//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11159 SUBJECT: GRB 100901A: Swift detection of a burst with an optical afterglow DATE: 10/09/01 14:00:55 GMT FROM: Scott Barthelmy at NASA/GSFC S. Immler (CRESST/GSFC/UMD), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), S. Campana (INAF-OAB), V. D'Elia (ASDC), P. A. Evans (U Leicester), J. M. Gelbord (PSU), O. Godet (U Leicester), C. Gronwall (PSU), C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), O. M. Littlejohns (U Leicester), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), J. P. Osborne (U Leicester), C. Pagani (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), T. A. Pritchard (PSU), A. Rowlinson (U Leicester), 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 13:34:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100901A (trigger=433065). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 27.245, +22.744, which is RA(J2000) = 01h 48m 59s Dec(J2000) = +22d 44' 39" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single symmetric peak structure with a duration of about 10 sec. The peak count rate was ~800 counts/sec (15-350 keV), at ~1 sec after T_zero. The XRT began observing the field at 13:36:51.0 UT, 160.6 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 27.2642, 22.7584 which is equivalent to: RA(J2000) = 01h 49m 3.41s Dec(J2000) = +22d 45' 30.1" with an uncertainty of 3.0 arcseconds (radius, 90% containment). This location is 82 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 7.08e+20 cm^-2 (Kalberla et al. 2005). UVOT took a finding chart exposure of 150 seconds with the White filter starting 147 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 01:49:03.42 = 27.26424 DEC(J2000) = +22:45:30.8 = 22.75856 with a 90%-confidence error radius of about 0.81 arc sec. This position is 0.6 arc sec. from the center of the XRT-Enhanced error circle. The estimated magnitude is 19.67 with a 1-sigma error of about 0.18. No correction has been made for the expected extinction corresponding to E(B-V) of 0.10. Burst Advocate for this burst is S. Immler (immler AT milkyway.gsfc.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: 11160 SUBJECT: GRB 100901A: Faulkes Telescope North afterglow candidate DATE: 10/09/01 14:04:33 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), Z. Cano, A. Melandri (LJMU), D. Kopac (U. Ljubljana) report on behalf of a large collaboration: The Faulkes Telescope North automatically began observing Swift GRB 100901A (Immler et al. GCN Circ. 11159) on September 01, 13:36:29 UT, 2.32 minutes from the GRB trigger time. We clearly identify an uncatalogued object at the following position: RA(J2000.0): 01:49:03.41 Dec(J2000.0): +22:45:30.8 This is consistent with the UVOT candidate (GCN 11159). Observations are going on. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11161 SUBJECT: GRB 100901A: MASTER Optical Early Limits DATE: 10/09/01 14:55:56 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs K.Ivanov, O.Chuvalaev, V.Poleschuk, E.Konstantinov, V.Lenok, O.Gres, S.Yazev, N.M.Budnev, Irkutsk State University E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina, D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M. Kornilov Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov Ural State University, Kourovka Two MASTER robotic telescopes (MASTER-Net: http://observ.pereplet.ru) located near Baykal Lake (Tunka) and Blagoveschensk was pointed to the Swift GRB 100901A (Immler et al., GCN Circ 11159) 47 sec after Notice time (103 s after trigger time) and 45 s after Notice time (101s after trigger time). We have a number polarization, unfiltered and R images with exposition 20, 30, 40, 60... s. but near horizont. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? Filter -------------------------------------------------------------------------- 13:35:51 13:35:51 20 16.1 101.0 N Unfiltr 13:35:51 13:37:32 80 16.6 101.0 Y Unfiltr 13:35:53 13:36:13 20 16.5 103.0 N Polariz 13:35:53 13:38:02 90 17.4 103.0 Y Polariz The message may be cited. mailto: lipunov@sai.msu.ru //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11162 SUBJECT: GRB 100901A: confirmation of the afterglow DATE: 10/09/01 14:58:24 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Klunko, I. Korobtsev (ISTP), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the Swift GRB 100901A (Immler et al., GCN 11159) with AZT-33IK telescope of Sayan observatory (Mondy) starting Sep. 01 (UT) 13:44:30. We confirm the afterglow candidate (Immler et al., GCN 11159; Guidorzi et al., GCN 11160) at the following preliminary position (J2000) RA=01 49 03.29 Dec +22 45 30.0. We clearly detect the afterglow in single images of 60 s exposure obtained in R-filter. Observations are continuing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11163 SUBJECT: GRB 100901A: MASTER: the OT brightenning DATE: 10/09/01 15:41:39 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs K.Ivanov, O.Chuvalaev, V.Poleschuk, E.Konstantinov, V.Lenok, O.Gres, S.Yazev, N.M.Budnev, Irkutsk State University E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina, D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M. Kornilov Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov Ural State University, Kourovka We clearly see (MASTER-Net: http://observ.pereplet.ru) located near Baykal Lake (Tunka) and Blagoveschensk) brightenning OT at the Swift position (Immler et al., GCN Circ 11159). R mag = 17 (38 min after GRB time) The message may be cited. mailto: lipunov@sai.msu.ru //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11164 SUBJECT: GRB 100901A: Gemini-N Redshift DATE: 10/09/01 17:02:09 GMT FROM: Ryan Chornock at Harvard R. Chornock, E. Berger (Harvard), D. Fox (Penn State), A. J. Levan (U. Warwick), N. R. Tanvir, and K. Wiersema (U. Leicester) report on behalf of a larger collaboration: We obtained spectroscopy of the optical afterglow (Immler et al., GCN 11159; Guidorzi et al., GCN 11160; Ivanov et al., GCN 11161; Klunko et al., GCN 11162) of GRB 100901A (Immler et al., GCN 11159) using GMOS on the Gemini-North 8-m telescope starting on 2010 September 1.61 UT. A set of four 400s observations were obtained covering the wavelength range 3825-6675 Angstroms. Numerous absorption lines are