//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13744 SUBJECT: GRB 120911A: Swift detection of a burst DATE: 12/09/11 07:34:19 GMT FROM: David Palmer at LANL J. K. Cannizzo (NASA/UMBC), V. D'Elia (ASDC), P. A. Evans (U Leicester), C. Guidorzi (U Ferrara), C. B. Markwardt (NASA/GSFC), A. Maselli (INAF-IASFPA), K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sakamoto (AGU), M. H. Siegel (PSU) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team: At 07:08:33 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120911A (trigger=533268). Swift could not immediately slew due to the Earth limb constraint. The BAT on-board calculated location is RA, Dec 357.961, +63.099 which is RA(J2000) = 23h 51m 51s Dec(J2000) = +63d 05' 55" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of at least 30 sec. The peak count rate was ~2500 counts/sec (15-350 keV), at ~1 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+51.6 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is J. K. Cannizzo (cannizzo 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: 13745 SUBJECT: GRB 120911A: ROTSE-III Optical Limits DATE: 12/09/11 07:45:30 GMT FROM: Wiphu Rujopakarn at U AZ/Steward W. Rujopakarn (Steward), T. Guver (Sabanci U), report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 120911A (Swift trigger 533268; Cannizzo et al., GCN 13744), producing images beginning 9.2 s after the GCN notice time. An automated response took the first image at 07:09:04.2 UT, 30.4 s after the burst, under fair conditions. We took 10 5-sec, 10 20-sec and 40 60-sec exposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging is on going. Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma Swift/BAT error circle; however, we are limited as the field is somewhat crowded. Individual images have limiting magnitudes ranging from 15.5-16.6; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 07:09:04.2 07:09:09.2 5 15.5 30.4 N 07:09:04.2 07:10:46.4 50 16.9 30.4 Y //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13746 SUBJECT: GRB 120911A: Swift-XRT observations DATE: 12/09/11 09:07:47 GMT FROM: Phil Evans at U of Leicester S. Campana (INAF-OAB), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU) and G. Tagliaferri (INAF-OAB) report on behalf of the Swift-XRT team: The XRT began observing the field of GRB 120911A at 08:04:07.0 UT, 3333.2 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 357.98152, 63.09831 which is equivalent to: RA(J2000) = 23h 51m 55.56s Dec(J2000) = +63d 05' 53.9" with an uncertainty of 4.4 arcseconds (radius, 90% containment). This location is 33 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. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 6.66 x 10^21 cm^-2 (Kalberla et al. 2005). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13747 SUBJECT: GRB 120911A: Faulkes Telescope North observations DATE: 12/09/11 12:00:22 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), A. Gomboc (U. Ljubljana), F. Virgili (LJMU) on behalf of a large collaboration report: The 2-m Faulkes Telescope North automatically began observing GRB 120911A (Cannizzo et al. GCN Circ. 13744) on September 11 2012, 08:17:24 UT corresponding to ~70 minutes post burst trigger with BVRi' filters. Within the XRT error circle (Campana et al. GCN Circ. 13746), we don't see any uncatalogued object down to the following limits: Mid time from Exposure Filter Limit GRB (hr) (s) ---------------------------------------------------------- 1.37 240 R > 20.9 1.45 220 i' > 21.2 ---------------------------------------------------------- We note the presence of a faint, uncatalogued object in the i' band, lying at 5.8" from the XRT centroid, with a magnitude of i=21.0 +- 0.2 (calibrated against USNOB1 nearby stars) at the following position: RA(J2000) = 23:51:56.06 Dec(J2000)= +63:05:49.2 with an error of 0.6". Presently we cannot make any statement about its temporal behaviour. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13748 SUBJECT: GRB 120911A: Enhanced Swift-XRT position DATE: 12/09/11 12:16:14 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 2099 s of XRT Photon Counting mode data and 5 UVOT images for GRB 120911A, 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 = 357.97897, +63.09874 which is equivalent to: RA (J2000): 23h 51m 54.95s Dec (J2000): +63d 05' 55.5" 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: 13749 SUBJECT: GRB 120911A: Swift-BAT refined analysis DATE: 12/09/11 13:18:13 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. K. Cannizzo (NASA/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), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+863 