//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6494 SUBJECT: GRB 070611: Swift detection of a burst DATE: 07/06/11 02:08:47 GMT FROM: Scott Barthelmy at NASA/GSFC M. C. Stroh (PSU), S. D. Barthelmy (GSFC), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), D. Grupe (PSU), S. T. Holland (CRESST/GSFC/USRA), J. A. Kennea (PSU), W. B. Landsman (NASA/GSFC), C. B. Markwardt (GSFC/UMD), F. E. Marshall (NASA/GSFC), C. Pagani (PSU), D. M. Palmer (LANL), A. M. Parsons (GSFC), M. Stamatikos (NASA/ORAU) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 01:57:13 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070611 (trigger=282003). The BAT on-board calculated location is RA, Dec 1.987, -29.755 which is RA(J2000) = 00h 07m 57s Dec(J2000) = -29d 45' 18" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak with a duration of about 10 sec. The peak count rate was ~800 counts/sec (15-350 keV), at ~2 sec after the trigger. Because of an Earth limb constraint, the spacecraft did not slew promptly to the BAT position, and so there are no immediate XRT or UVOT data products to analyze. XRT and UVOT will begin observing this target at 02:50 UT. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6495 SUBJECT: GRB 070611: ROTSE-III Optical Limits DATE: 07/06/11 02:31:23 GMT FROM: Brad Schaefer at LSU Bradley E. Schaefer (Louisiana State), S.A. Yost (U Mich), E.S. Rykoff (U Mich), and F. Yuan (U Mich) report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 070611 (Swift trigger 282003; M. C. Stroh et al. 2007, GCN 6494), producing images beginning 7.6 s after the GCN notice time. An automated response took the first image at 01:57:58.6 UT, 44.7 s after the burst, under excellent conditions. We took 10 5-sec, 10 20-sec and 20 60-sec exposures, with further exposures now ongoing. These unfiltered images are calibrated relative to USNO A2.0 (R). Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma Swift/BAT error circle; the field is not crowded. Individual images have limiting magnitudes ranging from 15.7-17.2; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 01:57:58.6 01:58:03.6 5 15.8 44.7 N 01:57:58.6 01:59:16.6 78 17.0 44.7 Y 02:04:20.5 02:15:45.2 684 18.3 426.6 Y //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6496 SUBJECT: GRB 070611; Swift-XRT position DATE: 07/06/11 04:06:42 GMT FROM: Michael Stroh at PSU/Swift GRB 070611; Swift-XRT position M.C. Stroh, J. A. Kennea & C. Pagani (PSU) report on behalf of the Swift-XRT team: We have analyzed the first 1.8 ks of prompt downlinked data for GRB 070611 (trigger=282003, GCN Circ. 6494). Because of an Earth limb constraint, the spacecraft did not slew promptly to the BAT position and the XRT observations started 3.3 ks since the BAT Trigger. In the BAT error circle we find an uncatalogued source at position RA, Dec 1.9912, -29.7568 which is RA(J2000) = 00 07 57.9 Dec(J2000) = -29 45 24.3 with an uncertainty of 5.1 arcsec (radius, 90% containment). The XRT position is 15arcsec from the BAT on board position (GCN Circ. 6494), within the BAT error circle. We are waiting for additional downlinked data to assess the fading behavior of the proposed X-ray afterglow. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6497 SUBJECT: GRB 070611: ROTSE-III Detection of Late Rising Optical Counterpart DATE: 07/06/11 04:26:49 GMT FROM: Eli Rykoff at U of Michigan/ROTSE Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit E. S. Rykoff, F. Yuan, S. A. Yost (U. Mich), report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 070611 (Swift trigger 282003; Stroh et al., GCN 6494), producing images beginning 7.6 s after the GCN notice time, as reported in GCN 6495 (Schaefer, et al.). These unfiltered images are calibrated relative to USNO-B1.0 (R). Further analysis reveals a faint, late-rising counterpart at a position consistent with the XRT position reported in GCN 6496 (Stroh, et al.). At a midpoint of 2157 s after the burst (in a 600 s stacked image), the counterpart was at a peak magnitude of 18.4+/-0.1 at a position: 00:07:58.0 -29:45:19.4 (J2000) [uncertainty < 1"] The counterpart then faded below 19th magnitude by 6000 s post-burst. A jpeg image is available at http://www.rotse.net/images/gsb282003_3c041-050_key.jpg Note that the object marked 156 is the candidate in question. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6499 SUBJECT: GRB 070611: VLT redshift DATE: 07/06/11 13:34:01 GMT FROM: Christina Thoene at Niels Bohr Institute,DARK Cosmo Ctr Christina C. Thoene (DARK), Pall Jakobsson (Univ. of Hertfordshire), Johan P. U. Fynbo, Daniele Malesani, Jens Hjorth (DARK) and Paul M. Vreeswijk (ESO) report: We observed the OT (Rykoff et al., GCN 6497) of GRB 070611 (Stroh et al., GCN 6494) with FORS2/VLT using grism 300V through thin clouds. 2x30 min spectra were acquired starting on June 11, UT 09:37. In the spectra, we detect Lyman alpha, SiII, OI, CII, CIV and AlII from which we infer a redshift of z=2.04 for that burst. In addition, we detect Mg II and Fe II from an intervening system at z=1.29. We thank the Paranal staff for excellent support, in particular Arjan Bik and Mario van den Ancker. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6502 SUBJECT: GRB 070611, Swift-BAT refined analysis DATE: 07/06/11 16:20:31 GMT FROM: Ann M. Parsons at NASA/GSFC/Swift L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), M.C. Stroh (PSU), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 070611 (trigger #282003) (Stroh et al., GCN Circ. 6494). The BAT ground-calculated position is RA, Dec = 2.003, -29.758 deg which is RA(J2000) = 0h 8m 0.8s Dec(J2000) = -29d 45' 28" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 50%. The BAT light curve shows a single, symmetric peak. T90 (15-350 keV) is 12.0 +- 1 sec (estimated error including systematics). There is a possible second episode of emission ( at ~4.5 sigma) starting at T+70 and lasting for ~15 sec. The time-averaged spectrum from T-6.3 to T+7.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.66 +- 0.22. The fluence in the 15-150 keV band is 3.9 +- 0.6 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+2.76 sec in the 15-150 keV band is 0.8 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6503 SUBJECT: GRB 070611: Swift-XRT refined analysis DATE: 07/06/11 18:10:42 GMT FROM: Michael Stroh at PSU/Swift M.C. Stroh, C. Pagani & J. Racusin report on behalf of the Swift XRT team: We have analysed the first four orbits of XRT data of GRB 070611 (Stroh et al., GCN Circ. 6494) with total exposure time of 8.9 ks in Photon Counting mode. The calculated XRT position is RA(J2000) = 1.9927, Dec (J2000) = -29.7557, corresponding to: RA(J2000) = 00h 07m 58.3s Dec(J2000) = -29d 45' 20.4" with an uncertainty of 4.0 arcsec (radius, 90% containment). This is 6.1 arcsec from the initial XRT position, and 3.4 arcsec from the ROTSE-III optical candidate reported by Rykoff, et al. (GCN Circ. 6497). The XRT light curve follows a power-law decay with index 0.83 +/- 0.27 continuing through T+30 ks. The PC spectrum can be fit with an absorbed power law with photon index of 1.9 +/- 0.5 and column density of (5 +/- 5) E20 cm-2, consistent with the Galactic absorption column density (1.34E20 cm-2; Dickey & Lockman, 1990). The absorbed (unabsorbed) 0.3-10.0 keV average flux in the T+3 ks - T+30 ks time interval is 6.056E-13 (6.825E-13) ergs cm-2 s-1. Assuming that the source continues its decay at the present rate, we predict an XRT count rate of 4.9E-3 counts/s at T+24 h, which corresponds to an absorbed (unabsorbed) flux of 2.144E-14 (2.417E-14) ergs cm-2 s-1. This circular is an official product of the Swift XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6504 SUBJECT: GRB 070611: Swift/UVOT Observations DATE: 07/06/11 20:39:22 GMT FROM: Wayne Landsman at GSFC/SSAI W. Landsman (NASA/GSFC), F.E. Marshall (NASA/GSFC) and M.C. Stroh (PSU) report on behalf of the Swift/UVOT team. UVOT took a finding chart exposure of 98 seconds of the field of GRB 070611 (Stroh et al., GCN 6494) with