GRB091026A

This page lists all entries on GRB091026A in GRBweb

Summary Fermi GBM IPN Swift GCN 10081 GCN 10082 GCN 10084 GCN 10085 GCN 10087 GCN 10089 GCN 10091 GCN 10094 GCN 10133

Summary table
Variable Value Source
GRB_name_Fermi GRB091026550
T0 13:11:27.900 UTC Fermi_GBM
ra 276.5743° Swift
decl -86.1116° Swift
pos_error 1.94e-04° Swift
T90 8.96 s Fermi_GBM
T90_error 1.379 s Fermi_GBM
T90_start 13:11:27.900 UTC Fermi_GBM
fluence 1.38e-06 erg/cm² Fermi_GBM
fluence_error 7.20e-08 erg/cm² Fermi_GBM
T100 43.7 s
GBM_located False
mjd 55130.549628472225 Fermi_GBM
Fermi GBM table
GRB_name_Fermi GRB091026550
trigger_name bn091026550
ra 276.5729°
decl -86.1114°
pos_error 5.01e+00°
datum 2009-10-26
t_trigger 13:11:33.020 UTC
T90 8.96 s
T90_error 1.379 s
T90_start 13:11:27.900 UTC
fluence 1.38e-06 erg/cm²
fluence_error 7.20e-08 erg/cm²
flux_1024 3.86e+00 erg/cm²/s
flux_1024_error 4.94e-01 erg/cm²/s
flux_1024_time -3.20e+00 erg/cm²/s
flux_64 8.67e+00 erg/cm²/s
flux_64_error 2.40e+00 erg/cm²/s
IPN table
GRB_name GRB091026A
ra 276.5833°
decl -86.1167°
pos_error 5.00e-02°
Swift table
GRB_name GRB091026A
t_trigger 13:11:30 UTC
ra 276.5743°
decl -86.1116°
pos_error 1.94e-04°
T90 41.6 s
fluence 1.80e-06 erg/cm²
GCN 10081 table
GRB_name GRB091026A
GCN_number 10081
Detection_method Swift Det
t_trigger 13:11:30 UTC
ra 276.5830°
decl -86.1210°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10081 SUBJECT: GRB 091026: Swift detection of a Gamma Ray Burst DATE: 09/10/26 13:23:09 GMT FROM: Scott Barthelmy at NASA/GSFC C. B. Markwardt (CRESST/GSFC/UMD), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), D. Grupe (PSU), C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), J. A. Kennea (PSU), V. Mangano (INAF-IASFPA), J. Mao (INAF-OAB), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), P. Roming (PSU), B. Sbarufatti (INAF-IASFPA), M. H. Siegel (PSU) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift Team: At 13:11:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 091026 (trigger=373871). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 276.583, -86.121 which is RA(J2000) = 18h 26m 20s Dec(J2000) = -86d 07' 16" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a FRED pulse with a duration of about 20 sec. The peak count rate was ~2500 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 13:12:48.9 UT, 78.7 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 276.59337, -86.11056 which is equivalent to: RA(J2000) = 18h 26m 22.41s Dec(J2000) = -86d 06' 38.0" with an uncertainty of 4.0 arcseconds (radius, 90% containment). This location is 37 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (8.36e+20 cm^-2, Kalberla et al. 2005), with an excess column of 3.6 (+2.72/-2.29) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 3.42e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 87 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.13. Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN 10082 table
GRB_name GRB091026A
GCN_number 10082
Detection_method Swift-XRT Other
ra 276.5725°
decl -86.1115°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10082 SUBJECT: GRB 091026: Updated Swift-XRT position DATE: 09/10/26 14:10:46 GMT FROM: Phil Evans at U of Leicester P.A. Evans and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT Team: Using the full set of promptly downlinked XRT event mode data totalling 760 s in Photon Counting mode, and 2 UVOT images, we find an enhanced XRT position for GRB 091026 (Markwardt et al. GCN Circ. 10081) of RA, Dec = 276.5725, -86.1115 (degrees) which is equivalent to: RA (J2000) = 18 26 17.41 DEC (J2000) = -86 06 41.5 with an uncertainty of 2.1 arcsec (radius, 90% containment). This circular is an official product of the Swift-XRT team.