sec from recent telemetry downlinks, we report further analysis of BAT GRB 120911A (trigger #533268) (Cannizzo, et al., GCN Circ. 13744). The BAT ground-calculated position is RA, Dec = 357.966, 63.090 deg, which is RA(J2000) = 23h 51m 51.9s Dec(J2000) = +63d 05' 25.6" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 23%. The mask-weighted light curve shows two barely overlapping peaks starting at ~T-4 sec, peaking at ~T+1 and ~T+17 sec, and ending at ~T+50 sec. T90 (15-350 keV) is 17.8 +- 3.9 sec (estimated error including systematics). The time-averaged spectrum from T-1.84 to T+24.10 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.71 +- 0.16. The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.30 sec in the 15-150 keV band is 2.7 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/533268/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13750 SUBJECT: GRB 120911A: Swift-XRT refined Analysis DATE: 12/09/11 16:15:12 GMT FROM: Kim Page at U.of Leicester K.L. Page (U. Leicester) and J. K. Cannizzo (NASA/UMBC) report on behalf of the Swift-XRT team: We have analysed 7.2 ks of XRT data for GRB 120911A (Cannizzo et al. GCN Circ. 13744), from 3.3 ks to 17.3 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 13748). The light curve can be modelled with a power-law decay with a decay index of alpha=1.31 (+0.22, -0.21). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.0 (+/-0.4). The best-fitting absorption column is 8.4 (+3.4, -1.8) x 10^21 cm^-2, consistent with the Galactic value of 6.7 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 5.4 x 10^-11 (1.0 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 8.4 (+3.4, -1.8) x 10^21 cm^-2 Galactic foreground: 6.7 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 2.0 (+/-0.4) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00533268. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13751 SUBJECT: GRB 120911A: Swift/UVOT Upper Limits DATE: 12/09/11 18:48:50 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (MSSL-UCL) and J. K. Cannizzo (NASA/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120911A 3323 s after the BAT trigger (Cannizzo et al., GCN Circ. 13744). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 13748) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 3323 3473 147 >20.5 white 3323 11009 1229 >21.6 v 3479 15918 1278 >19.9 b 4300 10097 1160 >21.5 u 4095 5730 393 >20.4 w1 3890 5526 393 >20.0 m2 3684 5320 393 >21.1 w2 4710 11585 757 >20.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.12 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13752 SUBJECT: GRB 120911A: Fermi/LAT upper limit DATE: 12/09/11 21:05:23 GMT FROM: Weikang Zheng at U.of Michigan Weikang Zheng and Carl Akerlof (Umich), report on behalf of the ROTSE collaboration: We analyzed Fermi/LAT data of GRB 120911A (Cannizzo et al., GCN 13744) as a follow-up of routine search in Swift trigger catalogs in our LAT data processing pipeline using both the matched filter technique (Akerlof et al. 2010, ApJ, 725, L15; 2011 ApJ, 726, 22; 2012, arXiv:1205.3066; Zheng et al. 2012, ApJ 745,72; ApJ, 756, 64) and likelihood method. We do NOT detect high energy photon emission from both methods. A standard data selection method is applied when extracting the LAT photon data with energy E > 100 MeV, and a duration of T0 - T0+47.5s after the trigger. A zenith angle cut of <105 degree is applied to all photons. The burst location of GRB 120911A was only ~14 degrees from the LAT boresight, almost in the center of the LAT field of view, and the zenith angle was about 40 degrees at trigger time. Using the likelihood method, we estimated the upper limit in LAT energy range (0.1 - 10 GeV) is 1.1e-05 (photons cm^-2 s^-1) by assuming a spectral index of -2.2. The pipeline result of GRB 120911A is given in the following link: http://www.rotse.net/LAT/SwiftTriggers/369040116/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13753 SUBJECT: GRB120911A: MITSuME Okayama Optical upper limits DATE: 12/09/12 06:18:19 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: We observed the field of GRB 120911A (Cannizzo et al., GCNC 13744) 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 2012-09-11 13:46:32 UT, (~6.6 h after the burst). We did not find any new point source within the enhanced XRT circle (Beardmore et al., GCNC 13748) in all the three bands. 