//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11370 SUBJECT: GRB 101024A: Swift detection of a burst with an optical afterglow DATE: 10/10/24 12:03:25 GMT FROM: Phil Evans at U of Leicester M. De Pasquale (UCL-MSSL), A. P. Beardmore (U Leicester), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), P. T. O'Brien (U Leicester), C. Pagani (U Leicester), C. J. Saxton (UCL-MSSL), B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC) and R. L. C. Starling (U Leicester) report on behalf of the Swift Team: At 11:39:29.82 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 101024A (trigger=437016). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 66.475, -77.248 which is RA(J2000) = 04h 25m 54s Dec(J2000) = -77d 14' 50" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The lightcurve shows 4 distinct peaks, with the brightest peaking at T0+10s. Duration was about 23s. The XRT began observing the field at 11:40:46.8 UT, 77.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 66.5064, -77.2648 which is equivalent to: RA(J2000) = 04h 26m 1.54s Dec(J2000) = -77d 15' 53.2" with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 66 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (6.52 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.2 (+1.39/-1.27) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 81 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 04:26:01.73 = 66.50719 DEC(J2000) = -77:15:55.9 = -77.26552 with a 90%-confidence error radius of about 0.64 arc sec. This position is 2.1 arc sec. from the center of the XRT error circle. The estimated magnitude is 19.38 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.09. Burst Advocate for this burst is M. De Pasquale (mdp@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: 11372 SUBJECT: GRB 101024A: Enhanced Swift-XRT position DATE: 10/10/24 14:20:40 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 614 s of XRT Photon Counting mode data and 1 UVOT images for GRB 101024A, 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 = 66.50630, -77.26539 which is equivalent to: RA (J2000): 04h 26m 1.51s Dec (J2000): -77d 15' 55.4" 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) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11373 SUBJECT: GRB 101024A: GRAS06 optical observations DATE: 10/10/24 14:59:45 GMT FROM: Veli-Pekka Hentunen at Taurus Hill Obs,A95 Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill Observatory, Varkaus, Finland) report: GRAS06 (Global-Rent-a-Scope, Moorook, Australia) RCOS-16 telescope and SBIG STL-1001E CCD camera were used to detect GRB 101024A optical afterglow. The observations were started at 2010-10-24 11:58:06 (UT) and stopped at 2010-10-24 12:30:00 (UT). Three unfiltered observations with 600s exposure times were made. The afterglow was detected at following position RA 04 26 01.43 and DEC -77 15 55.9 consistent those given by Evans P.A. et al. (GCN 11370) to within positional errors. The following magnitudes were obtained from the observations using NOMAD1 0127-0023968 (V = 16.94) as the comparison: Tmid(s) + T0 Filter Exp (sec) Mag Mag err Limit 1416 unfiltered 600 19.2 0.4 21.0 2074 unfiltered 600 20.8 0.8 21.0 2730 unfiltered 600 >21.0 21.0 A jpg image of the 600sec observations is available at the following URL: http://cutenews.kassiopeia.net/data/upimages/GRB101024A.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11374 SUBJECT: GRB 101024A: Swift-BAT refined analysis DATE: 10/10/24 17:55:08 GMT FROM: Scott Barthelmy at NASA/GSFC T. N. Ukwatta (GWU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), M. De Pasquale (UCL-MSSL) N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 101024A (trigger #437016) (De Pasquale, et al., GCN Circ. 11370). The BAT ground-calculated position is RA, Dec = 66.465, -77.261 deg, which is RA(J2000) = 04h 25m 51.6s Dec(J2000) = -77d 15' 39.7" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 76%. The mask-weighted light curve consists of 4 peats, the first starting at ~T-2 sec, peaking at ~T_zero, then the 3 remaining peaks at T+3 sec, ~T+10, and ~T+18 sec, and returning to background at ~T+30 sec. T90 (15-350 keV) is 18.7 +- 0.5 sec (estimated error including systematics). The time-averaged spectrum from T-0.3 to T+20.1 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.15 +- 0.31, and Epeak of 60.0 +- 9.3 keV (chi squared 49.9 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.5 +- 0.1 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+9.39 sec in the 15-150 keV band is 5.5 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.84 +- 0.07 (chi squared 66.9 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/437016/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11375 SUBJECT: GRB101024A: Swift/UVOT DATE: 10/10/24 19:21:47 GMT FROM: Massimiliano de Pasquale at MSSL-UCL M. De Pasquale (UCL-MSSL) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 101024A 82 s after the BAT trigger (De Pasquale et al., GCN Circ. 11370). An optical afterglow is detected within the refined XRT error circle (Beardmore et al., GCN Circ. 11372) in the white filter finding chart. The same source is detected very marginally in the sum of the following white filter exposures. It is not found in any other filter, either in single and in summed exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 82 232 147 19.4 +/- 0.2 u_FC 294 543 246 >20.3 white 573 6068 413 22.3 +/- 0.6 (2.1 sigma) v 624 6479 413 >20.0 b 549 5864 413 >20.6 u 294 5659 459 >20.6 w1 673 5454 216 >20.1 m2 648 5249 221 >19.7 w2 599 6274 413 >20.5 The values quoted above are not corrected for the non-negligible Galactic extinction due to the reddening of E(B-V) = 0.09 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11378 SUBJECT: GRB 101024A: Fermi GBM observation DATE: 10/10/24 22:06:01 GMT FROM: Sheila McBreen at MPE S. McBreen (UCD/MPE) report on behalf of the Fermi GBM Team: "At 11:39:33.60 UT on 24 October 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 101024A (trigger 309613175/101024486) which was also detected by the Swift-BAT (De Pasquale et al. 2010, GCN 11370). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 142 degrees. The GBM light curve consists of three pulses with the first pulse starting about 5 seconds before the trigger. The event has a duration (T90) of about 24 (+/-2) s (50-300 keV). The time-averaged spectrum from T0-0.003 s to T0+19.456 s is adequately fit by a power law function with an exponential high energy cutoff. The power law index is 1.4 (+1.6/-0.8) and the cutoff energy, parameterized as Epeak, is 56.25 (+5.96/-5.54) keV (CSTAT 447 for 359 d.o.f.). The event fluence (10-1000 keV) in this time interval is (1.2 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+5.5 s in the 8-1000 keV band is 8.2 +/- 0.5 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11380 SUBJECT: GRB 101024A: Zadko observatory - Gingin. Optical observations DATE: 10/10/25 09:57:20 GMT FROM: Myrtille LAAS-BOUREZ at U.Western Australia GRB 101024A: Zadko observatory - Gingin. Optical observations ------------------------------------------------------------- M. Laas-Bourez (UWA/ICRAR), A. Klotz (CESR-UPS-CNRS), D. Coward (UWA), D. Blair (UWA), M. Boer (OHP-CNRS), P. Thierry (CESR-UPS-CNRS) report: We imaged the field of GRB 101024A detected by SWIFT (trigger 437016) with the Zadko robotic telescope (D=100cm) located at the observatory - Gingin, Australia. The observations started 215s after the GRB trigger (199s after the notice). The elevation of the field increased from 27 degrees above horizon and weather conditions were good with humidity (77%). We detect a new fading source in the error box given by SWIFT We detected the candidate couterpart mentioned by De Pasquale et al. (GCNC 11370) at the following position (+/- 0.5 arcsec): RA(J2000.0) = 04h26m01s76 DEC(J2000.0) = -77d15m55s64 The first image is trailed with a duration of 30.0s (see the description in Klotz et al., 2006, A&A 451, L39). IT was taken between 214.7s - 244.7s after GRB. It will be analyzed later. Next images show the decay of the OT: OT was R=16.75 between 259s and 289s after GRB, filter C OT was R=17.07 between 305s and 335s after GRB, filter C OT was R=17.15 between 349s and 379s after GRB, filter C OT was R=17.19 between 394s and 424s after GRB, filter C Magnitudes were estimated with the star : NOMAD1 0127-0023961 and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon=290.5330 lat=-34.1439 This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11381 SUBJECT: GRB 101024A: Swift XRT refined analysis DATE: 10/10/25 11:32:55 GMT FROM: Rhaana Starling at U of Leicester R.L.C. Starling, P.A. Evans, K.L. Page (U. Leicester) and M. De Pasquale (UCL-MSSL) report on behalf of the Swift-XRT team: We have analysed 11 ks of Swift XRT data for GRB 101024A (De Pasquale et al. GCN Circ. 11370), from 62 s to 57.2 ks after the BAT trigger. The data comprise 8 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 11372). The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=5.0 (+5.0, -3.9). At T+77 s the decay flattens to an alpha of -0.03 (+0.16, -0.18) before breaking again at T+870 s to a final decay with index alpha=1.30 (+0.10, -0.09). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.95 (+0.13, -0.10). The best-fitting absorption column is 1.06 (+0.29, -0.13) x 10^21 cm^-2, in excess of the Galactic value of 6.5 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 1.30, the count rate at T+24 hours will be 6.0 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.4 x 10^-13 (3.1 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00437016. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11382 SUBJECT: GRB 101024A: Zadko observatory - Gingin. Optical observations refined analysis DATE: 10/10/26 08:46:02 GMT FROM: Myrtille LAAS-BOUREZ at U.Western Australia GRB 101024A: Zadko observatory - Gingin. Optical observations refined analysis ------------------------------------------------------------------------------- M. Laas-Bourez (UWA/ICRAR), A. Klotz (CESR-UPS-CNRS), D. Coward (UWA), D. Blair (UWA), M. Boer (OHP-CNRS), P. Thierry (CESR-UPS-CNRS) report: We analyzed carefully early images of GRB101024A taken with the Zadko telescope, Gingin, Australia (see Laas-Bourez et al. 2010 GCNC 11380). Images are unfiltered. Magnitudes are converted into R band using the star NOMAD1 0127-0023961 R=13.61 supposing (V-R)=0.6 for the optical counterpart of the GRB. Magnitudes are not corrected for galactic dust extinction. ------------------------------- start end Rmag (s) (s) ------------------------------- 215 222 16.55 +/-0.15 222 245 16.72 +/-0.15 259 289 16.86 +/-0.12 305 335 17.06 +/-0.12 349 379 17.24 +/-0.12 394 424 17.23 +/-0.12 ------------------------------- Considering a law decay in flux proportional to t^-alpha, there is a consistent decrease with alpha ~ 1.1 between 215 and ~ 360 seconds. After 360 seconds, a plateau seems to be reached lasting at least 60 seconds. Compared to the UVOT data taken in the same range of time (De Pasquale et al. 2010 GCNC 11375) the optical afterglow is very red, consistent with a redshift z>2. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11383 SUBJECT: GRB 101024A: GROND optical/NIR observations DATE: 10/10/26 17:45:31 GMT FROM: Thomas Kruehler at MPE/MPI T. Kruehler, F. Olivares, M. Nardini and J. Greiner (all MPE Garching) report on behalf of the GROND team: GROND (Greiner et al. 2008, PASP 120, 405), mounted at the 2.2m MPG/ESO telescope at La Silla Observatory (Chile), started observations of the field of GRB 101024A (de Pasquale et al., GCN #11370) in g'r'i'z'JHK at 07:42 UT on 2010-10-26, 43.7 h after the burst. We detect the optical afterglow (de Pasquale et al., GCNs #11370, 11375, Hentunen et al., GCN #11373, Laas-Bourez et al., GCNs #11380, 11382) marginally in the r' and i' bands. Preliminary AB magnitudes and upper limits at a midtime of 08:14 UT on 2010-10-26 in stacked images with 50 min of total integration time in each g'r'i'z' and 40 min in JHK are: g' > 24.1 r' = 24.5 +- 0.3 i' = 23.8 +- 0.2 z' > 23.7 J > 21.8 H > 21.3 K > 20.5 These magnitudes have been derived by calibrating the images against the GROND zeropoints and 2MASS field stars and are not corrected for the expected foreground reddening of E(B-V)=0.088 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11422 SUBJECT: Optical observation of GRB 101024A DATE: 10/11/23 01:47:10 GMT FROM: AAVSO GRB Network at AAVSO Chris Stockdale (Churchill, Victoria, Australia) reports to the AAVSO International High Energy Network the following optical observation of GRB 101024 (GCN #11370, De Pasquale et al.): Chris Stockdale reports a detection of the optical afterglow of GRB 101024 (GCN #11370, De Pasquale et al.; #11371, De Pasquale et al.; #11373, Hentunen et al.; #11382, Laas-Bourez et al.; #11383 Kruehler et al.), detecting the afterglow at the same position as the Swift UVOT position. The afterglow was observed unfiltered for 24 minutes beginning at 12:42:07 UT on 2010 October 24. Thirteen exposures of 24 minutes were taken for the detection; a median combination of images 2 through 13 having a midpoint time of 12:54:25 UT on 2010 October 24 yields a CR magnitude of 19.3 with calculated S/N of 5.5; the magnitude was measured relative to the R-band catalog magnitude of USNO-B1.0 0127-0023867 (R=15.7). Observations were made using an SBIG ST-7XME CCD camera attached to a 280 mm Schmidt-Cassegrain. The position of the afterglow was imaged for an additional 60 minutes subsequent to these frames, but the source was not detected. The AAVSO High Energy Network was made possible through grants from the Charles Curry Foundation and NASA.