present. The highest redshift system is at z=1.408, with many absorptions from Fe II, Al II, and Si II. The presence of several Fe II* absorptions establishes this as the redshift of the host galaxy of GRB 100901A. Two intervening systems at z=1.315 and 1.318 also have absorptions from Mg II and Fe II. We thank A. Stephens and the Gemini staff for their help in obtaining these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11165 SUBJECT: GRB 100901A: MASTER power low decay DATE: 10/09/01 17:46:51 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina, D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M. Kornilov Sternberg Astronomical Institute, Moscow State University K.Ivanov, O.Chuvalaev, V.Poleschuk, E.Konstantinov, V.Lenok, O.Gres, S.Yazev, N.M.Budnev, Irkutsk State University V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov Ural State University, Kourovka We clearly see (MASTER-Net: http://observ.pereplet.ru, Tunka) OT after 386 s (T-T_trigger) at the Swift position (Immler et al., GCN Circ 11159) and strongly brighter than UVOT estimation (Immler et al., GCN Circ 11159). After this time we see power low decay F ~ t_(-alpha), with alpha ~ 0.5+-0.2. This is preliminary result. Observations are continued at Tunka, Ural and Kislovodsk in different filters. The message may be cited. mailto: lipunov@sai.msu.ru //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11166 SUBJECT: GRB 100901A: optical observation at Mt.Terskol DATE: 10/09/01 18:50:15 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, A. Sergeev (Terskol Branch of Institute of Astronomy), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We started observation of the Swift GRB 100901A (Immler et al., GCN 11159) with the Z-600 telescope of Mt.Terskol observatory in R-filter on Sep.01 (UT) 17:50. In a combined image we clearly detect the afterglow (Immler et al., GCN 11159; Guidorzi et al., GCN 11160; Ivanov et al., GCN 11161; Klunko et al., GCN 11162). Preliminary photometry is based on the reference star USNO-B1.0 #1127-0027231 RA(J2000) = 01 49 06.78 Dec(J2000) = +22 47 03.3 assuming R=15.37: T0+ Filter, Exposure, OT (d) (s) 0.1821 R 5x60 17.28 +/-0.03 The finding chart can be found at http://grb.rssi.ru/GRB100901A/GRB100901A_R_100901_Terskol.jpg //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11167 SUBJECT: GRB 100901A: Enhanced Swift-XRT position DATE: 10/09/01 21:59:30 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 52 s of XRT Photon Counting mode data and 1 UVOT images for GRB 100901A, 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 = 27.26485, +22.75850 which is equivalent to: RA (J2000): 01h 49m 3.56s Dec (J2000): +22d 45' 30.6" with an uncertainty of 2.2 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: 11168 SUBJECT: GRB 100901A: optical observation at Mt.Terskol DATE: 10/09/01 23:22:35 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, A. Sergeev (Terskol Branch of Institute of Astronomy) and A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We are continuing observations of the Swift GRB 100901A (Immler et al., GCN 11159) with the Z-600 telescope of Mt.Terskol observatory in R-filter (Andreev et al., GCN 11166). In a combined image at mid time Sep. 01 (UT) 20:09 we still detect bright afterglow (Immler et al., GCN 11159; Guidorzi et al., GCN 11160; Ivanov et al., GCN 11161; Klunko et al., GCN 11162). Preliminary photometry is based on the reference star USNO-B1.0 #1127-0027231 RA(J2000) = 01 49 06.78 Dec(J2000) = +22 47 03.3 assuming R=15.37: T0+ Filter, Exposure, OT (d) (s) 0.2742 R 5x60 17.05 +/-0.02 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11169 SUBJECT: GRB 100901A: Swift-BAT refined analysis DATE: 10/09/02 01:02:07 GMT FROM: Scott Barthelmy at NASA/GSFC T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), S. Immler (CRESST/GSFC/UMD), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+663 sec from recent telemetry downlinks, we report further analysis of BAT GRB 100901A (trigger #433065) (Immler, et al., GCN Circ. 11159). The BAT ground-calculated position is RA, Dec = 27.252, 22.751 deg, which is RA(J2000) = 01h 49m 00.5s Dec(J2000) = +22d 45' 02.9" with an uncertainty of 3.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 40%. The mask-weighted light curve shows two main peaks. The first starts at ~T-5 sec, peaks at ~T+5 sec, and ends at ~T+10 sec. The second starts at ~T+300 sec, peaks at ~T+390, and ends at ~T+490 sec. We note that the burst location went out of the BAT FoV at T+650 sec during a slew due to an observing constraint. T90 (15-350 keV) is 439 +- 33 sec (estimated error including systematics). The time-averaged spectrum from T-2.4 to T+471.8 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.52 +- 0.21. The fluence in the 15-150 keV band is 2.1 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-1.81 sec in the 15-150 keV band is 0.8 +- 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/433065/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11170 SUBJECT: GRB 100901A - NOT optical observation DATE: 10/09/02 03:09:25 GMT FROM: Annalisa De Cia at U of Reykjavik,Science Inst. A. De Cia, P.M. Vreeswijk and P. Jakobsson (University of Iceland) report: We observed the field of GRB 100901A (Immler et al., GCN 11159) with the NOT equipped with ALFOSC in good weather conditions. Observations were carried out in the R filter for 15 minutes, with mean time 12.13 hours after the GRB trigger. We measure R=17.3 for the afterglow, not corrected for Galactic extinction, calibrated against the USNO-B1.0 1127-0027231 reference star (R=15.37) used by Andreev et al., GCN 11166 and GCN 11168. time after trigger exposure (s) R mag 12.13 hours 3 x 300 17.3 We acknowledge the careful assistence of the NOT staff, in particular Tapio Pursimo. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11171 SUBJECT: GRB 100901A: Swift-XRT Team refined analysis DATE: 10/09/02 06:00:48 GMT FROM: Kim Page at U.of Leicester K.L. Page (U. Leicester) and S. Immler (CRESST/GSFC/UMD) report on behalf of the Swift-XRT team: We have analysed 13 ks of XRT data for GRB 100901A (Immler et al., GCN Circ. 11159), from 128 s to 33.2 ks after the BAT trigger. The data comprise 448 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN. Circ 11167). The first snapshot (data collected until ~620 s after the trigger) consists of a number of superimposed flares, with the main peak around 410 s; this peak was also seen in the BAT data (Sakamoto et al., GCN Circ. 11169). The light curve then shows a decaying trend with alpha = 0.74 +/- 0.12, until around 12 ks, after which there is a small rebrightening, to a plateau level of around 0.3 count s^-1. A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.68 (+/-0.04). The best-fitting absorption column is 3.6 (+0.7, -0.6) x 10^21 cm^-2, at a redshift of 1.408 (Chornock et al., GCN Circ 11164), in addition to the Galactic value of 7.1 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.19 (+/-0.07) and a best-fitting absorption column of 3.9 (+/-0.9) x 10^21 cm^-2 (in addition to the Galactic vale). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1. Because of the rebrightening/plateau shape of the light curve at this time, we cannot sensibly predict the count rate at 24 hours. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00433065. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11172 SUBJECT: GRB100901A: MITSuME Okayama Optical Observation DATE: 10/09/02 06:13:46 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 100901A (Immler et al., GCN 11159) 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 2010-09-1 13:36:08 UT (~2.0 min after the burst). We detected the previously reported afterglow (Immler et al., GCN 11159; Guidorzi et al., GCN 11160; Klunko et al., GCN 11162; Ivanov et al., GCN 11165; Andreev et al., GCN 11166, GCN 11168; De Cia et al., GCN 11170) in all the three bands. Our results show that the brightness of the afterglow began to increase at ~0.14 days after the burst. Photometric results and three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err ---------------------------------------------------------------------- 0.01195 13:51:23 1560.0 18.6 0.5 17.4 0.1 16.8 0.2 0.03343 14:22:18 1560.0 18.1 0.1 17.9 0.1 17.4 0.1 0.05475 14:53:00 1560.0 18.7 0.1 18.5 0.1 17.6 0.1 0.07594 15:23:32 1440.0 18.7 0.1 18.4 0.1 18.0 0.2 0.09685 15:53:38 1500.0 18.9 0.1 18.5 0.1 18.0 0.2 0.11790 16:23:57 1560.0 19.1 0.2 18.7 0.2 17.9 0.2 0.13912 16:54:30 1560.0 18.8 0.1 18.4 0.1 17.8 0.1 0.16013 17:24:46 1500.0 18.7 0.1 18.0 0.1 17.2 0.1 0.18107 17:54:55 1560.0 18.2 0.1 17.6 0.1 17.1 0.1 0.20223 18:25:23 1500.0 18.0 0.1 17.7 0.1 17.0 0.1 0.22363 18:56:12 1500.0 18.2 0.1 17.6 0.1 17.0 0.1 ---------------------------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11173 SUBJECT: GRB 100901A: THO optical observations DATE: 10/09/02 08:55:23 GMT FROM: Veli-Pekka Hentunen at Taurus Hill Obs,A95 Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill Observatory, Varkaus, Finland) report: Taurus Hill Observatory (A95, Varkaus, Finland) C-14 telescope and SBIG ST-8XME CCD camera were used to detect GRB 100901A optical afterglow. The observations were started at 2010-09-01 21:08:30 (UT) and stopped at 2010-09-02 01:11:13 (UT). A number of unfiltered and BVR observations with varying exposure times were made. The afterglow was detected at following position RA 1 49 03.45 and DEC +22 45 30.5 consistent those given by Immler s. et al. (GCN 11159) and Guidorzi C. et al. (GCN 11160) to within positional errors. The following magnitudes were obtained from the observations using USNO-B1.0 1127-0027231 (R = 15.37 and B = 16.38)) as the comparison: +T0 (hour) Filter Exp (sec) Mag Mag err Limit 7.606 unfiltered 2x120 17.1 0.1 18.4 7.678 unfiltered 2x120 17.2 0.2 18.5 10.607 unfiltered 3x300 17.3 0.1 19.6 11.141 Rc 3x300 17.4 0.1 20.0 11.228 B 3x300 18.1 0.2 19.1 A jpg color image of the 4x300sec observations is available at the following URL: http://cutenews.kassiopeia.net/data/upimages/GRB100901A_LRGB_web_nuoli.jpg //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11174 SUBJECT: GRB 100901A: SARA-N observations DATE: 10/09/02 12:28:03 GMT FROM: Adria C. Updike at Clemson U Adria C. Updike, Dieter H. Hartmann (Clemson University) and William Keel, Erin Darnell (U Alabama) report: We observed the field of GRB 100901A (Immler et al., GCN 11159) with the 0.9m SARA-North telescope located at KPNO beginning 18 hours and 45 minutes after the trigger under good conditions. In 240s exposures, we clearly detect the afterglow in all images. Filter Mag Mag error UT Start --------------------------------------- B 18.7 0.1 08:20 V 18.2 0.1 08:24 R 18.0 0.1 08:28 I 17.9 0.1 08:32 Magnitudes are reported relative to the USNO B1.0 and NOMAD catalogs field stars. Observations in all bands continued for 4 hours. Further observations are planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11175 SUBJECT: GRB 100901A : HCT optical observations DATE: 10/09/02 13:34:34 GMT FROM: D.K. Sahu at Indian Inst of Astrophysics,Bangalore D.K. Sahu, B.C. Bhatt, Sonam Arora and Pepsi Anto (IIA, Bangalore) report. Optical afterglow of GRB 100901A (Immler et al. GCN 11159) was obsrved with the 2m. Himalayan Chandra Telescope of the Indian Astronomical Observatory, Hanle, India. A series of exposures were taken in Bessell V, R and I bands, between 17:35 UT and 22:15 UT on 01/09/2010. The optical afterglow was detected in all our frames. The preliminary R and I magnitudes of the optical afterglow calibrated using USNO B1.0 1127-0027231 reference star (R=15.37, I=15.13) is as under: Mid UT Exposure Filter Mag 17:42 300sec R 17.34 +/- 0.05 19:44 300sec R 17.03 +/- 0.05 22:05 300sec R 17.08 +/- 0.04 17:51 300sec I 17.05 +/- 0.05 19:51 300sec I 16.76 +/- 0.04 This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11176 SUBJECT: Swift/UVOT Observations of GRB100901A DATE: 10/09/02 13:40:17 GMT FROM: Tyler Pritchard at PSU T. A. Pritchard (PSU) and Immler (CRESST/GSFC/UMD) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100901A 147 s after the BAT trigger (Immler et al., GCN Circ. 11159). We detect an object not present in the DSS in all filters within 0.1 arcsec of the Enhanced Swift-XRT position (Osborne et al., GCN Circ. 11169) Preliminary magnitudes and 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) 147 297 147 19.55 ± 0.19 u (FC) 305 555 246 17.52 ± 0.10 white 585 605 20 18.58 ± 0.32 white 4849 5051 198 18.66 ± 0.07 b 561 581 19 17.85 ± 0.30 b 4644 4844 197 18.69 ± 0.11 u 305 555 246 17.52 ± 0.10 u 4439 4639 197 18.08 ± 0.10 v 129 139 10 >17.21 v 3824 4024 197 18.50 ± 0.21 w1 4234 4434 197 18.53 ± 0.16 m2 4029 4229 197 19.22 ± 0.32 w2 611 626 15 >17.6 w2 5055 5255 197 >20.04 w2 9620 10520 885 20.73 ± 0.32 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.10 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11177 SUBJECT: GRB 100901A: Vega telescope optical afterglow observation DATE: 10/09/02 14:40:47 GMT FROM: Drejc Kopac at Math Phys U,Slovenia D. Kopac, B. Dintinjana and A. Gomboc (U. Ljubljana) report: We observed the field of GRB 100901A (Immler et al., GCN 11159) with the 0.7m Vega telescope located in Ljubljana, starting at 20:31:31 UT on 2010 September 01, approx. 