//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12228 SUBJECT: GRB 110801A: Swift detection of a burst with an optical counterpart DATE: 11/08/01 20:01:04 GMT FROM: Scott Barthelmy at NASA/GSFC M. De Pasquale (UCL-MSSL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), J. A. Kennea (PSU), A. Melandri (INAF-OAB), C. J. Mountford (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sakamoto (NASA/UMBC), B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU), E. Sonbas (GSFC/USRA/Adiyaman Univ.), C. A. Swenson (PSU), E. Troja (NASA/GSFC/ORAU) and T. N. Ukwatta (MSU) report on behalf of the Swift Team: At 19:49:42 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 110801A (trigger=458521). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 89.285, +80.988 which is RA(J2000) = 05h 57m 08s Dec(J2000) = +80d 59' 18" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a few weak peaks with a duration of about 70 sec. The peak count rate was ~700 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 19:51:21.9 UT, 98.9 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 89.4307, +80.9548 which is equivalent to: RA(J2000) = 05h 57m 43.36s Dec(J2000) = +80d 57' 17.2" with an uncertainty of 4.9 arcseconds (radius, 90% containment). This location is 146 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. 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) = 05:57:44.73 = 89.43637 DEC(J2000) = +80:57:21.6 = 80.95600 with a 90%-confidence error radius of about 0.62 arc sec. This position is 5.4 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.03 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.08. Burst Advocate for this burst is M. De Pasquale (mdp AT mssl.ucl.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12229 SUBJECT: GRB 110801A: ROTSE-III Detection of re-brightening from OT DATE: 11/08/01 21:15:02 GMT FROM: Weikang Zheng at U.of Michigan GRB 110801A: ROTSE-III Detection of re-brightening from OT W. Zheng (U Mich), T. Guver (U Arizona), report on behalf of the ROTSE collaboration: ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe, Turkey, responded to GRB 110801A (Swift trigger 458521; Pasquale et al. GCN 12228). The first image was at 19:52:57.7 UT, 194.7 s after the burst. The unfiltered images are calibrated relative to USNO A2.0. We detect the OT at UVOT location (GCN 12228), the OT appeared to be re-brightening to ~15.0 mag at ~1400s after the burst. Continuing observations are in progress. [GCN OPS NOTE(01aug11): Per author's request (at GCN's request), the language was changed to remove the implication that the delay in observing was tied to the Notice arrival time. The delay was due to weather and dome operations. The "(8.7 s after the GCN notice time)" was removed from the text.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12230 SUBJECT: GRB 110801A: TLS Optical afterglow confirmation DATE: 11/08/01 21:22:52 GMT FROM: Ana Nicuesa at TLS Tautenburg GRB 110801A: TLS Optical afterglow Confirmation A. Nicuesa Guelbenzu, X. Luo, S. Klose, U. Laux, B. Stecklum (all at TLS Tautenburg) report: We observed the afterglow of GRB 110801A (M. De Pasquale et al., GCN 12228) with the 2m/1.34m Schmidt telescope of the Thueringer Landessternwarte Tautenburg starting about 20 min after the GRB trigger. The afterglow is clearly detected in the R band images at the position of the UVOT detection. We confirm the re-brightening of the afterglow as reported by ROTSE III (Zheng et al. 2011, GCN 12229). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12232 SUBJECT: GRB 110801A: Enhanced Swift-XRT position DATE: 11/08/02 02:01:09 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 1989 s of XRT Photon Counting mode data and 5 UVOT images for GRB 110801A, 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 = 89.43603, +80.95615 which is equivalent to: RA (J2000): 05h 57m 44.65s Dec (J2000): +80d 57' 22.2" 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: 12233 SUBJECT: GRB110801A: MITSuME Ishigakijima Optical Observation DATE: 11/08/02 05:13:46 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (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 110801A (Pasquale et al., GCNC 12228) 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 2011-08-01 19:53:51 UT (~4 min after the burst). We detected the previously reported afterglow (Pasquale et al., GCNC 12228; Zheng and Guver, GCNC 12229; Guelbenzu et al., GCNC 12230) in all the three bands. Photometric results 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 ---------------------------------------------------------------------- 0.00323 19:54:21 60.0 16.16 0.07 15.14 0.04 14.44 0.04 0.00404 19:55:31 60.0 15.35 0.06 14.29 0.04 13.57 0.04 0.00485 19:56:41 60.0 15.38 0.06 14.28 0.04 13.56 0.04 0.00731 20:00:14 60.0 15.54 0.06 14.51 