GCN 10084 table
GRB_name GRB091026A
GCN_number 10084
Detection_method Swift-XRT Det
ra 276.5708°
decl -86.1116°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10084 SUBJECT: GRB 091026: Enhanced Swift-XRT position DATE: 09/10/26 18:59:15 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 512 s of XRT Photon Counting mode data and 1 UVOT images for GRB 091026, 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 = 276.57076, -86.11163 which is equivalent to: RA (J2000): 18h 26m 16.98s Dec (J2000): -86d 06' 41.9" with an uncertainty of 1.9 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.
GCN 10085 table
GRB_name GRB091026A
GCN_number 10085
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 10085 SUBJECT: GRB 091026: Swift-XRT refined analysis DATE: 09/10/26 20:03:52 GMT FROM: Phil Evans at U of Leicester P.A. Evans, J.P. Osborne (U. Leicester) and C. B. Markwardt (CRESST/GSFC/UMD) report on behalf of the Swift-XRT team: We have analysed 2.2 ks of XRT data for GRB 091026 (Markwardt et al. GCN Circ. 10081), from 85 s to 6.8 ks after the BAT trigger. The data comprise 326 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 10084). The light curve shows three flares in the first snapshot, with peaks at T0+180 s, T0+340 s and T0+~890 s. The orbital gap interrupts the final flare, making its peak time somewhat uncertain. If these flares are disregarded (i.e. fitting only the data from 85 s to 150 s and 2 ks to 6.8 ks), the underlying light curve can be modelled with an initial power-law decay with an index of alpha=3.40 (+0.31, -0.26), followed by a break at T+149 s to an alpha of 0.98 (+0.07, -1.7). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.97 (+/-0.08). The best-fitting absorption column is 2.93 (+0.28, -0.27) x 10^21 cm^-2, in excess of the Galactic value of 8.4 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.01 (+0.18, -0.17) and a best-fitting absorption column of 3.5 (+0.7, -0.6) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.6 x 10^-11 (7.6 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 0.98, the count rate at T+24 hours will be 0.018 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.3 x 10^-13 (1.4 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00373871. This circular is an official product of the Swift-XRT team.
GCN 10087 table
GRB_name GRB091026A
GCN_number 10087
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 10087 SUBJECT: GRB 091026: Swift/UVOT Upper Limits DATE: 09/10/26 22:38:01 GMT FROM: Peter Curran at MSSL P.A. Curran (MSSL-UCL) and C.B. Markwardt (CRESST/GSFC/UMD) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 091026 87 s after the BAT trigger (Markwardt et al., GCN 10081). No optical afterglow consistent with the enhanced XRT position (Evans et al., GCN 10084) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) exposures and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag ----------------------------------------------------------- white (FC) 87 237 147 >21.00 u (FC) 300 550 246 >20.36 white 87 12292 950 >22.09 v 629 5959 236 >19.63 b 555 6778 235 >20.62 u 300 6573 462 >20.72 w1 678 6369 236 >20.09 m2 826 6164 216 >19.85 w2 605 16097 561 >20.70 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.13 in the direction of the burst (Schlegel et al. 1998).
