This file contains all 4 bursts: GRB 080319A abd GRB 080319B and GRB 080319C and GRB 080319D //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7426 SUBJECT: GRB 080319A: Swift detection of a burst DATE: 08/03/19 06:18:20 GMT FROM: David Palmer at LANL C. Pagani (PSU), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD), D. M. Palmer (LANL), J. L. Racusin (PSU) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift Team: At 05:45:42 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080319A (trigger=306754). The Swift slew to the burst was delayed because of an earth constraint. The BAT on-board calculated location is RA, Dec 206.354, +44.079 which is RA(J2000) = 13h 45m 25s Dec(J2000) = +44d 04' 44" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multiple peaks with a duration of about 40 sec. The peak count rate was ~800 counts/sec (15-350 keV), at ~10 sec after the trigger. The XRT began observing the field at 05:54:59.4 UT, 557.4 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 206.33306, 44.08029 which is equivalent to: RA(J2000) = 13h 45m 19.94s Dec(J2000) = +44d 04' 49.1" with an uncertainty of 2.6 arcseconds (radius, 90% containment). This location is 54 arcseconds from the BAT onboard position, within the BAT error circle. A power-law fit to a spectrum formed from promptly downlinked event data does not constrain the column density, so we cannot provide limits on the redshift using spectroscopy and the relation from Grupe et al. (2007). A summary of the promptly downlinked data is given at http://www.swift.ac.uk/sper/306754/. UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 562 seconds after the BAT trigger. A possible low-significance afterglow candidate has been found at the XRT position in the initial data products. The magnitude is white = 21.7 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.01. Burst Advocate for this burst is C. Pagani (pagani AT astro.psu.edu). 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: 7427 SUBJECT: GRB 080319B: Swift detection of an intense burst with a bright optical counterpart DATE: 08/03/19 06:32:26 GMT FROM: David Palmer at LANL J. L. Racusin (PSU), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD), C. Pagani (PSU), D. M. Palmer (LANL) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift Team: At 06:12:49 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080319B (trigger=306757). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 217.926, +36.303 which is RA(J2000) = 14h 31m 42s Dec(J2000) = +36d 18' 10" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed one bright but complex peak with a duration of about 50 sec, with an extended tail. The peak count rate was ~70,000 counts/sec (15-350 keV), at ~20 sec after the trigger. The XRT began observing the field at 06:13:49.7 UT, 60.5 seconds after the BAT trigger. XRT found a very bright fading, uncatalogued X-ray source located at RA, Dec 217.9196, +36.3041 which is equivalent to: RA(J2000) = 14h 31m 40.7s Dec(J2000) = +36d 18' 14.7" with an uncertainty of 4.7 arcseconds (radius, 90% containment). This location is 18 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to assess possible redshift constraints using X-ray spectroscopy and the nH-z relation from Grupe et al. (2007). UVOT took a finding chart exposure of 400 seconds with the V filter starting 175 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image. This position is consistent with the XRT error circle, but the source is so bright that a precise UVOT position is not possible due to saturation effects. The estimated magnitude is 11.5 with a 1-sigma error of about 0.5 mag. No correction has been made for the expected extinction of about 0.04 magnitudes. Burst Advocate for this burst is J. L. Racusin (racusin AT astro.psu.edu). 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: 7428 SUBJECT: GRB 080319B: UVOT Position DATE: 08/03/19 06:45:10 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. T. Holland (CRESST/USRA/GSFC) and J. L. Racusin (PSU) reports on behalf of the Swift/UVOT team: The UVOT position of GRB 080319B (Racusin et al. 2008 GCN Circ. 7427) is RA(J2000.0) = 14:31:40.98 Dec(J2000.0) = +36:18:08.8 with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7429 SUBJECT: GRB080319A: P60 Optical Afterglow Observations DATE: 08/03/19 06:49:33 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko reports on behalf of a larger collaboration: We have imaged the field of GRB080319A (Pagani et al., GCN 7426) with the automated Palomar 60-inch telescope beginning approximately 2.5 minutes after the burst. Inside the XRT error circle (and consistent with the UVOT candidate) we find a single faint, fading point source at coordinates (J2000.0): RA: 13:45:20.01 Dec: +44:04:48.6 with an estimated uncertainty of ~ 0.3". Using the USNO-B catalog as a reference, we measure a magnitude of R ~ 20.25 +/- 0.2 in our initial R-band image. Further observations are planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7430 SUBJECT: GRB 080319B: KAIT OA DATE: 08/03/19 06:56:36 GMT FROM: Weidong Li at UC Berkeley KAIT/LOSS W. Li, J. S. Bloom, R. Chornock, R. Foley, D. A. Perley, and A. V. Filippenko, University of California at Berkeley, on behalf of the KAIT GRB team, report: KAIT responded to GRB 080319B (Swift trigger 306757) and was taking images. There is a bright afterglow at position RA = 14:31:40.97 DEC = +36:18:07.9 (equinox J2000) The measured magnitude is R = 15.4 at 06:49:07 UT. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7431 SUBJECT: GRB 080319B: REM observations DATE: 08/03/19 08:06:39 GMT FROM: Stefano Covino at Brera Astronomical Observatory S. Covino, P. D'Avanzo, 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. Meurs, L. Nicastro, E. Palazzi, E. Pian, S. Piranomonte, L. Stella, G. Stratta, G. Tagliaferri, G. Tosti, V.Testa, S.D. Vergani, 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 080319B on March 19 06:13:32 UT (about 43 seconds after the burst). We clearly detect the afterglow reported in GCN 7427, 7428, 7430 (Racusin et al.; Holland et al.; Li et al.). The object was still at H~12.5 at about 22 min from the burst time. Further analyses and observations are in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7432 SUBJECT: GRB 080319B: Super-LOTIS Detection of a Bright OT DATE: 08/03/19 08:09:38 GMT FROM: Grant Williams at Steward Observatory P. A. Milne (Steward Observatory) and G. G. Williams (MMTO), on behalf of the Super-LOTIS Collaboration, report: The robotic 0.6-m Super-LOTIS telescope began observing the error box of GRB 080319B (Swift Trigger 306757, Racusin et al. GCN 7427) at 06:27:00.3 UT, 851 seconds after the trigger. We identify a bright source consistent within the UVOT candidate. Using the USNO-B1.0 star (1263-0223138) at RA=14:31:39.66, Dec=+36:18:54.5 with R2MAG=14.98 as a reference, we estimate the following R-band magnitude for the transient: t_start (UT) exp t (s) t_start-t_0 (s) R Mag ---------------------------------------------------------------- 06:27:00.3 60 851 R = 13.52 +/- 0.01 Additional observations and analysis are ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7433 SUBJECT: GRB080319B Liverpool Telescope optical afterglow candidate DATE: 08/03/19 08:25:53 GMT FROM: James Smith at ARI,Liverpool John Moors U R.J. Smith (Liverpool JMU), A. Gomboc (U. Ljubljana), N. Tanvir (Leicester) A. Melandri, C.G. Mundell, I.A. Steele, S. Kobayashi, D. Bersier (Liverpool JMU) report: The 2-m Liverpool Telescope (La Palma) observed the position of GRB 080319B (SWIFT trigger 306757) starting 30 min after the GRB trigger time. We detect an optical afterglow candidate in r' filter at 14:31:41 +36:18:09 J2000 consistent with the uncatalogued source visible in the UVOT data. Filter t_mid (min from GRB) Tot_Exp (s) R -------------------------------------------------------------- r' 30.64 120 14.9 r' 32.83 120 15.1 r' 35.02 120 15.2 ------------------------------------------------------------- Observations were performed in SDSS r' filter and magnitudes calibrated vs R2 USNO-B1 magnitudes for a few selected stars. No further observations were possible due to approaching twilight. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7434 SUBJECT: GRB 080319b: Early IR Imaging from PAIRITEL DATE: 08/03/19 08:30:12 GMT FROM: Josh Bloom at UC Berkeley J. S. Bloom, D. Starr, and D. A. Perley (UC Berkeley) report: We began observations of GRB080319b with PAIRITEL at 2008-03-19 06:14:51 UT and will continue for several hours until sunrise. The source is exceedingly bright in the first few minutes, visible on individual 7.8 sec exposures in JHKs bands. Preliminary photometry, which may be affected to non-linearities at these bright flux levels, is given below. # t (MJD) terr (day) filt mag merr ##################################### 54544.262141 0.000454 k 8.613900 0.033214 0 0 54544.261788 0.000454 j 9.110600 0.041347 0 0 A comparison with 2MASS may be found at: http://lyra.berkeley.edu/~jbloom/grb080319b.png This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7435 SUBJECT: GRB0 080319B : LOAO optical observation DATE: 08/03/19 09:10:40 GMT FROM: Yuji Urata at Saitama U Y. Urata, M. Im, I. Lee, K.Y Huang, W.K. Zheng, L.P. Xin on behalf of EAFON report: "We have been monitoring the GRB 080319B optical afterglow (Racusin et al. GCN 7427) using Mt. Lemmon 1m telescope with B, V, R, I and z' band filter. The brightness at about 80 min after the burst is R~16.0 mag. derived from USNO-B1.0 catalog. Comparing with the further reports by Li et al (GCN 7430), and Milen & Williams (GCN 7432), the light curve shows shallower decay from around 0.05 days after the burst. Further analysis and observations are in progress." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7436 SUBJECT: GRB 080319A: optical observations at the NOT DATE: 08/03/19 11:06:34 GMT FROM: Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center D. Malesani, J. P. U. Fynbo, P. M. Vreeswijk (DARK), C. Villforth (NOT), report on behalf of a larger collaboration: We observed the field of GRB 080319A (Pagani et al., GCN 7426) with the Nordic Optical Telescope, starting on 2008 March 19.265 UT. Exposures in the R and I bands were secured. We detect the afterglow reported by Cenko (GCN 7429). Compared to the USNO-B1 star 1340-0249427 at RA = 13:45:26.457, Dec = +44:04:45.56 (R1 = 15.79), we measure R = 21.03 +- 0.09 on Mar 19.27088 UT (44.4 min after the GRB). A finding chart is posted at: http://www.astro.ku.dk/~malesani/GRB/080319A/080319A_finder.jpg We acknowledge excellent support from the NOT observing staff. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7437 SUBJECT: GRB 080319B: Gemini-South Spectroscopy DATE: 08/03/19 11:28:33 GMT FROM: Ryan Foley at UC Berkeley R. J. Foley, D. Perley, and J. S. Bloom (UCB) on behalf of the GRAASP collaboration report: We obtained 2x1800 sec exposures of the optical afterglow (GCN 7428, 7430) of GRB 080319B (GCN 7427) using GMOS on the Gemini-South telescope with the R831 grating. The observations started at 20080319.35 (~2 hours after the initial Swift trigger). Initial reductions show a featureless continuum with no strong absorption systems, emission lines, or breaks. Given our wavelength range of 595 - 815 nm, we can place the following constraints on the redshift (in order of descending confidence): (1) The lack of a Lyman limit implies z < 5.5. (2) The lack of damped Lya or obvious Lya forest implies z < 3.9. (3) The lack of obvious Mg II absorption implies z < 1.1. Further analysis is in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7438 SUBJECT: GRB 080319B: Change in power law decay index DATE: 08/03/19 11:36:37 GMT FROM: Weidong Li at UC Berkeley KAIT/LOSS W. Li, R. Chornock, D. A. Perley, and A. V. Filippenko, University of California at Berkeley, on behalf of the KAIT GRB team: We have analyzed the KAIT data on GRB 080319B (GCN 7472, 7428) as reported in GCN 7430. Preliminary reduction of the unfiltered data, calibrated to SDSS observations of the field, shows a smooth light curve from t = 20 to 120 minutes after the BAT trigger, with an apparent change in power-law decay index at t ~ 35 minutes. The power-law decay index is measured to be -1.89 +/- 0.04 between t = 20.1 to 26.3 minutes after the BAT trigger, and -1.23 +/- 0.02 between t=60.9 to 117.2 minutes after the BAT trigger. The shallower decay is also observed at t ~ 80 minutes as noted in GCN 7435. We note this change in power-law decay index is reminiscent of what has been observed in GRB 990123 (e.g. Akerlof et al. 1999, Nature 398, 400) and GRB 021211 (e.g. Li et al. 2003, ApJ 586, L9), and suggests a transition from reverse shock to forward shock emission. Selected KAIT unfiltered photometry, all unfiltered data calibrated to the R band via the SDSS calibration: t(start; seconds after BAT trigger) exp mag merr 1207 20.0 14.110 0.008 1394 20.0 14.417 0.011 1576 20.0 14.645 0.011 1991 20.0 15.063 0.011 2912 20.0 15.710 0.014 3770 20.0 16.053 0.015 4380 20.0 16.247 0.014 5005 20.0 16.415 0.019 6820 20.0 16.843 0.017 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7439 SUBJECT: GRB 080319b prompt optical observation by Pi-of-the-Sky DATE: 08/03/19 11:55:07 GMT FROM: Grzegorz Wrochna at Soltan Inst.for Nuclear Studies M.Cwiok, W.Dominik, G.Kasprowicz, A.Majcher, A.Majczyna, K.Malek, L.Mankiewicz, M.Molak, K.Nawrocki, L.W.Piotrowski, D.Rybka, M.Sokolowski, J.Uzycki, G.Wrochna, A.F.Zarnecki on behalf of "Pi of the Sky" collaboration http://grb.fuw.edu.pl "Pi of the Sky" apparatus located at Las Campanas Observatory imaged the region of GRB 080319b (Swift triger 306757 at 06:12:49 UT) before, during and after the GRB with 10s exposures (IR-cut filter only). We observe optical emission at the position given by Swift XRT. start - end comment 6:12:33 - 6:12:43 not visible (>12 mag) 6:12:47 - 6:12:57 visible (~10 mag) 6:13:01 - 6:13:11 max. brightness (~6 mag) Full light curve fill be published later. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7440 SUBJECT: GRB 080319A: REM observations DATE: 08/03/19 11:59:06 GMT FROM: Stefano Covino at Brera Astronomical Observatory S. Covino, P. D'Avanzo, 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. Meurs, L. Nicastro, E. Palazzi, E. Pian, S. Piranomonte, L. Stella, G. Stratta, G. Tagliaferri, G. Tosti, V.Testa, S.D. Vergani, 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 080319A (GCN 7426, Pagani et al.) about 40 seconds after the burst. We do no detect any source at the position of the optical afterglow identified by Cenko et al. (GCN 7429) and Malesani et al. (GCN 7436) with a 3sigma upper limit of H~15.0 in the first coadded frame at about 100sec after the burst. [GCN OPS NOTE(19mar08): Per author's request, the Cenko reference was added.