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' Rc Ic ------------------------------------------------------ 0.31808 14:46:35 5940.0 >20.6 >19.8 >19.2 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13754 SUBJECT: GRB 120911A: Fermi GBM observation DATE: 12/09/12 07:02:43 GMT FROM: David Gruber at MPE David Gruber (MPE) reports on behalf of the Fermi GBM Team: "At 07:08:33.99 UT on 11 September 2012, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 120911A (trigger 369040116 / 120911298). which was also detected by the Swift/BAT (Cannizzo et al. 2012, GCN 13744). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 11 degrees. The GBM light curve consists of two pulses with a duration (T90) of about 22 s (50-300 keV). The time-averaged spectrum from T0-4.6 s to T0+22.0 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.36 +/- 0.26 and the cutoff energy, parameterized as Epeak, is 64.2 +/- 5.1 keV The event fluence (10-1000 keV) in this time interval is (2.34 +/- 0.04)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.38 s in the 10-1000 keV band is 4.31 +/- 0.27 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: 13759 SUBJECT: GRB 120911A: optical upper limit ISON-NM DATE: 12/09/13 07:13:47 GMT FROM: Alexei Pozanenko at IKI, Moscow L. Elenin (KIAM), A. Volnova (SAI MSU), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 120911A (Cannizzo et al., GCN 13744) with 0.45-m telescope of ISON-NM observatory starting on Sep. 11 (UT) 07:10:42, i.e ~130 s after burst trigger. We took several unfiltered images of 30 s and 60 s exposures. Within enhanced XRT afterglow position (Beardmore et al., GCN 13748) we do not detect any new object. A preliminary photometry of single and co-added frames is based on the USNO-B1.0 (R2) nearby stars is following: T0+, Exposure, OT, UL (3 sigma) mid, d (s) 0.0017 30 n/d 18.4 0.0028 5x30 n/d 19.1 0.0175 60x30 n/d 20.2 0.0590 30x120 n/d 20.6 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13760 SUBJECT: GRB 120911A: optical upper limit CrAO DATE: 12/09/13 07:18:31 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev, N.Pit' (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 120911A (Cannizzo et al., GCN 13744) with AZT-11 telescope of CrAO observatory starting on Sep. 11 (UT) 21:10:38. We took several images in R-filter of 180 s exposure. Within enhanced XRT afterglow position (Beardmore et al., GCN 13748) we do not detect any new object. A preliminary photometry of co-added frame is based on the USNO-B1.0 (R2) nearby stars is following: T0+, Filter Exposure, OT, UL (3 sigma) mid, d (s) 0.6130 R 20x180 n/d 20.9 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13776 SUBJECT: Corrections to the Fermi-LAT upper limits for GRB 120807A, 120908A, 120909A, and 120911A DATE: 12/09/17 21:22:46 GMT FROM: Weikang Zheng at U.of Michigan Weikang Zheng and Carl Akerlof (Umich), report on behalf of the ROTSE collaboration (the authors are not affiliated with the Fermi Collaboration), The recent GCN Circulars we reported about Fermi-LAT upper limits for GRB 120807A (GCN 13608), 120908A (GCN 13742), 120909A (GCN 13742), and 120911A (GCN 13752) contain an error about the upper limits estimation due to a wrong method. We apologize for the confusion. We thank Giacomo Vianello from LAT group for pointing it out and making suggestion to correct it. We've updated our pipeline result with the appropriate method (see The Fermi LAT team, Ackermann et al., 2012, ApJ, 754, 121). We report the corrected upper limit result (100 MeV -300 GeV; T0-T0 +47.5s) for the 4 GRBs again: GRB 120807A : 5.42e-05 ph/cm2/s GRB 120908A : 1.79e-04 ph/cm2/s GRB 120909A : 8.70e-05 ph/cm2/s GRB 120911A : 3.81e-05 ph/cm2/s //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18183 SUBJECT: KAIT Optical Upper Limits for GRB 120422A, 120724A, 120803B, 120911A, and 120923A DATE: 15/08/20 18:55:59 GMT FROM: Xiang-Gao Wang at GuangXi U Xianggao Wang (UC Berkeley, GXU, UNLV), WeiKang Zheng, Alexei V. Filippenko (UC Berkeley), and S. Bradley Cenko (GSFC) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to Swift GRBs 120422A (Troja et al., GCN 13243), 120724A (D'Avanzo et al., GCN 13510), 120803B (Racusin et al. GCN 13566), 120911A (Cannizzo et al., GCN 13744), and 120923A (Yershov et al., GCN 13796) at 510 s, 202 s, 196 s, 147 s, and 236 s after the burst, respectively. Observations were performed with an automatic sequence in the clear (roughly R), V, and I filters, and the exposure time was 20 s per image. We do not detect any new sources within the XRT error circles. We estimate the following upper limits (magnitudes) in clear-band images for each GRB calibrated to USNO B1.0: GRB Start-Time Coadd-Images Mid-time Upper-Limit (3 sigma) 120422A 510 s 20 s x 6 758 s 20.6 120724A 202 s 20 s x 10 647 s 20.7 120803B 196 s 20 s x 10 644 s 21.7 120911A 147 s 20 s x 6 501 s 20.9 120923A 236 s 20 s x 6 563 s 21.0