GCN 10089 table
GRB_name GRB091026A
GCN_number 10089
Detection_method Swift-BAT Det
ra 276.6570°
decl -86.1130°
Circular_text TITLE: GCN CIRCULAR NUMBER: 10089 SUBJECT: GRB 091026: Swift-BAT refined analysis DATE: 09/10/26 23:31:38 GMT FROM: Craig Markwardt at NASA/GSFC/UMD T. N. Ukwatta (GWU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 091026 (trigger #373871) (Markwardt, et al., GCN Circ. 10081). The BAT ground-calculated position is RA, Dec = 276.657, -86.113 deg which is RA(J2000) = 18h 26m 37.7s Dec(J2000) = -86d 06' 47.2" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 36%. The mask-weighted light curve shows a single FRED-like peak which starts to rise around T-5 sec, peaks near T+0 sec, and has a long tail extending to about T+120 sec. T90 (15-350 keV) is 41.6 +- 7.2 sec (estimated error including systematics). The time-averaged spectrum from T-3.7 to T+47.9 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.53 +- 0.11. The fluence in the 15-150 keV band is 1.8 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.18 sec in the 15-150 keV band is 2.2 +- 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/373871/BA/
GCN 10091 table
GRB_name GRB091026A
GCN_number 10091
Detection_method GROND
Circular_text TITLE: GCN CIRCULAR NUMBER: 10091 SUBJECT: GRB 091026: GROND Upper Limits DATE: 09/10/27 05:38:20 GMT FROM: Adria C. Updike at Clemson U Robert Filgas (Tautenburg Obs.), Adria Updike (Clemson University), Arne Rau, and Jochen Greiner (both MPE Garching) report on behalf of the GROND team: We observed the field of GRB 091026 (Swift trigger 373871; Markwardt et al., GCN #10081) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile). Observations started at 00:48 UT on Oct 27, 2009, 11.6 hours after the GRB trigger. They were performed at an average seeing of 2" and at an average airmass of 1.94. We do not detect a source within the Swift-XRT error circle reported by Evans et al. (GCN #10084) down to g' > 24.8 mag, r' > 24.2 mag, i' > 23.9 mag, z' > 23.7 mag, J > 22.2 mag, H > 21.3 mag and K > 20.2 mag. Magnitudes are given in the AB system and calibrated against USNO as well as 2MASS field stars, and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V) = 0.13 mag in the direction of the burst (Schlegel et al. 1998).
GCN 10094 table
GRB_name GRB091026A
GCN_number 10094
Detection_method Suzaku WAM Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 10094 SUBJECT: GRB 091026: Suzaku WAM observation of the prompt emission DATE: 09/10/28 07:03:39 GMT FROM: Norisuke Ohmori at Miyazaki U N. Ohmori, E. Sonoda, K. Kono, H. Hayashi, A. Daikyuji, Y. Nishioka, K. Noda, M. Yamauchi (Univ. of Miyazaki), M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA), K. Yamaoka, S. Sugita (Aoyama Gakuin U.), Y. E. Nakagawa, T. Tamagawa (RIKEN), S. Hong (Nihon U.), N. Vasquez (Tokyo Tech.), Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa (Hiroshima U.), W. Iwakiri, M. Tashiro, Y. Terada, A. Endo, K. Onda, T. Sugasahara (Saitama U.), Y. Urata (NCU), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), on behalf of the Suzaku WAM team, report: The long GRB 091026 (Swift-BAT trigger #373871; Markwardt et al., GCN Circ. 10081) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 13:11:29.812 UT (=T0). The observed light curve shows a multi-peaked structure, starting at T0-1 s and ending at T0+13 s, with a total duration (T90) of about 9 s. The fluence in 100 - 1000 keV was 1.47 (-0.40, +0.29) x 10^6 erg/cm^2. The 1-s peak flux measured from T0+1.5 s was 0.59 (-0.30, +0.19) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-1 s to T0+13 s is well fitted by a single power-law with a photon index of 1.86 (-0.25, +0.33) (chi^2/d.o.f. = 77/50). All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included. The light curves for this burst will be available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html
GCN 10133 table
GRB_name GRB091026A
GCN_number 10133
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 10133 SUBJECT: GRB091026 : IRSF NIR upper limit DATE: 09/11/04 16:35:22 GMT FROM: Kenta Nishimoto at Nagoya U/MOA-II K. Nishimoto, T. Sako (Nagoya Univ.) on behalf of the MOA Collaboration, M. Kurita, T. Nagayama (Nagoya Univ.) on behalf of the IRSF Collabration report: We searched for a NIR afterglow of GRB091026 (Markwardt et al., GCN 10081) starting from 18:43:32.3 UT on 2009 Oct 26 (5.5 hours after the burst) with the SIRIUS on the IRSF 1.4m telescope at SAAO in South Africa. In images of a 300sec exposure with J, H and Ks filter, we did not find any object within the error circle of the Swift XRT source position (Evans. et al., GCN 10084). A 5 sigma upper limits are the followings. J > 18.35 H > 17.39 K > 16.70 This photometry was done by using the DoPhot and calibrated against the 2MASS cataloged stars