This file contains 3 bursts: 'A', 'B', and 'C'. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8237 SUBJECT: GRB 080916: Swift detection of a burst with optical afterglow DATE: 08/09/16 10:03:53 GMT FROM: David Palmer at LANL H. Ziaeepour (UCL-MSSL), L. Vetere (PSU), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), S. Campana (INAF-OAB), P. A. Evans (U Leicester), C. Gronwall (PSU), H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (MSSL), V. Mangano (INAF-IASFPA), J. Mao (INAF-OAB), S. R. Oates (UCL-MSSL), K. L. Page (U Leicester), D. M. Palmer (LANL), B. Preger (ASDC), P. Romano (INAF-IASFPA), T. Sakamoto (NASA/UMBC), M. Stamatikos (NASA/ORAU), R. L. C. Starling (U Leicester) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 09:45:20 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080916 (trigger=324895). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 336.302, -57.022 which is RA(J2000) = 22h 25m 12s Dec(J2000) = -57d 01' 17" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 60 sec. The peak count rate was ~5000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 09:46:30.8 UT, 70.2 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 336.27802, -57.02190 which is equivalent to: RA(J2000) = 22h 25m 6.72s Dec(J2000) = -57d 01' 18.8" with an uncertainty of 3.3 arcseconds (radius, 90% containment). This location is 46 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 1.83e+20 cm^-2 (Kalberla et al. 2005). UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 76 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 22:25:06.19 = 336.2758 DEC(J2000) = -57:01:22.8 = -57.0230 with a 1-sigma error radius of about 0.5 arc sec. This position is 5.9 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.3 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 0.02. Burst Advocate for this burst is H. Ziaeepour (hz AT mssl.ucl.ac.uk). 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: 8238 SUBJECT: GRB 080916: REM candidate afterglow DATE: 08/09/16 10:04:09 GMT FROM: Stefano Covino at Brera Astronomical Observatory D. Fugazza, S. Covino, P. D'Avanzo, 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 080916 on Sep 16 starting from about 20 s after the GRB time. We see a source not present in the 2MASS catalogue with approximately H~14.5 one minute after the burst at the coordinates RA=22:25:06.19, DEC=-57:01:24.1 (error 1 arcsec). Further observations are in progress. [GCN OPS NOTE(16sep08): The author requests that people should use the 8238 Circular as the primary source. The 8239 Circular was the result of multiple efforts of a distributed team.] [GCN OPS NOTE(16sep08): Per author's request, DM was removed from the author list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8239 SUBJECT: GRB 080916: REM detection of the NIR afterglow DATE: 08/09/16 11:45:46 GMT FROM: Angelo Antonelli at Obs. Astro. di Roma L.A. Antonelli, S. Covino, P. D'Avanzo, D. Fugazza, 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 080916 (Ziaeepour et al. GCN 8237) on Sep 16 starting observations about 19.4 sec after the GRB. We clearly detect a NIR source at RA(J2000)=22:25:06.13, Dec.(J2000) =-57:01:22 with an uncertainty of 1" which is compatible with the position of the UVOT source (Ziaeepour et al. GCN 8237). At the beginning of the observation the source had a magnitude H=14.0+/-0.3, calibrated against 2MASS. The source showed a clear fading behavior during the REM observation. [GCN OPS NOTE(16sep08): The author requests that people should use the 8238 Circular as the primary source. The 8239 Circular was the result of multiple efforts of a distributed team.] [GCN OPS NOTE(16sep08): Per author's request, DM was removed from the author list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8240 SUBJECT: GRB 080916B: Swift detection of a burst DATE: 08/09/16 14:55:24 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT G. Stratta (ASDC), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), C. Guidorzi (INAF-OAB), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), S. D. Hunsberger (PSU), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), J. Mao (INAF-OAB), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), S. R. Oates (UCL-MSSL), J. P. Osborne (U Leicester), K. L. Page (U Leicester), M. Perri (ASDC), B. Preger (ASDC), R. L. C. Starling (U Leicester), M. C. Stroh (PSU) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 14:44:47 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080916B (trigger=324907). The BAT on-board calculated location is RA, Dec 163.624, +69.044 which is RA(J2000) = 10h 54m 30s Dec(J2000) = +69d 02' 39" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 50 sec. The peak count rate was ~750 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+18.9 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is G. Stratta (giulia.stratta AT asdc.asi.