//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9161 SUBJECT: GRB 090419: Swift detection of a burst DATE: 09/04/19 13:59:53 GMT FROM: David Burrows at PSU/Swift G. Stratta (ASDC), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), N. P. M. Kuin (MSSL), V. Mangano (INAF-IASFPA), J. Mao (INAF-OAB), R. Margutti (Univ Bicocca&OAB), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), A. M. Parsons (GSFC), M. Perri (ASDC), P. Romano (INAF-IASFPA) and B. Sbarufatti (INAF-IASFPA) report on behalf of the Swift Team: At 13:43:31 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090419 (trigger=349592). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 196.976, -75.609 which is RA(J2000) = 13h 07m 54s Dec(J2000) = -75d 36' 30" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a slow single peak taking 30 seconds to rise to a maximum with a duration of at least 90 seconds, and an additional peak at T+320. The peak count rate was ~800 counts/sec (15-350 keV), at ~30 sec after the trigger. The XRT began observing the field at 13:45:31.0 UT, 119.7 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 196.92907, -75.60534 which is equivalent to: RA(J2000) = 13h 07m 42.98s Dec(J2000) = -75d 36' 19.2" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 44 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 (1.2e+21 cm^-2, Kalberla et al. 2005), with an excess column of 1.1 (+0.85/-0.64) x 10^22 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 5.55e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 126 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 typical 3-sigma upper limit has been about 19.6 mag. The coverage of the XRT error circle by the 8'x8' region for the list of sources generated on-board is uncertain because the large number of sources filled the available telemetry. No correction has been made for the expected extinction corresponding to E(B-V) of 0.30. Burst Advocate for this burst is G. Stratta (giulia.stratta AT asdc.asi.it). 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: 9164 SUBJECT: GRB 090419: Enhanced Swift-XRT position DATE: 09/04/19 16:59:55 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 1541 s of XRT Photon Counting mode data and 1 UVOT images for GRB 090419, 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 = 196.92894, -75.60586 which is equivalent to: RA (J2000): 13h 07m 42.95s Dec (J2000): -75d 36' 21.1" 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: 9167 SUBJECT: GRB 090419: Swift-BAT refined analysis DATE: 09/04/20 01:33:40 GMT FROM: Scott Barthelmy at NASA/GSFC H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), G. Stratta (ASDC), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+704 sec from recent telemetry downlinks, we report further analysis of BAT GRB 090419 (trigger #349592) (Stratta, et al., GCN Circ. 9161). The BAT ground-calculated position is RA, Dec = 197.006, -75.615 deg, which is RA(J2000) = 13h 08m 01.5s Dec(J2000) = -75d 36' 55.6" with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%. The mask-weighted light curve shows a long burst with multiple peaks. The first peak starts at ~T-30 sec. There are comparably bright peaks at T+50, 100, and 320 sec. There is continued emmission out to at least T+1000 sec and possibly T+1800 sec. T90 (15-350 keV) is 450 +- 50 sec (estimated error including systematics). The time-averaged spectrum from T+8.1 to T+522.8 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.38 +- 0.16. The fluence in the 15-150 keV band is 2.5 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+37.18 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. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/349592/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9169 SUBJECT: GRB 090419: GROND detection of afterglow candidate DATE: 09/04/20 08:28:04 GMT FROM: Jochen Greiner at MPI P. Afonso (MPE Garching), S. Klose (Tautenburg) T. Kruehler and J.Greiner (both MPE Garching) report on behalf of the GROND team: We observed the field of GRB 090419 (Swift trigger 349592, G. Stratta et al.,GCN #9161) simultaneously in g'r'i'z'JHK with GROND mounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile). Observations started on 19 Apr. 2009 at 23:12 UT, 9.5 h after the burst. Inside the