0.04 13.79 0.04 0.00976 20:03:45 60.0 15.71 0.07 14.67 0.04 13.98 0.04 0.01222 20:07:18 60.0 15.77 0.07 14.79 0.04 14.12 0.04 0.01466 20:10:48 60.0 15.89 0.07 14.91 0.04 14.24 0.04 ---------------------------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12234 SUBJECT: GRB 110801A: Afterglow redshift from 10.4m GTC DATE: 11/08/02 06:33:02 GMT FROM: Antonio Deugarte at IAA-CSIC A. Cabrera Lavers (GTC), A. de Ugarte Postigo (DARK/NBI), A.J. Castro-Tirado, J. Gorosabel, C.C. Thoene (IAA-CSIC), R. Domínguez (GTC) report on behalf of a larger collaboration: We have observed the afterglow of GRB 110801A (De Pasquale et al. GCNC 12228) using OSIRIS at the 10.4m GTC telescope (La Palma, Spain). Observations consisted on 2x900s + 1x600s exposures using the R1000B grating (resolution ~1000) with coverage between 3600 and 7500 Angstrom. Observations started at 3:30 UT (7.7h after the burst). In a preliminary analysis, using archival calibrations, we detect a high signal to noise ratio continuum with absorption features that include CII, SiIV, SiII, CIV, FeII, AlII, AlIII, NiII, ZnII, and MnII, as well as fine structure FeII* and NiII* at a common redshift of z=1.858, which we identify as the redshift of the afterglow. We also identify two intervening systems at z=1.246 and z=0.745 through the presence of the MgII doublet. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12235 SUBJECT: GRB 110801A: Swift-XRT refined Analysis DATE: 11/08/02 09:00:16 GMT FROM: Andy Beardmore at U Leicester A.P. Beardmore (U. Leicester) and M. De Pasquale (UCL-MSSL) report on behalf of the Swift-XRT team: We have analysed 9.9 ks of XRT data for GRB 110801A (De Pasquale et al. GCN Circ. 12228), from 89 s to 24.0 ks after the BAT trigger. The data comprise 566 s in Windowed Timing (WT) mode (the first 7 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 Evans et al. (GCN. Circ 12232). The light curve initially shows a number of flares, the largest peaking at 500-600 count/s between T+355 s and T+390 s after the trigger. Once this flare has decayed, the light curve after T+800 s can be modelled by a power-law with a slope of 1.12 +/- 0.06. A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.754 (+0.025, -0.026). The best-fitting absorption column is 6.4 (+/-0.6) x 10^21 cm^-2, at a redshift of 1.858, in addition to the Galactic value of 6.2 x 10^20 cm^-2 (Kalberla et al. 2005). We note this spectrum includes strong spectral evolution through the flare. The PC mode spectrum has a photon index of 2.04 (+/-0.09) and a best-fitting absorption column of 1.6 (+1.6, -1.4) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (4.5 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Galactic foreground: 6.2 x 10^20 cm^-2 Intrinsic column: 1.6 (+1.6, -1.4) x 10^21 cm^-2 at z=1.858 Photon index: 2.04 (+/-0.09) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00458521. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12236 SUBJECT: Swift/UVOT observations of GRB110801A DATE: 11/08/02 12:52:23 GMT FROM: Massimiliano de Pasquale at MSSL-UCL M. De Pasquale (MSSL-UCL) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 110801A 109 s after the BAT trigger (De Pasquale et al., GCN Circ. 12228). A source consistent with the XRT position (Evans et al., GCN Circ. 12232) is detected in the initial and summed UVOT exposures, except in um2 filter and a detection in uw2, at 2 sigma confidence level. Since the redshift of this event is 1.86 (Cabrera Lavers, GCN Circ. 12234), we think the weak detection in uw2 is due to flux in the reddest part of this filter. The refined UVOT position is: RA (J2000) = 05:57:44.87 = 89.43695 (deg.) Dec (J2000) = +80:57:21.1 = 80.95592 (deg.) with an estimated uncertainty of 0.51 arc sec. (radius, 90% confidence). The afterglow shows a quick rise from the first exposure up to ~300s. Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white (fc) 109 259 147 18.06 ± 0.07 white 109 6337 727 17.23 ± 0.05 v 598 6747 451 17.07 ± 0.06 b 523 6132 432 17.47 ± 0.05 u (fc) 267 517 246 15.89 ± 0.05 u 267 5927 488 15.68 ± 0.04 w1 647 5722 255 17.92 ± 0.11 m2 622 6904 404 >20.2 w2 573 6543 452 20.48 ± 0.41 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.08 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12237 SUBJECT: GRB 110801A: Swift-BAT refined analysis DATE: 11/08/02 14:06:06 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), M. De Pasquale (UCL-MSSL), 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+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 110801A (trigger #458521) (De Pasquale, et al., GCN Circ. 12228). The BAT ground-calculated position is RA, Dec = 89.415, 80.958 deg, which is RA(J2000) = 05h 57m 39.6s Dec(J2000) = +80d 57' 28.5" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 78%. The mask-weighted light curve shows two main clusters of peaks. The first starts at ~T-30 sec, with a maximum at ~T+2 sec, and a long exponental decay almost down to background before the second cluster. The second cluster starts ~T+310 sec, peaks at ~T+340 sec, and ending at ~T+550 sec. T90 (15-350 keV) is 385 +- 10 sec (estimated error including systematics). The time-averaged spectrum from T-24.2 to T+385.