (90% confidence). Because of the presence of a magnitude 6.3 star in the UVOT Field of View, 2.3 arcmin from the XRT location, UVOT will not be able to observe this burst. There was some extra delay in processing this burst. It was originally a subthreshold trigger (Image_signif=6.49 sigma). The automated processing for the XRT position had a problem. This circular is based on manual processing. Burst Advocate for this burst is F. E. Marshall (marshall 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: 9492 SUBJECT: GRB 090607: Faulkes Telescope North observations DATE: 09/06/07 08:18:10 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), A. Melandri (Liverpool JMU), P. O'Brien, N. Tanvir (U. Leicester) on behalf of a large collaboration report: On 2009 June 07 at 06:01:12 UT we observed the Swift-BAT GRB 090607 (Marshall et al., GCN Circ. 9491) with the 2-m Faulkes Telescope North. Observations started 31 minutes after the BAT trigger time and were performed using the B, V, R and i' filters. We could not find any uncatalogued object inside the XRT error circle down to the following limiting magnitudes: Time Interval Total Exp Filter Limit (min from GRB) (s) (mag) ------------------------------------------- 31 - 82 720 R > 21.8 35 - 75 520 i' > 21.6 ------------------------------------------- Magnitudes in the R and i' filters have been calibrated against nearby field stars using USNOB1-R2 and SDSS-i catalogue values, respectively. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9493 SUBJECT: GRB 090607: GRAS001 optical observations DATE: 09/06/07 09:00:11 GMT FROM: Veli-Pekka Hentunen at Taurus Hill Obs,A95 Markku Nissinen (Taurus Hill Observatory) and Veli-Pekka Hentunen (Taurus Hill Observatory) report: We used Global-rent-a-scope GRAS001 Tak Mewlon 0.30m telescope with FLI IMG1024 Dream Machine at RAS Observatory Mayhill H06 (New Mexico, USA) for follow-up observations of GRB090607 (F. E. Marshall et al., GCN 9491). The observations were started on June 7, at 06:11 UTC (1.0 hours after the burst) and stopped on June 7, at 07:12 UTC. Three unfiltered 120s and two unfiltered 600s images were taken. We did not find any new object in the XRT error circle. Upper limit for the observations is >18.5 mag (3UL). Quoted upper limit has been derived using POSSII J and USNO-B1.0 field stars as reference. Filter Tmid(s) Exp(s) Mag (CR) USNO-B1.0 unfiltered 07:01:32 2x600 >18.5 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9494 SUBJECT: GRB 090607: Swift-BAT refined analysis of the SHB DATE: 09/06/07 11:32:02 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), F. E. Marshall (NASA/GSFC) D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090607 (trigger #354299) (Marshall, et al., GCN Circ. 9491). The BAT ground-calculated position is RA, Dec = 191.194, 44.108 deg, which is RA(J2000) = 12h 44m 46.7s Dec(J2000) = +44d 06' 28.4" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%. The mask-weighted light curve shows two narrow peaks. The first starts at T-0.1 sec, peaks at T+0.1 sec, and ends at T+0.7sec. The second peak starts at ~T+1.7 sec, peaks at T+2.2 sec, and ends at T+2.5 sec. There is no hint of emission out to at least T+243 sec. T90 (15-350 keV) is 2.3 +- 0.1 sec (estimated error including systematics). The time-averaged spectrum from T+0.1 to T+2.5 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.25 +- 0.30. The fluence in the 15-150 keV band is 1.1 +- 0.2 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.01 sec in the 15-150 keV band is 0.7 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. Based on the shortness of the duration and the spectral hardness, we believe this to be a short hard burst. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/354299/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9495 SUBJECT: GRB 090607: Swift/UVOT Upper Limits DATE: 09/06/07 16:42:02 GMT FROM: Peter Curran at MSSL P.A. Curran (UCL-MSSL) and F. Marshall (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 090607 75 s after the BAT trigger (Marshall et al., GCN Circ. 9491). No optical afterglow consistent with the XRT position (Marshall et al., GCN Circ. 9491) 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 uvw1 12715 13943 1209 >20.8 u 75 1233 1140 >21.2 v 11448 12707 1239 >20.4 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9496 SUBJECT: GRB 090607: XRT Team Refined Analysis DATE: 09/06/07 18:39:42 GMT FROM: Kim Page at U.of Leicester K.L. Page, A.P. Beardmore, P.A. Evans (U. Leicester) & F.E. Marshall (NASA/GSFC) report on behalf of the Swift-XRT team: We have analysed the four orbits of XRT data obtained for GRB 090607 (Marshall et al., GCN Circ. 9491), comprising 108 s of Windowed Timing (WT) mode and 9.5 ks of Photon Counting (PC) mode. The refined XRT position is RA, Dec = 191.16914, 44.10503, which is equivalent to RA (J2000) = 12 44 40.59 Dec(J2000) = +44 06 18.10 with an uncertainty of 3.7 arcsec (radius, 90% containment). The X-ray light-curve initially brightens slightly, with a power-law of alpha = -0.8 +/- 0.5 until 150 +10/-8 s, at which point the afterglow starts to decay with alpha = 5.6 +0.5/-0.3. Between ~200 and 400 s after the trigger there is a deviation from the decay in the form of a flare. The afterglow is no longer detected after the end of the first orbit of data (~2365 s after the trigger). The WT data show a softening trend with time. A spectrum formed from the PC mode data from the first orbit can be fitted with a power-law of photon index Gamma = 1.88 +/- 0.21, absorbed by the Galactic column of 1.8x10^20 cm^-2. The observed (unabsorbed) 0.3-10 keV flux over this time is 5.5x10^-12 (5.8x10^-12) erg cm^-2 s^-1, which corresponds to a counts to observed (unabsorbed) flux conversion factor of 3.9x10^-11 (4.1x10^-11) erg cm^-2 count^-1. Because of the lack of detection after the first orbit of data, we cannot sensibly predict the future count rate. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00354299. This circular is an official product of the Swift-XRT team.