//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13845 SUBJECT: GRB 121011A: Swift detection of a burst with optical afterglow DATE: 12/10/11 11:36:05 GMT FROM: Judith Racusin at GSFC J. L. Racusin (NASA/GSFC), D. N. Burrows (PSU), V. D'Elia (ASDC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), B.P. Gompertz (U Leicester), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), C. Pagani (U Leicester), K. L. Page (U Leicester), B. Sbarufatti (INAF-OAB/PSU) and R. L. C. Starling (U Leicester) report on behalf of the Swift Team: At 11:15:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 121011A (trigger=535764). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 260.200, +41.137 which is RA(J2000) = 17h 20m 48s Dec(J2000) = +41d 08' 12" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 10 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 11:17:07.9 UT, 97.5 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 260.21504, 41.11179 which is equivalent to: RA(J2000) = 17h 20m 51.61s Dec(J2000) = +41d 06' 42.4" with an uncertainty of 4.3 arcseconds (radius, 90% containment). This location is 99 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 consistent with the Galactic value of 2.34 x 10^20 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 6.36e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 108 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 17:20:51.22 = 260.21340 DEC(J2000) = +41:06:36.9 = 41.11024 with a 90%-confidence error radius of about 0.63 arc sec. This position is 9.1 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.76 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03. Burst Advocate for this burst is J. L. Racusin (judith.racusin AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13846 SUBJECT: GRB 121011A: MITSuME Okayama Optical Observation DATE: 12/10/11 12:11:41 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 121011A (Racusin et al., GCNC 13845) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2012-10-11 11:17:00 UT, (~90 sec after the burst) We detected the previously reported afterglow (Racusin et al., GCNC 13845) in all the three bands. Photometric results of the OT are listed below. We used SDSS catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err ----------------------------------------------------------------------- 0.00449 11:21:58 540.0 17.23 0.09 16.81 0.05 16.11 0.05 0.01159 11:32:11 540.0 17.36 0.10 16.65 0.04 16.10 0.04 ------------------------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13847 SUBJECT: GRB121011A : Xinglong TNT optical observation DATE: 12/10/11 12:35:21 GMT FROM: L.P. Xin at NAOC L. P. Xin, Y. L. Qiu, J. Y. Wei, J. Wang, J. S. Deng, C. Wu, X. H. Han on behalf of EAFON report: We began to observe GRB121011A ( Racusin et al., GCN 13845 ) with Xinglong TNT telescope at 11:17:24(UT), about 2 min after the burst. A series of white and R-band images were obtained. The OT reported by (Racusin et al., GCN 13845; Kuroda et al. 13845 ) was detected in all images. The brightness of this OT was about R=16.8 mag at 10 min after the burst, calibrated by USNO B1.0 R2 mag. The brightness is consistent with the report by Kuroda et al. 13845. This message may be cited.