GRB090926B

This page lists all entries on GRB090926B in GRBweb

Summary Fermi GBM IPN Swift GCN 9935 GCN 9939 GCN 9940 GCN 9941 GCN 9943 GCN 9944 GCN 9947 GCN 9949 GCN 9957 GCN 9996

Summary table
Variable Value Source
GRB_name_Fermi GRB090926914
T0 21:55:28.525 UTC Fermi_GBM
ra 46.3081° Swift
decl -39.0060° Swift
pos_error 1.81e-04° Swift
T90 64.001 s Fermi_GBM
T90_error 1.557 s Fermi_GBM
T90_start 21:55:29.549 UTC Fermi_GBM
fluence 1.05e-05 erg/cm² Fermi_GBM
fluence_error 2.77e-08 erg/cm² Fermi_GBM
redshift 1.2400
T100 129.175 s
GBM_located False
mjd 55100.91352459491 Fermi_GBM
Fermi GBM table
GRB_name_Fermi GRB090926914
trigger_name bn090926914
ra 46.3179°
decl -39.0111°
pos_error 3.76e+00°
datum 2009-09-26
t_trigger 21:55:28.525 UTC
T90 64.001 s
T90_error 1.557 s
T90_start 21:55:29.549 UTC
fluence 1.05e-05 erg/cm²
fluence_error 2.77e-08 erg/cm²
flux_1024 4.51e+00 erg/cm²/s
flux_1024_error 2.90e-01 erg/cm²/s
flux_1024_time 1.89e+01 erg/cm²/s
flux_64 6.12e+00 erg/cm²/s
flux_64_error 1.33e+00 erg/cm²/s
IPN table
GRB_name GRB090926B
ra 46.3167°
decl -39.0167°
pos_error 5.00e-02°
redshift 1.2400
Swift table
GRB_name GRB090926B
t_trigger 21:55:48 UTC
ra 46.3081°
decl -39.0060°
pos_error 1.81e-04°
T90 109.7 s
fluence 7.30e-06 erg/cm²
redshift 1.2400
GCN 9935 table
GRB_name GRB090926B
GCN_number 9935
Detection_method Swift Det
t_trigger 21:55:48 UTC
ra 46.3180°
decl -39.0110°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9935 SUBJECT: GRB 090926B: Swift detection of a burst DATE: 09/09/26 22:20:28 GMT FROM: Scott Barthelmy at NASA/GSFC D. Grupe (PSU), S. D. Barthelmy (GSFC), J. R. Cummings (NASA/UMBC), J. A. Kennea (PSU), P. T. O'Brien (U Leicester), P. Romano (INAF-IASFPA), M. Stamatikos (OSU/NASA/GSFC), M. A. Stark (PSU) and L. Vetere (PSU) report on behalf of the Swift Team: At 21:55:48 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090926B (trigger=370791). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 46.318, -39.011 which is RA(J2000) = 03h 05m 16s Dec(J2000) = -39d 00' 40" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak with a duration of about 20 sec. The peak count rate was ~1600 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 21:57:16.8 UT, 88.3 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 46.30693, -39.00545 which is equivalent to: RA(J2000) = 03h 05m 13.66s Dec(J2000) = -39d 00' 19.6" with an uncertainty of 3.6 arcseconds (radius, 90% containment). 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 1.91e+20 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 3.15e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 98 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 0.02. Burst Advocate for this burst is D. Grupe (grupe AT astro.psu.edu). 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 9939 table
GRB_name GRB090926B
GCN_number 9939
Detection_method Swift-BAT Det
ra 46.3100°
decl -38.9970°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9939 SUBJECT: GRB 090926B: Swift-BAT refined analysis DATE: 09/09/27 03:51:16 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), D. Grupe (PSU), 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), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-61 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090926 (trigger #370791) (Grupe, et al., GCN Circ. 9935). The BAT ground-calculated position is RA, Dec = 46.310, -38.997 deg which is RA(J2000) = 03h 05m 14.3s Dec(J2000) = -38d 59' 