/////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7573 SUBJECT: GRB 080409: Swift detection of a burst DATE: 08/04/09 01:46:36 GMT FROM: David Palmer at LANL S. T. Holland (CRESST/USRA/GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), K. M. McLean (GSFC/UMD), K. L. Page (U Leicester), D. M. Palmer (LANL), R. L. C. Starling (U Leicester) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 01:22:57 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080409 (trigger=308812). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 84.333, +5.085 which is RA(J2000) = 05h 37m 20s Dec(J2000) = +05d 05' 07" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 10 sec. The peak count rate was ~5000 counts/sec (15-350 keV), at ~0.7 sec after the trigger. The XRT began observing the field at 01:24:21.6 UT, 84.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 84.33035, 5.08523 which is equivalent to: RA(J2000) = 05h 37m 19.28s Dec(J2000) = +05d 05' 06.8" with an uncertainty of 2.9 arcseconds (radius, 90% containment). This location is 9.5 arcseconds from the BAT onboard position, within the BAT error circle. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (2.34e+21 cm^-2, Kalberla et al. 2005), with an excess column of 4.5 (+4.33/-3.19) x 10^21 cm^-2 (90% confidence). The relation of Grupe et al. (2007) implies that this burst has a redshift z<4.3, although high redshift fits to the absorbed XRT spectrum are possible if paired with an anomalously large column. A summary of the promptly downlinked data is given at http://www.swift.ac.uk/sper/308812/. UVOT took a finding chart exposure of 95 seconds with the White (160-650 nm) filter starting 87 seconds after the BAT trigger. No 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 19.5 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.78 mag. Burst Advocate for this burst is S. T. Holland (sholland 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: 7574 SUBJECT: GRB 080409: REM optical/NIR observations DATE: 08/04/09 02:28:26 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo, S. Covino, D. Malesani, D. Fugazza, L.A. Antonelli, L. Calzoletti, S. Campana, G. Chincarini, M.L. Conciatore, S. Cutini, V. D'Elia, F. D'Alessio, F. Fiore, P. Goldoni, D. Guetta, C. Guidorzi, G.L. Israel, E. Maiorano, N. Masetti, A. Melandri, E.J.A. Meurs, L. Nicastro, E. Palazzi, E. Pian, F. Piranomonte, S. Piranomonte, L. Stella, G. Stratta, G. Tagliaferri, G. Tosti, V. Testa, S.D. Vergani, and F. Vitali, report on behalf of the REM team: The robotic 60-cm REM telescope located at La Silla (Chile) observed automatically the field of the GRB 080409 (Holland et al., GCN 7573) starting about 81 seconds after the burst. Airmass was large (about 2.9). Preliminary photometry of our earliest images (R: 30 s, H: 50 s) reveal no new sources inside the XRT error circle down to 3sigma limiting magnitudes of H ~ 15.0 and R ~ 17.0. [GCN OPS NOTE(09apr08): Per author's request, the "080309" in the Subject-line and in the body of the Circular was changed to "080409".] /////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7575 SUBJECT: GRB 080409: Enhanced Swift-XRT position DATE: 08/04/09 04:12:30 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 91 s of overlapping XRT Photon Counting mode and UVOT data for GRB 080409, 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 = 84.32975, +5.08484 which is equivalent to: RA (J2000): 05h 37m 19.14s Dec (J2000): +05d 05' 05.4" with an uncertainty of 2.0 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 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method. This circular was automatically generated, and is an official product of the Swift-XRT team. /////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7579 SUBJECT: Swift/UVOT observations of GRB080409 DATE: 08/04/09 13:01:18 GMT FROM: Patricia Schady at MSSL/Swift Swift/UVOT began settled observations of the field of GRB 080409 starting 88s after the BAT trigger (Holland et al., GCN Circ 7573). We do not detect an optical/uv afterglow at the enhanced XRT position (Evans et al., GCN Circ. 7575) in the initial finding chart observations or subsequent summed images down to the following 3 sigma upper limits: Filter T_start T_stop Exp. Mag UL (3sig) (s) (s) (s) white 88 187 93 > 20.22 white 682 7079 494 > 21.16 v 188 587 393 > 19.45 v 721 12243 1099 > 20.03 b 667 676 412 > 20.42 u 642 661 432 > 20.13 uvw1 618 637 430 > 19.86 uvm2 593 12940 1070 > 20.23 uvw2 697 11330 1082 > 20.46 The above magnitudes are not corrected for the large Galactic extinction in the line of sight to GRB 080409, corresponding to a reddening of E(B-V)=0.78 mag (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT flight system described in Poole et al. (2008, MNRAS, 383, 627). /////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////// //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7582 SUBJECT: GRB 080409: Swift-BAT refined analysis DATE: 08/04/10 13:14:20 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift D. Palmer (LANL), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC) , J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), S. T. Holland (CRESST/USRA/GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), 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+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 080409 (trigger #308812) (Holland, et al., GCN Circ. 7573). The BAT ground-calculated position is RA, Dec = 84.304, 5.078 deg which is RA(J2000) = 05h 37m 12.9s Dec(J2000) = +05d 04' 39.9" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 46%. The mask-weighted light curve shows 3 well-separated peaks, at T-13, T+0, and T+10 sec, that are about 1, 2, and, 2 sec wide respectively. The first is much smaller than the others, the second at T+0 is the largest. T90 (15-350 keV) is 20.2 +- 8.0 sec (estimated error including systematics). The time-averaged spectrum from T-13.1 to T+10.4 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.10 +- 0.20. The fluence in the 15-150 keV band is 6.1 +- 0.7 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+0.00 sec in the 15-150 keV band is 3.7 +- 0.3 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/308812/BA/