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8241 SUBJECT: GRB 080916A: Enhanced Swift-XRT position DATE: 08/09/16 15:21:27 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 2559 s of XRT Photon Counting mode data and 3 UVOT images for GRB 080916A, 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 = 336.27682, -57.02271 which is equivalent to: RA (J2000): 22h 25m 6.44s Dec (J2000): -57d 01' 21.7" 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), the current algorithm is an extension of this method. This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8242 SUBJECT: GRB 080916B: Swift-XRT afterglow detection DATE: 08/09/16 15:36:21 GMT FROM: Matteo Perri at ISAC/ASDC G. Stratta, M. Perri, P. Evans report on behalf of the Swift-XRT Team: The XRT began observing the field at 15:07:22.2 UT, 1354.9 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 163.66560, 69.06574 which is equivalent to: RA(J2000) = 10h 54m 39.74s Dec(J2000) = +69d 03' 56.7" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 94 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 1.8e+20 cm^-2 (Kalberla et al. 2005). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8243 SUBJECT: GRB 080916A, Swift-BAT refined analysis DATE: 08/09/16 17:06:23 GMT FROM: Scott Barthelmy at NASA/GSFC W. Baumgartner (GSFC/UMBC), 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), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU), H. Ziaeepour (UCL-MSSL) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 080916A (trigger #324895) (Ziaeepour, et al., GCN Circ. 8237). The BAT ground-calculated position is RA, Dec = 336.289, -57.026 deg, which is RA(J2000) = 22h 25m 09.3s Dec(J2000) = -57d 01' 33.7" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 82%. The mask-weighted light curve shows two overlapping FRED peaks starting at ~T-3 sec and ending at ~T+100 sec. T90 (15-350 keV) is 60 +- 7 sec (estimated error including systematics). The time-averaged spectrum from T-2.4 to T+88.6 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.17 +- 0.21, and Epeak of 94.6 +- 23.0 keV (chi squared 48.0 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 4.0 +- 0.1 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+1.25 sec in the 15-150 keV band is 2.7 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.63 +- 0.05 (chi squared 64.5 for 57 d.o.f.). 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/324895/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8244 SUBJECT: GRB 080916A: Swift XRT refined analysis DATE: 08/09/16 17:19:57 GMT FROM: Rhaana Starling at U of Leicester R.L.C. Starling (U. Leicester) and H. Ziaeepour (MSSL-UCL) report on behalf of the Swift-XRT team: We have analysed the first two orbits of Swift XRT data for GRB 080916A (Ziaeepour et al., GCN Circ. 8237) from T0+70 s to T0+7440 s with total exposure time 3.4 ks. The enhanced X-ray position is given in Evans et al., GCN Circ. 8241. The light curve can be represented by a 5-segment broken power law with an initial decay alpha1=1.3+0.4/-0.6 breaking at Tbk1=102+4/-6 s to a steep decay of alpha2=3.5+/-0.3 until Tbk2=190+25/-13 s. The light curve then flattens to alpha3=1.07+0.06/-0.3 and breaks at Tbk3=690+150/-140 s to a further steep decay of alpha4=2.9+2/-0.8. From Tbk4=1270+240/-220 s the decay becomes shallow again with alpha5=0.3+/-0.2. The spectrum from 3.2 ks of Photon Counting mode data can be fit with an absorbed power law with photon index Gamma=2.1+/-0.2 and intrinsic absorption (in excess of the Galactic value of 1.8e20 cm-2) of nH=(2.6+0.7/-0.6)e21 cm-2. This is consistent with the spectrum formed from the initial 170 s of Windowed Timing mode data. The observed (unabsorbed) count rate to flux conversion is 1 count/s = 4.0e-11 (6.8e-11) erg/cm2/s. The predicted count rate at T+24hr would be approximately 0.1 count/s if the decay continues on the current plateau-like phase. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8245 SUBJECT: GRB 080916C: Fermi GBM Detection DATE: 08/09/16 18:09:46 GMT FROM: Alexander van der Horst at NASA/MSFC Adam Goldstein (UAH) and Alexander van der Horst (NASA/MSFC) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 00:12:45 UT on 16 September 2008, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located the bright GRB 080916C (trigger 243216766 / 080916.009). The on-ground calculated location, using the GBM trigger data, is RA = 121.8, Dec = -61.3 (J2000 degrees, equivalent to J2000 8h 07m, -61d 18'), with a statistical uncertainty of less than 1 degree (radius, 1-sigma containment) and an additional systematic error which is currently estimated to be 2 to 3 degrees. The angle from the Fermi Large Area Telescope (LAT) boresight is 52 degrees. This GRB has several peaks, with T90 (50-300 keV) = 66 s and T50 (50-300 keV) = 33 s. This burst is detected up to several MeV; spectral analysis is ongoing." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8246 SUBJECT: GRB 080916C: Fermi LAT observation DATE: 08/09/16 18:25:23 GMT FROM: Nicola Omodei at INFN(Pisa)/GLAST H. Tajima (SLAC), J. Bregeon (INFN Pisa), J. Chiang (SLAC), G. Thayer (SLAC) on behalf of the Fermi LAT team: We report a detection by the Fermi Large Area Telescope (LAT) of emission from the long GRB 080916C, which was triggered by the Fermi Gamma-ray Burst Monitor (GBM) at 00:12:45 UT on September 16th 2008 (GCN 8245). The angle of the GBM best position (RA, Dec=121.8,-61.3) with respect to the LAT boresight was 52 degrees at the time of the trigger, which is close the edge of our field of view. The data from the Fermi LAT shows a significant increase in the event rate within 10 degrees of the GBM location after the GBM trigger that is spatially and temporally correlated with the GBM emission with high significance. More than 10 photons are observed above 1 GeV during this time. The best LAT on-ground localization is found to be (RA,Dec=119.88, -56.59) with a 90% containment radius of 0.13 deg (statistical; 68% containment radius: 0.09 deg, preliminary systematic error is less than 0.1 deg) which is consistent with the GBM localization. This circular is an official product of the Fermi LAT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8247 SUBJECT: GRB 080916B: Enhanced Swift-XRT position DATE: 08/09/16 19:40:44 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 1049 s of XRT Photon Counting mode data and 1 UVOT images for GRB 080916B, 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 = 163.66512, +69.06545 which is equivalent to: RA (J2000): 10h 54m 39.63s Dec (J2000): +69d 03' 55.6" with an uncertainty of 5.1 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method. This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8249 SUBJECT: GRB080916A: Refined Swift/UVOT Observations DATE: 08/09/16 19:58:10 GMT FROM: Samantha Oates at MSSL S. R. Oates (UCL-MSSL) and H. Ziaeepour (UCL-MSSL) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 080916A, 78s after the BAT trigger (Ziaeepour et al., GCN 8237). We detect the afterglow in all of the UVOT filters at the position: RA(J2000.0) = 22:25:06.20 DEC(J2000.0) = -57:01:22.9 with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence). This position is consistent with the UVOT enhanced XRT position (Evans et al., GCN 8241) and the REM position (Fugazza et al., GCN 8238). UVOT magnitudes are reported below for the finding charts (fc) and images: Filter Tstart(s) Tstop Expo(s) Magnitude/3sigUL ----------------------------------------------------- white (fc) 78 178 98 18.33 +/- 0.06 white 872 972 98 18.47 +/- 0.06 v (fc) 182 582 393 17.55 +/- 0.06 v 978 1378 393 18.39 +/- 0.11 b 1458 1477 19 18.90 +/- 0.35 u 538 658 19 17.53 +/- 0.19 w1 613 633 19 18.25 +/- 0.39 m2 741 1565 39 18.42 +/- 0.40 w2 692 864 39 18.75 +/- 0.37 ----------------------------------------------------- These magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E{B-V} = 0.02 mag (Schlegel et al. 1998). The photometry is on the UVOT flight system described in Poole et al. (2008,MNRAS,383,627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8250 SUBJECT: GRB 080916B, Swift-BAT refined analysis DATE: 08/09/16 20:55:15 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), G. Stratta (ASDC), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team) report: Using the data set from T-239 to T+617 sec from the recent telemetry downlink, we report further analysis of BAT GRB 080916B (trigger #324907) (Strata, et al., GCN Circ. 8240). The BAT ground-calculated position is RA, Dec = 163.632, 69.061 deg, which is RA(J2000) = 10h 54m 31.6s Dec(J2000) = +69d 03' 38.2" with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 