50.9" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 26%. The mask-weighted light curve shows a sharp rise at T-20 sec, then a complex peak reaching a maximum at T-1 sec, followed by an approximately exponential decay. T90 (15-350 keV) is 109.7 +- 11.3 sec (estimated error including systematics). The time-averaged spectrum from T-21.6 to T+133.2 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.52 +- 0.24, and Epeak of 78.3 +- 7.0 keV (chi squared 57.75 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 7.3 +- 0.2 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T-1.31 sec in the 15-150 keV band is 3.2 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.54 +- 0.00 (chi squared 125.34 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/370791/BA/
GCN 9940 table
GRB_name GRB090926B
GCN_number 9940
Detection_method Swift Other
ra 46.3084°
decl -39.0060°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9940 SUBJECT: GRB 090926B: Swift XRT refined analysis DATE: 09/09/27 04:16:40 GMT FROM: Dirk Grupe at PSU/Swift-XRT D. Grupe (PSU), P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team: We have analysed the first two orbits of XRT data of GRB090926B (Grupe et al. GCN Circ. 9935). The data comprise 307 s in Windowed Timing (WT) mode and 1985 s in Photon Counting (PC) mode. Using 1692 s of XRT Photon Counting mode data and 1 UVOT images, 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 = 46.30840, -39.00600 which is equivalent to: RA (J2000): 03 05 14.01 Dec (J2000): -39 00 21.5 with an uncertainty of 1.7" (radius, 90% confidence). This position is 32.7" from the BAT ground-calculated position given in Baumgartner et al (GCN circular 9939). 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). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.84+/-0.07 with an absorption column of (1.70+/-0.22)e21 cm^-2 which is in excess of the Galactic value of 1.91 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum results is a slightly flatter X-ray spectrum with Gamma = 1.58+0.22-0.20. The absorption column density, however, is consistent with the WT result. Based on the excess absorption, according to Grupe et al. (2007, AJ, 133, 2216), the redshift of this burst is most likely less than 4.0. The light curve can be modelled with a broken power-law decay with an index of alpha=2.00+/-0.05, followed by a break at T+712+190/-160 s to an alpha of 1.23 (-0.17, +0.07). If the afterglow continues to dacay with a slope of 1.23, the predicted count rate 24 hours after the trigger is 3.4e-3 counts s^-1 or 1.6e-13 ergs s^-1 cm^-2. This circular is an official product of the Swift-XRT team.
GCN 9941 table
GRB_name GRB090926B
GCN_number 9941
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 9941 SUBJECT: GRB 090926B: NOT optical observation DATE: 09/09/27 05:05:31 GMT FROM: Dong Xu at DARK,NBI D. Xu, D. Malesani (DARK/NBI), S. Barros (Queen Univ., Belfast), P. Jakobsson (Univ. Iceland), report on behalf of a larger collaboration. We observed the field of GRB 090926B (Grupe et al., GCN 9935) with the NOT equipped with ALFOSC. Observations were carried out in the R and I bands, at high airmass (~2.5), starting on 2009 Sep 27.122 UT (4.99 hr after the GRB) and 27.146 UT (5.58 hr after the GRB), respectively. No source is visible inside the enhanced X-ray error circle (Grupe et al., GCN 9940; http://www.swift.ac.uk/xrt_positions), down to a limiting magnitude R ~ 23 based on USNO-B1 stars in the field.