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7441 SUBJECT: GRB 080319C: KAIT OA candidate DATE: 08/03/19 12:33:15 GMT FROM: Weidong Li at UC Berkeley KAIT/LOSS W. Li, R. Chornock, and A. V. Filippenko, University of California at Berkeley, on behalf of the KAIT GRB team, report: KAIT responded to GRB 080319C (Swift trigger 306778) and was taking images. There is an afterglow candidate at position RA = 17:15:55.54 DEC = +55:23:30.8 (equinox J2000) The measured magnitude is R = 17.4 at 12:27:55 UT. Further observations are ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7442 SUBJECT: GRB 080319C: Swift detection of a burst with an optical afterglow DATE: 08/03/19 12:45:58 GMT FROM: Scott Barthelmy at NASA/GSFC C. Pagani (PSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), O. Godet (U Leicester), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), V. Mangano (INAF-IASFPA), J. P. Osborne (U Leicester), K. L. Page (U Leicester), A. M. Parsons (GSFC), J. L. Racusin (PSU), B. Sbarufatti (INAF-IASFPA), M. Stamatikos (NASA/ORAU), R. L. C. Starling (U Leicester), G. Stratta (ASDC) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 12:25:56 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080319C (trigger=306778). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 258.973, +55.410 which is RA(J2000) = 17h 15m 54s Dec(J2000) = +55d 24' 35" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows several overlapping FRED-like peaks starting at T+0 and ending around T+20 sec. The peak count rate was ~8000 counts/sec (15-350 keV), at ~T+0 sec after the trigger. The XRT began observing the field at 12:29:40 UT, 224 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 258.9828, 55.3920 which is equivalent to: RA(J2000) = 17h 15m 55.86s Dec(J2000) = +55d 23' 31.2" with an uncertainty of 4.5 arcseconds (radius, 90% containment). This location is 3 arcseconds from the optical afterglow candidate position. UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 227 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 17:15:55.51 = 258.9813 DEC(J2000) = +55:23:30.8 = +55.3919 with a 1-sigma error radius of about 0.5 arc sec. This position is 67.4 arc sec. from the center of the BAT error circle. This is consistent with the KAIT position (Li et al., 2008, GCNC 7441). The estimated magnitude is white = 18.8 with a 1-sigma error of about 0.5 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03. Burst Advocate for this burst is C. Pagani (pagani AT astro.psu.edu). 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: 7443 SUBJECT: GRB 080319C: Early Super-LOTIS Observations DATE: 08/03/19 13:30:10 GMT FROM: Grant Williams at Steward Observatory G. G. Williams (MMTO) and P. A. Milne (Steward Observatory), on behalf of the Super-LOTIS Collaboration, report: The robotic 0.6-m Super-LOTIS telescope began observing the error box of GRB 080319C (Swift Trigger 306778, Pagani et al. GCN 7442) at 12:26:38.5 UT, 42.5 seconds after the trigger. Our initial observations include 5 x 10s exposures, 5 x 20s exposures, and 30 x 60s exposures, all in the R-band. We detect the afterglow reported by Li et al. (GCN 7441) in our earliest 10 second exposure. Using the USNO-B1.0 star (453-025776) at RA=17:15:51.7, Dec=55:23:38.4 with R2MAG=14.61, we estimate the following R-band magnitude for the OT: t_start (UT) exp t (s) t_start-t_0 (s) R Mag ---------------------------------------------------------------- 12:26:38.5 10 42.5 R = 16.83 +/- 0.13 Additional observations and analysis are ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7444 SUBJECT: VLT/UVES redshift of GRB 080319B DATE: 08/03/19 13:34:33 GMT FROM: Paul Vreeswijk at Dark Cosmology Centre,U.of Copenhagen P.M. Vreeswijk (DARK), A. Smette (ESO), D. Malesani, J.P.U. Fynbo, Bo Milvang-Jensen (DARK), P. Jakobsson (U. Hertfordshire), A.O. Jaunsen (U. Oslo) and C. Ledoux (ESO) report on behalf of a larger collaboration: We observed the optical afterglow of GRB 080319B (Racusin et al., GCN 7427) with the Ultraviolet and Visual Echelle Spectrograph (UVES) mounted at ESO's VLT Kueyen. Observations were performed in rapid-response mode starting on 2008 March 19 at 07:18 UT. The highest redshift system that we identify based on the MgII doublet and various other features has z=0.937, the presumed redshift of GRB 080319B. Another system is identified at z=0.530. We acknowledge excellent support from the observing staff at Paranal, in particular Swetlana Hubrig and Elena Mason. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7445 SUBJECT: GRB 080319b light curve by Pi-of-the-Sky DATE: 08/03/19 13:38:20 GMT FROM: Grzegorz Wrochna at Soltan Inst.for Nuclear Studies M.Cwiok, W.Dominik, G.Kasprowicz, A.Majcher, A.Majczyna, K.Malek, L.Mankiewicz, M.Molak, K.Nawrocki, L.W.Piotrowski, D.Rybka, M.Sokolowski, J.Uzycki, G.Wrochna, A.F.Zarnecki on behalf of "Pi of the Sky" collaboration http://grb.fuw.edu.pl Following GCN 7439 we give the preliminary light curve of GRB 080319b (IR-cut filter only): start - end frame magnitudo 6:12:33 - 6:12:43 <=96 limit >11.48 6:12:47 - 6:12:57 97 9.83 6:13:01 - 6:13:11 98 5.76 6:13:16 - 6:13:26 99 6.00 6:14:03 - 6:14:13 100 8.26 6:14:17 - 6:14:27 101 8.77 6:14:32 - 6:14:42 102 9.10 6:14:46 - 6:14:56 103 10.27 6:15:27 - 6:14:37 104 10.50 6:15:41 - 6:14:51 105 11.10 6:15:56 - 6:16:06 106 11.21 6:16:40 - 6:16:50 107 11.79 6:16:54 - 6:17:04 108 11.95 More information will be published at http://grb.fuw.edu.pl //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7446 SUBJECT: GRB 080319B: REM early data DATE: 08/03/19 13:44:13 GMT FROM: Stefano Covino at Brera Astronomical Observatory S. Covino, P. D'Avanzo, 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. Meurs, L. Nicastro, E. Palazzi, E. Pian, S. Piranomonte, L. Stella, G. Stratta, G. Tagliaferri, G. Tosti, V.Testa, S.D. Vergani, F. Vitali report on behalf of the REM team: We started a refined analysis of the REM observations of GRB 080319B (GCN 7427, Racusin et al.). As already reported by Cwiok et al. (GCN 7439 and 7445) the optical counterpart of this GRB was exceptionally bright at early time. We measured, about 1 min after the burst, R~6.4 assuming R=11.20 for the USNO star at coordinates RA,DEC = 14:31:23.61, 36:21:56.5. The source was already almost 2 mag fainter half a minute later. In the H band the source was H~5 around the same epoch. Further analyses are in progress. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7447 SUBJECT: GRB 080319A, Swift-BAT refined analysis DATE: 08/03/19 15:04:20 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), C. Pagani (PSU), D. Palmer (LANL), 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-120 to T+182 sec from recent telemetry downlinks, we report further analysis of BAT GRB 080319A (trigger #306754) (Pagani, et al., GCN Circ. 7426). The BAT ground-calculated position is RA, Dec = 206.352, 44.080 deg, which is RA(J2000) = 13h 45m 24.6s Dec(J2000) = +44d 04' 47.3" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 7%. The mask-weighted light curve shows two main over-lapping FRED-like peaks starting at ~T-5 sec, peaking at T+5 and T+25 sec, and ending at ~T+70 sec. T90 (15-350 keV) is 64 +- 36 sec (estimated error including systematics). The time-averaged spectrum from T-7.7 to T+72.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.60 +- 0.13. The fluence in the 15-150 keV band is 4.8 +- 0.4 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+31.80 sec in the 15-150 keV band is 1.2 +- 0.2 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/306754/BA/ Due to a large backlog in downlinking the full data on this burst, we currently do not have the usual data set out to long times yet. Should the remaining data show that there is ongoing activity for this burst past the data cutoff at T+182sec, then we will issue an updated 'refined analysis' circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7448 SUBJECT: GRB 080319A: Enhanced Swift-XRT position DATE: 08/03/19 16:01:24 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 596 s of overlapping XRT Photon Counting mode and UVOT data for GRB 080319A, 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 = 206.33318, +44.08038 which is equivalent to: RA (J2000): 13h 45m 19.96s Dec (J2000): +44d 04' 49.4" 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 http://www.swift.ac.uk/xrt_positions/Goad.pdf). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7449 SUBJECT: GRB 080319B: Enhanced Swift-XRT position DATE: 08/03/19 16:04:51 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 1859 s of overlapping XRT Photon Counting mode and UVOT data for GRB 080319B, 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 = 217.92113, +36.30269 which is equivalent to: RA (J2000): 14h 31m 41.07s Dec (J2000): +36d 18' 09.7" with an uncertainty of 1.4 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). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7450 SUBJECT: GRB 080319A/B/C: INTEGRAL SPI-ACS light curves available DATE: 08/03/19 16:08:28 GMT FROM: Volker Beckmann at ISDC V. Beckmann (ISDC), S. Mereghetti (INAF/IASF-Milano), A. von Kienlin (MPE), M. Beck, V. Savchenko (ISDC), J. Borkowski (CAMK/Torun), D. Gotz (CEA/Saclay) report on behalf of the INTEGRAL SPI-ACS GRB team: The three GRB reported on 2008-03-19 by the Swift team (GCN 7426, 7427, 7442) have been independently detected by the SPI Anti-Coincidence System (ACS) on-board INTEGRAL. Burst T0 duration max counts in 50 msec ------------------------------------------------------ GRB080319A 05:45:41 10s 370 GRB080319B 06:12:47 57s 5500 GRB080319C 12:25:55 25s 1200 The SPI-ACS light curves are available (both as images and data files) at http://isdc.unige.ch/Soft/ibas/ibas_acs_web.cgi The light curves, binned at 50 ms, are derived from 91 independent detectors with different lower energy thresholds (mainly between 50 keV and 150 keV) and an upper threshold at about 100 MeV. The ACS response varies as a function of the GRB incident angle. For these reasons we caution that the count rates cannot be easily translated into physical flux units. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7451 SUBJECT: VLT/UVES redshift of GRB 080319B from FeII fine-structure lines DATE: 08/03/19 16:36:37 GMT FROM: Paul Vreeswijk at Dark Cosmology Centre,U.of Copenhagen P.M. Vreeswijk, Bo Milvang-Jensen (DARK), A. Smette (ESO), D. Malesani, J.P.U. Fynbo (DARK), P. Jakobsson (U. Hertfordshire), A.O. Jaunsen (U. Oslo) and C. Ledoux (ESO) report on behalf of a larger collaboration: Besides the absorption systems at z=0.937 and z=0.530 reported in GCN 7444, we also note the presence of two other systems at z=0.715 and z=0.760 along the sightline toward GRB 080319B. The rest-frame equivalent width of MgII 2796 for both the z=0.937 and z=0.715 systems is large: greater than 1A. Finally, we detect several transitions from FeII fine-structure levels from the z=0.937 system. Assuming that the GRB afterglow is responsible for the FeII excitation (see Prochaska et al. 2006, ApJ, 648, 95; Vreeswijk et al. 2007, A&A, 468, 83), this confirms the z=0.937 system to be the host of GRB 080319B. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7452 SUBJECT: GRB 080319B: TORTORA synchronous observation DATE: 08/03/19 17:33:14 GMT FROM: Sergey Karpov at SAO RAS S. Karpov, G. Beskin, S. Bondar, C. Bartolini, G. Greco, A. Guarnieri, D. Nanni, A. Piccioni, F. Terra, E. Molinari, G. Chincarini, F.M. Zerbi, S. Covino, V. Testa, G. Tosti, F. Vitali, L.A. Antonelli, P. Conconi, G. Cutispoto, G. Malaspina, L. Nicastro, E. Palazzi, E. Meurs, P. Goldoni report on behalf of the TORTOREM team: TORTORA wide-field optical camera (12 cm diameter, 20x25 deg FOV, TV-CCD, unfiltered) mounted on REM robotic 60-cm telescope located at La Silla (Chile) observed the field of GRB 080319B (GCN 7427, Racusin et al.) before, during and after the gamma-emission with 0.13 s time resolution. We observe optical emission at the position given by Swift XRT: 1. We did not detect any transient brighter than 8.5m (unfiltered, near B) at T-100 - T+16 s 2. We detect rapidly rising OT (~5 second rise front) and observe it between T+16 and T+30, the peak brightness has been around 5 m 3. Between T+30 and T+36 the observations have been paused due to repointing of REM telescope 4. Since T+36 we continuously observe the transient until it faded below the detection limit (~8.5m) at T+90 s The detailed analysis is in progress. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7453 SUBJECT: GRB 080319D: Swift detection of a burst with a possible optical afterglow DATE: 08/03/19 17:42:09 GMT FROM: Scott Barthelmy at NASA/GSFC P. J. Brown (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), O. Godet (U Leicester), S. T. Holland (CRESST/USRA/GSFC), S. Immler (CRESST/GSFC/UMD), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), P. T. O'Brien (U Leicester), J. P. Osborne (U Leicester), C. Pagani (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), M. Perri (ASDC), J. L. Racusin (PSU), M. Stamatikos (NASA/ORAU), R. L. C. Starling (U Leicester), E. Troja (U Leicester/INAF-IASFPA) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 17:05:09 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080319D (trigger=306793). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 99.480, +23.933 which is RA(J2000) = 06h 37m 55s Dec(J2000) = +23d 56' 01" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual with an image trigger, the prompt light curve does not not show any clear structure. We will be able to tell more with the full data set. The XRT began observing the field at 17:07:36.9 UT, 147.5 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued, variable X-ray source with an enhanced position: RA, Dec 99.47270, 23.94306 which is equivalent to: RA(J2000) = 06h 37m 53.45s Dec(J2000) = +23d 56' 35.5" with an uncertainty of 3.0 arcseconds (radius, 90% containment). This location is 44 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 consistent with the Galactic value of 2.17e+21 cm^-2 (Kalberla et al. 2005), so we cannot constrain the redshift at this time using the relation from Grupe et al. (2007). A summary of the promptly downlinked data is given at http://www.swift.ac.uk/sper/306793/. UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 152 seconds after the BAT trigger. A possible afterglow candidate has been found in the initial data products, at a magnitude of ~19 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.19. The position of the tentative UVOT source is: RA(J2000) = 06h 37m 53.6s Dec(J2000) = +23d 56' 34.1" Burst Advocate for this burst is P. J. Brown (pbrown AT astro.psu.edu). 