7 hours after the trigger. We took 10 images in R band with exposure time 180s and we clearly detect the optical afterglow (Guidorzi et al., GCN 11160). Our preliminary photometry yields Mid time from Filter Magnitude trigger (days) ------------------------------------- 0.302 R 17.2 +- 0.1 ------------------------------------- Magnitude is calibrated against the USNO-B1.0 1127-0027192 reference star (R2=17.58) and is not corrected for Galactic extinction. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11178 SUBJECT: GRB 100901A: MASTER optical flare at 420s discovery DATE: 10/09/02 18:20:57 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina, D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M. Kornilov Sternberg Astronomical Institute, Moscow State University K.Ivanov, O.Chuvalaev, V.Poleschuk, E.Konstantinov, V.Lenok, O.Gres, S.Yazev, N.M.Budnev, Irkutsk State University V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov Ural State University, Kourovka We (MASTER-Net: http://observ.pereplet.ru, Tunka, Ivanov et al., GCN Circ 11161) clearly detected optical flare (maxmag~17.0,unfiltered) at 426+-40 s after trigger time (Immler et al., GCN Circ 11159) synchronously with Xray flare (Page et al., GCN Circ 11171). We have ~ 11 hours Unfiltered, R,I, Polarization continuously observations on same telescope systems. The redaction is continued. The first 10 000 s relative optical flux light curve is available at http://observ.pereplet.ru/images/GRB100901A/opt_flux_lc.png The message may be cited. mailto: lipunov@sai.msu.ru //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11179 SUBJECT: GRB 100901A: ROTSE-III Detection DATE: 10/09/02 19:20:08 GMT FROM: Shashi Bhushan Pandey at ROTSE S. B. Pandey and W. Zheng (U Mich), report on behalf of the ROTSE collaboration: Due to bad weather conditions, the ROTSE-3a telescope at Siding Springs Observatory, Australia did not respond to GRB 100901A (Swift trigger 433065, Immler S. et al., GCN 11159). Automated re-pointing of ROTSE-3c at the H.E.S.S. site at Mt. Gamsberg, Namibia and ROTSE-3b at the McDonald Observatory, Texas observed the optical afterglow starting ~ 8.6 to 22.0 hours after the burst. The optical afterglow was detected in all the stacked frames. The optical afterglow candidate appears to decay with a power-law index of ~1.2 at later epochs. Further imaging is ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11180 SUBJECT: GRB 100901A: 1.5m OSN BVRI-band observations. DATE: 10/09/02 19:34:45 GMT FROM: Juan Carlos Tello at IAA-CSIC R. Sánchez-Ramírez, J.C. Tello, A. Sota, J. Gorosabel, A.J. Castro-Tirado (IAA-CSIC, Granada), report on behalf of a larger collaboration: "We have taken several series of BVRI-band images of the Swift GRB 100901A (Immler et al. GCNC 11159) optical afterglow (Guidorzi et al. GCNC 11160) with the 1.5m telescope at Observatorio de Sierra Nevada, Spain. The afterglow is well detected in the four bands, with preliminary average magnitudes (calibrated against USNO B1.0 and GSC 3.2 stars) of B~18.0 (Sep 2.021 UT), V~17.4 (Sep 2.035 UT), R~17.3 (Sep 2.003 UT) and I~17.3 (Sep 2.049 UT)." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11184 SUBJECT: GRB 100901A: ISON-NM optical observations DATE: 10/09/02 20:41:25 GMT FROM: Leonid Elenin at ISON L. Elenin, I. Molotov (ISON), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 100901A (Immler et al. GCN Circ. 11159) with 0.45-m telescope of ISON-NM observatory on Sep. 02 (UT) 09:55:53 - 10:22:06. The afterglow (Immler et al., GCN 11159; Guidorzi et al., GCN 11160; Ivanov et al., GCN 11161; Klunko et al., GCN 11162) is well detected. For the preliminary photometry of unfiltered image we used USNO-B1.01127-0027229 field stars, assuming R=16.16: T-T0 filter exposure mag. mag. error -------------------------------------------------------------- 0.8561 W 20x60 17.82 +/- 0.03 -------------------------------------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11186 SUBJECT: GRB100901A: Errata of MITSuME Okayama about reference catalog DATE: 10/09/03 01:07:19 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: The reference catalog reported in GCN 11172 is incorrect. We used SDSS calalog for flux calibration. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11187 SUBJECT: GRB 100901A: TLS Observations: Break? DATE: 10/09/03 01:34:04 GMT FROM: Alexander Kann at TLS Tautenburg D. A. Kann, S. Klose, U. Laux, and B. Stecklum (TLS Tautenburg) report: We observed the afterglow of the double-peaked Swift GRB 100901A (Immler et al., GCN 11159) with the TLS 1.34m Schmidt telescope through several holes in the persistent cloud cover. Otherwise, conditions were excellent. We clearly detect the afterglow in all single 300 sec frames at high signal-to-noise (statistical error 0.03 - 0.04 mag). In comparison to five USNOB1.0 (R2 magnitude) stars, we find: time Rc dRc 1.382892 18.93 0.13 1.386920 19.00 0.15 1.422927 19.04 0.13 1.426955 19.13 0.14 We compile all available GCN data (Klunko et al., GCN 11162; Gorbovsky et al., GCN 11163; Andreev et al., GCN 11166; Andreev et al., GCN 11168; De Cia et al., GCN 11170; Kuroda et al., GCN 11172; Hentunen et al., GCN 11173; Updike et al., GCN 11174; Sahu et al., GCN 11175; Pritchard & Immler, GCN 11176; Kopac et al., GCN 11177; Ivanov et al., GCN 11178; Sánchez-Ramírez et al., GCN 11180; Elenin et al., GCN 11184) and can make the following statements on the light curve evolution of this extraordinary burst: The light curve shows three peaks. The first is the prompt flare