53%. The mask-weighted light curve shows a weak FRED-like peak starting at ~T-4 sec, peaking at ~T+3 sec, and ending at ~T+50 sec. There is a possibility of very weak emission lasting out to at least T+350 sec, at which time the spacecraft slewed away fro the burst location. T90 (15-350 keV) is 32 +- 8 sec (estimated error including systematics). The time-averaged spectrum from T-3.3 to T+35.7 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.49 +- 0.23. The fluence in the 15-150 keV band is 6.3 +- 0.9 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+3.30 sec in the 15-150 keV band is 0.6 +- 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/324907/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8251 SUBJECT: IPN Triangulation and Energy Spectrum of GRB080916C DATE: 08/09/16 22:36:31 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and J. Goldsten, on behalf of the MESSENGER NS GRB team, S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team E. Bellm, D. M. Smith, R. P. Lin, J. McTiernan, R. Schwartz, C. Wigger, W. Hajdas, and A. Zehnder, on behalf of the RHESSI GRB team, A. von Kienlin, G. Lichti, and A. Rau, on behalf of the INTEGRAL SPI-ACS GRB team, and E. Del Monte, I. Donnarumma, Y. Evangelista, M. Feroci, I. Lapshov, F. Lazzarotto, L. Pacciani, M. Galli, and M. Marisaldi, on behalf of the AGILE Team, report: GRB080916C (Goldstein and van der Horst, GCN 8245; Tajima et al., GCN 8246) was also observed by AGILE (MCAL, SuperAGILE, and ACS - but not localized), RHESSI, INTEGRAL (SPI-ACS), Konus-Wind, and MESSENGER. A preliminary triangulation gives a long, narrow error box centered at RA, Dec = 119.830, -56.790 degrees (0.2 degrees from the center of the LAT error circle), whose corners are: RA(2000) DEC(2000) 119.486 -62.130 120.126 -62.702 119.901 -50.632 120.321 -51.274 A figure is posted at ssl.berkeley.edu/ipn3/080916C. Using the RHESSI data between 100 keV and 17 MeV, the time-integrated spectrum for the 62-second interval beginning at 00:12:46 UT can be described by a cutoff power law with alpha ~ -1.2 +/- 0.3, Epeak ~ 1100 +/- 500 keV, and fluence ~ (9.0 +/- 1.6) x 10^-5 ergs/cm^2 (100 keV - 10 MeV). Both the triangulation and the energy spectrum can be substantially improved. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8252 SUBJECT: GRB 080916B: Swift UVOT Refined Analysis DATE: 08/09/17 00:42:53 GMT FROM: Erik Hoversten at Swift/Penn State E. A. Hoversten (PSU) and G. Stratta (ASDC) report on behalf of the Swift UVOT team: The Swift/UVOT began settled observations of the field of GRB 080916B, 1359s after the BAT trigger (Stratta et al., GCN 8240). There is a possible detection of an afterglow in the UVOT white filter at: RA (J2000) 10:54:39.78 Dec (J2000) 69: 3:57.9 with an estimated uncertainty of 0.8 arcsec (radius, 90% confidence). This position is consistent with the UVOT enhanced XRT position (Evans et al., GCN 8247). The afterglow candidate does not appear in the DSS images, and photometry from the second orbit of Swift observations suggests that it has faded. UVOT magnitudes and 3-sigma upper limits are reported in the following table: Filter T_start T_stop Exp(s) Mag (3-sigma upper limit) ----------------------------------------------------- white 1359.0 1458.8 98.2 20.50 +/- 0.21 white 7826.0 8025.7 196.6 > 21.27 v 1340.9 2920.7 342.1 > 19.62 b 1516.3 2676.5 155.6 > 20.32 u 1491.6 2651.7 155.6 > 19.91 uvw1 1467.3 2627.3 155.5 > 19.91 uvm2 1604.9 3076.8 285.0 > 20.06 uvw2 1556.0 2716.0 155.5 > 19.91 The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight of E_{B-V} = 0.02 mag. All photometry is on the UVOT flight system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8253 SUBJECT: GRB 080916C: Swift/XRT detection of possible afterglow DATE: 08/09/17 04:41:53 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT Jamie A. Kennea reports on behalf of the Swift Team: At 17:08 UT, September 16th 2008 Swift began TOO observations of the Fermi GBM and LAT detected GRB 080916C (GCN 8245,8246). Preliminary analysis of downlinked data from this observation reveals a single point source detected in the field of view at RA, Dec = 119.8459, -56.63891 which is equivalent to: RA (J2000): 07h 59m 23.0s Dec (J2000): -56d 38' 20.1" with an estimated uncertainty of 8 arcsec (radius, 90% confidence). We note that this point source is uncatalogued and 189 arcseconds from the center of the Fermi LAT error circle (GCN 8246), within the LAT 90% confidence error circle. Currently we cannot determine if this source is fading, and therefore cannot confirm if this source is associated with GRB 080916C. Observations of this source are on-going. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8254 SUBJECT: GRB080916A: Spectroscopic redshift DATE: 08/09/17 07:35:16 GMT FROM: Johan U. Fynbo at U.Copenhagen J. P. U. Fynbo, D. Malesani, J. Hjorth, J. Sollerman, C. C. Thoene (DARK), report on behalf of a larger collaboration. We observed the field of GRB 080916A (Ziaeepour et al., GCN 8237) with the ESO VLT equipped with FORS1. Observations started on 2008 Sep 17.097 UT, 17.1 hr after the burst, for a total exposure time of 1 hr with the 300V grism. Based on MgII absorption and emission lines from [OII] and [OIII] we infer a redshift for GRB080916A of z=0.689 (based a preliminary wavelength calibration). We acknowledge excellent support from the observing staff at Paranal, in particular Dominique Naef, Heidi Korhonen and Chris Lidman. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8255 SUBJECT: GRB 080916C: Enhanced XRT position DATE: 08/09/17 09:01:33 GMT FROM: Phil Evans at U of Leicester P.A. Evans, J.P. Osborne, A.P. Beardmore and M.R. Goad, (U. Leicester) report on behalf of the Swift-XRT team. Using 1310 s of XRT Photon Counting mode data and 1 UVOT images, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching to the USNO-B1 catalogue): RA, Dec = 119.84706, -56.63788 which is equivalent to: RA (J2000): 07 59 23.29 Dec (J2000): -56 38 16.4 with an uncertainty of 2.1 arcsec (90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8257 SUBJECT: GRB 080916C: GROND Detection of the Optical Afterglow Candidate DATE: 08/09/17 10:55:42 GMT FROM: Christian Clemens at MPE C. Clemens (MPE), A. Rossi (Tautenburg Obs.), J. Greiner and S. McBreen (both MPE) report on behalf of the GROND team: GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile) observed the field of GRB 080916C, which triggered Fermi GBM (Goldstein et al., GCN #8245) and for which significant correlated emission was detected by the Fermi LAT (Tajima et al., GCN #8246). The field was followed up by Swift XRT (Kennea et al., GCN #8253). Observations started at 07:57 UT on September 17th, 2008, 31.7 hr after the GBM trigger. They were performed at an average seeing of 1.5" and at an average airmass of 1.7 as well as under bright moon. We found a faint source at the edge of the astrometrically corrected 2.1'' Swift-XRT error circle reported by Evans et al. (GCN #8255) at RA (J2000.0) = 07h 59m 23.32s DEC (J2000.0) = -56d 38' 18.0'' with an uncertainty of 0.5". Based on the first 50 min of effective exposures, we estimate a preliminary magnitude of z' ~ 21.74 mag +/- 0.17. Given magnitude is calibrated against USNO-B1 field stars. No statement about variability can be made at this point. Further observations are planned. Please note, that no correction for the Galactic foreground reddening of E(B-V) = 0.32 mag (Schlegel et al., 1998) has been applied. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8258 SUBJECT: Konus-Wind observation of GRB 080916C DATE: 08/09/17 11:30:55 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The long GRB 080916ó (Fermi GBM trigger 243216766/080916.009; Goldstein and van der Horst, GCN 8245; Tajima et al., GCN 8246; Hurley et al., GCN 8251) triggered Konus-Wind at T0=764.632 s UT (00:12:44.632). The burst light curve shows the main part with a duration of ~70 s followed by a weak tail seen at least till ~T0+200 s. As observed by Konus-Wind the burst had a fluence of (1.24 +/- 0.17)x10^-4 erg/cm2, and a 256-ms peak flux measured from T0+3.168 s of (1.19 +/- 0.30)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+71.424 s) is well be fitted (in the 20 keV - 10 MeV range) by GRBM (Band) model for which: the low-energy photon index is alpha = -1.040(-0.058, +0.065), the high energy photon index beta = -2.26(-0.40, +0.21), the peak energy Ep = 505(-70, +79) keV (chi2 = 75.6/84 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/GRB080916_T00764/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8259 SUBJECT: Konus-Wind observation of GRB 080916A DATE: 08/09/17 14:31:01 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, D. Svinkin, M. Ulanov and T. Cline, on behalf of the Konus-Wind team report: The long GRB 080916A (Swift-BAT trigger # 324895: Ziaeepour et al., GCN 8237, Baumgartner et al. 8243) triggered Konus-Wind at T0=35121.715 s UT (09:45:21.715). The burst light curve shows a single pulse with a duration of ~40 s. As observed by Konus-Wind