the White (160-650 nm) filter starting 3295 seconds after the BAT trigger. The UVOT finding chart was delayed due to an Earth limb constraint. We detect the afterglow candidate reported by Rykoff et al. (GCN 6497), and measure a position of RA(J2000) = 00 07 58.01 Dec(J2000) = -29 45 20.0 with an estimated 90% uncertainty of 0.5". Because of a configuration problem, most subsequent UVOT images do not include the afterglow position, but there is a 3.5 sigma detection in a subsequent image taken with the UVW1 (2600 A) filter. Magnitudes and 3 sigma upper limits are reported below. Filter T_start(sec) Exposure(sec) Mag White 3295 98 19.12 ± 0.11 UVW1 4632 197 19.51 ± 0.31 UVW1 10046 886 >20.72 (3 sigma) UVM2 4427 197 >19.64 (3 sigma) UVW2 4019 197 >19.97 (3 sigma) The lack of detections in the UVM2 (2260 A) and UVW2 (1930 A) filters are consistent with the redshift of z=2.04 reported by Thoene et al. (GCN 6499). No correction has been made for the expected reddening of E(B-V) = 0.012 [GCN OPS NOTE(11jun07): Per author's request, the Subject-line was corrected; "070610" was changed to "070611".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6528 SUBJECT: GRB 070611: Watcher Observations DATE: 07/06/13 17:57:50 GMT FROM: Gary Melady at UCD Gary Melady, John French, (University College Dublin), Petr Kubanek, Martin Jelinek (IAA CSIC Granada, Spain) on behalf of the Watcher collaboration report: The Watcher 40cm robotic telescope, located at Boyden Observatory, South Africa, began imaging the field of GRB 070611 (Stroh et al., GCN 6494) at 01:58:33 UT, 1m 17s after the Swift trigger (40s after receipt of the GCN notice). We combined our initial series of 10s exposures to create a 440s unfiltered image with an exposure mid-time of 2:05:21 (501s after the burst). This shows no new source in the XRT error box (Stroh et al., GCN 6496) down to an R-band limiting magnitude of approx. 19.2 (in comparison to USNO-B1). Later images show a faint, uncatalogued source within the XRT error box coincident with the ROTSE detection (Rykoff et al., GCN 6497). These observations are summarised below: mean time UT t-t0(s) exp(s) Rmag -------------------------------------------------------- 02:18:56 1316 900 19.08 +/- 0.24 02:32:48 2148 210 18.53 +/- 0.24 02:37:11 2411 180 19.12 +/- 0.30 02:42:46 2746 240 18.99 +/- 0.26 02:48:54 3144 330 19.19 +/- 0.24 The source is not detected in subsequent observations down to an R-band limiting magnitude of approx 19.2. The field was no longer observed after 02:54 due to the system's incorrect handling of the retracted XRT position. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6601 SUBJECT: GRB 070611: VLT observations DATE: 07/07/06 09:59:43 GMT FROM: Pall Jakobsson at U Hertfordshire Pall Jakobsson (U. Hertfordshire), Daniele Malesani, Dong Xu, Johan P.U. Fynbo, Jens Hjorth and Christina C. Thoene (DARK, NBI) report: Using FORS1 on the Very Large Telescope during non-photometric conditions, we obtained a total of 4200 s R-band imaging of the GRB 070611 field (Stroh et al., GCN 6494) on June 15.375 (4.26 days after the burst). On the edge of the refined XRT circle (Butler 2007, AJ, 133, 1027; DSS catalog; version 3.6), we clearly detect a source that is consistent with the UVOT position (Landsman et al., GCN 6504). Compared to the acquisition image obtained on June 11.040 (7.58 hr post-burst; Thoene et al., GCN 6499), the source has faded by dm = 5.3 +/- 0.3 mag. If the optical afterglow displays a similar fading behaviour as the X-ray afterglow with a possible jet-break around 1 day (Stroh et al., GCN Report 63.3), we would expect dm = 3.5 +/- 1.4 mag. Thus, the VLT observations are marginally consistent with a break occurring in the optical band as well. We note that the source is somewhat extended at the latter epoch, implying that the host might contribute to the flux and hence the observed dm could be larger. An image of the field (on June 15.375) is shown at: http://star-www.herts.ac.uk/~palli/grb070611/grb070611.jpg