reported by Ivanov et al., GCN 11178 (it should also be seen strongly in the UVOT u band event mode finding chart). The second peak is at ~ 0.026 days, reported by Gorbovsky et al., GCN 11163. Then another rebrightening sets in (Kuroda et al., GCN 11172), which peaks at about 0.35 days (e.g.,Sahu et al., GCN 11175, also seen strongly in the X-rays, Page & Immler, GCN 11171) . The afterglow begins to decay after that, and we find that the decay seems to have become steeper between the latest reported data (Updike et al., GCN 11174; Elenin et al., GCN 11184) and our detections at ~1.4 days. This may possibly be a jet break. Note that the R1 magnitudes are systematically ~ 0.2 mag brighter and thus the significance of the break is reduced if this calibration is used instead. Observationally, the late rebrightening makes this one of the brightest afterglows ever detected beyond 0.35 days, on par with that of GRB 060729 and several others. Comparing the extraordinary light curve evolution with our afterglow data base (Kann et al. 2010, ApJ, 720, 1513), we find that the evolution is remarkably similar to that of two other afterglows, namely GRB 060906 (Cenko et al. 2009, ApJ, 693, 1484) and GRB 970508 (e.g., Garcia et al. 1998, ApJ, 500, L105). In the extinction-corrected z = 1 system (we assume beta = 0.6, A_V = 0.1 - typical values - for GRB 100901A, and use z = 1.408, Chornock et al., GCN 11164), we find that the large-amplitude optical flares of these three afterglows can be brought to a reasonable match if we shift the GRB 060906 light curve by (Delta t = x 4.8; Delta mag = + 0.4) (it is faster and brighter) and that of GRB 970508 by (Delta t = / 8.2; Delta mag = - 3.7) (it is slower and fainter). In log-log space, all three rebrightenings look remarkably similar. GRB 100901A and GRB 060906 match strongly except that the rebrightening of GRB 060906 has a lower total amplitude - the pre- and post-rebrightening decay slopes are strongly similar. For GRB 970508, the optical flare evolves faster, also, the pre-flare evolution is a flat plateau. The post-flare decay is again very similar. Pandey & Zheng (GCN 11179) report a post-flare decay of alpha ~ 1.2 for GRB 100901A, and Zeh et al. 2006, ApJ, 637, 889 indeed find alpha = 1.24 +/- 0.01 for GRB 970508! Finally, we point out that the strong, late optical flare may be an energy injection, and the shells which have produced this refreshed shock may be the same ones that created the second BAT flare at 390 seconds (Sakamoto et al., GCN 11169) which also was seen in the optical (Gorbovsky et al., GCN 11163). Such reverberation effects have been discussed by Vestrand et al. 2006, Nature, 442, 172 (GRB 050820A) as well as Guidorzi et al. 2007, A&A, 474, 793 (GRB 070311). Further optical and especially NIR follow-up is strongly encouraged. Monitoring in Tautenburg will continue in the next days if weather permits. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11189 SUBJECT: GRB100901A: MITSuME Okayama Optical Observation at 1 day after the burst DATE: 10/09/03 05:48:08 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 100901A (Immler et al., GCN 11159) 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 2010-09-2 16:51:50 UT (~1.14 day after the burst). We detected the previously reported afterglow (Immler et al., GCN 11159; Guidorzi et al., GCN 11160; Klunko et al., GCN 11162; Ivanov et al., GCN 11165; Andreev et al., GCN 11166, GCN 11168; De Cia et al., GCN 11170; Kuroda et al., GCN 11172) in all the three bands. Photometric results of the OT are listed below. The magnitudes are obtained from the sum of exposures. No significant variation was detected during these exposures, though the S/N was not so good. We used SDSS catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err ---------------------------------------------------------------------- 1.17902 17:51:57 6060.0 19.4 0.1 19.0 0.1 18.5 0.1 ---------------------------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11190 SUBJECT: GRB 100901A: Kanata Telescope observation of the optical afterglow DATE: 10/09/03 06:03:58 GMT FROM: Michitoshi Yoshida at Okayama Astrophysical Obs M. Yoshida, M. Sasada, T. Komatsu and K. S. Kawabata (HASC, Hiroshima University) We performed R band imaging observation of the optical afterglow of GRB 100901A (Immler et al., GCN 11159) with the 1.5m Kanata telescope of Hiroshima University. The observation was made from 2010-09-02 15:07:24 UT (~1.06 day after the burst) to 15:50:33 UT. The previously reported afterglow (e.g Immler et al. GCN 11159; Kuroda et al. GCN 11172; or Kann et al. GCN 11187) was clearly detected. The afterglow showed a marginal increasing trend in brightness within this observation. Photometric results of the afterglow are listed below. We used USNO- B1.0 1127-0027231 (R = 15.37) for flux calibration. #T0+[day] MID-UT T-EXP[sec] Rc err ----------------------------------------------- 1.070266 15:15:21 900.0 18.62 0.10 1.081620 15:31:42 900.0 18.60 0.07 1.096759 15:53:30 900.0 18.54 0.04 ----------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11191 SUBJECT: GRB 100901A: optical observation at Mt.Terskol DATE: 10/09/03 06:56:22 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, A. Sergeev (Terskol Branch of Institute of Astronomy) and A.Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We are continuing observations of the Swift GRB 100901A (Immler et al., GCN 11159) with the Z-600 telescope of Mt.Terskol observatory in R-filter (Andreev et al., GCN 11166). In a combined image at mid time Sep. 03 (UT) 00:36 we detect afterglow (Immler et al., GCN 11159; Guidorzi et al., GCN 11160; Ivanov et al., GCN 11161; Klunko et al., GCN 11162). In comparison with our previous photometry (Andreev et al., GCNs 11166, 11168) below we used several reference stars of SDSS DR7 and Lupton transformation ugriz -> BVRI: T0+ Filter, Exposure, OT (d) (s) 1.4599 R 10x120 19.22 +/- 0.05 The photometry above is consistent with steady decay based on early photometry (Kann et al, GRB 11187). We note however the systematic faintness of about ~0.25m in SDSS DR7 in comparison with USNO-B1.0 R2 which can explain possible contradiction of MITSUME observation calibrated against SDSS (Kuroda et al, GCN 11189) and photometry reported