GCN 9943 table
GRB_name GRB090926B
GCN_number 9943
Detection_method MAXI Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 9943 SUBJECT: GRB 090926B: MAXI GSC detection DATE: 09/09/27 07:27:48 GMT FROM: Nobuyuki Kawai at Tokyo Tech M. Morii (Tokyo Tech), M. Nakajima (Nihon U.), M. Matsuoka, K. Kawasaki, S. Ueno, H. Tomida, M. Suzuki, M. Ishikawa (JAXA), T. Mihara, M. Kohama, Y.E. Nakagawa, M. Sugizaki, T. Yamamoto (RIKEN), N. Kawai, K. Sugimori (Tokyo Tech), A. Yoshida, K. Yamaoka, S. Nakahira (AGU), H. Tsunemi, M. Kimura (Osaka U.), H. Negoro, S. Miyoshi, H. Ozawa, R. Ishiwata, (Nihon U.), Y. Ueda, N. Isobe, S. Eguchi, K. Hiroi (Kyoto U.) report on behalf of the MAXI team: The Gas Slit Camera (GSC) of MAXI, the all-sky X-ray monitor on the ISS, detected a bright X-ray source at the position consistent with GRB 090926B (Grupe et al, GCN Circ. 9935) in the energy range of 2-30 keV. The nominal location of the source as measured by GSC is (R.A., Dec.) = (46.3 deg, -39.1 deg) = (03:05:12, -39:06:00)(J2000) with an estimated systematic uncertainty of about 1 degree. The start time of the source detection (above 3 sigma level) was 21:55:31 UT on 26 September 2009, and seen until 21:55:55 UT. The start time was 17 sec earlier than the Swift-BAT trigger time, approximately consistent with the rise epoch (T-20) reported in the BAT refined analysis (Baumgartner et al., GCN Circ. 9939). The X-ray flux at the peak was about 0.3 Crab (uncorrected). There are significant time structures within the transit light curve, which would be simply triangular for a steady source. The all-sky image and the light curve is shown at the MAXI web site http://maxi.riken.jp/ at the "News" section. MAXI is currently in the commissioning phase that runs for three months. The systematic uncertainty in localization will be significantly improved with the progress of the alignment calibration.
GCN 9944 table
GRB_name GRB090926B
GCN_number 9944
Detection_method Optical
ra 46.3081°
decl -39.0062°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9944 SUBJECT: GRB 090926B: optical object in error circle DATE: 09/09/27 07:45:32 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst Daniele Malesani, Johan P. U. Fynbo (DARK/NBI) and V. D'Elia (ASDC and INAF/OAR) report on behalf of a larger collaboration: We observed the field of GRB 090926B (Grupe et al., GCN 9935; Morii et al., GCN 9943) with the VLT UT1 equipped with FORS2. Seeing was 0.8-0.9". Preliminary inspection of the image reveals a faint, slightly extended source at a position consistent with the revised XRT error circle (Grupe et al., GCN 9940; http://www.swift.ac.uk/xrt_positions). Its coordinates are (0.5" error): RA(J2000) = 03:05:13.94 Dec(J2000) = -39:00:22.2 and its magnitude (based on archival zeropoints) is R ~ 23 on 2009 Sep 27.246 UT (7.97 hr after the GRB). Inspection of the NOT images (Xu et al., GCN 9941) reveals a faint nebulosity, with a luminosity level consistent with the VLT measurement. Presently, it is not clear whether this source is related to the GRB or not. It may be the host galaxy, or the blend of two faint, adjacent objects. Further observations are planned to evaluate its variability. We gladly acknowledge excellent support from the ESO observing staff during a busy night, in particular Yuri Beletsky, and Stephane Brillant.
GCN 9947 table
GRB_name GRB090926B
GCN_number 9947
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 9947 SUBJECT: GRB 090926B: VLT spectroscopy DATE: 09/09/27 11:21:59 GMT FROM: Pall Jakobsson at U of Iceland Johan P. U. Fynbo, Daniele Malesani (DARK/NBI), Pall Jakobsson (U. Iceland) and Valerio D'Elia (ASDC and INAF/OAR) report on behalf of a larger collaboration: We observed the afterglow of GRB 090926B (Grupe et al, GCN 9935; Morii et al., GCN 9943). Using FORS2 on the Very Large Telescope, we have obtained 3*30 min spectra (300V grating) of the optical afterglow candidate (Malesani et al., GCN 9944). Observations commenced roughly 8 hours after the burst. The combined spectrum shows an emission line, presumably corresponding to [O II] 3727 at z = 1.24. At his redshift we find several other absorption features, including Mg II, Fe II and Al III. Hence, we interpret the spectrum as a combination of the GRB afterglow and the host galaxy. We acknowledge excellent support from the ESO observing staff, in particular Yuri Beletsky and Stephane Brillant.