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.84 +- 0.10. The fluence in the 15-150 keV band is 4.7 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+341.78 sec in the 15-150 keV band is 1.1 +- 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/458521/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12238 SUBJECT: GRB 110801A: MASTER OT observations DATE: 11/08/02 17:32:35 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs A.V. Parhomenko, A. Tlatov, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory K.Ivanov, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev,E.Konstantinov, Irkutsk State University E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M. Kornilov,A.Sankovich Sternberg Astronomical Institute, Moscow State University V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov Ural State University, Kourovka V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka(Siberia) was pointed to the GRB110801A 101 sec after GRB time at 2011-08-01 19:51:23 UT. Unfortunatelly the objects was not in focus because recently photometer modification. On our first (20s exposure) set we haven`t found optical transient within SWIFT error-box (De Pasquale et al., GCN 12228). The 3-sigma upper limit has been about 14.0 mag (white+polarizator). MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located near Kislovodsk (Caucasus Mountains) closed roof 20 min before trigger due to cloudy condidtions. The telescope was repointed to the GRB110901A only 47 min 40 sec after trigger time at 2011-08-01 20:37:22 UT. We found OT at UVOT postion (De Pasquale et al., GCN 12228). The results of our photometry are: Time_Start T_mean-T_trig exp time m error Band UT s s 20:37:22 2950 180 16.13 0.06 R 20:44:29 3377 180 16.12 0.06 R 20:48:01 3589 180 16.29 0.08 R 20:48:01 3589 180 16.03 0.06 White 20:51:24 3792 180 16.43 0.06 R 20:51:24 3792 180 16.19 0.06 White 23:20:14 12722 180 17.75 0.10 R The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.08 in the direction of the burst (Schlegel et al. 1998). The power low index (F~t^-aplha) apha ~1.0+-0.1 during this observations in R-band. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12239 SUBJECT: GRB 110801A: Evidence for a jet break DATE: 11/08/02 21:38:15 GMT FROM: Ana Nicuesa at TLS Tautenburg A. Nicuesa Guelbenzu, S. Klose, S. Schmidl, A. Rossi, U. Laux, B. Stecklum (all at TLS Tautenburg) report: We re-observed the afterglow of GRB 110801A (M. De Pasquale et al., GCN 12228) with the 2m/1.34m Schmidt telescope of the Thueringer Landessternwarte Tautenburg starting about 24 hours after the GRB trigger. A stacking of the first 15 minutes of the second epoch data does not show the afterglow in the R band down to 21 mag (Vega system). We conclude that a jet break has occurred within the last 24 hours. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12240 SUBJECT: GRB110801A: MITSuME Ishigakijima Optical Observation at 1 day after the burst DATE: 11/08/03 04:58:24 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (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 110801A (De Pasquale et al., GCNC 12228) 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 2011-08-02 17:38:02 UT (~21.8 h after the burst). We detected the previously reported afterglow (Pasquale et al., GCNC 12228; Zheng and Guver, GCNC 12229; Guelbenzu et al., GCNC 12230; Kuroda et al., GCNC 12233) in all the three bands. Photometric results 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 ---------------------------------------------------------------------- 0.95038 18:38:15 5760.0 21.5 0.3 20.3 0.2 19.1 0.2 ---------------------------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12241 SUBJECT: GRB 110801A: SAO RAS optical observations DATE: 11/08/03 08:08:25 GMT FROM: Vladimir Sokolov at SAO RAS V. V. Sokolov, A. S. Moskvitin, T. A. Fatkhullun, (SAO RAS) report on behalf of a larger collaboration: We observed the field of GRB 110801A (De Pasquale et al., GCN 12228) with the 6-m BTA of SAO RAS (Russia) equipped with the Scorpio. The observations were carried out in the B and Rc bands at 00:07:36 -- 00:13:36 UT, August, 02 (since 4.35 hours after the trigger). The weather conditions were tolerable, seeing around 2".5. Magnitudes of optical transient are as follows: B = 19.02 +/- 0.02 R = 18.10 +/- 0.01 Calibration were done against the magnitudes B2 = 16.74 and R2 = 15.73 of the USNO-B.1 star 1709-0023450 (R.A. = 05:57:24.91 Dec.