in Yoshida et al (GCN 11190). Detailed calibration of the field stars is necessary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11197 SUBJECT: GRB 100901A: HCT optical observations DATE: 10/09/03 19:52:42 GMT FROM: D.K. Sahu at Indian Inst of Astrophysics,Bangalore D.K. Sahu, Sonam Arora, N. Shantikumar Singh and Sreeja S. Kartha (IIA, Bangalore) report. We observed the optical afterglow of GRB 100901A (Immler et al., GCN 11159) in Bessell V, R, and I bands with the 2m. Himalayan Chandra Telescope of the Indian Astronomical Observatory, Hanle, India. Observations were made between 18:43 UT and 19:50 UT on 02/09/2010. The optical afterglow was detected in our individual frames of 300sec each in R and I bands. The preliminary R and I magnitudes of the optical afterglow calibrated using USNO B1.0 1127-0027231 reference star (R=15.37, I=15.13) is as under: Mid UT Exposure Filter Mag 18:50 3X300sec R 18.71 +/- 0.10 19:12 3X300sec I 17.51 +/- 0.15 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11198 SUBJECT: GRB 100901A: Lightbuckets Optical Observations DATE: 10/09/03 20:02:34 GMT FROM: Tilan Ukwatta at GSFC/GWU T. N. Ukwatta (GWU/GSFC), T. Sakamoto (GSFC/UMBC), N. Gehrels (GSFC), and K. S. Dhuga (GWU) We observed the Swift GRB 100901A (Immler et al., GCN 11159) with the Lightbuckets 0.61m rental telescope LB-0001 in Rodeo, NM, USA. Under good weather conditions, observations were carried out in the R filter starting Sep. 02 (UT) 07:05 (~ 17.5 hours after the GRB trigger) and a followup observation was performed on Sep. 03 (UT) 07:01 under acceptable weather conditions. The burst afterglow is clearly detected with a R magnitude of ~18.05 in the first observation. The afterglow, not corrected for Galactic extinction, is calibrated against the USNO-B1.0 R1 mag catalog. Time after trigger Exposure (s) R Magnitude 17.5 hours (0.7 days) 3 x 60 ~ 18.05 41 hours (1.7 days) 10 x 60 > 19.1 We acknowledge the helpful assistance of the Lightbuckets staff, in particular LightBuckets CEO Stephen G. Cullen. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11200 SUBJECT: GRB 100901A: multicolor photometry at Mt.Terskol DATE: 10/09/03 21:36:18 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, A. Sergeev (Terskol Branch of Institute of Astronomy), A.Pozanenko (IKI), N. Parakhin, S. Velichko, N. Borachok (IC AMER) V. Petkov (Baksan Neutrino Observatory INR RAS) on behalf of larger GRB follow up collaboration report: We performed multicolor observations of the afterglow (Immler et al., GCN 11159; Guidorzi et al., GCN 11160; Ivanov et al., GCN 11161; Klunko et al., GCN 11162) of the Swift GRB 100901A (Immler et al., GCN 11159) with the Zeiss-2000 and Meade-35 telescopes of Mt.Terskol of the first day after burst onset. The afterglow photometry is based on several reference stars of SDSS DR7 and Lupton transformation ugri -> BV: T0+ Filter, OT (d) Telescope: Meade-35 0.3527 V 17.80+/-0.05 Telescope: Zeiss-2000 0.3704 B 18.11+/- 0.02 0.4490 B 18.45+/- 0.02 0.4579 V 18.06+/- 0.02 0.4634 r(Gunn) 17.85+/- 0.02 0.4714 g(Gunn) 18.37+/- 0.02 The photometry is still preliminary and can be updated later. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11201 SUBJECT: GRB 100901A: optical observation at Mt.Terskol DATE: 10/09/04 01:15:38 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, A. Sergeev (Terskol Branch of Institute of Astronomy) and A.Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We are continuing observations of the Swift GRB 100901A (Immler et al., GCN 11159) with the Z-600 telescope of Mt.Terskol observatory in R-filter. In combined images we still detect afterglow (Immler et al., GCN 11159). The photometry is based on several reference stars of SDSS DR7 and Lupton transformation griz -> R used in our previous reports (GCNs 11191, 11200): T0+ Filter, Exposure, OT (d) (s) 2.4073 R 15x120 20.13 +/-0.12 2.4282 R 15x120 20.28 +/-0.16 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11208 SUBJECT: GRB 100901A: UKIRT zYJHK Observation DATE: 10/09/04 14:41:16 GMT FROM: Myungshin Im at Seoul Nat U Myungshin Im, Changsu Choi, Hyunsung Jun, Eugene Kang (CEOU/Seoul National University), Y. Urata (NCU), P. Choi (Pomona College), T. Sakamoto (NASA/GSFC), N. R. Tanvir (U. Leicester), and A. Levan (U. Warwick) on behalf of a larger collaboration We observed GRB 100901A (Immler et al. GCN 11159) in z, Y, J, H, and K filters using UKIRT. The observation started at Sept. 04, 10:49:31 UT or roughly 2.88 days after the BAT alert. We detect the afterglow in images in all the filters, with a preliminary magnitude of K=17.82 +- 0.2 mag (Vega) calibrated against a 2MASS star at RA=01h49m05.59s and Dec=22d44m51.86s. The K-band magnitude is consistent with an expected brightness in NIR assuming fading of the brightness with alpha=1.2 a spectral slope of beta=0.6 since the report of Kann et al. (GCN 11187). Further observation of the object is ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11211 SUBJECT: GRB 100901A: Submm observations from SMA DATE: 10/09/05 07:20:30 GMT FROM: Antonio Deugarte at IAA-CSIC A. de Ugarte Postigo (DARK/NBI), S. Martin Ruiz (ESO), G. Petitpas (SMA), and A. J. Castro-Tirado (IAA-CSIC) report on behalf of a larger collaboration: "We have observed the field of GRB 100901A (Immler et al. GCNC 11159) from SMA in the 345 GHz band starting on September 3rd at 9 UT (43.5 h after the burst). The observing conditions were very good, with a water vapour of PWV~1 mm. However, preliminary analysis does not show any new source at the position of the afterglow down to a 3-sigma limit of 2.25 mJy." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11213 SUBJECT: Optical observations of GRB 100901A DATE: 10/09/05 13:54:39 GMT FROM: AAVSO GRB Network at AAVSO Stefano Sposetti (Gnosca, Switzerland) reports to the AAVSO International High Energy Network the following optical observations of GRB 100901A (GCN #11159, Immler et al.): Stefano Sposetti reports a clear detection of the optical afterglow of GRB 100901A (GCN #11159, Immler et al., and many subsequent reports), and obvious fading over the four hour span of observations. The afterglow was observed unfiltered (R-band zero point) beginning at 23:25UT on 2010 September 01 (approximately 10 hours post-burst), and continuing to 03:50 UT on 2010 September 02. Observations were made using an SBIG ST8XE CCD attached to a 0.4-m Newtonian sited in Gnosca, Switzerland. A total of sixty 30-second integrations and 215 60-second integrations were obtained. An ensemble of stars from the USNO-A2.0 catalog were used for the magnitude comparison. The frames were co-added into sixteen frames of 15-minutes duration each, to enable time-series photometry. Signal-to-noise in all of the images was between 24 and 52. The following time-series data were derived: date mag(CR) Sept 1.98105 17.43 Sept 1.99242 17.50 Sept 2.00391 17.49 Sept 2.01520 17.53 Sept 2.02619 17.66 Sept 2.03711 17.67 Sept 2.04803 17.57 Sept 2.05896 17.63 Sept 2.07011 17.66 Sept 2.08135 17.72 Sept 2.09257 17.83 Sept 2.10413 17.79 Sept 2.11637 17.80 Sept 2.12767 17.79 Sept 2.13897 17.85 Sept 2.15026 17.91 The AAVSO High Energy Network was made possible through grants from the Charles Curry Foundation and NASA. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11221 SUBJECT: GRB 100901A: Possible WSRT Radio Detection DATE: 10/09/06 04:36:07 GMT FROM: Alexander van der Horst at NASA/MSFC A.J. van der Horst (NASA/MSFC/ORAU), K. Wiersema (U of Leicester), A.P. Kamble, R.A.M.J. Wijers, E. Rol (U of Amsterdam) and C. Kouveliotou (NASA/MSFC) report on behalf of a large collaboration: "We observed the position of the GRB 100901A afterglow at 4.9 GHz with the Westerbork Synthesis Radio Telescope at September 3 20.35 UT to September 4 08.50 UT, i.e. 2.29 - 2.79 days after the burst (GCN 11159). We detect a radio source at the position of the X-ray and UV/optical counterpart (GCN 11195) at the 4-sigma level, with a flux density of 134 +/- 33 microJy. We would like to thank the WSRT staff for scheduling and obtaining these observations." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11234 SUBJECT: GRB 100901A: ISON-NM optical observations DATE: 10/09/06 17:30:05 GMT FROM: Leonid Elenin at ISON L. Elenin, I. Molotov (ISON) and A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We continue observation of the Swift GRB 100814A (Immler et al. GCN Circ. 11159) with 0.45-m telescope of ISON-NM observatory on Sep. 04 (UT) 09:04:35 - 10:06:19, Sep. 05 (UT) 08:45:52 - 09:50:20 and Sep. 06 (UT) 09:36:57 - 11:14:22. The afterglow (Immler et al., GCN 11159; Guidorzi et al., GCN 11160; Ivanov et al., GCN 11161; Klunko et al., GCN 11162) is well detected on stacked images for three epochs. Preliminary photometry of unfiltered image against USNO-B1.0 1127-0027229, assuming R=16.16 is following: T-T0 filter exposure mag. mag. error -------------------------------------------------------------- 2.8336 W 12x300 19.78 +/- 0.25 3.8206 W 12x300 20.38 +/- 0.20 4.8700 W 20x300 20.97 +/- 0.22 -------------------------------------------------------------- The images of GRB100901A is available at: http://www.spaceobs.org/images/GRB1000901A-3epochs.jpg //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11236 SUBJECT: GRB 100901A: TLS observations, SDSS calibration, decay slope DATE: 10/09/06 18:56:47 GMT FROM: Alexander Kann at TLS Tautenburg D. A. Kann, U. Laux and B. Stecklum (TLS Tautenburg) report: We obtained further observations at multiple epochs of the afterglow of GRB 100901A (Immler et al., GCN 11159) with the TLS 1.34m Schmidt telescope. After another completely overcast night, we obtained data under good to excellent conditions in the third and fourth nights. For our first epoch (Kann et al., GCN 11187) we had used 5 USNO B1.0 R2 stars. Now, we compare their magnitudes with those derived from the SDSS catalog. We find that two of the stars we used, at RA = 01:49:05.595, Dec. = +22:44:51.96; RA = 01:48:59.497, Dec. = +22:46:18.56 must be variable, they yield strongly divergent zero points compared to the SDSS values for the other three stars. For the other three stars, which yield a stable zero point, we find: RA = 01:48:49.484, Dec. = +22:47:42.14; USNO R2 = 18.44; SDSS = 18.46 RA = 01:48:53.990, Dec. = +22:48:30.07; USNO R2 = 17.73; SDSS = 17.91 RA = 01:49:06.790, Dec. = +22:47:02.97; USNO R2 = 15.37; SDSS = 15.64 Note that the last star has been used by many observers to calibrate the afterglow, we find that it is 0.27 mag fainter, this is in agreement with what was reported by Andreev et al., GCN 11191. Recalibrating all reported magnitudes based on this calibration with this value strongly reduces the scatter in the light curve. Note the recently reported magnitudes by Elenin et al. (GCN 11234) are about 0.4 magnitudes too bright. Using these three stars, we re-calibrate our earlier data and add additional observations as follows: Mid-Time Rc dRc Exptime 1.384629 19.16 0.03 1 x 300 1.388656 19.24 0.04 1 x 300 1.424663 19.28 0.03 1 x 300 1.428691 19.36 0.03 1 x 300 1.432719 19.25 0.04 1 x 300 1.436747 19.18 0.04 1 x 300 3.309522 20.53 0.07 4 x 300 3.549130 20.70 0.04 1 x 600 + 2 x 450 + 4 x 300 4.398521 21.30 0.05 4 x 600 4.424271 21.31 0.26 1 x 120 4.430357 21.37 0.13 1 x 600 4.559408 21.27 0.10 1 x 600 Midtime is in days after the trigger, exposure time in seconds. We find that all observations after one day can be fit with a single power law with slope alpha = 1.46. This is steeper than the slope reported by Pandey & Zheng (GCN 11179), in agreement with the break proposed by Kann et al. (GCN 11187), though we caution the Delta alpha is shallow (and in agreement with the theoretical value for a cooling break) and there may still be calibration issues. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11246 SUBJECT: GRB 100901A: TLS Detection at 5.5 days DATE: 10/09/07 05:13:41 GMT FROM: Alexander Kann at TLS Tautenburg D. A. Kann, F. Ludwig and B. Stecklum (TLS Tautenburg) report: We observed the afterglow of the Swift GRB 100901A (Immler et al., GCN 11159) with the TLS 1.34m Schmidt telescope under excellent conditions in the fifth night. We obtained 3 x 600 sec images in Rc, the afterglow is faintly visible in each single image and well-detected in the stack. Calibration against the SDSS (Kann et al., GCN 11236) yields Rc = 21.91 +/- 0.11 at 5.550556 days after the GRB. This is somewhat subluminous compared to the extrapolation of the earlier decay (Kann et al., GCN 11236) but only further deep observations can confirm if another break has occured. Further observations are improbably due to upcoming inclement weather. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11255 SUBJECT: GRB 100901A: CrAO optical observations DATE: 10/09/07 18:32:18 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev (CrAO), D. Shakhovkoy, A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the afterglow (Immler et al., GCN 11159) of the Swift GRB 100901A (Immler et al., GCN 11159) with AZT-11 telescope of CrAO observatory on September 3 (UT) 20:24 - 21:18 and 5 (UT) 22:39 - 23:51. The afterglow photometry is based on the same reference stars of SDSS DR7 used in our previous reports (GCNs 11191, 11200): T0+ Filter, Exposure, mag. (mid, d) (s) 2.3045 R 19x180 20.07 +/- 0.08 4.4045 R 18x180 21.10 +/- 0.20 The photometry is compatible with photometry at the same period (4.39 - 4.55 days) reported by Kann et al (GCN 11236). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11256 SUBJECT: GRB 100901A: Confirmation of WSRT Radio Detection DATE: 10/09/07 19:33:23 GMT FROM: Alexander van der Horst at NASA/MSFC A.J. van der Horst (NASA/MSFC/ORAU), K. Wiersema (U of Leicester), A.P. Kamble, R.A.M.J. Wijers, E. Rol (U of Amsterdam) and C. Kouveliotou (NASA/MSFC) report on behalf of a large collaboration: "We observed the position of the GRB 100901A afterglow at 4.9 GHz with the Westerbork Synthesis Radio Telescope at September 6 20.33 UT to September 7 08.30 UT, i.e. 5.28 - 5.78 days after the burst (GCN 11159). We confirm our earlier detection (GCN 11221) and measure a brightening of the radio counterpart at the position of the X-ray and UV/optical afterglow (GCN 11195), with a flux density of 193 +/- 30 microJy. We would like to thank the WSRT staff for scheduling and obtaining these observations." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11257 SUBJECT: EVLA detection of radio afterglow of GRB100901A DATE: 10/09/07 21:09:26 GMT FROM: Poonam Chandra at Royal Mil. College Canada Poonam Chandra (RMC) and Dale A. Frail (NRAO) report on behalf of a larger collaboration: "We observed GRB 100901A (Immler et al. GCN 11159) with the Expanded Very Large Array (EVLA) on September 06.47 UT at a C band wide receiver (receiver frequency range 4-8 GHz). We detect the radio afterglow of the GRB at the Swift-XRT position (Osborne et al. GCN 11167) at 4.5 and 7.9 GHz frequencies. The flux densities at 4.5 and 7.9 GHz bands are 331+/-30 uJy and 440+/-27 uJy, respectively. The EVLA is still undergoing active commissioning and we caution that these results should be considered preliminary. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11258 SUBJECT: GRB100901A: IAO optical upper limits at 4 days after the burst DATE: 10/09/08 18:36:26 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (OAO, 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 100901A (Immler et al., GCN 11159) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. The observation started on 2010-09-05 19:53:16 UT (~4.3 day after the burst). We did not detect the previously reported afterglow (Immler et al., GCN 11159 and many follow-up observations) in all the three bands. Three sigma upper limits of the OT are listed below. We used SDSS catalog for flux calibration. T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 4.26159 19:50:52 1080.0 >21.6 >21.3 >19.8 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11266 SUBJECT: GRB 100901A: optical observation in Maidanak, break confirmation DATE: 10/09/10 01:48:03 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (SAI MSU), A. Pozanenko (IKI), M. Ibrahimov (MAO), B. Hafizov (MAO), B. Satovski (Astrotel) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 100901A (Immler et al., GCN 11159) with AZT-22 telescope of Maidanak observatory starting Sep. 7 (UT) 20:32:06. We clearly detect the afterglow (Immler et al., GCN 11159 and other follow-up ground based observations) in R-filter. The photometry of a stacked image is based on the same reference SDSS-DR7 stars used by our collaboration previously (GCNs 11191, 11200, 11255): T0+ Filter, Exposure, mag. (mid, d) (s) 6.2977 R 4*300 22.05+/-0.09 The photometry above confirms suggested break (Kann et al, GCN 11246) in a light curve of the afterglow. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11270 SUBJECT: GRB 100901A: optical observations in Mondy and R-light curve DATE: 10/09/10 09:59:02 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (SAI MASU), A. Pozanenko (IKI), E. Klunko, I. Korobtsev (ISTP) on behalf of larger GRB follow up collaboration report: We observed the Swift GRB 100901A (Immler et al., GCN 11159) with AZT-33IK telescope of Sayan observatory (Mondy) starting Sep. 01 (UT) 13:44:30 and continued observations within 2 nights after burst onset. Preliminary light curve of Mondy observation in R as well as R, r and nonfiltered observations inreported on behalf of our follow up collaboration (Klunko et al, GCN 11162; Andreev et al, GCN 11166; Andreev et al, GCN 11168; Elenin et al, GCN 11184; Andreev et al, GCN 11191; Andreev et al, GCN 11200; Andreev et al, GCN 11201; Elenin et al, GCN 11234; Rumyantsev et al, GCN 11255; Volnova et al, GCN 11266) can be found at http://grb.rssi.ru/GRB100901A/GRB100901A_lc.png The photometry calibration was performed against the same SDSS DR7 stars. There are some distinct features of the light curve. The tail of the flare reported earlier (Ivanov et al, GCN 11178), the rapid increase brightness after power law decay until 0.1d since trigger, the deep gap at ~0.13d, and the bump at ~0.3d corresponding to the bump in XRT light curve (Page et al, GCN 11171). We also confirm the late break between 5 and 6 days of the afterglow (Kann et al, GCN 11246; Volnova et al, GCN 11266). [GCN OPS NOTE(10sep10): Per author's request, the Subject line was changed from 100906A to 100901A.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11271 SUBJECT: GRB 100901A: errata of GRB name in GCN 11270 DATE: 10/09/10 10:43:36 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: In Subject field of GCN 11270 we erroneously reported the GRB name. It should be "GRB 100901A: optical observations in Mondy and R-light curve" The light curve of GRB 100906A will be reported later. We apologize for possible inconvenience.