GCN 9949 table
GRB_name GRB090926B
GCN_number 9949
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 9949 SUBJECT: GRB090926B: Swift/UVOT Upper Limits DATE: 09/09/27 12:42:23 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) and D. Grupe (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 090926B 98s after the BAT trigger (Grupe et al., GCN 9935). We do not detect any source at the position reported by VLT (Malesani et al., GCN 9944) and the enhanced Swift XRT position (Grupe et al. GCN 9940). The 3-sigma upper limits for the finding charts (FC) and summed images are: Filter T_start T_stop Exp(s) Mag (3-sigma upper limit) ------------------------------------------------------------- white(FC) 98 248 147 > 21.02 white 591 2053 303 > 21.21 v 641 2103 175 > 19.19 b 567 5976 226 > 20.32 u(FC) 310 560 246 > 20.30 u 715 5900 333 > 20.22 uvw1 691 5695 333 > 20.25 uvm2 5290 5490 197 > 19.77 uvw2 616 1389 58 > 19.09 ------------------------------------------------------------- The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight of E_(B-V) = 0.02 mag. All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627).
GCN 9957 table
GRB_name GRB090926B
GCN_number 9957
Detection_method Fermi GBM Det
t_trigger 21:55:28.530 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 9957 SUBJECT: GRB 090926B: Fermi GBM detection DATE: 09/09/28 01:34:51 GMT FROM: Michael S. Briggs at UAH and MSFC Michael S. Briggs (UA Huntsville), reports on behalf of the Fermi GBM Team: "At 21:55:28.53 UT on 26 Sept 2009, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 090926B (trigger 275694930 / 090926.914), which also triggered the Swift BAT 19 seconds later (D. Grupe et al., GCN 9935). The GBM location is consistent with the Swift BAT location. The angle from the Fermi LAT boresight is approximately 100 degrees. The GBM light curve shows multiple peaks with a duration (T90) of 81 +/- 13 s (10 to 1000 keV). The time-averaged spectrum from T0 to T0+48.6 s is best fit by cutoff power law with Epeak = 91 +/- 2 keV and index = -0.13 +/- 0.06. The fluence (10 to 1000 keV) in this time interval is (8.7 +/- 0.3)E-06 erg/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN 9996 table
GRB_name GRB090926B
GCN_number 9996
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 9996 SUBJECT: GRB 090926B: Skynet/PROMPT Observations DATE: 09/10/06 04:07:49 GMT FROM: Josh Haislip at U.North Carolina J. Haislip, D. Reichart, K. Ivarsen, A. LaCluyze, A. Foster, J. Moore, A. Oza, M. Schubel, J. Styblova, A. Trotter, J. A. Crain, and M. Nysewander report: Skynet observed the Swift/BAT localization of GRB 090926B (Grupe et al., GCN 9935) with four of the 16" PROMPT telescopes at CTIO beginning 2.7 hours after the trigger in UVRI. We do not detect the afterglow (Grupe et al., GCN 9935; Malesani, Fynbo & D'Elia, GCN 9944). Stacking only images that increase the limiting magnitude yields: mean 1-sig. 1-sig. time 3-sig. sys. stat. since lim. cal. cal. cal. trig. tel. exp. fil. mag. stars unc. unc. (h) (# x s) (mag) (mag) 2.7 PROMPT-4 4 x 80 R 19.9 40 USNO B1 0.424 0.002 2.7 PROMPT-2 4 x 80 V 18.2 11 NOMAD 0.099 0.003 2.7 PROMPT-5 3 x 80 I 18.2 32 USNO B1 0.414 0.003