= +80:57:39.8, Epoch = 2000). The magnitudes of OT were not corrected for the Galactic extinction E(B-V) = 0.08 in the direction of the burst (Schlegel et al. 1998). Also we obtained 2 x 600 sec. spectrum (range = 4000 -- 8400A, resolution FWHM = 10A) at 00:19:54 -- 00:41:24 UT. At the noisy relatively blue continuum we marginally detected only the C IV absorption line corresponding to the red shift reported by Cabrera Lavers et al. (GCN 12234). The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12246 SUBJECT: GRB 110801A: optical observations in CrAO DATE: 11/08/04 15:56:39 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev (CrAO), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the field of GRB 110801A (Pasquale et al. GCN 12228) with Shajn telescope of CrAO observatory on between Aug. 2 (UT) 22:03 and Aug. 3 (UT) 00:27 under variable weather conditions and a mean seeing of 2.1 arsces. We took several frames with exposure of 60 s in R-band. On a stacked image we detected the optical counterpart (Pasquale et al. GCN 12228, Zheng et al. GCN 12229). A photometry is based on the USNO B1.0 star 1709-0023450 (05 57 24.91 +80 57 39.8) assuming R=15.73. T0+ Filter, Exposure, mag. uplim (3 sigma) (mid, d) (s) 1.1428 R 74x60 21.60 +/- 0.09 23.2 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12275 SUBJECT: GRB 110801A: optical observations at Mt. Terskol observatory DATE: 11/08/13 13:40:30 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, N. Parakhin, A. Sergeev (Terskol Branch of Institute of Astronomy), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed field of the Swift GRB 110801A (Pasquale et al. GCN 12228) with Zeiss-600 telescope of Mt.Terskol observatory in R filter starting on Aug. 02 (UT) 00:25. In a stacked image we clearly detect optical afterglow (Pasquale et al. GCN 12228, Zheng et al. GCN 12229). A photometry is based on the USNO B1.0 star 1709-0023450 (05 57 24.91 +80 57 39.8) assuming R=15.73. T0+ Filter, Exposure, mag. (mid, d) (s) 0.1951 R 4x180 18.35 +/- 0.10 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12276 SUBJECT: GRB 110801A: Konus-Wind and Swift/BAT joint spectral analysis DATE: 11/08/15 15:05:55 GMT FROM: Takanori Sakamoto at NASA/GSFC T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), M. Stamatikos (OSU), J. Tueller (GSFC), and T. Ukwatta (MSU) V. Pal'shin, S. Golenetskii, R.Aptekar, E. Mazets, D. Frederiks, and T. Cline on behalf of the Konus-Wind team, We performed the Konus-Wind and the Swift/BAT joint spectral analysis of GRB 110801A (Swift/BAT trigger #458521: De Pasquale et al., GCN Circ. 12228, Barthelmy et al. GCN Circ. 12237). Since the Konus-Wind observed this GRB in the waiting mode, we only have 3 channel spectral data for the Konus-Wind which cover the energy range from 20 keV to 1.2 MeV. The joint spectral analysis of the Konus-Wind and the Swift/BAT data allows us to derive the broad-band spectral parameters of this burst. The time interval of the spectral data is chosen from T0(BAT)-26.43 to T0(BAT)+64.83 sec and from T0(BAT)+332.74 to T0(BAT)+388.67 sec where T0(BAT) is the trigger time of BAT at 19:49.43 UTC to include two time-separated episodes. The energy ranges which we used in the joint spectral analysis are 20-1200 keV and 14-150 keV for the Konus-Wind and the Swift/BAT respectively. The spectral data of two instruments are fitted with the spectral model multiplied by the constant factor to take into account the systematic effective area uncertainties in the response matrices of each instrument. The spectrum is well fitted with a power-law with exponential cutoff model: dN/dE ~ E^{alpha}*exp(-(2+alpha)*E/Epeak). The constant factors of each instrument agree within 10%. No systematic residual from the best fit model is seen in the spectral data of each instrument (see Sakamoto et al. 2011, PASJ, 63, 215 for the spectral cross-calibration). The best fit spectral parameters are: alpha = -1.70 (-0.15/+0.12) and Epeak = 140 (-60/+900) keV (chi2/dof = 74/58). The best fit spectral parameters for the GRB (Band) model fixing beta = -2.5 are: alpha = -1.70 (-0.15/+0.22), and Epeak = 140 (-50/+1270) keV (chi2/dof = 74/58). The energy fluence in the 15-1200 keV band calculated by a power-law with exponential cutoff model for this 147.2 sec interval is 7.3 (-0.9/+ 1.7)x10^-6 erg/cm2. Assuming z=1.858 (Cabrera Lavers et al. GCN Circ. 12234) and a standard cosmology model with H_0 = 71 km/s/Mpc, Omega_M = 0.27, Omega_Lambda = 0.73, the isotropic energy release is E_iso = 1.0 (-0.2/+0.3) x10^53 erg in 1 keV to 10 MeV at the GRB rest frame extrapolating the best Band function fit fixing beta = -2.5. All the quoted errors are at the 90% confidence level. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB110801A/