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: 7454 SUBJECT: GRB 080319C: MASTER-VWF-Kislovodsk optical observation DATE: 08/03/19 17:46:32 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs MASTER-Net Team: V. Lipunov, V.Kornilov, D.Kuvshinov, E.Gorbovskoy, N.Tyurina, A.Belinski, A.Krylov, N.Shatskiy, A.Sankovich, V.Vladimirov, P.Gritsyk, V.Vibornov, A.Kuznetsov, P.Balanutsa Sternberg Astronomical Institute, Moscow Union 'Optic' A. Tlatov, I.Golubov Kislovodsk Solar Station of the Pulkovo observatory K.Ivanov Irkutsk State University I.Zalognikh Ural State University, Kourovka MASTER Very Wide Field Camera located at Kislovodsk Solar Station (http://observ.pereplet.ru, D=70 mm, 420 square degrees, 11 Mpixel's CCD) has moved to the Swift-BAT trigger 306793 and it has taken a series of 5s exposures starting 92 s after notice arrivel time 708 s after GRB time at 17 16 57 UT under good weather condition and moon. There is no OT was found inside Swift error box brighter than 11.5m. MASTER-Net team congratulate "Pi of the Sky" - Team with wonderfull and long-awaited result (Cwiok et al. GCN 7445)! This message can be cited. Mailto: lipunov@sai.msu.ru //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7455 SUBJECT: GRB 080319D: MASTER-VWF-Kislovodsk optical observation DATE: 08/03/19 17:49:54 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs Correction to GCN 7454! MASTER-Net Team: V. Lipunov, V.Kornilov, D.Kuvshinov, E.Gorbovskoy, N.Tyurina, A.Belinski, A.Krylov, N.Shatskiy, A.Sankovich, V.Vladimirov, P.Gritsyk, V.Vibornov, A.Kuznetsov, P.Balanutsa Sternberg Astronomical Institute, Moscow Union 'Optic' A. Tlatov, I.Golubov Kislovodsk Solar Station of the Pulkovo observatory K.Ivanov Irkutsk State University I.Zalognikh Ural State University, Kourovka MASTER Very Wide Field Camera located at Kislovodsk Solar Station (http://observ.pereplet.ru, D=70 mm, 420 square degrees, 11 Mpixel's CCD) has moved to the Swift-BAT trigger 306793 and it has taken a series of 5s exposures starting 92 s after notice arrivel time 708 s after GRB time at 17 16 57 UT under good weather condition and moon. There is no OT was found inside Swift error box brighter than 11.5m. MASTER-Net team congratulate "Pi of the Sky" - Team with wonderfull and long-awaited result (Cwiok et al. GCN 7445)! This message can be cited. Mailto: lipunov@sai.msu.ru //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7456 SUBJECT: GRB 080319B: Hobby-Eberly Telescope Spectroscopy DATE: 08/03/19 17:58:58 GMT FROM: Antonino Cucchiara at PSU A. Cucchiara & D. B. Fox (PSU) report on behalf of a larger collaboration: "Starting on 2008 March 18.49 UT we used the Marcario LRS spectrograph on the Hobby-Eberly Telescope (R ~ 230 ) to obtain one 1200s spectra of the optical afterglow (Holland et al., GCN 7428) of GRB 080319B (Racusin et al., GCN 7427). The spectrum covers the wavelength range 4100 to 10,500 Angstrom. We observe multiple metal absorption features including the MgII doublet (2796, 2803 A) and MgI (2852 A) at z ~ 0.937. We also detect lines at z ~ 0.760 (MnII 2576, MnII 2594 and CaI 4227), z ~ 0.715 (MgII doublet) and z ~ 0.530 (NaI 5890,5896). Our observations are consistent with the redshift and features reported by Vreeswijk et al. (GCN 7444, 7451)." [GCN OPS NOTE(19mar08): Per author's request, the date in the Subject-line was changed from "080519B" to "080319B". And the date in the first line was changd from "18.49" to 19.49".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7457 SUBJECT: GRB 080319C: AGILE-MCAL observation of the prompt emission DATE: 08/03/19 19:09:02 GMT FROM: Sandro Mereghetti at IASF/CNR M. Marisaldi (INAF/IASF Bologna), F. Fornari (INAF/IASF Milano), C. Labanti, F. Fuschino, M. Galli, A. Bulgarelli, F. Gianotti, M. Trifoglio, G. Di Cocco (INAF/IASF Bologna), E. Costa, E. Del Monte, I. Donnarumma, Y. Evangelista, M. Feroci, I. Lapshov, F. Lazzarotto, L. Pacciani, M. Rapisarda, P. Soffitta (INAF/IASF Roma), A. Giuliani, S. Vercellone, A. Chen, S. Mereghetti, A. Pellizzoni, F. Perotti, M. Fiorini, P. Caraveo (INAF/IASF Milano), M. Tavani, G. Pucella, F. D'Ammando, V. Vittorini, A. Argan, A. Trois (INAF/IASF Rome), G. Barbiellini, F. Longo, E. Vallazza (INFN Trieste), P. Picozza, A. Morselli (INFN Roma-2), M. Prest (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), and P. Giommi, C. Pittori, (ASDC) and L. Salotti (ASI), on behalf of the AGILE Team, report: "The Swift localized GRB 080319C (Pagani et al., GCN 7442) triggered the Mini-Calorimeter (MCAL) instrument onboard the AGILE satellite at 12:25:56 UT (=T0). The MCAL instrument covers the energy range 350 keV - 10 MeV, without imaging capabilities. The MCAL light curve shows two main overlapping broad peaks, the first peaking at T0 and the second peaking at T0+9s in the 350-700 keV energy band. Above 700 keV only the first peak is still detected, with 5 sigma detection also in the 1.4-2.8 MeV energy band. Using the preliminary in-flight calibration, we can estimate the 1-s peak flux in the 350-700 keV energy band at T0 to be 2.0(-0.8,+0.9) photons/cm2/s. The Swift localization is out of the field of view of the AGILE Gamma-Ray Imaging Detector (GRID), sensitive in the 50 MeV - 50 GeV energy range. Analysis of the GRID count rate does not show any detection. The event was well outside of the SuperAGILE field of view as well, but the event passed through the collimator shield and was weakly detected in the count rate." We incidentally note that the brighter GRB 080319B (Racusin et al. GCN 7427) was not observed by the AGILE instruments due to Earth occultation. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7458 SUBJECT: GRB 080319D: Swift/UVOT Refined Analysis of the Fading Optical Afterglow Candidate DATE: 08/03/19 19:54:49 GMT FROM: Stefan Immler at NASA/GSFC S. Immler (CRESST/GSFC/UMD) and P. J. Brown (PSU) report on behalf of the Swift UVOT team: The Swift/UVOT observations of the field of GRB 080319D (trigger 306793) starting 151 seconds after the BAT trigger (Brown, et al., GCN Circ. 7453) reveal a fading optical afterglow candidate. The white and v-filter magnitudes are as follows: Filter T_start (s) T_stop (s) Exp (s) Mag (3-sigma UL) ---------------------------------------------------------------------------------------------- White 151 251 100 19.7+/-0.3 White 866 966 100 20.2+/-0.4 v 257 657 400 >19.5 v 972 1362 400 >19.5 ---------------------------------------------------------------------------------------------- No correction has been made for the expected Galactic extinction corresponding to E(B-V) of 0.19 (Schlegel, et al. 1998). The position of the optical afterglow candidate is RA (2000) = 06h 37m 53.6s Dec (2000) = +23d 56' 34.2" with an uncertainty of 0.5 arcsec, which is 2.2 arcsec offset from the XRT position (Brown, et al., GCN Circ. 7453). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7459 SUBJECT: GRB 080319B: Swift-XRT Team Refined Analysis DATE: 08/03/19 20:06:16 GMT FROM: Judith Racusin at PSU J. Racusin (PSU), D. N. Burrows (PSU), P. A. Evans (U Leicester), C. Pagani (PSU), report on behalf of the Swift-XRT Team: We have analysed the first four orbits of Swift-XRT data obtained for GRB 080319B (Racusin et al. GCN Circ. 7427), totaling 1.1 ks of Windowed Timing (WT) data beginning 64 s after the BAT trigger, and 4 ks of Photon Counting (PC) data beginning 5 ks after the BAT trigger. The UVOT-enhanced XRT position has been given by Evans et al. in GCN Circ 7449. The bright X-ray light-curve can be fit by a broken power-law, with an initial decay index of 1.46 +/- 0.01 followed, after a break at 6100 +/- 440 seconds, by a steeper decay index of 2.48 +/- 0.10. Both the WT and PC spectra are strongly affected by photon pile-up, which can alter the spectral fits. To eliminate these effects, we exclude the central 8 pixel radius region of the WT data, and the central 3 pixel radius region of the PC data when creating the spectra. Preliminary fits to the WT spectrum (64-4943 seconds), modeled with an absorbed power-law, result in a photon index of 1.65 +/- 0.02 and an absorbing column at z=0.937 (Vreeswijk et al., GCN Circ. 7444) of NH = (5.28 +/- 1.03)e20 cm^-2, in addition to Galactic absorption of 1.12e20 cm^-2 in the direction of the burst, with a reduced Chi^2=1.05. The PC spectrum (5-19 ks) can be modeled as an absorbed power-law, with photon index of 1.92 +/- 0.07 and an absorbing column at z=0.937 of NH = (23.5 +/- 5.6)e20 cm^-2, in addition to the Galactic absorption, with a reduced Chi^2=1.06. If we freeze the NH in the PC model to the WT fitted value, we fit a photon index of 1.73 +/ 0.04, with a reduced Chi^2=1.4, which excludes this model as a viable fit. As another attempt to model the spectra without NH evolution, we freeze the WT NH to the value from the PC spectral fits and add an additional low energy thermal component. The resulting fits yield a photon index of 1.73 +/- 0.02, kT=0.06 +/- 0.01 keV, and a reduced Chi^2=1.07. Therefore, the extra thermal component is a possible explanation for the apparent spectral evolution. Assuming the source continues to decay with the same decay index of 2.5, we predict an XRT count rate of 8.8e-4 counts/s at T+24 hours, which corresponds to an 0.3-10.0 keV observed (unabsorbed) flux of 6.1e-14 (6.2e-14) ergs cm^-2 s^-1. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7460 SUBJECT: GRB 080319C: Swift-XRT Team Refined Analysis DATE: 08/03/19 20:13:43 GMT FROM: Claudio Pagani at PSU/Swift-XRT C. Pagani, J. L. Racusin, J.A. Kennea, D. N. Burrows (PSU) and P. A. Evans (U Leicester) report on behalf of the Swift-XRT team: The Swift-XRT started observing GRB 080319C (trigger=306778, Pagani et al. GCN 7442) at 12:29:40 UT, 224 seconds after the BAT trigger. The Swift slew to the burst was delayed because of an Earth constraint. The current dataset consist of 2.2ks of Photon Counting mode data from the first orbit of observation. Using 595 s of overlapping XRT Photon Counting mode and UVOT 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 = 258.97980, 55.39197 which is equivalent to: RA (J2000): 17 15 55.15 Dec (J2000): +55 23 31.1 with an uncertainty of 1.7 arcsec (radius, 90% confidence). The 0.3-10 keV X-ray light curve starts at a count rate of ~7 counts/s and peaks at ~18 counts/s at T+360 seconds, after which it shows a decline with a decay slope of 0.9 +/- 0.1 with hints of superimposed flaring activity. The spectrum of the PC data can be well fit by an absorbed powerlaw with photon index 1.73 +/- 0.06 and column density of (1.5 +/- 0.1)e21 cm^-2, in excess of the Galactic column density of 2.21e20 cm^-2 in this direction. The average observed 0.3-10 keV flux is 1.0e-10 erg cm^-2 s^-1, which corresponds to an unabsorbed flux of 1.3e-10 erg cm^-2 s^-1. The counts to observed flux conversion factor at the time of this spectrum is 4.3e-11 erg cm^-2 count^-1. If the underlying powerlaw decay continues as is, we predict an XRT count rate of 0.11 counts/s at T+24hr, which corresponds to an observed 0.3-10keV flux of 4.7e-12 erg cm^-2 s^-1. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7461 SUBJECT: GRB080319B: Prompt PROMPT Detections DATE: 08/03/19 20:21:30 GMT FROM: Mark Schubel at UNC/PROMPT M. Schubel, D. Reichart, M. Nysewander, A. LaCluyze, K. Ivarsen, J. A. Crain, A. Foster, T. Brennan, J. Haislip, J. Styblova, and A. Trotter report: Skynet observed the localization of GRB 080319B (Racusin et al., GCN 7427) with three of the 16" PROMPT telescopes at CTIO beginning 32 seconds after the trigger (15 seconds after notification) in UVRI. We detect the afterglow (Racusin et al., GCN 7428) in all filters. At 92 seconds after the burst we measure V ~ 8.6 mag (calibrated to 3 NOMAD stars), and at 147 seconds we measure I ~ 8.9 mag (calibrated to 6 USNO B1 stars). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7462 SUBJECT: GRB 080319B, Swift-BAT refined analysis DATE: 08/03/19 20:21:44 GMT FROM: Scott Barthelmy at NASA/GSFC J. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), J. L. Racusin (PSU), 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-120 to T+182 sec from recent telemetry downlinks, we report further analysis of BAT GRB 080319B (trigger #306757) (Racusin, et al., GCN Circ. 7427). The BAT ground-calculated position is RA, Dec = 217.919, 36.300 deg which is RA(J2000) = 14h 31m 40.7s Dec(J2000) = +36d 17' 58.4" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a large long bump of a peak starting at ~T-10 sec, ramping up until ~T+10 sec, then mostly a flat top with some small structure superposed, then starting to decay at ~T+50 sec. It returns nearly to background by ~T+64 sec at which point there is a loss of data due to an on-board data product buffer overflow. The data resumes at T+120 sec. There is still detectable emission in the BAT 15-350 keV band out to T+180 sec (the limit of the data downlinked so far). From other count rate data products, we can say that there is no other peaks during the 60-sec missing event data window and that the low-level emission is about 10-15% of the peak emission. Given the missing data, T90 (15-350 keV) has to be >50 sec (estimated error including systematics). The time-averaged spectrum from T-3.8 to T+62.2 and T+120 to T+151 sec is fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.04 +- 0.02. The fluence in the 15-150 keV band is 8.1 +- 0.1 x 10^-05 erg/cm2. The 1-sec peak photon flux measured from T+16.87 sec in the 15-150 keV band is 24.8 +- 0.5 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/306757/BA/ Due to a large backlog in downlinking the full data on this burst, we currently do not have the usual data set out to long times yet. Should the remaining data show that there is ongoing activity for this burst past the data cutoff at T+182sec, then we will issue an updated 'refined analysis' circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7463 SUBJECT: GRB 080319A: Swift-XRT Team Refined Analysis DATE: 08/03/19 22:07:29 GMT FROM: Claudio Pagani at PSU/Swift-XRT C. Pagani and J. L. Racusin (PSU) report on behalf of the Swift-XRT team: The Swift-XRT started observing GRB 080319A (trigger=306754, Pagani et al. GCN 7426) at 05:54:59.4 UT, 557.4s after the trigger. The Swift slew to the burst was delayed because of an Earth constraint and XRT observations were interrupted by the Swift trigger on GRB 080319B. The current observations consist of Photon Counting mode data from T+560s to T+1632s and from T+35ks to T+37ks. The best XRT position is the UVOT-enhanced position from Beardmore et al. (GCN 7448), consistent with the optical afterglow position reported by Cenko (GCN 7429). The 0.3-10 keV X-ray light curve starts at a count rate of ~1 counts/s and shows a decline with a decay slope of 0.94 +/- 0.05. The spectrum of the PC data from T+560s to T+1632s can be well fit by an absorbed powerlaw with photon index 2.1 +/- 0.3 and column density of (1.0 +/- 0.7)e21 cm^-2, in excess of the Galactic column density of 1.45e20 cm^-2 in this direction. The average observed 0.3-10keV flux is 1.6e-11 erg cm^-2 s^-1, which corresponds to an unabsorbed flux of 2.1e-11 erg cm^-2 s^-1. The counts to observed flux conversion factor at the time of this spectrum is 3.7e-11 erg cm^-2 count^-1. If the underlying powerlaw decay continues as is, we predict an XRT count rate of 0.008 counts/s at T+24hr, which corresponds to an observed 0.3-10keV flux of 2.9e-13 erg cm^-2 s^-1. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7464 SUBJECT: GRB 080319B: RAPTOR observations of a naked eye burst DATE: 08/03/19 22:09:52 GMT FROM: Przemyslaw R. Wozniak at LANL P. Wozniak, W.T. Vestrand, J. Wren, and H. Davis (Los Alamos National Laboratory) The RAPTOR sky monitoring system began observing the location of GRB 080319B more than an hour before the Swift BAT trigger 306757 (Racusin et al., GCN 7427). The first exposure with detectable optical emission started ~2 seconds after the trigger at 06:12:50.9 UT. A peak brightness of 5.6 mag was recorded in time interval from 06:13:21.2 to 06:13:31.2 UT, before the end of the gamma-ray emission. Using the redshift z=0.937 from Vreeswijk et al. (GCN 7444) the estimated luminosity of GRB 080319B exceeds that of GRB 990123. Our response arrays RAPTOR-P and T began imaging at 06:14:24.3 UT following the XRT localization trigger that interrupted the ongoing follow-up measurements of GRB 080319A. The OT is detected by both response instruments including all channels (V,R,I,clear) of the simultaneous multicolor imager RAPTOR-T. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7465 SUBJECT: GRB080319B - SDSS Pre-Burst Observations DATE: 08/03/19 22:57:48 GMT FROM: Richard J. Cool at U.of AZ/Steward Obs Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona), David W. Hogg (NYU), Michael R. Blanton (NYU), David J. Schlegel (LBNL), J. Brinkmann (APO), Donald Q. Lamb (Chicago), Donald P. Schneider (PSU), and Daniel E. Vanden Berk (PSU) report: The Sloan Digital Sky Survey (SDSS) imaged the field of burst GRB080319B prior to the burst. As these data should be useful as a pre-burst comparison and for calibrating photometry, we are supplying the images and photometry measurements for this GRB field to the community. Data from the SDSS, including 5 FITS images, 3 JPGS, and 3 files of photometry and astrometry, are being placed at http://mizar.as.arizona.edu/~grb/public/GRB080319B We supply FITS images in each of the 5 SDSS bands of a 8'x8' region centered on the GRB position (ra=217.920 (14:31:40.7), dec=36.3041 (36:18:14.8); GCN 7427), as well as 3 gri color-composite JPGs (with different stretches). The units in the FITS images are nanomaggies per pixel. A pixel is 0.396 arcsec on a side. A nanomaggie is a flux-density unit equal to 10^-9 of a magnitude 0 source or, to the extent that SDSS is an AB system, 3.631e-6 Jy. The FITS images have WCS astrometric information. In the file GRB080319B_sdss.calstar.dat, we report photometry and astrometry of 193 bright stars (r<20.5) within 15' of the burst location. The magnitudes presented in this file are asinh magnitudes as are standard in the SDSS (Lupton 1999, AJ, 118, 1406). Beware that some of these stars are not well-detected in the u-band; use the errors and object flags to monitor data quality. In the files GRB080319B_sdss.objects_flux.dat and GRB080319B_sdss.objects_magnitudes.dat, we report photometry of 705 objects detected within 6' of the GRB position. We have removed saturated objects and objects with model magnitudes fainter than 23.0 in the r-band. The fluxes listed in GRB080319B_sdss.objects_flux.dat are in nanomaggies while the magnitudes listed in GRB080319B_sdss.objects_magnitudes.dat are asinh magnitudes. All quantities reported are standard SDSS photometry, meaning that they are very close to AB zeropoints and magnitudes are quoted in asinh magnitudes. Photometric zeropoints are known to about 2% rms. None of the photometry is corrected for dust extinction. The Schlegel, Finkbeiner, and Davis (1998) predictions for this region are A_U=0.059 mag, A_g=0.043 mag, A_r = 0.031 mag, A_i=0.024 mag, and A_z=0.017 mag. The file GRB080319B_sdss.spectro.dat contains a list of the 3 objects with SDSS spectroscopy within 6 arcminutes of the GRB position. In addition to the redshift and 1-sigma error for each object, this file also lists the object spectroscopic classification. SDSS astrometry is generally better than 0.1 arcsecond per coordinate. Users requiring high precision astrometry should take note that the SDSS astrometric system can differ from other systems such as those used in other notices; we have not checked the offsets in this region. More detailed information pertaining to our SDSS GRB releases can be found in our initial data release paper (Cool et al. 2006, PASP 118, 733). See the SDSS DR4 documentation for more details: http://www.sdss.org/dr5. These data have been reduced using a slightly different pipeline than that used for SDSS public data releases. We cannot guarantee that the values here will exactly match those in the data release in which these data are included. In particular, we expect the photometric calibrations to differ by of order 0.01 mag. This note may be cited, but please also cite the SDSS data release paper, Adelman-McCarthy et al. (2007, ApJS, 172, 634), when using the data or referring to the technical documentation. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7467 SUBJECT: GRB 080319A SDSS Pre-Burst Observations DATE: 08/03/19 23:12:13 GMT FROM: Richard J. Cool at U.of AZ/Steward Obs Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona), David W. Hogg (NYU), Michael R. Blanton (NYU), David J. Schlegel (LBNL), J. Brinkmann (APO), Donald Q. Lamb (Chicago), Donald P. Schneider (PSU), and Daniel E. Vanden Berk (PSU) report: The Sloan Digital Sky Survey (SDSS) imaged the field of burst GRB080319A prior to the burst. As these data should be useful as a pre-burst comparison and for calibrating photometry, we are supplying the images and photometry measurements for this GRB field to the community. Data from the SDSS, including 5 FITS images, 3 JPGS, and 3 files of photometry and astrometry, are being placed at http://mizar.as.arizona.edu/~grb/public/GRB080319A We supply FITS images in each of the 5 SDSS bands of a 8'x8' region centered on the GRB position (ra=206.333 (13:45:19.9), dec=44.0803 (44:04:49.1); GCN 7426), as well as 3 gri color-composite JPGs (with different stretches). The units in the FITS images are nanomaggies per pixel. A pixel is 0.396 arcsec on a side. A nanomaggie is a flux-density unit equal to 10^-9 of a magnitude 0 source or, to the extent that SDSS is an AB system, 3.631e-6 Jy. The FITS images have WCS astrometric information. In the file GRB080319A_sdss.calstar.dat, we report photometry and astrometry of 227 bright stars (r<20.5) within 15' of the burst location. The magnitudes presented in this file are asinh magnitudes as are standard in the SDSS (Lupton 1999, AJ, 118, 1406). Beware that some of these stars are not well-detected in the u-band; use the errors and object flags to monitor data quality. In the files GRB080319A_sdss.objects_flux.dat and GRB080319A_sdss.objects_magnitudes.dat, we report photometry of 404 objects detected within 6' of the GRB position. We have removed saturated objects and objects with model magnitudes fainter than 23.0 in the r-band. The fluxes listed in GRB080319A_sdss.objects_flux.dat are in nanomaggies while the magnitudes listed in GRB080319A_sdss.objects_magnitudes.dat are asinh magnitudes. All quantities reported are standard SDSS photometry, meaning that they are very close to AB zeropoints and magnitudes are quoted in asinh magnitudes. Photometric zeropoints are known to about 2% rms. None of the photometry is corrected for dust extinction. The Schlegel, Finkbeiner, and Davis (1998) predictions for this region are A_U=0.075 mag, A_g=0.055 mag, A_r = 0.040 mag, A_i=0.030 mag, and A_z=0.021 mag. The file GRB080319A_sdss.spectro.dat contains a list of the 6 objects with SDSS spectroscopy within 6 arcminutes of the GRB position. In addition to the redshift and 1-sigma error for each object, this file also lists the object spectroscopic classification. SDSS astrometry is generally better than 0.1 arcsecond per coordinate. Users requiring high precision astrometry should take note that the SDSS astrometric system can differ from other systems such as those used in other notices; we have not checked the offsets in this region. More detailed information pertaining to our SDSS GRB releases can be found in our initial data release paper (Cool et al. 2006, PASP 118, 733). See the SDSS DR4 documentation for more details: http://www.sdss.org/dr5. These data have been reduced using a slightly different pipeline than that used for SDSS public data releases. We cannot guarantee that the values here will exactly match those in the data release in which these data are included. In particular, we expect the photometric calibrations to differ by of order 0.01 mag. This note may be cited, but please also cite the SDSS data release paper, Adelman-McCarthy et al. (2007, ApJS, 172, 634), when using the data or referring to the technical documentation. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7468 SUBJECT: GRB 080319C - SDSS Pre-Burst Observations DATE: 08/03/19 23:20:53 GMT FROM: Richard J. Cool at U.of AZ/Steward Obs Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona), David W. Hogg (NYU), Michael R. Blanton (NYU), David J. Schlegel (LBNL), J. Brinkmann (APO), Donald Q. Lamb (Chicago), Donald P. Schneider (PSU), and Daniel E. Vanden Berk (PSU) report: The Sloan Digital Sky Survey (SDSS) imaged the field of burst GRB080319C prior to the burst. As these data should be useful as a pre-burst comparison and for calibrating photometry, we are supplying the images and photometry measurements for this GRB field to the community. Data from the SDSS, including 5 FITS images, 3 JPGS, and 3 files of photometry and astrometry, are being placed at http://mizar.as.arizona.edu/~grb/public/GRB080319C We supply FITS images in each of the 5 SDSS bands of a 8'x8' region centered on the GRB position (ra=258.983 (17:15:55.9), dec=55.3920 (55:23:31.2); GCN 7442), as well as 3 gri color-composite JPGs (with different stretches). The units in the FITS images are nanomaggies per pixel. A pixel is 0.396 arcsec on a side. A nanomaggie is a flux-density unit equal to 10^-9 of a magnitude 0 source or, to the extent that SDSS is an AB system, 3.631e-6 Jy. The FITS images have WCS astrometric information. In the file GRB080319C_sdss.calstar.dat, we report photometry and astrometry of 467 bright stars (r<20.5) within 15' of the burst location. The magnitudes presented in this file are asinh magnitudes as are standard in the SDSS (Lupton 1999, AJ, 118, 1406). Beware that some of these stars are not well-detected in the u-band; use the errors and object flags to monitor data quality. In the files GRB080319C_sdss.objects_flux.dat and GRB080319C_sdss.objects_magnitudes.dat, we report photometry of 508 objects detected within 6' of the GRB position. We have removed saturated objects and objects with model magnitudes fainter than 23.0 in the r-band. The fluxes listed in GRB080319C_sdss.objects_flux.dat are in nanomaggies while the magnitudes listed in GRB080319C_sdss.objects_magnitudes.dat are asinh magnitudes. All quantities reported are standard SDSS photometry, meaning that they are very close to AB zeropoints and magnitudes are quoted in asinh magnitudes. Photometric zeropoints are known to about 2% rms. None of the photometry is corrected for dust extinction. The Schlegel, Finkbeiner, and Davis (1998) predictions for this region are A_U=0.134 mag, A_g=0.098 mag, A_r = 0.071 mag, A_i=0.054 mag, and A_z=0.038 mag. The file GRB080319C_sdss.spectro.dat contains a list of the 4 objects with SDSS spectroscopy within 6 arcminutes of the GRB position. In addition to the redshift and 1-sigma error for each object, this file also lists the object spectroscopic classification. SDSS astrometry is generally better than 0.1 arcsecond per coordinate. Users requiring high precision astrometry should take note that the SDSS astrometric system can differ from other systems such as those used in other notices; we have not checked the offsets in this region. More detailed information pertaining to our SDSS GRB releases can be found in our initial data release paper (Cool et al. 2006, PASP 118, 733). See the SDSS DR4 documentation for more details: http://www.sdss.org/dr5. These data have been reduced using a slightly different pipeline than that used for SDSS public data releases. We cannot guarantee that the values here will exactly match those in the data release in which these data are included. In particular, we expect the photometric calibrations to differ by of order 0.01 mag. This note may be cited, but please also cite the SDSS data release paper, Adelman-McCarthy et al. (2007, ApJS, 172, 634), when using the data or referring to the technical documentation. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7469 SUBJECT: GRB 080319B: optical observations DATE: 08/03/20 00:35:10 GMT FROM: Martin Jelinek at Inst.Astrophys.Andalucia,Granada Martin Jelinek, Alberto J. Castro-Tirado (IAA-CSIC Granada), Virginie Chantry (Université de Liege) and Jorge Plá (IAC La Laguna), on behalf of a larger collaboration, report: "We are imaging the naked eye GRB 080319B detected by Swift (GCN 7427) using.both the 1.2m Mercator Telescope at Obs. del Roque de los Muchachos in La Palma, and the 0.8m IAC80 at Obs. del Teide in Tenerife. Our R-band magnitude measured on an image starting at 22:56UT (16.75 hr after the burst) is about R=21.0. Further images are planned throughout the whole night." This message can be cited. -- Martin Jelinek, +420602105255, +34617840945, sirrah.cz/mates Instituto de Astrofisica de Andalucia, Granada # vim:set ai et sts=8 tw=60: //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7470 SUBJECT: GRB 080319B: ROTSE-III Observations of Optical Counterpart DATE: 08/03/20 01:07:48 GMT FROM: Heather Swan at U.of Michigan/ROTSE H. Swan (U Mich), F. Yuan (U Mich), W. Rujopakarn (Steward) ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 080319B (Swift trigger 306757; Racusin et al., GCN 7427) and began imaging at 06:13:11.06 UT (5.3 sec after the GCN notice time) under suboptimal conditions, because of condensation present on the CCD. Observations continued until about 5 hours after the trigger. This condensation made the analysis very difficult, but we detect the OT first reported in GCN 7428. Further analysis is ongoing. These unfiltered images are calibrated to the USNO B1.0 R2 catalog. start UT end UT mag mlim(of image) 06:13:11.06 06:13:16.06 5.35 9.8 06:14:30.66 06:14:50.66 8.49 13.0 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7475 SUBJECT: GRB 080319C: KAIT OA observations DATE: 08/03/20 05:43:41 GMT FROM: Weidong Li at UC Berkeley KAIT/LOSS W. Li and A. V. Filippenko, University of California, Berkeley, report on behalf of the KAIT GRB team: We have analyzed the KAIT observations of the optical afterglow (OA) of GRB 080319C (GCN 7442, GCN 7460) as reported in GCN 7441. Our first 5 s unfiltered observation started at 12:27:11 UT, 75 s after the BAT trigger. Four subsequent 5 s exposures from t = 81 s to 100 s indicate a smoothly decaying behavior (but perhaps not power law). After reaching a minimum at t = 180 s (or perhaps a bit earlier), the OA brightened steeply to a second prominent peak centered at t ~ 320 s, after which the OA decayed as an approximate power law, with evidence for a gradually steepening decay index. Selected photometry, all unfiltered but calibrated to the R band via USNO B1: t_start (s) exp (s) mag mag_err 75 5.0 17.353 0.057 100 5.0 17.71 0.062 180 20.0 17.95 0.051 271 20.0 17.322 0.022 362 20.0 17.32 0.023 453 20.0 17.487 0.027 845 20.0 18.06 0.048 1429 20.0 18.866 0.096 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7476 SUBJECT: GRB 080319B: second epoch imaging from Canarias (correction to GCN7469) DATE: 08/03/20 05:47:23 GMT FROM: Martin Jelinek at Inst.Astrophys.Andalucia,Granada Martin Jelinek, Alberto J. Castro-Tirado (IAA-CSIC Granada), Virginie Chantry (Université de Liege) and Jorge Plá (IAC La Laguna), on behalf of a larger collaboration, report: "We were imaging the naked eye GRB 080319B detected by Swift (GCN 7427) using.both the 1.2m Mercator Telescope at Obs. del Roque de los Muchachos in La Palma, and the 0.8m IAC80 at Obs. del Teide in Tenerife. Between two epochs of imaging, one started at 22:56 (~16.75hr after the GRB), the other at 3:27UT (20h after) we measure an aproximate decay index of ~1.3. Our R-band magnitude measured on an image starting at 22:56UT (16.75 hr after the burst) was about R=19.8. The value reported in the previous GCN 7469 has been incorrect." This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7477 SUBJECT: GRB 080319C: Early RAPTOR Observations DATE: 08/03/20 06:07:34 GMT FROM: James Wren at LANL J. Wren, W.T. Vestrand, P.R. Wozniak, H. Davis of Los Alamos National Laboratory report: Our RAPTOR telescopes responded to Swift trigger 306778 (Pagani et al., GCN 7442) at 12:26:30.66 UTC, 33.70 seconds after the trigger. We detect the optical counterpart initially reported by Li (GCN 7441). Our measurements are consistent with those reported by KAIT (GCN 7441 and 7475) and Super-LOTIS (7443). Our images became dominated by the morning twilight at about 12:35 UTC. The unfiltered measurements reported in the following table are calibrated to the USNO-B1 R band. t-mid(s) exp(s) mag mag-err ----------------------------------------- 47.60 5.0 16.97 0.32 85.27 80.3 17.65 0.18 177.36 61.5 18.22 0.36 228.87 61.1 17.32 0.16 293.28 61.7 17.41 0.20 358.12 62.1 17.13 0.16 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7481 SUBJECT: GRB 080319B: WSRT Radio Observations DATE: 08/03/20 10:56:40 GMT FROM: Alexander van der Horst at NASA/MSFC A.J. van der Horst (NASA/ORAU) reports on behalf of a large collaboration: "We observed the position of the GRB 080319B afterglow at 4.9 GHz with the Westerbork Synthesis Radio Telescope at March 19 20.24 UT to March 20 8.22 UT, i.e. 14.0 - 26.0 hours after the burst (GCN 7427). We do not detect a radio source at the position of the optical counterpart (GCN 7428). The three-sigma rms noise in the map around that position is 84 microJy per beam. The formal flux measurement for a point source at the position of the optical counterpart is 59 +/- 26 microJy. We would like to thank the WSRT staff for rapidly scheduling and obtaining these observations." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7482 SUBJECT: Konus-Wind observation of GRB 080319B DATE: 08/03/20 12:04:43 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team report: The bright GRB 080319B (Swift-BAT trigger #306757: Racusin et al., GCN 7427, Cummings et al., GCN 7462) triggered Konus-Wind at T0=22370.339 s UT (06:12:50.339). The burst light curve shows a single complex pulse with a duration of ~60 s, followed by a long decaying tail seen up to T-T0 ~200 s in the G1(18-70 keV) and G2(70-300 keV) bands and even beyond in the G1 band. Preliminary analysis of the Konus-Wind data yields the burst fluence of 5.72(-0.13, +0.14)x10^-4 erg/cm2, and a 64-ms peak flux measured from T0+19.2 s of (2.17 +/- 0.21)x10^-5 erg/cm2/s (both in the 20 keV - 7 MeV energy range). The time-integrated spectrum of the main pulse (from T0 to T0+59.648 s) can be fitted (in the 25 keV - 7 MeV range) by GRBM (Band) model for which: the low-energy photon index is alpha = -0.822(-0.012, +0.014), the high energy photon index beta = -3.87(-1.09, +0.44), the peak energy Ep = 651 (-14, +13) keV (chi2 = 96.2/81 dof). All the quoted errors are at the 90% confidence level. Assuming z = 0.937 (Vreeswijk et al., GCN 7444, 7451) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.3, Omega_\Lambda = 0.7, the isotropic energy release is E_iso ~1.32x10^54 erg, the maximum luminosity is (L_iso)_max ~9.67x10^52 erg/s, and Ep_rest ~1261 keV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB080319_T22370/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7483 SUBJECT: GRB 080319C, Swift-BAT refined analysis DATE: 08/03/20 13:57:13 GMT FROM: Scott Barthelmy at NASA/GSFC M. Stamatikos (GSFC/ORAU), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), C. Pagani (PSU), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-120 to T+88 sec from recent telemetry downlinks, we report further analysis of BAT GRB 080319C (trigger #306778) (Pagani, et al., GCN Circ. 7442). The BAT ground-calculated position is RA, Dec = 259.006, 55.393 deg which is RA(J2000) = 17h 16m 01.4s Dec(J2000) = +55d 23' 33.0" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 30%. For the limited event-by-event data we have received on this burst, the mask-weighted light curve shows 2 (possibly 3) overlapping FRED-like peaks starting at T-0.5 sec, peaking at T+0.2 sec, and ending at ~T+50 sec. The event-by-event data for this m-w lightcurve ends at T+88 sec. The on-board raw countrate lightcurve shows no activity after the T+88 sec limit of the event data, but the sensitivity is significantly less for this data product. T90 (15-350 keV) is 34 +- 9 sec (estimated error including systematics). The time-averaged spectrum from T-0.3 to T+51.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.37 +- 0.07. The fluence in the 15-150 keV band is 3.6 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.13 sec in the 15-150 keV band is 5.2 +- 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/306778/BA/ If we receive any more data on this burst and it shows any on-going activity beyond the current data limit of T+88 sec, then we will issue a revised circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7484 SUBJECT: GRB 080319B optical observations DATE: 08/03/20 13:57:38 GMT FROM: AAVSO GRB Network at AAVSO Veli-Pekka Hentunen (Varkaus, Finland), Arto Oksanen (Muurame, Finland), and Petri Kehusmaa (Hyvinkaa, Finland) report to the AAVSO High Energy Network the following optical detections and upper limits of GRB 080319B (Racusin et al., GCN Circular #7427): Veli-Pekka Hentunen and Markku Nissinen (Taurus Hill Obs., Varkaus, Finland) report the detection of the optical afterglow of GRB 080319B (Racusin et al., GCN Circular #7427). The afterglow was observed unfiltered for a total of 1500 seconds using an SBIG ST8-XME CCD mounted on a Meade LX200 0.3-m telescope. Observations commenced approximately 15.3 hours post-burst; the mid-point of the observations was 2008 March 19.8999 UT. The afterglow was clearly detected at an unfiltered magnitude of 19.08 +/- 0.02, calibrated relative to USNO-A2.0 1200-07324239. A detailed report of this observation is available at the following URL: ftp://ftp.aavso.org/grb/Veli-PekkaHentunen_080319B_2454545.53358_.txt A FITS image of this observation is available at the following URL: ftp://ftp.aavso.org/grb/Veli-PekkaHentunen_080319B_2454545.53358_.fits Petri Kehusmaa (Slope Rock Observatory, Hyvinkaa, Finland) reports a non-detection of the optical afterglow of GRB 080319B. The afterglow was observed through a V filter for a total of 1800 seconds using an SBIG ST-7XME CCD mounted on a 0.2-m telescope. Observations commenced approximately 17 hours post-burst; the mid-point of the observations was 2008 March 19.9675 UT. The afterglow was not detected in the V-band with an upper limit of R=17.6 (calibrated relative to USNO-A2.0). A detailed report of this observation is available at the following URL: ftp://ftp.aavso.org/grb/PetriKehusmaa_GRB080319B_2454545.93778_.txt A FITS image of this observation is available at the following URL: ftp://ftp.aavso.org/grb/PetriKehusmaa_GRB080319B_2454545.93778_.fits Arto Oksanen and Olli-Pekka Reimaala (Hankasalmi Obs., Hankasalmi, Finland) also report the detection of the optical afterglow of GRB 080319B. The afterglow was observed unfiltered for a total of 2040 seconds (17 x 120s) using an SBIG STL-1001E CCD mounted on an RC Optical Systems 0.4-m telescope. Observations commenced approximately 19.3 hours post-burst; the mid-point of the observations was 2008 March 20.0639 UT. The afterglow was clearly detected at an unfiltered (CR) magnitude 19.0 +/- 0.1, calibrated relative to USNO-A2.0. Note that this magnitude uses a different comparison star from that of Hentunen and Nissinen (see above), and may be offset by a few tenths of a magnitude. A detailed report of this observation is available at the following URL: ftp://ftp.aavso.org/grb/ArtoOksanen_GRB080319B_2454545.72325_.txt A FITS image of this observation is available at the following URL: ftp://ftp.aavso.org/grb/ArtoOksanen_GRB080319B_2454545.72325_.fits The AAVSO thanks the Curry Foundation for their continued support of the AAVSO International High Energy Network. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7485 SUBJECT: GRB 080319B: Allen Telescope Array Observations DATE: 08/03/20 14:16:39 GMT FROM: Josh Bloom at UC Berkeley Garrett Keating, Geoffrey Bower, Rick Forster, and J. S. Bloom (UC Berkeley) report for the Allen Telescope Array team: "The Allen Telescope Array observed GRB 080319B (Racusin et al.; GCN 7247) at a frequency of 1.43 GHz. Observations were obtained on 20 March 2008 between 5 and 7 UT. From this initial dataset, we report a non-detection at the location of afterglow with a 3 sigma upper limit of 18 mJy. Observations are continuing." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7486 SUBJECT: GRB 080319B: Gemini-South photometry DATE: 08/03/20 14:26:36 GMT FROM: Daniel Perley at U.C. Berkeley D. A. Perley, J. S. Bloom (UC Berkeley) and H.-W. Chen (U Chicago) report: On the night of 2008-03-20 (UT) we observed the optical afterglow of GRB 080319B (GCN 7427, Racusin et al.) with Gemini-South + GMOS in g, r, i, and z filters (4x180s in each filter). The source is well-detected in all bands. Magnitudes, calibrated to SDSS DR6, are: UTstart UTend t(hr) filt mag err 06:52:17 07:10:19 24.808 g 20.95 0.09 07:11:19 07:26:11 25.099 r 20.55 0.03 07:27:10 07:42:04 25.363 i 20.40 0.05 07:43:04 07:57:55 25.686 z 20.32 0.03 We thank the observing staff for performing these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7487 SUBJECT: Konus-Wind observation of GRB 080319C DATE: 08/03/20 14:34:46 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team report: The long GRB 080319C (Swift-BAT trigger #306778: Pagani et al., GCN 7442, Stamatikos et al., GCN 7483) triggered Konus-Wind at T0=44757.938 s UT (12:25:57.938). The burst light curve shows a multipeaked structure with a total duration of ~15 s. As observed by Konus-Wind the burst had a fluence of 1.50(-0.21, +0.34)x10^-5 erg/cm2, and a 256-ms peak flux measured from T0+0.256 s of 3.35(-0.70, +0.79)x10^-6 erg/cm2/s (both in the 20 keV - 4 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+16.640 s) is well fitted (in the 20 keV-4 MeV range) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.20 +/- 0.10, and Ep = 594(-131, +224) keV (chi2 = 79.3/73 dof). Fitting by GRBM (Band) model yields: the low-energy photon index is alpha = -1.01 +/- 0.13, the high energy photon index beta = -1.87(-0.63, +0.15), the peak energy Ep = 307(-92, +141) keV (chi2 = 76.1/72 dof). All the quoted errors are at the 90% confidence level. The Konus-Wind light curve of this GRB is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB080319_T44757/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7490 SUBJECT: GRB 080319D: Swift XRT refined analysis DATE: 08/03/20 20:01:09 GMT FROM: Dirk Grupe at PSU/Swift-XRT Dirk Grupe and Peter Brown (PSU) report on behalf of the Swift-XRT team: The Swift-XRT started observing GRB 080319D (trigger=306793, Brown et al. GCN 7453) at 17:07:37 UT, 148 seconds after the BAT trigger. The astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue) is: RA, Dec = 99.47254, +23.94275 which is equivalent to: RA (J2000): 06 37 53.41 Dec (J2000): +23 56 33.9 with an uncertainty of 1.7 arcsec (radius, 90% confidence). The 0.3-10 keV X-ray light curve starts with three flares up to 20 counts/s. The afterglow decays very fast and started to flatten at about 1000 s after the burst. The light curves shows another break at about 5 ks after the burst and is currently decaying with a decay slope of 1.3. The spectrum of the PC data can be well fit by an absorbed single powerlaw with photon index 2.12 ± 0.27 and column density of (3.8 ± 1.4)e21 cm-2. This is in excess of the Galactic column density of 2.17e21 cm-2 in this direction. Using this spectrum we estimated a count rate to flux conversion of 1 count/s converts to 6.28e-11 ergs/cm2/s. If the underlying powerlaw decay continues as is, we predict an XRT count rate of 1.6e-3 counts/s at T+24 hours and 6.5e-4 counts/s at T+48 hours after the burst, or 1.0e-13 ergs/s/cm2 and 4.1e-14 ergs/s/cm2, respectively. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7493 SUBJECT: GRB 080319B - CARMA mm Observations DATE: 08/03/21 02:06:56 GMT FROM: S. Bradley Cenko at Caltech D. C.-J. Bock (CARMA), P. C. Chandra (NRAO/UVA), S. R. Kulkarni (Caltech), D. A. Frail (NRAO), and S. B. Cenko (Caltech) report on behalf of a larger collaboration: We have observed the position of GRB080319B (Racusin et al.; GCN 7247) with the Combined Array for Research in Millimeter-wave Astronomy (CARMA) at 95 GHz on 2008 March 20 (mean time 11:30 UT). We report a non-detection at the optical afterlow position with a 3-sigma limit of 0.75 mJy. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7495 SUBJECT: GRB 080319A: UVOT Observations DATE: 08/03/21 11:33:57 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. T. Holland (CRESST/GSFC/USRA) and C. Pagani (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT observed the field of GRB 080319A starting 542 s after the BAT trigger (Pagani et al., GCN Circ. 7426). We detect the optical afterglow in the white filter at the location of the P60 source (Cenko, 2008, GCN Circ. 7429). Magnitudes and upper limits are reported below. Filter T_start (s) T_stop Exposure Mag Err Comment v 669 1544 432 >20.7 3-sigma UL b 767 1480 29 >19.8 3-sigma UL u 743 1618 58 >19.9 3-sigma UL white 562 662 98 21.1 0.3 875 975 98 >21.4 3-sigma UL The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0 .02 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). No early-time upper limits are available for the uvw1, uvm2, and uvw2 filters due to the lack of data resulting from the slew to GRB 080319B, which occurred 25 minutes after GRB 080319A. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7496 SUBJECT: GRB 080319B: UVOT Observations DATE: 08/03/21 11:34:39 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. T. Holland (CRESST/USRA/GSFC) & J. L. Racusin (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT observed the field of GRB 080319B starting 51 s after the BAT trigger (Racusin et al., GCN Circ. 7427). We detect the optical afterglow all filters. Preliminary magnitudes are reported below. Filter T_start (s) T_stop Exposure Mag Err Comment v 175 575 393 <11.5 Saturated b 654 664 10 13.39 0.01 u 630 649 19 12.44 0.01 uvw1 605 625 19 12.49 0.02 uvm2 581 600 19 13.39 0.05 uvw2 685 705 19 13.36 0.04 white 67 169 98 <13.9 Saturated The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0 .01 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: 7497 SUBJECT: GRB 080319C: UVOT Observations DATE: 08/03/21 11:37:34 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. T. Holland (CRESST/USRA/GSFC) & C. Pagani (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT observed the field of GRB 080319C starting 210 s after the BAT trigger (Pagani et al., GCN Circ. 7442). We detect the optical afterglow in the v, b, u, and white filters at location of the KAIT optical afterglow (Li, et al., 2008, GCNC 7441). The UVOT source position is RA(J2000.0) = 17:15:55.49 Dec(J2000.0) = +55:23:30.6 with an estimated uncertainty of +/-0.53 arcsec (radius, 90% confidence). Magnitudes and upper limits are reported below. Filter T_start (s) T_stop Exposure Mag Err Comment v 334 353 19 18.09 0.30 b 433 443 10 19.02 0.53 u 408 581 39 19.08 0.36 uvw1 383 2410 214 >20.0 3-sigma UL uvm2 358 2385 175 >19.6 3-sigma UL uvw2 463 2336 175 >19.9 3-sigma UL white 227 327 98 18.81 0.08 The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0 .03 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). The non-detections in the three ultraviolet filters may indicate that the redshift is z >~ 3. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7498 SUBJECT: GRB 080319D, Swift-BAT refined analysis DATE: 08/03/21 13:15:13 GMT FROM: Scott Barthelmy at NASA/GSFC T. Ukwatta (GWU) S. D. Barthelmy (GSFC), P. J. Brown (PSU), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 080319D (trigger #306793) (Brown, et al., GCN Circ. 7453). The BAT ground-calculated position is RA, Dec = 99.479, 23.982 deg which is RA(J2000) = 06h 37m 55.0s Dec(J2000) = +23d 58' 56.0" with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 59%. The mask-weighted light curve shows a roughly symmetric peak starting at ~T+0, peaking at ~T+23, and ending at ~T+50 sec. T90 (15-350 keV) is 24 +- 4 sec (estimated error including systematics). The time-averaged spectrum from T+5.0 to T+34.5 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.92 +- 0.35. The fluence in the 15-150 keV band is 3.2 +- 0.7 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+25.35 sec in the 15-150 keV band is 0.1 +- 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/306793/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7499 SUBJECT: GRB080319B: Time-Independent XRT Spectrum DATE: 08/03/21 16:41:56 GMT FROM: Nat Butler at MIT/CSR Nat Butler (UC Berkeley) reports: I have applied our time-dependent pileup correction code (Butler & Kocevski 2007; ApJ, 663, 407) to the XRT spectrum of GRB080319B (see, Racusin et al., GCN 7459). Although I find similar temporal properties in the afterglow decay to those quoted by the XRT team, I find significantly different spectral properties. Notably, there is no significant evidence for a time-variation in N_H and no significant need for a thermal component. The WT model (0.4-10 keV) and PC mode (0.3-10 keV) spectra fitted jointly and well (chi^2/nu=799.70/788) with an absorbed powerlaw yields: Gamma = 1.84+/-0.01 N_H = 1.7+/-0.1 x 10^21 cm^(-2) @ z=0.937 (Vreeswijk et al., GCN 7451), in addition to the expected Galaxy contribution along the line of sight. Here we assume the solar chemical abundances from Anders & Ebihara (1982). This value of N_H implies ~2 mag extinction in the observer frame V band assuming the mean Galactic dust+gas properties. Allowing the photon indices to vary separately: Gamma1=1.84^{+0.1}_{-0.2} and Gamma2=1.85+/-0.05, closely consistent. The fractional possible increase in rest-frame N_H between the WT mode data (t=660s to 4.95 ksec) and the PC mode data (t=4.95 to 174 ksec) is modest and weakly significant: 0.74^{+0.43}_{-0.37}%. I suspect the indicated variations are purely due to calibration uncertainties in the WT mode data. The hard WT mode spectral fit in GCN 7459 can be reproduced by relaxing our pileup correction. Additional evidence disfavors an interpretation of an evolving X-ray spectrum: Time resolved fits to the WT mode data show no significant evidence for spectral evolution in the WT mode data considered alone. See, http://astro.berkeley.edu/~nat/080319B_spec.jpg The light curve is a simple (broken) powerlaw for the WT mode data, with no flaring. Afterglows with such light curves typically exhibit weak or no spectral evolution (e.g., Butler & Kocevski 2007, ApJ, 668, 400). There is no significant variations in the X-ray hardness ratio for this event. See, http://astro.berkeley.edu/~nat/080319B_hardness.jpg A fit to BAT data (see also, Cummings et al., GCN 7462) in a time region (58s to 303s; chi^2/nu=36.46/55) overlapping the XRT observation has a roughly consistent powerlaw (Gamma=2.1+/-0.1), and also allows for a smooth extrapolation in flux between BAT and XRT assuming a simple powerlaw model connecting the flux in both instruments. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7500 SUBJECT: GRB 080319D: optical upper limit DATE: 08/03/21 17:57:03 GMT FROM: Giuseppe Greco at U Bologna G. Greco (Bologna University), F. Terra (Second University of Roma "Tor Vergata"), C. Bartolini, A. Guarnieri, A. Piccioni (Bologna University), F. Munz, G. Pizzichini (INAF/IASF Bologna), D. Nanni (INAF/OAR and Second University of Rome "Tor Vergata"), A. Shearer (Centre for Astronomy, Galway), R. Gualandi (Bologna Observatory) report: We observed the field of GRB 080319D (Brown et al., GCN 7453) with the 152 cm telescope located in Loiano, under unfavourable conditions due to full moon light. One Rc-band observation (1x600 sec) was done on 2008 March at 20.779 UT middle exposure time. We do not detect any object at the position of the candidate afterglow reported by Immler et al. (GCN 7458). Our 3-sigma limiting magnitude is R~20 (based on the Nomad1 catalogue). The image has been posted in our public directory from where it can be retrieved by sftp using hostname: ermione.bo.astro.it username: publicGRB password: GRB_bo. directory: GRB080319D //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7501 SUBJECT: GRB 080319B: optical upper limit DATE: 08/03/21 18:51:16 GMT FROM: Giuseppe Greco at U Bologna G. Greco (Bologna University), F. Terra (Second University of Roma "Tor Vergata"), C. Bartolini, A. Guarnieri, A. Piccioni (Bologna University), F. Munz, G. Pizzichini (INAF/IASF Bologna), D. Nanni (INAF/OAR and Second University of Rome "Tor Vergata"), A. Shearer (Centre for Astronomy, Galway), R. Gualandi (Bologna Observatory) report: We observed the field of GRB 080319B (GCN 7427, Racusin et al.) with the 152 cm telescope located in Loiano under unfavorable conditions due to the illumination of the full moon. By adding four consecutive 10 min exposures in the Rc filter at mean time 2008 March 20.947 UT we do not detect any object at the position of the optical bright afterglow reported by Racusin et al. (GCN 7428). Our 3-sigma limiting magnitude is R~20.3 (based on Nomad1 catalogue). The image has been posted in our public directory from where it can be retrieved by sftp using hostname: ermione.bo.astro.it username: publicGRB password: GRB_bo. directory: GRB080319B //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7502 SUBJECT: GRB 080319B: TORTORA light curve DATE: 08/03/21 19:54:17 GMT FROM: Sergey Karpov at SAO RAS S. Karpov, G. Beskin (SAO RAS, Russia), S. Bondar (RIPI, Russia), C. Bartolini, G. Greco, A. Guarnieri, A. Piccioni (Astronomy Department of Bologna University, Italy), D. Nanni, F. Terra (Second University of Roma "Tor Vergata", Italy), E. Molinari, G. Chincarini, F.M. Zerbi, S. Covino, V. Testa (Osservatorio Astronomico di Brera, Italy), G. Tosti (Universita di Perugia, Italy), F. Vitali, L.A. Antonelli (Osservatorio Astronomico di Roma, Italy), P. Conconi, G. Cutispoto (Osservatorio Astronomico di Catania, Italy), G. Malaspina (Osservatorio Astronomico di Brera, Italy), L. Nicastro (Istituto di Astrofisica Spaziale e Fisica Cosmica, Palermo, Italy), E. Palazzi (Istituto di Astrofisica Spaziale e Fisica Cosmica, Bologna, Italy), E. Meurs (Dunsink Observatory, Ireland), P. Goldoni (Observatori Astronomic - Universitat de Valencia Edificio de Institutos de Investigacion, Spain) report on behalf of TORTOREM team: Following GCN 7452 we publish a preliminary light curve of GRB 080319b with reduced temporal resolution (10 frames time binning, 1.3 seconds effective exposure, no gaps between frames). The photometry is performed in instrumental system and calibrated towards the V magnitudes of nearby Tycho2 stars. The light curve is available online at http://vo.astronet.ru/~karpov/grb080319b_lc_10.gif The light curve shows fast (~5 seconds) uprise towards the peak V=5.5 at T+23, complex multi-peak structure till T+50 and featureless decay then. In total, the transient has been visible for ~65 seconds; 6 seconds in the T+30 - T+36 interval are currently excluded from the analysis due to repointing of REM telescope at that time. The light curve is consistent with the one published by Pi of the Sky (Cwiok et al, GCN 7445). The video sequence of the data is available at http://vo.astronet.ru/~karpov/grb080319b.avi and with reduced temporal resolution at http://vo.astronet.ru/~karpov/grb080319b_lowres.avi The results of analysis of full-resolution (0.13s exposure) data will be published later. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7503 SUBJECT: GRB 080319D: GROND Observations DATE: 08/03/21 20:53:09 GMT FROM: Christian Clemens at MPE C. Clemens, S. Klose (Tautenburg Obs.), J. Greiner, A. Kupcu Yoldas, A. Yoldas, T. Kruehler and G. Szokoly (Eoetvoes Univ., Budapest and MPE Garching) (all others MPE Garching) report on behalf of the GROND team: We observed the field of GRB 080319D (SWIFT trigger 306793; P. J. Brown et al., GCN 7453) simultaneously in g', r', i', z', J, H and K with GROND (Greiner et al. 2008, PASP) mounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile). Observations started at 00:15 UT on March 20th, 2008, about 7.2 hrs after the GRB trigger at an airmass of 1.7 to 2.5. We obtained 0.5 hrs of total integration time in g', r', i' and z' and found a source, which might be the host galaxy, also present in the DSS2 red images at RA (J2000.0) = 06h 37m 53.56s DEC (J2000.0) = 23d 56' 34.2'' within the 0.5'' Swift UVOT error circle reported by S. Immler et al. in GCN 7458. The object is seen in all bands except K, implying a redshift smaller than 3.5. Our co-added images reveal roughly estimated magnitudes of g' = 21.3, r' = 20.7, i' = 19.9 and z' = 19.7, calibrated against USNO-B catalogue stars. No statement about variability, i.e. an additional contribution from afterglow light, can be made at this point. Further observations are planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7504 SUBJECT: GRB 080319B: Optical observation (Brno, CZ) DATE: 08/03/21 21:58:31 GMT FROM: Rudolf Novak at N.Copernicus Obs/Czech Rep We observed GRB 080319B using 40cm Newtonian telescope, SBIG ST-7XMEi CCD camera and R-band Kron-Cousins filter. We found afterglow to be R=20.0+-0.3 mag at 2008.03.20 0.125 UT. Given time is mid-exposure (total exposure: 6.7h). Weather conditions were poor because of clouds and Moon. We used 13 nearby USNO-B1.0 stars to get R magnitude. An aperture photometry package Munipack (http://adsabs.harvard.edu/abs/1998stel.conf...30H) was used for data reduction. Rudolf Novak Nicholas Copernicus Observatory & Planetarium in Brno, Czech Republic (http://ccd.astronomy.cz) Filip Hroch Masaryk University, Brno (http://monteboo.blogspot.com) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7506 SUBJECT: Radio Detection of GRB 080319B DATE: 08/03/22 21:08:48 GMT FROM: Alicia Soderberg at Caltech Alicia Soderberg (Princeton), Poonam Chandra (U. Virginia), and Dale Frail (NRAO) report on behalf of a larger collaboration: "We observed the field of GRB 080319B (GCN 7427) with the Very Large Array beginning at Mar 21.56 UT. At 4.86 GHz we detect a radio source coincident with the optical afterglow position (GCN 7428) at coordinates (J2000): RA = 14 31 41.01 +/- 0.05 Dec = 36 18 09.7 +/- 0.4 with flux density 189 +- 39 microJy. Further observations are scheduled. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7507 SUBJECT: GRB 080319B: Second & Third Epoch WSRT Radio Observations DATE: 08/03/23 02:43:15 GMT FROM: Alexander van der Horst at NASA/MSFC A.J. van der Horst (NASA/ORAU) reports on behalf of a large collaboration: "We re-observed the position of the GRB 080319B afterglow at 4.9 GHz with the Westerbork Synthesis Radio Telescope at March 21.84 to 22.03 UT and at March 22.84 to 23.03 UT, i.e. 2.7 and 3.7 days after the burst (GCN 7427). We do not detect a radio source at the position of the optical counterpart (GCN 7428) at 2.7 days. The three-sigma rms noise in the map around that position is 108 microJy per beam. We note that this upper limit is not consistent with the almost simultaneous VLA detection at 4.86 GHz reported in GCN 7506. We tentatively detect a radio source at 4 sigma significance at 3.7 days, with a flux density of 163 +/- 39 microJy. We would like to thank the WSRT staff for scheduling and obtaining these observations." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7508 SUBJECT: GRB 080319C: Suzaku WAM observation of the prompt emission DATE: 08/03/23 23:47:34 GMT FROM: Makoto Tashiro at Saitama U/Swift K.Onda, M. Tashiro, Y. Terada, Y. Urata, A. Endo, M. Suzuki, N. Kodaka, K. Morigami (Saitama U.), M. Ohno, T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima U.), T. Tamagawa (RIKEN), K. Yamaoka, Y. E. Nakagawa, S. Sugita (Aoyama Gakuin U.), T. Enoto, R. Miyawaki, K. Nakazawa, K. Makishima (Univ. of Tokyo), E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara (Univ. of Miyazaki), M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report: The long GRB 080319C (Swift/BAT trigger #306778 ; Pagani et al., GCN 7442) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 12:25:56 UT (=T0). The observed light curve shows a multi-peaked structure starting at T0s, ending at T0+14s with a duration (T90) of about 13 seconds. The fluence in 100 - 1000 keV was 6.4(+0.4, -0.9)*10^-6 erg/cm^2. The 1-s peak flux measured from T0+2s was 4.2(+0.2, -0.3) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0s to T0+13s is well fitted by a power-law with exponential cutoff model: dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with alpha 0.67(+0.30, -0.36), and Epeak 761(+255, -136) keV (chi^2/d.o.f. = 32.2/23). All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included. The light curves for this burst are available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7509 SUBJECT: GRB 080319B: Spitzer Mid-infrared Observations DATE: 08/03/24 05:59:23 GMT FROM: S. Bradley Cenko at Caltech H. Teplitz (IPAC), M. Werner (JPL), S. B. Cenko, S. R. Kulkarni and A. Rau (Caltech) report on behalf of a larger collaboration: We have imaged the field of GRB080319B (Racusin et al., GCN 7427) with the blue filter (15.8 um) of the IRS peak-up camera on board the Spitzer Space Telescope. Observations consisted of 60 pointings, each with two dithered 30 s cycles, beginning at March 21.81 UT (~ 2.55 d after the burst). At the location of the optical afterglow, we measure a flux density of 35.7 +/- 3.9 uJy. We wish to thank the entire Spitzer team for the prompt execution of these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7511 SUBJECT: GRB 080319B : Apparent spectral evolution in very early Swift/XRT WT mode data: intrinsic or pile-up effect? DATE: 08/03/24 22:35:33 GMT FROM: Binbin Zhang at UNLV Bin-Bin Zhang (University of Nevada Las Vegas), Enwei Liang (Guangxi University, China) and Bing Zhang (University of Nevada Las Vegas) report: We have processed the Swift XRT data of GRB 080319B, paying special attention to the possible spectral evolution in the WT mode data (Racusin et al. GCN 7459; cf. Butler GCN 7499). We perform a time-dependent spectral analysis using the method described in (Zhang, Liang & Zhang 2007, ApJ, 666, 1002). Since the early data are strongly affected by photon pile-up, we use a box annulus region for the WT mode data (outer radius 40*20, inner radius 8*20; see also Racusin et al. GCN 7459) and time-dependent circle annulus regions for the PC mode data to extract spectra and lightcurves. We fit the time-dependent spectra using a simple power-law model with the absorption from the MilkyWay Galaxy (NH_G=1.12e20 cm^{-2} ) and from the host galaxy (NH_host=7.3e20 cm^{-2}, obtained from fitting to the integrated 1st orbit WT mode spectrum). We confirm Butler (GCN 7499) that the apparent spectral evolution after 200 seconds is due to instrumental "pile up" effect. However, in the very early time t ~ (68-100) seconds, an apparent weak but significant hard-to-soft spectral evolution sustains even if we take into account the pile-up corrections. The photon index evolves from 1.67 ± 0.02 to 1.77 ± 0.02 during this period. Our results can be found at http://grb.physics.unlv.edu/~xrt/xrtweb/080319B/080319B.html. To make sure that this early-time spectral evolution is not due to the pile-up effect, we extract the time-dependent spectra with box annuli having different sizes. By excluding the central regions, we enlarge the outer radius up to 80 pixel * 20 pixel to make sure that there are enough photons for the spectral analysis. Our tests show that even if the inner box size is as large as 30 pixel * 20 pixel (spectra in annuli with such a large inner radius is not possible to be affected by the pile-up effect), the early time (before 200 seconds) XRT WT data still show significant spectral evolution. We therefore cautiously conclude that this early spectral evolution is likely intrinsic. Strong hard-to-soft spectral evolution has been seen in the early steep decay phase of many GRB X-ray afterglows (e.g. Zhang et al. 2007, 666, 1002), which points towards a non-forward-shock origin of the emission. We notice that the lightcurve before 200 seconds show several weak flaring/flicking features, which is more easily seen in linear scale (see http://grb.physics.unlv.edu/~xrt/xrtweb/080319B/earlylc.png). In view that some steep decay segments with overlapping flares typically show hard-to-soft spectral evolution (Group C in Zhang et al. 2007), we suspect that the weak spectral evolution in this burst is also related to the weak flaring/flicking features. It is however puzzling why this segment naturally transforms to a smooth decay after 200 seconds which show no further spectral evolution. Throughout our fit we have fixed the NH_host values. Another possibitly is that the apparent spectral evolution is caused by a varying NH_host value (Racusin et al. GCN 7459). We test such a scenario by fixing the photon index to \Gamma=1.76 (average value after 200s) and fit the time-dependent spectra before 200s using the same model (wabs*zbwas*zwabs) but allowing NH_host to be a free parameter. We obtain acceptable fits, and found that the NH_host in the early time evolves dramatically to one half of its initiall valve (from ~ 1.1e21 cm^{-2} to ~ 6.6e20 cm^{-2}). The time evolution of the NH_host value can be found at http://grb.physics.unlv.edu/~xrt/xrtweb/080319B/nh.png. This is another plausible physical scenario, although a model for the rapid depletion of NH_host is called for. The reduced chi2 in our fitting to the wabs*zwabs*powerlaw model is typically ~1. Although a possible thermal component has been suggested (cf. Racusin et al. GCN 7459), in our fitting no thermal component is required by the data. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7514 SUBJECT: GRB 080319D: GROND Detection of the Optical Counterpart DATE: 08/03/25 12:41:09 GMT FROM: Christian Clemens at MPE C. Clemens, S. Klose (Tautenburg Obs.), J. Greiner, A. Kupcu Yoldas, A. Yoldas, T. Kruehler and G. Szokoly (Eoetvoes Univ., Budapest and MPE Garching) (all others MPE Garching) report on behalf of the GROND team: We observed the field of GRB 080319D for a second time at 23:43 UT on March 23rd, 2008, about 4.3 days after the GRB trigger with 0.5 hrs of total integration time in g', r', i' and z'. We do not detect any object within the Swift UVOT error circle (S. Immler et al., GCN #7458) to the following 3-sigma upper limits: g' > 24.7, r' > 23.4, i' > 22.7 and z' > 22.5. This indicates a clear fading of the optical afterglow compared to our first epoch observations (C. Clemens et al., GCN #7503). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7517 SUBJECT: GRB 080319C: Gemini-North spectroscopic redshift DATE: 08/03/25 18:37:49 GMT FROM: Klaas Wiersema at U of Leicester K. Wiersema, N. Tanvir (University of Leicester), P. Vreeswijk, J. Fynbo (DARK Cosmology Centre), R. Starling, E. Rol (Leicester) and P. Jakobsson (Hertfordshire) report on behalf of a large collaboration: We observed the afterglow of GRB 080319C (GCN 7442) with Gemini North, using the GMOS-N instrument. We took spectra using the B600 grism (exposure time 4 x 900s) in bad weather conditions: exposures were taken through holes in the cloud deck. Observations started at 14:51 UT on March 19th. The spectrum shows several absorption lines of C IV, Al II, Si II, Al III, Mg I and the CrII / ZnII blend. From these we find the redshift z = 1.95. We are very grateful to the Gemini staff, in particular Paul Hirst, for executing these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7519 SUBJECT: GRB080319B: optical observations DATE: 08/03/25 21:41:49 GMT FROM: Alexei Pozanenko at IKI, Moscow Yu. Krugly, I. Slyusarev (Institute of Astronomy of Kharkiv National University), A. Pozanenko (IKI) report on behalf of larger collaboration: We observed the afterglow of GRB080319B (Racusin et al. GCN 7427) with 0.7m telescope of Institute of Astronomy, Kharkiv National Univ. starting on (UT) March 19, 18:20 and continuing to March 20, 02:44. The series consist of continuous observations in R and a few frames were taken in V around (UT) 19:58. The afterglow (Racusin et al. GCN 7427, Holland et al. GCN 7428, Li et al. GCN 7430) is detected in the obtained single images. Preliminary photometry of combined images reveals a possible rapid decline of the light curve between (UT, mid time) 18:25 (R~19.1) and 19:04 (R~19.9) and then light curve flattering toward the end of observation March 20 (UT) 02:00 (R~20.1). The light curve between (UT) 19:00 and 02:39 is close to a constant and not compatible with power law decay index of alpha=1.2. The magnitude of the comparison star is based on SDSS calibration (Cool et al, GCN 7465). The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7528 SUBJECT: GRB080319B, BVRcIc field calibration DATE: 08/03/28 12:39:47 GMT FROM: Arne A. Henden at AAVSO A. Henden (AAVSO) reports: While the field of GRB080319B has been observed by SDSS, we have also obtained a four-night BVRcIc field calibration using the 35cm robotic telescope at Sonoita Research Observatory. The calibration file has a limiting magnitude around V=16, with good standards brighter than V=11 or so. The file is available at ftp://ftp.aavso.org/public/calib/grb/grb080319b.dat This calibration is based on numerous Landolt standards, and has an external zeropoint error of about 0.02mag. We are continuing calibration of this field, moving to the west to pick up the 9th magnitude star SAO 64192, and will extend the calibration file when that photometry is available. Our system is available for any other bright BVRI calibrations (4 D. A. Perley, J. S. Bloom (UC Berkeley) and H.-W. Chen (U Chicago) report: We have continued to monitor the optical afterglow of GRB 080319B from Gemini-South. Additional images were taken on UT March 21, 25, and 28. Despite the presence of the Moon and low elevation of the target, the afterglow remains detected in all filters. We report on photometry, calibrated to SDSS DR6, as follows (including an improved analysis of images obtained on UT March 20, previously reported in GCN 7486). t(hr) filt mag err 24.808 g 20.83 0.05 25.099 r 20.53 0.02 25.363 i 20.37 0.03 25.686 z 20.32 0.04 48.653 r 21.56 0.03 144.553 g 23.59 0.15 144.886 r 23.49 0.09 145.220 i 23.13 0.06 145.553 z 23.48 0.11 216.703 r 23.56 0.06 217.036 i 23.28 0.06 The object appears visibly extended at late times, with a possible projection extending to the south; this may be the host galaxy of this gamma-ray burst. The imaging was acquired under variable seeing conditions and we caution that the presence of an underlying host may complicate the photometry. While roughly consistent with simple power-law decay of alpha=1.2-1.3 (e.g. GCN 7438, Li et al.), in detail the observations deviate slightly from a simple power-law, including a flattening in the last two sets of observations that may be due host galaxy light (and possibly a small amount of supernova contribution.) In addition, we note the presence of a very red source at an offset of 2.65" (slightly west of south) from the afterglow. Preliminary photometry of this object gives the following: g = 24.3 +/- 0.2 (marginal detection) r = 23.76 +/- 0.06 i = 22.55 +/- 0.03 z = 21.71 +/- 0.03 This offset corresponds to 21 kpc at a redshift of 0.937 (Vreeswijk et al., GCN 7451). It is dominated by a bright PSF-like center but also is visibly extended to the south. It may be an intervening absorber. Further follow-up is planned and encouraged. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7558 SUBJECT: GRB 080319B: TORTORA light curve (Correction) DATE: 08/04/01 11:21:31 GMT FROM: Sergey Karpov at SAO RAS S. Karpov, G. Beskin (SAO RAS, Russia), S. Bondar (RIPI, Russia), C. Bartolini, G. Greco, A. Guarnieri, A. Piccioni (Astronomy Department of Bologna University, Italy), D. Nanni, F. Terra (Second University of Roma "Tor Vergata", Italy), E. Molinari, G. Chincarini, F.M. Zerbi, S. Covino, V. Testa (Osservatorio Astronomico di Brera, Italy), G. Tosti (Universita di Perugia, Italy), F. Vitali, L.A. Antonelli (Osservatorio Astronomico di Roma, Italy), P. Conconi, G. Cutispoto (Osservatorio Astronomico di Catania, Italy), G. Malaspina (Osservatorio Astronomico di Brera, Italy), L. Nicastro (Istituto di Astrofisica Spaziale e Fisica Cosmica, Palermo, Italy), E. Palazzi (Istituto di Astrofisica Spaziale e Fisica Cosmica, Bologna, Italy), E. Meurs (Dunsink Observatory, Ireland), P. Goldoni (APC, SAp/CEA, Paris) report on behalf of TORTOREM team: We performed additional analysis of Tortora data on early optical transient of GRB 080319B (GCN 7427, Racusin et al.) reported by us in GCN 7502 and found the systematic error of 6.1 s in the time zero point. To compensate it, all data points have to be shifted 6.1 s to earlier times. The modified light curve, also including minor photometric adjustments, is available at http://vo.astronet.ru/~karpov/grb080319b_lc_10_shifted.gif We apologize for any inconvenience this may have caused. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7567 SUBJECT: GRB 080319B: Potential Jet Break Observed by Swift-XRT and UVOT DATE: 08/04/07 19:44:51 GMT FROM: Judith Racusin at PSU J.L. Racusin (PSU), S.R. Oates (UCL-MSSL), P. Schady (UCL-MSSL), S. T. Holland (CRESST/USRA/GSFC), D.N. Burrows (PSU), report on behalf of the Swift XRT and UVOT teams: We have analyzed the first 19 days of Swift XRT data from GRB 080319B (Racusin et al. GCN 7427), with a total exposure time of 200 ks. The light curve can be fit by a triple broken power-law with initial decay slope of 1.54+/-0.01, breaking at 2790+/-664 s to a slope of 1.85+/-0.05, breaking again at 41.4+/-9.0 ks to a slope of 1.17+/-0.06, and finally breaking at 1.04+/-0.43 Ms to a slope of 2.9+/-2.3. If this last break is interpreted as a jet break, the jet opening half-angle is 8 degrees x (n/10 cm^-3)^(1/8). We obtained Eiso=1.3x10^54 ergs (25 kev - 7 MeV) from Golenetskii et al. (GCN 7482), assuming cosmological parameters of H_0=70 km/s/Mpc, Omega_M=0.3, Omega_Lambda = 0.7. The corresponding beaming corrected energy is 1.3 x 10^52 ergs. The uncertanties in the post-jet break slope and time are large. Therefore, the evidence for a break is preliminary and further observations will be required to confirm it. Late-time UVOT white filter observations are also suggestive of a break at approximately the same time as the X-ray break. However, further observations are needed to confirm the break because the afterglow flux is near the UVOT detection limit. We strongly encourage additional late-time optical follow-up to further test for achromaticity and constrain the possible jet break. This circular is an official product of the Swift Team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7569 SUBJECT: GRB 080319B: HST observations DATE: 08/04/08 00:55:27 GMT FROM: Nial Tanvir at IofA U.Cambridge N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick), A. S. Fruchter, J. Graham (STScI), K. Wiersema, E. Rol (U. Leicester) report on behalf of a larger collaboration: We obtained observations of GRB 080319B (GCN 7427) with HST/WFPC2 in F606W and F814W filters on 2008 April 7th (2 orbits in each filter). These data show the fading afterglow at magnitude F(814W_AB)=24.2 and F(606W_AB)=24.5. This fading is consistent within the errors with a continued power-law decline in optical brightness. PSF subtraction reveals no obvious sign of an underlying host galaxy, although there is what appears to be a separate galaxy 1.5 arcsec to the south, which might be producing one of the foreground absorption systems (GCN 7451). A colour image showing the field around the GRB is available at: http://www.star.le.ac.uk/~nrt3/080319b.html Further analysis is ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7570 SUBJECT: GRB 080319A: Early RAPTOR optical limits DATE: 08/04/08 20:42:18 GMT FROM: James Wren at LANL J. Wren, W.T. Vestrand, P.R. Wozniak, H. Davis of Los Alamos National Laboratory report: Our RAPTOR telescopes imaged the location of Swift trigger 306754 (Pagani et al., GCN 7426). We do not detect the optical counterpart initially reported by Cenko et al. (GCN 7429). The location of the counterpart was within the field of view of our continuous all-sky monitoring system. We can place 5 sigma limits at approximately magnitude 9.0 during the time period within 5 minutes both before and after the trigger. Our narrow-field instruments began observing the location at 05:46:51.90 UTC, 69.8 s after the Swift trigger, but also did not detect the counterpart. The limiting magnitudes of our unfiltered observations when calibrated to the USNO-B1 R-band are given in the following table. t-mid(s) exp(s) mag mag-err -------------------------------------------- -19.18 10.0 9.0 5 sigma limit 14.07 10.0 9.0 5 sigma limit 72.35 5.0 16.9 5 sigma limit 156.60 10.0 17.4 5 sigma limit 423.25 30.0 18.0 5 sigma limit //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7621 SUBJECT: GRB 080319B: Continued Gemini-N monitoring DATE: 08/04/15 22:36:51 GMT FROM: Nial Tanvir at IofA U.Cambridge N. R. Tanvir (U. Leicester), D. A. Perley (UC Berkeley), A. J. Levan (U. Warwick), J. S. Bloom (UC Berkeley), A. S. Fruchter (STScI) and E. Rol (U. Leicester) report: We obtained a further epoch of observations of GRB 080319B with Gemini-North/GMOS on April 14 UT. These observations yielded the following magnitudes: g=25.80+/-0.09, r=24.93+/-0.07, i=24.22+/-0.05. Although the r-band magnitude is consistent with a continued power-law decline in flux, the source is now clearly much redder than it was at early times, suggesting it is likely contaminated by light from a host galaxy and/or associated supernova. The g-band observation, which would be less contaminated by any SN light, indicates a steeper decline which may be consistent with a break in the underlying afterglow light curve (GCN 7567). The absence of any extended emission in the previous HST observations (GCN 7569) argues against a significant host contribution, although a very compact host is not ruled out. Further analysis is ongoing. We thank Gemini staff astronomers, particularly Sandy Leggett, for their support in obtaining these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7627 SUBJECT: GRB 080319B: Jet Break, Energetics, Supernova DATE: 08/04/16 18:58:13 GMT FROM: Alexander Kann at TLS Tautenburg D. A. Kann, S. Schulze (TLS Tautenburg) & A. C. Updike (Clemson University) report: In light of recent reports on the further evolution of GRB 080319B, we did a preliminary analysis of the multiwavelength data set. Jet Break: Racusin et al. (GCN 7567) reported the existence of a potential jet break at 1.04 +/- 0.43 Ms in the X-ray band, with a hint of a steeper decay seen in the optical as well. Using the most up-to-date data from the Swift XRT light curve repository (Evans et al. 2007), we confirm the findings of the Swift team and derive (using data starting at 0.5 days after the GRB): chi^2/d.o.f. = 39/58 alpha_1 = 1.01 +/- 0.05 alpha_2 = 2.40 +/- 0.39 t_b = 9.43 +/- 1.73 days (0.815 +/- 0.149 Ms) n = 5 fixed, no "host galaxy" These values are in agreement with those of the Swift team, with significantly reduced errors. We note that there seems to be a steep decay in the X-ray light curve from 0.35 to 0.5 days, and a similar evolution has been reported in the optical (Krugly et al., GCN 7519) at about the same time. This is reminiscent of the X-ray light curve of GRB 070110 (Troja et al. 2007). In the optical, we add data from Perley et al. (GCN 7535) and Tanvir et al. (GCN 7621) to the data set from Bloom et al. 2008 (arXiv:0803.3215). Tanvir et al. report a significant reddening, which we confirm. At the moment, it is unclear how much the host galaxy and a potential supernova contribute in the g band, but a roughly achromatic steepening is seen in this band (Tanvir et al.) in comparison to the X-ray light curve. Energetics: Using the prompt emission data derived from Konus-Wind (Golenetskii et al., GCN 7482), we find in the bolometric band (1 - 10000 keV, host frame): E_iso = 1.32 +/- 0.03 x 10^54 erg (log E_iso = 54.12) In the sample of Kann et al. 2007 (arXiv:0712.2186), only two GRBs (000131 and 990123) exceed this value. Using the jet break time derived above, as well as the redshift z=0.937 (Vreeswijk et al., GCN 7444), and assuming standard parameters (constant-density medium, circumburst density n = 10 cm^-3, efficiency eta = 0.2), we find: theta_jet = 10.24 +/- 0.71 degrees E_jet = 2.11 +/- 0.30 x 10^52 erg (log E_jet = 52.3) This value is comparable to or higher than for GRB 050904 (Tagliaferri et al. 2005, Frail et al. 2006), GRB 050820A (Cenko et al. 2006) and GRB 070125 (Updike et al. 2008, Chandra et al. 2008), implying that this is the fourth hyper-energetic GRB (cf. Chandra et al. 2008). We note that broadband modeling may refine the circumburst density; if it is significantly higher than 10 cm^-3, the colimation-corrected energy will also be significantly higher. Supernova: In the i' band, the afterglow does not show a late steep decay, indicating the possibility of a supernova that is by now contributing to the optical transient (Tanvir et al.). Using the composite light curve (Bloom et al.) shifted to the i' band (using the early Rc - i' color), and assuming an achromatic break (t_b, alpha_2 fixed from the X-ray fit) and no host galaxy, we find, using data after 0.7 days (after the steep decay + plateau phase, Krugly et al.): chi^2/d.o.f. = 44/10 (scatter) alpha_1 = 1.33 +/- 0.02 k = 2.40 +/- 0.15 s = 1 fixed (stretch factor) k is the peak luminosity in units of the SN 1998bw peak luminosity. This is a high value (Ferrero et al. 2006) and represents an upper limit on the SN flux. Assuming m_host(i') = 25, we find k = 1.24 +/- 0.14, a more reasonable result, indicating the contribution of a host galaxy to the late afterglow. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7635 SUBJECT: GRB080319A: MAGIC telescope GeV observation DATE: 08/04/20 19:22:07 GMT FROM: Markus Garczarczyk at MPI/MAGIC Garczarczyk M., Gaug M., Antonelli A., Bastieri D., Covino S., Galante N., La Barbera A., Longo F. and Scapin V. for the MAGIC collaboration The MAGIC Imaging Atmospheric Cherenkov Telescope performed a follow-up observation of the BAT burst GRB080319A (GCN circular 7426, Pagani et al.). We received the GCN alert at 05:46:45 UT (T0+63s), data taking with MAGIC started at 05:50:32 UT (T0+290s). The observation continued for 1736s, starting at the zenith angle of 35 degrees. No evidence for VHE gamma-ray emission above the analysis threshold of 175 GeV was found. The observation was carried out in (less sensitive) moon-observation mode. A preliminary analysis, for the hypothesis of steady emission and assumption of a differential photon spectral index of -2.5, yields the following 95% CL differential flux upper limits, including a 30% systematic uncertainty on the telescope efficiency: E (125- 175 GeV): 0.57 * 10^-10 erg/cm^2/s E (175- 300 GeV): 0.11 * 10^-10 erg/cm^2/s E (300-1000 GeV): 0.06 * 10^-10 erg/cm^2/s for a time window from 05:50:01 UT to 06:19:01 UT. For the same time window, we can also exclude emission of a constant flux in any 100s time bin smaller than: E (125- 175 GeV): 13.97 * 10^-10 erg/cm^2/s E (175- 300 GeV): 4.34 * 10^-10 erg/cm^2/s E (300-1000 GeV): 1.46 * 10^-10 erg/cm^2/s This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7636 SUBJECT: GRB 080319A : Liverpool and Faulkes Telescopes Observations DATE: 08/04/21 17:34:09 GMT FROM: Andrea Melandri at Liverpool John Moores U A. Melandri (Liverpool JMU), A. Gomboc (Ljubljana), C. Guidorzi (INAF-OAB), R.J. Smith, I.A. Steele, C.G. Mundell, D.F. Bersier, M.F. Bode, M.J. Burgdorf, S. Kobayashi, C.J. Mottram (Liverpool JMU), P. O'Brien, N. Bannister, N. Tanvir (U. Leicester) report on behalf of larger GRB collaboration: We observed the field of GRB 080319A (trigger = 306754, Pagani et al. GCN 7426) with the Liverpool Telescope (T_start = 32 min after the burst event) and the Faulkes Telescope North (T_start = 525 min after the burst event). The optical counterpart reported by Cenko et al. (GCN 7429) and Malesani et al. (GCN 7436), is clearly visible inside the XRT error circle (Beardmore et al., GCN 7448) in our first images : Telescope Filter DT_mean(min) Exposure(s) Mag Err ---------------------------------------------------------------------- LT r' 34.2 360 21.45 0.16 LT r' 43.3 600 21.94 0.40 FTN r' 542.3 1000 >20.61 ---------------------------------------------------------------------- Magnitudes were calibrated with respect to SDSS calibration's field (Cool et al. GCN 7467). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 7710 SUBJECT: GRB 080319B: Further HST observations and underlying host DATE: 08/05/12 18:35:30 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), A.S. Fruchter (STScI) and J. Graham (STScI) report: We have obtained a second epoch of HST observations of GRB 080319B on 11 May 2008. 2 orbits (3200s) of observations were taken in the F606W and F814W filters. The afterglow has clearly faded from our first epoch of observations and a faint host galaxy is now visible at the afterglow location. We measure magnitudes for the combined (afterglow+host) source of; F606W(AB)=26.3 +/ -0.1 F814W(AB)=25.9 +/ -0.1 Relative astrometry between the two epochs of HST observations suggests that the afterglow is marginally (0.1 +/- 0.05 arcseconds) offset from the centroid of the host galaxy in the F606W image. This implies that the afterglow may not be the dominant source of light at the current epoch, and is likely significantly fainter than the magnitudes quoted above.