the burst had a fluence of 5.54(-0.66, +0.79)x10^-6 erg/cm2, and a 256-ms peak flux measured from T0+1.024 s of 1.05(-0.40, +0.41)x10^-6 erg/cm2/s (both in the 20 keV - 1 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+33.024 s) is well fitted (in the 20 keV-1 MeV range) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.00(-0.32, +0.38), and Ep = 129(-21, +33) keV (chi2 = 32.0/51 dof). Fitting by GRBM (Band) model yields only an upper limit on the high energy photon index: beta < -2.43. All the quoted errors are at the 90% confidence level. Assuming z = 0.689 (Fynbo et al., GCN 8254) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, Omega_\Lambda = 0.73, the isotropic energy release E_iso ~7x10^51 erg, the peak luminosity (L_iso)_max ~ 2x10^51 erg/s, and Ep_rest ~220 keV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB080916_T35121/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8260 SUBJECT: GRB 080916B: Swift-XRT refined analysis DATE: 08/09/17 15:17:17 GMT FROM: Matteo Perri at ISAC/ASDC G. Stratta, M. Perri, B. Preger (ASDC) report on behalf of the Swift-XRT team: We have analyzed the first two orbits of Swift XRT data of GRB 080916B (Stratta et al., GCN Circ. 8242), consisting of 2.8 ks of Photon Counting data collected starting from 22.8 min after the burst. During the XRT observation, from T0+1.4 ks to T0+8.5 ks, the source shows a fading behaviour from 0.08 cts/s to 0.02 cts/s. Assuming a power law model, the best fit decay index is alpha = 1.0 ± 0.2. At this rate we predict a count rate level of 1.7 x 10-3 cts/s one day after the trigger. The 0.3-10 keV extracted spectrum (2.8 ks of integration time) is consistent with an absorbed power law model. Fixing the column density to the Galactic value (NH = 1.8 x 1020 cm-2 from Kalberla et al. 2007) the best fit photon index is 2.0 ± 0.5. The observed 0.3-10.0 keV flux is (1.0+/-0.6) x 10-12 erg cm-2 s-1 which corresponds to an unabsorbed flux of 1.1 x 10-12 erg cm-2 s-1. The count to observed flux conversion factor is 6.6 x 10-11 erg cm-2 count-1. This Circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8261 SUBJECT: GRB 080916C: Swift XRT refined analysis DATE: 08/09/17 15:24:55 GMT FROM: Matteo Perri at ISAC/ASDC M. Perri, B. Preger, G. Stratta (ASDC) report on behalf of the Swift XRT team: The Swift XRT started observing the field of the FERMI GRB 080916C (Goldstein et al., GCN Circ. 8245) at 2008-09-16 17:11:28 UT, about 17 hours after the trigger. We confirm that the X-ray source reported by Kennea (GCN Circ. 8253) is the afterglow of the GRB. Using 2614 s of XRT Photon Counting mode data and 2 UVOT images, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching to the USNO-B1 catalogue): RA, Dec = 119.84684, -56.63801 which is equivalent to: RA (J2000): 07 59 23.24 Dec (J2000): -56 38 16.8 with an uncertainty of 1.9 arcsec (90% confidence). This position is consistent with the XRT position reported by Evans et al. (GCN Circ. 8255) using less data. The X-ray light curve from T+61 ks to T+102 ks can be fit with a single power-law model with a decay index of 1.7 (-0.7) (+1.0). A 7.6 ks exposure X-ray spectrum from T+61 ks to T+102 ks can be well fit by an absorbed power-law model with a photon index of 2.1 (+0.9 -0.7) and a column density of 3.7 (+3.3) (-2.1) x 10^21 cm^-2. We note that the Galactic column density value in the direction of the burst is 1.5 x 10^21 cm^-2. The observed 0.3-10.0 keV flux is 8.6 x 10-13 erg cm^-2 s^-1 which corresponds to an unabsorbed flux of 1.5 x 10^-12 erg cm^-2 s^-1. Providing the source continues to decay at the same rate, we predict an observed flux of about 3 x 10^-13 erg cm^-2 s^-1 at T+2 days. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8262 SUBJECT: GRB 080916C: Swift UVOT Refined Analysis DATE: 08/09/17 17:59:31 GMT FROM: Erik Hoversten at Swift/Penn State E. A. Hoversten (PSU), P. Schady (MSSL-UCL), and M. Perri (ASDC) report on behalf of the Swift UVOT team: The Swift/UVOT began observations of the field of GRB 080916C 17.0 hours after the Fermi GBM dectection (Goldstein & van der Horst, GCN 8245). No afterglow is detected within the XRT error circle (Evans, et al., GCN 8255) in any of the observed UVOT filters. UVOT magnitude 3-sigma upper limits are reported in the following table: Filter T_start T_stop Exp(s) Mag (3-sigma upper limit) ------------------------------------------------------------- v 101253 101857 590 > 19.75 u 96469 97132 645 > 19.99 uvw1 66675 67517 829 > 20.34 uvw1 95562 96462 886 > 