//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13848 SUBJECT: GRB 121011A: MASTER-Net early OT light curve DATE: 12/10/11 13:10:07 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, A.Sankovich, D.Denisenko Moscow Lomonosov State University, Sternberg Astronomical Institute, A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinski, I.Zalozhnich, A. Popov, A. Bourdanov, A. Punanova Ural Federal University Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB121011.47 10 sec s after notice time and 51 sec after GRB time at 2012-10-11 11:16:21.301 UT in two polarizations. The 5-sigma upper limit of the first (10s exposure) set has been about 17.0 mag MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka was pointed to the GRB 121011A 65 sec s after notice time and 106 sec after GRB time at 2012-10-11 11:17:14 UT in two polarizations. On our first (10s exposure) set we haven't found optical transient within SWIFT error box. The weather conditions were not very good. The first individual image on which we see the OT was taken on 2012-10-11 at 11:19:20, i.e 230 sec. after the GRB time. The maximum brightness (calibrated to 0.8*R+0.2*B from USNO-B1.0) was 16.1. The preliminary light curve is available here: http://master.sai.msu.ru/static/GRB/GRB121011_pre_lc.png We note that nothing is visible at the position of the OT on the Palomar DSS plates and on color-combined SDSS image, implying the host galaxy is fainter than 22.5 m. The reduction of the whole data set is continuing. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13849 SUBJECT: Planned XMM-Newton and IRAM observation of GRB 121011A DATE: 12/10/11 13:35:40 GMT FROM: Bruce Gendre at ASDC B. Gendre (ASDC/OaR/INAF), C. Feruglio (IRAM), G. Stratta (OaR) report on behalf of a larger collaboration: The GRB 121011A will be observed by XMM-Newton from 2012 Oct. 11 18:33 UT, until Oct 12 at 11:30 UT. This observation is coordinated with an IRAM observation at the Interferometer of the Plateau de Bure. We encourage any follow-up at all wavelengths, and specially spectroscopic observations to derive a redshift for this event. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13850 SUBJECT: GRB 121011A: Enhanced Swift-XRT position DATE: 12/10/11 18:35:03 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 127 s of XRT Photon Counting mode data and 1 UVOT images for GRB 121011A, 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 = 260.21466, +41.11031 which is equivalent to: RA (J2000): 17h 20m 51.52s Dec (J2000): +41d 06' 37.1" with an uncertainty of 2.1 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) 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: 13852 SUBJECT: GRB 121011A, Swift-BAT refined analysis DATE: 12/10/11 21:14:11 GMT FROM: Scott Barthelmy at NASA/GSFC M. Stamatikos (OSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), J. L. Racusin (NASA/GSFC), T. Sakamoto (AGU), G. Sato (ISAS), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from recent telemetry downlinks, we report further analysis of BAT GRB 121011A (trigger #535764) (Racusin, et al., GCN Circ. 13845). The BAT ground-calculated position is RA, Dec = 260.204, 41.123 deg, which is RA(J2000) = 17h 20m 49.0s Dec(J2000) = +41d 07' 22.4" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 32%. The mask-weighted light curve shows a single pulse starting at ~T-9 sec, peaking at ~T+1 sec, and ending at ~T+110 or ~T+150 sec. T90 (15-350 keV) is 75.6 +- 12.7 sec (estimated error including systematics). The time-averaged spectrum from T-7.45 to T+80.10 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.10 +- 0.73, and Epeak of 101.5 +- 42.2 keV (chi squared 40.6 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.7 +- 0.7 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T-0.69 sec in the 15-150 keV band is 1.2 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.20 +- 0.14 (chi squared 49.2 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/535764/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13853 SUBJECT: GRB 121011A: TNG optical observations DATE: 12/10/11 21:24:30 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK), P. D'Avanzo (INAF/OABr), A. Melandri (INAF/OABr), V. Nascimbeni (Univ. Padova), C. Padilla (INAF/TNG), report on behalf of the CIBO collaboration: We observed the optical afterglow of GRB 121011A (Racusin et al., GCN 13845) with the TNG equipped with DOLoRes. The afterglow is well detected in a single 5-min exposure, with a mean time Oct 11.829 UT (8.63 hr after the GRB). Its magnitude is R = 21.74 +- 0.06, assuming R = 17.84 for the USNO star at RA = 17:20:44.70, Dec = +41:04:52.7. The afterglow has the following coordinates (calibrated against USNO-B1 stars): RA = 17:20:51.22 Dec = +41:06:37.4 with an estimated uncertainty of 0.4". //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13854 SUBJECT: GRB 121011A: MASTER-Net bell light curve DATE: 12/10/11 21:27:48 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, D.Denisenko, V.Krushinski (Ural), V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, A.Sankovich Moscow Lomonosov State University, Sternberg Astronomical Institute, V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, A.Sankovich, D.Denisenko Moscow Lomonosov State University, Sternberg Astronomical Institute, A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory I.Zalozhnich, A. Popov, A. Bourdanov Ural Federal University Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) Two MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk and Tunka (Baykal lake) was pointed to the GRB 121011A (Racusin et al., GCNC 13848) 51 sec after Trigger time at 2012-10-11 11:16:21.301 UT and 106 sec after Trigger time at 2012-10-11 11:17:14 UT in four polarizations (Yurkov et al., GCNC 13845). Unfortunately the weather conditions were not very good at Tunka site. We detected OT (Racusin et al., GCNC 13848; Kuroda et al. GCNC 13845; Xin et al., GCNC 13847). The preliminary results of the photometry calibrated to 0.8*R+0.2*B from USNO-B1.0: UTC Tmean-Tgrb Exp,s. mag s/n magerr filter Site Coadd 11:16:21.0 56 10 >16.9 N/A N/A P/ Amur No 11:16:21.0 56 10 >16.9 N/A N/A P\ Amur No 11:16:21.0 96 80 >18.2 N/A N/A P/ Amur Yes 11:16:21.0 96 80 >18.2 N/A N/A P\ Amur Yes 11;18;29.0 200 40 >18.2 N/A N/A P/ Amur No 11;18;29.0 200 40 >18.2 N/A N/A P\ Amur No 11:19:20.429 255 50 17,38 5.9 0.18 P/ Amur No 11:19:20.461 255 50 17,17 5.8 0.19 P\ Amur No 11:20:21.37 321 60 16,89 8.9 0.12 P/ Amur No 11:20:21.396 321 60 16,9 8.1 0.13 P\ Amur No 11:21:32.001 397 70 16,77 11.1 0.10 P/ Amur No 11:21:32.02 397 70 16,81 11.5 0.09 P\ Amur No 11:22:52.945 487 90 16,59 14.7 0.07 P/ Amur No 11:22:52.998 487 90 16,49 15.8 0.07 P\ Amur No 11:24:33.654 599 110 16,42 18.7 0.06 P/ Amur No 11:24:33.678 599 110 16,57 16.6 0.07 P\ Amur No 11:26:34.121 729 130 16,55 17.6 0.06 P/ Amur No 11:26:34.144 729 130 16,5 18.4 0.06 P\ Amur No 11:28:54.944 885 160 16,69 18.1 0.06 P/ Amur No 11:28:54.947 885 160 16,7 15.5 0.07 P\ Amur No 11:31:45.672 1065 180 16,73 15.3 0.07 P/ Amur No 11:31:45.706 1065 180 16,72 14.2 0.08 P\ Amur No 11:35:11.589 1271 180 17,05 13.5 0.08 P/ Amur No 11:35:11.606 1271 180 17,03 11.1 0.10 P\ Amur No 11:38:37.563 1477 180 17,23 10.4 0.10 P/ Amur No 11:38:37.586 1477 180 17,25 10.3 0.11 P\ Amur No 11:42:12.62 1693 180 17,36 9.2 0.12 P/ Amur No 11:42:12.636 1693 180 17,48 7.7 0.14 P\ Amur No 11:45:38.297 1898 180 17,44 8.2 0.13 P/ Amur No 11:45:38.319 1898 180 17,44 7.2 0.15 P\ Amur No 11:49:03.877 2104 180 17,67 5.7 0.19 P/ Amur No 11:49:03.906 2104 180 17,73 5.0 0.22 P\ Amur No 11:52:29.982 2309 180 17,91 4.7 0.23 P/ Amur No 11:52:30.004 2309 180 17,82 5.4 0.20 P\ Amur No 11:55:55.714 2515 180 18,08 4.7 0.23 P/ Amur No 11:55:55.710 2515 180 18,04 3.4 0.32 P\ Amur No The mean (F/ - F\)/(F/ + F\) 100 < 2% during detection time. The light curve between 200 sec and 6600 sec is very simmetrical in log(F) - log (t) coordinates (like to bell) with parabolic low : m - m_max = - A (log t/t_max)^2 (1) A = 4.2 +/- 0.1 where t is time from GRB trigger in sec, t_max = 633+-11s, m_max = 16.60+/-0.02 . We stress that this formulae does not depend on redshift. The phenomenological formula discribed by Kocevski, D., Ryde, F., & Liang, E. (2003, ApJ, 596, 389) may be discussed in this situation but after z determination. The preliminary light curve is available here: http://master.sai.msu.ru/static/GRB/GRB121011_lc.gif The preliminary approximation (formula(1)) is available here: http://master.sai.msu.ru/static/GRB/GRB121011_lc_aproximation.png This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13855 SUBJECT: GRB 121011A: optical observations DATE: 12/10/11 22:32:41 GMT FROM: Alexei Pozanenko at IKI A. Volnova (SAO MSI, IKI), A. Matkin (UAFO, ISON), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 121011A (Racusin et al., GCN 13845) with VT-50 (0.5-m) telescope of UAFO/ISON-Ussuriysk observatory starting on Oct. 11 (UT) 11:21:29, i.e. 6 minutes after burst trigger. We took several unfiltered images of 30 s exposures ending observations on (UT) 12:17:00. In initial frames we clearly detect afterglow (Racusin et al., GCN 13845). Preliminary photometry of some early images is based on USNO-B1.0 stars (R2): T_start T0+, Filter, exposure, OT (UT) mid (d) (s) 11:21:29 0.00433 none 30 16.70 +/- 0.08 11:27:04 0.00821 none 30 16.64 +/- 0.07 11:33:14 0.01249 none 30 16.80 +/- 0.10 11:38:12 0.01594 none 30 17.30 +/- 0.10 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13856 SUBJECT: GRB 121011A: NOT optical observations DATE: 12/10/11 22:54:21 GMT FROM: Dong Xu at Weizmann Inst J. P. U. Fynbo (DARK), D. Xu (WIS), D. Malesani (DARK), A. Sodor(Konkoly Observatory of Hungary, Royal Observatory of Belgium) , P. Jakobsson (U. Iceland) report on behalf of a larger collaboration: We observed the optical afterglow of GRB 121011A (Racusin et al., GCN13845) using the 2.5m Nordic Optical Telescope (NOT) equipped with ALFOSC. The afterglow is clearly detected in each of the two 300s exposures, with a mean time Oct. 11.830 UT (i.e., 8.666 hr after the BAT trigger). We found its magnitude R=21.76+/-0.10, calibrated with the USNO B1 star # 1310-0279773 (R1 = 17.84; same as calibration in Malesani et al., GCN #13853). We also carried out 2x20 min spectroscopic observations after the above photometry. There is a faint trace in the 2D spectrum but the S/N in the 1D spectrum is low. Preliminary analysis of the 1D spectrum shows very weak sign of z~0.58. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13857 SUBJECT: GRB 121011A: Swift-XRT refined Analysis DATE: 12/10/11 23:36:05 GMT FROM: Phil Evans at U of Leicester D.N. Burrows (PSU), O.M. Littlejohns (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. Maselli (INAF-IASFPA), J.A. Kennea (PSU), M.C. Stroh (PSU) and J.L. Racusin report on behalf of the Swift-XRT team: We have analysed 7.1 ks of XRT data for GRB 121011A (Racusin et al. GCN Circ. 13845), from 103 s to 16.8 ks after the BAT trigger. The data comprise 28 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 13850). The light curve can be modelled with a power-law decay with a decay index of alpha=1.50 (+/-0.04). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.71 (+0.35, -0.10). The best-fitting absorption column is consistent with the Galactic value of 2.3 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 (4.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 0 (+4.9, -0) x 10^20 cm^-2 Galactic foreground: 2.3 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.71 (+0.35, -0.10) If the light curve continues to decay with a power-law decay index of 1.50, the count rate at T+24 hours will be 5.9 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.3 x 10^-14 (2.5 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00535764. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13859 SUBJECT: GRB 121011A: Fermi-LAT detection of a burst DATE: 12/10/12 02:13:58 GMT FROM: Judith Racusin at GSFC M. Ohno (Hiroshima U.), G. Vianello (Stanford), J. L. Racusin (NASA/GSFC) and E. Sonbas (Adiyaman Univ.), report on behalf of the Fermi-LAT team: The Fermi Large Area Telescope (LAT) detected emission from GRB 121011A, also detected by Swift (Racusin et al. GCN 13845) and GBM (trigger 371646928/121011469) at approximately 11:15:25 UT on October 11, 2012. The burst location was inside the LAT field of view at an angle of ~56 degrees to the LAT boresight, and had a zenith angle of 86 degrees. No significant excess is seen using standard analysis procedures. Using the non-standard LAT Low Energy (LLE) data selection, over 100 counts above background were detected within a 20 s interval coinciding with the time of the GBM emission, with a significance of 4 sigma. This data selection has insufficient spatial resolution to provide a reliable LAT localization. This detection is due to low energy gamma-rays (below 100 MeV). Indeed, no events were observed above 100 MeV using the standard analysis classes. A GBM circular on GRB 121011A is forthcoming. The Fermi LAT point of contact for this burst is Eda Sonbas (edasonbas AT gmail.com). The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13860 SUBJECT: GRB 121011A: Fermi GBM observation DATE: 12/10/12 03:04:27 GMT FROM: Shaolin Xiong at UAH Shaolin Xiong (UAH), David Byrne (UCD) and Charles Meegan (USRA) report on behalf of the Fermi GBM Team: "At 11:15:25.70 UT on 11 October 2012, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 121011A (trigger 371646928 / 121011469), which was also detected by the Swift/BAT (Racusin et al. 2012, GCN 13845) and Fermi/LAT (M. Ohno et al. 2012, GCN 13859). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is ~56 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve shows a single peak with long tail with a duration (T90) of about 66 s (10-1000 keV). The time-averaged spectrum from T0+0.0 s to T0+67.6 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -1.09 +/- 0.07 and the cutoff energy, parameterized as Epeak, is 1160 +/- 410 keV. The event fluence (10-1000 keV) in this time interval is (1.00 +/- 0.05)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+7.23 s in the 10-1000 keV band is 2.2 +/- 0.2 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: 13861 SUBJECT: GRB 121011A: misprint in GCNC 13854 DATE: 12/10/12 05:26:37 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov Moscow Lomonosov State University, Sternberg Astronomical Institute, The correct formula (1) (Yurkov et al.,GCNC 13854) is: "The light curve between 200 sec and 6600 sec is very simmetrical in log(F) - log (t) coordinates (like to bell) with parabolic low : m - m_max = A (log t/t_max)^2 (1) A = 4.2 +/- 0.1 where t is time from GRB trigger in sec, t_max = 633+-11s, m_max = 16.60+/-0.02 . We stress that this formulae does not depend on redshift." This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13862 SUBJECT: GRB 121011A: NOT redshift retraction DATE: 12/10/12 09:20:33 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst J. P. U. Fynbo (DARK/NBI), D. Malesani (DARK/NBI), D. Xu (WIS), report on behalf of a larger collaboration: We performed a careful analysis of the spectrum secured at the NOT (Fynbo et al., GCN 13856) of the afterglow of GRB 121011A (Racusin et al., GCN 13845). We confirm that a faint continuum is visible in our data, but we cannot detect any clear feature with confidence. The redshift z = 0.58 suggested in GCN 13856 is therefore not correct. A sharp break is detected at the blue end of our spectrum around 4100 AA, but its interpretation is not straightforward. If due to Ly alpha at z = 2.3, than we would expect surviving flux blueward of the break. If due to the Lyman limit at z = 3.4, than we would expect to see the Lyman forest redward of the break, which we do not. We thus believe this break to be an artifact of the data, but encourage other observers to attempt spectroscopy with large area telescopes, also given the detection of the GRB by Fermi/LAT (Ohno et al., GCN 13859). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13864 SUBJECT: GRB 121011A: Swift/UVOT Detection DATE: 12/10/12 19:58:04 GMT FROM: Stephen Holland at STScI S. T. Holland (STScI) and J. L. Racusin (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 121011A 109 s after the BAT trigger (Racusin et al., GCN Circ. 13845). A source consistent with the XRT position (Evans et al. GCN Circ. 13850) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 17:20:51.23 = 260.21346 (deg.) Dec (J2000) = +41:06:37.1 = +41.11030 (deg.) with an estimated uncertainty of 0.52 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 109 258 147 18.96 +/- 0.06 v 4093 5729 393 19.81 +/- 0.21 b 3476 3676 197 19.51 +/- 0.18 u 4708 4908 197 19.67 +/- 0.18 w1 4503 15916 1183 >20.9 m2 4298 5933 393 >22.6 w2 3888 5524 393 >21.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13865 SUBJECT: GRB 121011A: optical observations DATE: 12/10/13 04:55:08 GMT FROM: Shashi Bhushan Pandey at ROTSE Brajesh Kumar, Vijay Kumar Bhatt, Archana Soam and S.B. Pandey (ARIES, Nainital, India, on behalf of larger Indian GRB collaboration). Follow-up observations of GRB 121011A (Racusin et al., GCN13845) were done using 1.04m telescope at Nainital in good sky conditions starting at 13:17:03 (UT) on 11-10-2012. Several frames in B, V, R_c and I_c pass-bands were obtained with exposure time of 300 sec each. The optical afterglow candidate (Racusin et al., GCNC 13845) is clearly detected in our frames. The preliminary photometry for the first R_c and I_c frames were 19.59 +- 0.02 mag and 19.14 +- 0.05 mag respectively, calibrated against nearby USNO stars. Further observations are continued. This massage may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13868 SUBJECT: GRB 121011A: WSRT radio observation DATE: 12/10/14 20:51:12 GMT FROM: Alexander van der Horst at U of Amsterdam A.J. van der Horst (University of Amsterdam) reports on behalf of a large collaboration: "We observed the position of the GRB 121011A afterglow at 4.9 GHz with the Westerbork Synthesis Radio Telescope at October 14 10.01 to 18.14 UT, i.e. 2.95 - 3.29 days after the burst (GCN 13845). We do not detect a radio source at the position of the optical counterpart (GCN 13853). The three-sigma rms noise in the map around that position is 75 microJy per beam. The formal flux measurement for a point source at the position of the optical counterpart is 44 +/- 25 microJy. We would like to thank the WSRT staff for scheduling and obtaining these observations." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13871 SUBJECT: PdB IRAM observation of GRB 121011A DATE: 12/10/15 15:59:29 GMT FROM: Bruce Gendre at ASDC B. Gendre (INAF-OAR/ASDC), C. Feruglio (IRAM), G. Stratta (INAF-OAR), A. Antonelli (INAF-OAR/ASDC), J.L. Atteia (IRAP/OMP), S. Basa (LAM/OAMP), M. Boër (Artemis/CNRS), S. Cutini (INAF-OAR/ASDC), V. D'Elia (INAF-OAR/ASDC), A. Klotz (IRAP/OMP), L. Piro (INAF-IAPS), repport: we observed the position of GRB 121011A (Racusin et al., GCN 13845) with the Interferometer of the Plateau de Bure on 2012-10-11, starting at 15:30 UT for 1.46 hours, at frequency 130 GHz. The observing conditions were good, with a stable atmosphere (phase rms below 35 degrees), Tsys~200 and water vapor about 6 mm. No afterglow has been detected, with an upper limit of 214 micro Jy. Given the radio non detection (van der Horst, GCN 13868) and the faintness of this object as seen in X-ray (Burrows et al., GCN 13857), no further observations are planned. We thank the technical staff of IRAM for fast support of the trigger. This message can be cited. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13873 SUBJECT: GRB 121011A Suzaku WAM observation of the prompt emission DATE: 12/10/16 08:58:49 GMT FROM: Masanori Ohno at Hiroshima U K. Takaki, Y. Hanabata, T. Kawano, R. Nakamura, Y. Tanaka, M. Ohno, Y. Fukazawa (Hiroshima U.), S. Sugita (Nagoya U.), H. Ueno, M. Tashiro, Y. Terada, W. Iwakiri, T. Yasuda, M. Asahina, S. Kobayashi, A. Sakamoto, Y. Ishida, S. Sugimoto (Saitama U.), M. Akiyama, N. Ohmori, E. Mochinaga, M. Yamauchi (Univ. of Miyazaki) Y. E. Nakagawa (Waseda U.), K. Yamaoka, M. Kokubun, T. Takahashi (ISAS/JAXA), Y. Urata, P. Tsai (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo), on behalf of the Suzaku WAM team, report: The long GRB 121011A (Swift/BAT trigger #535764; Racusin et al., GCN 13845; Fermi-LAT detection: Ohno et al., GCN 13777) was detected by the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 11:15:30.264 UT (=T0). The observed light curve shows a single peak structure starting at T0-10 s, ending at T0+30 s with the total duration (T90) is about 31 seconds. The fluence of main pulse in 100 - 1000 keV was 4.70 (-0.15, +0.10) x 10^-6 erg/cm^2 The 1-s peak flux measured at T0-1.0 s was 0.41 (-0.31, +0.29) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-10 s to T0+30 s is well fitted by by a single power-law with a photon index of 1.61 (-0.14, +0.18) (chi^2/d.o.f = 20.4/25). 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: 13884 SUBJECT: GRB 121011A: early optical light curve DATE: 12/10/18 23:12:12 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (SAI MSU, IKI), A. Matkin (UAFO, ISON), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We report the light curve of the optical afterglow of the Swift GRB 121011A (Racusin et al., GCN 13845). The afterglow was observed with VT-50 (0.5-m) telescope of UAFO/ISON-Ussuriysk observatory starting on Oct. 11 (UT) 11:21:29 (Volnova et al., GCN 13855). The light curve obtained from series of 30 s unfiltered imaging can be found at http://grb.rssi.ru/GRB121011A/GRB121011A_lc.png The photometry is based on several nearby USNO-B1.0 stars (R2). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13912 SUBJECT: GRB 121011A: optical observations DATE: 12/10/27 23:02:08 GMT FROM: Alina Volnova at SAI MSU A. Volnova (SAI MSU, IKI), Moskvitin (SAO RAS), V. Rumyantsev (CrAO), A. Pozanenko (IKI) We observed the field of the Swift GRB 121011A (Racusin et al., GCN 13845) with ZTSh telescope of CrAO on Oct. 15 between (UT) 17:36 and 18:54 under good weather condition with mean seeing of about 1.5 arcsec. We took 70 frames with exposure of 60 seconds in filter R. In a stacked image we do not detect any source within enhanced XRT error circle (Evans et al., GCN 13850). We also observed the field of this GRB with Zeiss-1000 telescope of SAO RAS on Oct. 17 between (UT) 17:45 and 18:38 under good weather conditions with mean seeing of about 2.4 arcsec. We took 12 frames with exposure of 200 seconds. On a stacked image we do not detect any source either. The photometry based on a USNO-B1 star #1310-0279773 (R1 = 17.84; same as calibration in Fynbo et al., GCN Circ. 13856; Malesani et al., GCN 13853) is following: T0+ Filter, Exposure, OT, UL (3 sigma), Telescope (days) (s) 4.292 R 70x60 n/d 23.5 ZTSh 6.294 R 12x200 n/d 22.3 Zeiss-1000