//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6692 SUBJECT: GRB 070802: Swift detection of a burst DATE: 07/08/02 07:46:54 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), S. Immler (GSFC/UMCP), V. Mangano (INAF-IASFPA), C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester), J. P. Osborne (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (Univ. Bicocca & INAF-OAB), G. Sato (GSFC/ISAS), B. Sbarufatti (INAF-IASFPA), M. Stamatikos (NASA/ORAU), G. Tagliaferri (INAF-OAB), D. E. Vanden Berk (PSU) and S. D. Vergani (DIAS-DCU) report on behalf of the Swift Team: At 07:07:25 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070802 (trigger=286809). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 36.851, -55.536 which is RA(J2000) = 02h 27m 24s Dec(J2000) = -55d 32' 10" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a peak with a duration of roughly 30 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~6 sec after the trigger. The XRT began taking data at 07:09:43 UT, 138 seconds after the BAT trigger. The XRT on-board centroid algorithm did not find a source in the image, however using 510s of promptly available data we find an uncatalogued source at Ra, Dec=36.8987, -55.52781 degrees, which is equivalent to: RA(J2000) = 02h 27m 35.69s Dec(J2000) = -55d 31' 40.1" with an estimated uncertainty of 4.4 arcsec (radius, 90% containment). This source is 101.6 arcsec from the BAT position, within the BAT error circle. UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 141 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of the BAT error circle. The typical 3-sigma upper limit has been about 18.5 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the BAT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for extinction of E(B-V) = 0.026. S. Immler is the burst advocate for this burst. Please contact him for any questions concerning this burst: immler AT milkyway.gsfc.nasa.gov . [GCN OPS NOTE(02aug06): Per author's request, the floating point form of the XRT Dec location was changed from "-55.2781" to "-55.52781". We thank Aybuke Kupcu-Yoldas for pointing out our error. And see GCN 6697 for an refined XRT position.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6693 SUBJECT: GRB 070802: LCO optical observations DATE: 07/08/02 07:57:09 GMT FROM: Edo Berger at Carnegie Obs E. Berger and D. Murphy (Carnegie) report: "We obtained a 180 sec R-band image of the position of GRB 070802 (GCN 6692) starting at 2007 August 2, 07:35:13 UT. We do not find any objects within the XRT error circle to a limit of R~21 mag. Further observations are in progress." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6694 SUBJECT: GRB 070802: GROND J band candidate DATE: 07/08/02 08:16:50 GMT FROM: Christian Clemens at MPE J. Greiner, C. Clemens, T. Kruehler, A. Kuepcue-Yoldas, N. Primak, G. Szokoly, A. Yoldas (all MPE Garching) and S. Klose (Tautenburg Obs.) report: The 7-channel imager GROND at the 2.2 m telescope of the La Silla Observatory (ESO/Chile) is observing the field of GRB 070802 (Swift trigger 286809, Barthelmy et al. 2007, GCN #6692). The observation started on August 2 at 07:17 UT, about 10 min after the GRB trigger. Observations are still ongoing. The observation consists of a series of exposures in g', r', i, z', Js, H and Ks. The automated data reduction pipeline finds an elongated source in the XRT error circle. This source has a magnitude of about Js = 20. This is the result of our first four minutes exposure. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6695 SUBJECT: GRB 070802: LCO I-band candidate DATE: 07/08/02 08:52:13 GMT FROM: Edo Berger at Carnegie Obs E. Berger and D. Murphy (Carnegie) report: "We also obtained a 360 sec I-band image of the position of GRB 070802 (GCN 6692) starting on 2007 August 2, 08:02:19 UT. Within the XRT error circle we detect a faint source with I~21.5 mag located at: RA = 02:27:35.88 DEC = -55:31:39.3 with an uncertainty of about 0.5" in each coordinate. If this is the afterglow of GRB 070802 the earlier non-detection in R-band may indicate a redshift z~4.5-6, or a highly reddened GRB at a lower redshift." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6696 SUBJECT: GRB 070802: V-band detection of the candidate afterglow DATE: 07/08/02 09:15:41 GMT FROM: Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center D. Malesani, J.P.U. Fynbo, P.M. Vreeswijk (DARK) report on behalf of a larger collaboration: We observed the field of GRB 070802 (Barthelmy et al., GCN 6692) with the ESO VLT equipped with FORS2. Inside the XRT error circle, we detect the object reported by Berger & Murphy (GCN 6695) and possibly Greiner et al. (GCN 6694), at the coordinates RA = 02:27:35.72 Dec = -55:31:39.01 The object is detected in the V, R, and I bands. No clear fading behaviour is detected between exposures taken at 8:01 UT and 8:13 UT. We acknowledge excellent support from the ESO staff, in particular Alain Smette. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6697 SUBJECT: GRB 070802: refined Swift XRT position DATE: 07/08/02 09:54:19 GMT FROM: Vanessa Mangano at INAF-IASFPA P.A. Evans (U. Leicester) and V. Mangano (INAF-IASFPA) report on behalf of the Swift/XRT team: We have reanalysed the promptly downlinked XRT data of GRB 070802 (Barthelmy et al. GCN Circ 6692) using PSF fitting and exposure maps to improve the XRT position. We find an improved position of RA, Dec=36.89776, -55.52851 whic is equivalent to: RA (J2000) = 02 27 35.46 Dec (J2000) = -55 31 42.7 With an uncertainty of 4.7" (radius, 90% containment). This position is 3.3" from the original XRT position sent out in GCN Circ. 6692. This circular is an official product of the Swift team. [GCN OPS NOTE(02aug07): Per author's request. the Subject line was changed from "070702" to "070802".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6698 SUBJECT: GRB 070802: VLT redshift DATE: 07/08/02 10:22:41 GMT FROM: Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center J.X. Prochaska (UCO/Lick), C.C. Thoene, D. Malesani, J.P.U. Fynbo, P.M. Vreeswijk (DARK), report: We observed the candidate afterglow of GRB 070802 (Barthelmy et al., GCN 6692; Berger et al., GCN 6695) with the ESO VLT + FORS2. A 30-min spectrum was acquired starting on Aug 2.378 UT. From the detection of several Fe lines, we measure z=2.45. We acknoweldge excellent support from the VLT staff, in particular Alain Smette. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6699 SUBJECT: GRB 070802, Swift-BAT refined analysis DATE: 07/08/02 15:04:30 GMT FROM: Scott Barthelmy at NASA/GSFC J. Cummings (GSFC/UMBC), L. Barbier (GSFC), S. D. Barthelmy (GSFC), E. Fenimore (LANL), N. Gehrels (GSFC), S. Immler (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), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+776 sec from recent telemetry downlinks, we report further analysis of BAT GRB 070802 (trigger #286809) (Barthelmy, et al., GCN Circ. 6692). The BAT ground-calculated position is RA, Dec = 36.903, -55.517 deg, which is RA(J2000) = 2h 27m 36.7s Dec(J2000) = -55d 31' 01" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 73%. The mask-weighted light curve for this 64-sec image trigger shows a single peak starting at T+5 sec and ending at ~T+50 sec. We note that there is a 3-sigma blip at T-150 lasting about 20 sec. T90 (15-350 keV) is 16.4 +- 1.0 sec (estimated error including systematics). The time-averaged spectrum from T+4.9 to T+23.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.79 +- 0.27. The fluence in the 15-150 keV band is 2.8 +- 0.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+6.15 sec in the 15-150 keV band is 0.4 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6700 SUBJECT: GRB 070802: Confirmation of the optical afterglow DATE: 07/08/02 17:55:59 GMT FROM: Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center D. Malesani, J.P.U. Fynbo, J. Hjorth, and P.M. Vreeswijk (DARK) report on behalf of a larger collaboration: We report further analysis of our images (Malesani et al., GCN 6696) of GRB 070802 (Barthelmy et al., GCN 6692). Observations span the range 08:01 - 10:09 UT, that is 0.9 - 3.0 hr after the GRB. The object reported by Greiner et al. (GCN 6694) and Berger & Murphy (GCN 6695) is well detected in all our images, and is clearly fading following a power-law decay with index alpha = 0.6+-0.1. Based on instrumental zeropoints, the afterglow looks significantly reddened, with a color R-I = 0.55+-0.1. We acknowledge excellent support from the VLT staff. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6701 SUBJECT: GRB070802: Swift/UVOT upper limits DATE: 07/08/02 19:10:36 GMT FROM: Patricia Schady at MSSL/Swift N.P.M. Kuin (MSSL) and S. Immler (GSFC)                report on behalf of the Swift-UVOT team: The Swift/UVOT observed the field of GRB070802 (trigger=286809) starting 2007-08-02 at 07:09:30, 125 s after the BAT trigger (Barthelmy et al. 2007, GCN Circ.6692). We do not find a new source in the UVOT observations at the location of the refined XRT position (Evans and Mangano, 2007, GCN Circ. 6697). The 3-sigma upper limits (in the UVOT photometric system, Breeveld et al., GCN Circ. 6614) for detecting a source inside the XRT error circle in the co-added frames (including the settling exposure and finding charts) are listed below: Filter Tstart Tstop Exposure Magnitude (s) (s) (s) (3-sigma UL) white 142 16875 589.9 >21.25 v 125 12514 773.2 >19.96 uvm2 654 4821 239.4 >19.84 uvw1 679 4969 182.3 >19.77 u 703 6307 219.6 >19.52 b 728 16681 1109.0 >21.27 uvw2 758 10893 1127.5 >21.16 The values quoted above are not corrected for the expected Galactic extinction corresponding to a reddening of E_{B-V} = 0.026 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6702 SUBJECT: GRB 070802: Swift-XRT refined analysis DATE: 07/08/02 19:48:18 GMT FROM: Vanessa Mangano at INAF-IASFPA V. Mangano, B. Sbarufatti, V. La Parola, E. Troja (INAF-IASF PA), P. Evans (U. Leicester) and S. Immler (GSFC) report on behalf of the Swift-XRT team: We have analysed the first three orbits of Swift-XRT data obtained for GRB 070802 (Barthelmy et al, GCN Circ. 6692), which include 3.4 ks of Photon Counting (PC) data. Using 599 s of overlapping XRT Photon Counting mode and UVOT V-band data, 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 = 36.89899, -55.52733 which is equivalent to: RA (J2000): 02 27 35.76 Dec (J2000): -55 31 38.4 with an uncertainty of 2.1 arcsec (radius, 90% confidence). This is 4.9 arcsec from the initial XRT position (Evans and Mangano, GCN Circ. 6697) and 38 arcsec from the BAT ground-calculated position (Cummings et al, GCN Circ. 6699). It is also 0.7 arcsec from the optical position of Malesani et al. (GCN Circ. 6696) and 1.4 arcsec from the I band position of Berger and Murphy (GCN Circ. 6695). The XRT light-curve decays with slope -2.0+/-0.2 up to about T+500 s, then flattens to slope -0.25+/-0.08. We do not see a further break up to T+17 ks. The spectrum can be fit with an absorbed power law with a photon index of 1.9+/-0.3 and a column density consistent with the Galactic value (2.9e20 cm^-2). The absorbed (unabsorbed) 0.3-10.0keV flux for the spectrum is (3.9+/-0.8)e-12 ((4.6+/-0.8)e-12) ergs cm^-2 s^-1. If the decay continues with a slope of ~ 0.2, the count rate at 24 hours is predicted to be 3e-2 count s^-1. Using the spectral fit described above, this corresponds to an observed flux of about 1.4e-12 ergs cm^-2 s^-1. This circular is an official product of the XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6704 SUBJECT: GRB 070802: REM optical observations DATE: 07/08/03 13:54:30 GMT FROM: Eliana Palazzi at IASF/CNR,Bologna E.Palazzi, S. Covino, L.A. Antonelli, L. Calzoletti, S. Campana, G. Chincarini, M.L. Conciatore, S. Cutini, P. D'Avanzo, V. D'Elia, F. Dalessio, F. Fiore, D. Fugazza, P. Goldoni, D. Guetta, C. Guidorzi, G.L. Israel, D. Malesani, N. Masetti, A. Melandri, E. Meurs, L. Nicastro, E. Pian, S. Piranomonte, D. Rizzuto, L. Stella, G. Stratta, G. Tagliaferri, G. Tosti, V. Testa, S.D. Vergani, F. Vitali report on behalf of the REM team: "We observed the field of the GRB 070802 (S. D. Barthelmy et al., GCN 6692) with the robotic 60-cm REM telescope located at La Silla (Chile). A set of observations was performed automatically in the R optical filter starting at 07:17:44 UT (52 sec after the Swift alert; about 10 minutes after the burst) and lasted about 40 minutes. The analysis of the first 15 minutes exposures do not show the optical/NIR afterglow candidate reported by J. Greiner et al (GCN 6694), E. Berger et al (GCN. 6695), D. Malesani et al (GCN. 6696). The 3-sigma limiting magnitude in the stacked images is R~17.0"