20.38 uvm2 61130 66667 1090 > 20.31 uvm2 94655 95555 886 > 20.20 uvw2 100347 101246 886 > 20.43 The quoted upper limits have not been corrected for the large expected Galactic extinction along the line of sight of E_{B-V} = 0.32 mag (Schlegel et al., 1998). All photometry is on the UVOT flight system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8263 SUBJECT: GRB 080916A: Fermi GBM detection DATE: 08/09/17 22:39:42 GMT FROM: Elisabetta Bissaldi at MPE E. Bissaldi (MPE), S. McBreen (MPE), C.A. Wilson-Hodge (NASA/MSFC) and A. von Kienlin (MPE) report on behalf of the Fermi GBM Team: "At 09:45:18 UT on 16 September 2008, the Fermi Gamma-ray Burst Monitor triggered and located GRB 080916A (trigger 243251119 / 080916406), which was also detected by Swift (Ziaeepour et al., GCN 8237) and Konus-Wind (Golenetskii et al., GCN 8259). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 331.5, Dec = -58.1 (equivalent to J2000 22h 06m, -58d 06'), with a statistical uncertainty of 3.2 degrees (radius, 1-sigma containment; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). This position is 2.8 deg from the Swift refined position (Evans et al., GCN 8241). The angle from the Fermi LAT boresight to the Swift position is 76 degrees. This long GRB consists of several peaks, with the brightest one lasting from T0 to T0+13 s and a second peak from T0+13 s to T0+24 s followed by weaker emission. T90 (25-1000 keV) is about 60 sec, in agreement with the Swift-BAT refined analysis (Baumgartner et al., GCN 8243), and T50 (25-1000 keV) is about 25 s. The time-averaged spectrum from T0 to T0+58 sec is adequately fit by a power law function with an exponential high energy cutoff. The power law index is -0.9 +/-0.1 and the cutoff energy, parameterized as Epeak, is 109 +/- 9 keV. The fluence (25-1000 keV) is 1.5 (+/- 0.5)E-05 erg/cm2 and the peak flux (25-1000 keV) on the 1 s timescale is 4.5 (+/- 0.7) ph/cm2/s. The spectral analysis results presented above are preliminary; final results will be published in the Fermi GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8264 SUBJECT: GRB 080916A: Rapid PROMPT Observations DATE: 08/09/17 22:57:02 GMT FROM: Rebecca Holmes at U.North Carolina R. Holmes, M. Schubel, J. Haislip, D. Reichart, M. Nysewander, A. LaCluyze, K. Ivarsen, J. A. Crain, A. Foster, T. Brennan, and A. Trotter report: Skynet observed the localization of GRB 080916A (Ziaeepour et al., GCN 8237) with four of the 16" PROMPT telescopes at CTIO beginning 56 seconds after the trigger in UBVRI. We detect the afterglow (Fugazza et al., GCN 8238) in I. At 56 seconds after the burst we measure I ~ 17.7 mag (calibrated to 5 USNO B1 stars). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8266 SUBJECT: GRB 080916A: GROND lightcurve DATE: 08/09/18 11:23:16 GMT FROM: Andrea Rossi at TLS Tautenburg A. Rossi (Tautenburg Obs.),T. Kruehler, J. Greiner, A. Yoldas, C. Clemens, R. Filgas (all MPE Garching), A. Kupcu Yoldas (ESO) and G. Szokoly (Eoetvoes Univ.,Budapest) report on behalf of the GROND team: GROND (Greiner et al. 2008, PASP 120, 405), mounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile), started observations of the field of GRB 080916A (Ziaeepour et al. GCN #8237) in g'r'i'z'JHK at 23:57:34 UT on 2008-09-16, 14 hours after the burst trigger. We clearly detect the optical afterglow detected by UVOT (Ziaeepour et al. GCN #8237) and REM telescope (Fugazza et al. GCN #8238). Observations continued for 60 min and were repeated at the mid-time 06:40 UT for total 60 min. Calibrating the field on USNO-B1 stars, we derive the following r band magnitudes, not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.019 mag (Schlegel et al. 1998): midtime(s) r er 52239 21.8 0.03 54054 21.9 0.04 74076 22.1 0.07 76260 22.3 0.07 The total r band light curve is well fitted by power law with index of 0.81+- 0.13. Assuming the optical light curve continues the decline with the same power law index, we predict r' band magnitudes 23.4 at 3 days after the burst. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8272 SUBJECT: GRB 080916C: GROND Confirmation of the Optical Afterglow DATE: 08/09/19 10:08:00 GMT FROM: Christian Clemens at MPE C. Clemens (MPE Garching), A. Rossi (Tautenburg Obs.), J. Greiner, S. McBreen, T. Kruehler, A. Yoldas (all MPE Garching), A. Kupcu Yoldas (ESO) and G. Szokoly (Eoetvoes Univ., Budapest) report on behalf of the GROND team: We observed the field of GRB 080916C for a second time with GROND at 08:04 UT on September 19th, 2008, 3.3 d after the GBM trigger with 54 min of effective exposures. Observations were performed at an average seeing of 1.7" and at an average airmass of 1.7. We do not detect the afterglow candidate first reported by Clemens et al. (GCN #8257) with the following 5-sigma upper limits: z' > 22.7 mag. These measurements strongly indicate a fading of the source compared to our first epoch observations. We therefore propose this is to be the afterglow of GRB 080916C. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8274 SUBJECT: GRB 080916C: IRSF/SIRUS NIR Observation DATE: 08/09/19 14:41:06 GMT FROM: Nobuyuki Kawai at Tokyo Tech T. Nagayama (Kyoto University) reports on behalf of the IRSF/SIRIUS team: We have imaged the field of GRB 080916C (van der Horst, GCN 8245) based on the localization by Fermi/LAT (Tajima et al, GCN 8246) in J, H, and Ks with the Simultaneous three-color InfraRed Imager for Unbiased Survey (SIRIUS) on the Nagoya-SAAO 1.4m telescope (IRSF) starting at 2:53 on September 17 UT for 50 min. The optical afterglow candidate suggested by Clemens et al. (GCN 8257, GCN 8272) was detected marginally in H and Ks bands. The preliminary magnitude was Ks= 18.6 +- 0.5. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8278 SUBJECT: GRB 080916C: Fermi GBM Spectral Analysis DATE: 08/09/20 23:41:31 GMT FROM: Alexander van der Horst at NASA/MSFC Alexander van der Horst (NASA/ORAU) and Adam Goldstein (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "We have performed spectral analysis of GRB 080916C (GCN 8245, 8246). The time averaged spectrum, from 8 keV up to 30 MeV, of the main emission up to 66 seconds after the burst is best fit by a Band function with Epeak = 424 +/- 24 keV, alpha = -0.91 +/- 0.02, and beta = -2.08 +/- 0.06. The fluence (8 keV - 30 MeV) is 1.9e-4 erg/cm^2. These spectral analysis results are preliminary; the final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8284 SUBJECT: GRB080916A: Suzaku WAM observation of the prompt emission DATE: 08/09/23 14:59:42 GMT FROM: Kazutaka Yamaoka at Aoyama Gakuin U M. Suzuki, M. Kokubun, M. Ohno, T. Takahashi (ISAS/JAXA), K. Yamaoka, S. Sugita (Aoyama Gakuin U.), Y.E. Nakagawa, T. Tamagawa (RIKEN), T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira, Y. Hanabata (Hiroshima U.), M. Tashiro, Y. Terada, Y. Urata, A. Endo, K. Onda, N. Kodaka, K. Morigami, T. Sugasahara, W. Iwakiri (Saitama U.), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara, N. Ohmori (Univ. of Miyazaki), S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report: The long GRB080916A (Swift/BAT trigger #324895; Ziaeepour et al., GCN 8237) was detected by the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 09:45:19.970 UT (=T0). The observed light curve shows a single peak at T0+0 s, followed by a second soft peak at ~T0+16 s with a total duration (T90) of about 20 seconds. The fluence in 100 - 500 keV was (2.57 +/- 0.32)x10^-6 erg/cm^2. The 1-s peak flux measured from T0+0 s was 1.54 (-0.12, +0.25) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-5s to T0+10s is fit by a single power-law with a photon index of 1.58 +/- 0.29 (chi^2/d.o.f = 13.1/12) in 100 - 500 keV. All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included. The light curves with 1/64 sec time resolution for this burst are now available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10019 SUBJECT: Radio observation of GRB080916c with ATCA DATE: 09/10/13 09:06:49 GMT FROM: Aquib Moin at CIRA/ATNF Aquib Moin (Curtin Institute of Radio Astronomy / Australia Telescope National Facility), Steven Tingay (Curtin Institute of Radio Astronomy), Chris Phillips (Australia Telescope National Facility), Gregory Taylor (University of New Mexico), Mark Wieringa (Australia Telescope National Facility) and Ralph Martin (Perth Observatory) report: We observed the XRT position of the GRB080916c (GCN 8261) at 5.5 GHz with the Australia Telescope Compact Array (ATCA) between 14:00:00 UT and 20:00:00 UT on July 01, 2009. We did not detect a radio source at the XRT position of the GRB080916c (GCN 8261). The radio flux density at the afterglow position found out to be 0.230 +/- 0.180 mJy/beam (1-sigma). The compact array was in its most compact configuration. The Australia Telescope Compact Array (/ Parkes telescope / Mopra telescope / Long Baseline Array) is part of the Australia Telescope which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. See the 5.5 GHz field image at: http://cira.ivec.org/dokuwiki/doku.php/grb/grb080916c_field_image