enhanced XRT error circle (J.P. Osborne et al., GCN #9164) we detect a single faint source in the z' and J band at: RA (J2000.0) = 13:07:43.13 DEC (J2000.0) = -75:36:22.4 with an uncertainty of 0.5" in each coordinate. Preliminary photometry yields the following AB magnitudes and upper limits in stacked images: Filter T_mid[h] Exp[s] AB Mag MagErr ---------------------------------------- g 11.5792 12x369 >24.6 r 11.5792 12x369 >25.1 i 11.5792 12x369 24.9 0.5 z 11.5792 12x369 24.2 0.1 J 11.5859 360x10 23.0 0.2 H 11.5859 360x10 >22.1 K 11.5859 360x10 >21.2 The quoted error is statistical only. There is an additional systematic error in the absolute calibration using the GROND zeropoints and 2MASS field stars which is expected to be in the 0.2 mag range. Quoted magnitudes are not corrected for the significant Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.30. Given the lack of information about variability and the rather high density of foreground stars we cannot definitely associate this source with GRB 090419 at this point. Because of the high Galactic foreground extinction, the upper limits in g'r' as well as the i'-z' color are not constraining, and the redshift is only constrained to below about 5. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9172 SUBJECT: GRB 090419: Swift-XRT refined analysis DATE: 09/04/20 15:19:33 GMT FROM: Matteo Perri at ISAC/ASDC G. Stratta and M. Perri (ASDC) report on behalf of the Swift-XRT Team: We have analysed the first 4 orbits of Swift-XRT data obtained from GRB 090419 (trigger 349592; Stratta, et al., GCN Circ. 9161), from T+128 s to T+271 s in Windowed Timing (WT) mode and from T+303 s to T+4.9 h in Photon Counting (PC) mode. The best position of the X-ray afterglow is the UVOT enhanced XRT position given in Osborne et al. (GCN Circ. 9164). The 0.3-10 keV X-ray light curve shows an initial flaring activity superimposed to a constant continuum at a level of ~5 counts/s up to ~520 s after the trigger that is consistent with being the X-ray tail of the BAT data (GCN Circ. 9167, Krimm et al.) during the prompt emission. Starting from 520 s up to 1200 s the count rate decays as a power law with alpha1=3.5+/-0.5 and from T+1200 to T+12 ks it features a flattening with index alpha2=1.1+/-0.2. If decaying at this rate, the afterglow will reach a count-rate of 1.3(0.6)E-3 counts/s at T+24(48)h. The average WT spectrum (corresponding to the initial flat decay phase) can be fitted by an absorbed power-law model (reduced chi square 1.0 with 18 degrees of freedom), with photon index 1.3+/-0.3, and equivalent hydrogen column density NH=(1.1+/-0.6)E22 cm-2 in excess with respect to the Galactic absorption value of 1.2E21 cm-2 (Kalberla et al. 2005). The average observed(unabsorbed) flux in the 0.3-10 keV band is 4.2(5.4)E-10 ergs cm-2 s-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00349510. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 9177 SUBJECT: GRB 090419: Swift/UVOT Observations DATE: 09/04/20 20:31:07 GMT FROM: Michael Siegal at Swift/PSU M. H. Siegel (PSU), E. A. Hoversten (PSU) and G. Stratta (ASDC) report on behalf of the Swift/UVOT team. The Swift/UVOT began observing the field of GRB 090419 126s after the BAT trigger (Stratta et al., GCN Circ. 9161). Data summed over the first orbit reveals a very faint (3.3 sigma) source in the white filter at the refined position of the X-ray afterglow (Osborne et al., GCN Circ. 9164). This source is not detected in the second orbit data. The detection and 3-sigma upper limits for the finding chart (fc) and summed exposures are reported below: FILTER T_start(s) T_stop Exposure Mag/3UL ============================================================= white fc 126 276 147 > 20.69 white 126 1706 410 21.07+-0.31 white 5320 6956 393 > 21.25 v 614 1756 136 > 18.93 v 5732 7367 393 > 19.60 b 540 1682 116 > 19.87 b 5116 13394 572 > 20.69 u 284 1829 362 > 20.25 u 6346 13206 1081 > 20.89 uvw1 664 1805 136 > 19.31 uvw1 6142 12292 1118 > 20.63 uvm2 639 1608 58 > 18.41 uvm2 5936 17728 465 > 19.99 uvw2 590 1731 136 > 19.37 uvw2 5527 7162 393 > 20.13 ============================================================= The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.296 (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627).