GRB090926A

This page lists all entries on GRB090926A in GRBweb

Summary Fermi GBM IPN Fermi LAT GCN 9933 GCN 9934 GCN 9936 GCN 9937 GCN 9938 GCN 9942 GCN 9948 GCN 9951 GCN 9953 GCN 9959 GCN 9961 GCN 9972 GCN 9982 GCN 9984 GCN 10003 GCN 10009 GCN 10020 GCN 10049 GCN 10113

Summary table
Variable Value Source
GRB_name_Fermi GRB090926181
T0 4:20:26 UTC Fermi_LAT
ra 353.4002° Fermi_LAT
decl -66.3241° Fermi_LAT
pos_error 3.06e-05° Fermi_LAT
T90 13.76 s Fermi_GBM
T90_error 0.286 s Fermi_GBM
T90_start 4:20:29.163 UTC Fermi_GBM
fluence 1.47e-04 erg/cm² Fermi_GBM
fluence_error 3.41e-07 erg/cm² Fermi_GBM
redshift 2.1062 GCN_circulars,Other
T100 16.923 s
GBM_located False
mjd 55100.18085648148 Fermi_LAT
Fermi GBM table
GRB_name_Fermi GRB090926181
trigger_name bn090926181
ra 353.4008°
decl -66.3239°
pos_error 2.49e+00°
datum 2009-09-26
t_trigger 4:20:26.987 UTC
T90 13.76 s
T90_error 0.286 s
T90_start 4:20:29.163 UTC
fluence 1.47e-04 erg/cm²
fluence_error 3.41e-07 erg/cm²
flux_1024 8.14e+01 erg/cm²/s
flux_1024_error 3.70e-01 erg/cm²/s
flux_1024_time 3.71e+00 erg/cm²/s
flux_64 1.36e+02 erg/cm²/s
flux_64_error 2.01e+00 erg/cm²/s
IPN table
GRB_name GRB090926A
ra 353.4000°
decl -66.3167°
pos_error 5.00e-02°
redshift 2.1062
Fermi LAT table
GRB_name_Fermi GRB090926181
GRB_name GRB090926A
MET 275631628.0
datum 2009-09-26
t_trigger 4:20:26 UTC
ra 353.4002°
decl -66.3241°
pos_error 3.06e-05°
GCN 9933 table
GRB_name GRB090926A
GCN_number 9933
Detection_method Fermi GBM Det
t_trigger 4:20:26.990 UTC
ra 354.5000°
decl -64.2000°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9933 SUBJECT: GRB 090926: Fermi GBM detection DATE: 09/09/26 14:27:11 GMT FROM: Elisabetta Bissaldi at MPE Elisabetta Bissaldi (MPE) reports on behalf of the Fermi GBM Team: "At 04:20:26.99 UT on 26 September 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090926 (trigger 275631628 / 090926181). The on-ground calculated location, using the GBM trigger data, is RA = 354.5, DEC = -64.2 (J2000 degrees, equivalent to 23h 38m, -64d 12'), with an uncertainty of 1.0 degree (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 48 degrees. Moreover, this burst was bright enough to result in a Fermi spacecraft repointing maneuver. The burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve consists of single pulse with a duration (T90) of 20 +/- 2 s (8-1000 keV). The time-averaged spectrum from T0 to T0+21 s is best fit by a Band function with Epeak = 314 (+/- 4) keV, alpha = -0.75 (+/-0.01) and beta = -2.59 (+0.04/-0.05) (C-stat 1136 for 478 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.45 +/- 0.04)E-04 erg/cm^2. The 1-sec peak photon flux measured starting from T0+3 s in the 8-1000 keV band is 80.8 +/- 0.4 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN 9934 table
GRB_name GRB090926A
GCN_number 9934
Detection_method Fermi LAT Det
t_trigger 4:20:26.990 UTC
ra 354.5000°
decl -64.2000°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9934 SUBJECT: GRB 090926: Fermi LAT detection DATE: 09/09/26 19:39:23 GMT FROM: Takeshi Uehara at Hiroshima U GRB 090926: Fermi LAT detection Takeshi Uehara, Hiromitsu Takahashi (Hiroshima University) and Julie McEnery (NASA/GSFC) report on behalf of the Fermi LAT team: At 04:20:26.99 (UT) on 26 Sep 2009, the Fermi Large Area Telescope (LAT) detected gamma rays from the long GRB 090926, which was triggered and located by the Fermi Gamma-ray Burst Monitor (GBM) (trigger 275631628 / 090926181, GCN9933). The angle of the GBM best position (RA, Dec= 354.5, -64.2) with respect to the LAT boresight was ~52 degrees at the time of the trigger, which is close the edge of our field of view. The data from the Fermi LAT shows a significant increase in the event rate within 2.5 degrees of the GBM location 7 s after the GBM trigger that is spatially and temporally correlated with the GBM emission with high significance. More than 150 photons above 100 MeV and more than 20 photons above 1 GeV are observed up to more than 200 s after the GBM trigger. The highest energy photon is a 19.6 GeV event which is observed 26 seconds after the GBM trigger. The best LAT on-ground localization is found to be (RA, Dec = 353.56, -66.34) with a 90% containment radius of 0.07 deg (statistical; 68% containment radius: 0.04 deg, preliminary systematic error is less than 0.1 deg) which is consistent with the GBM localization. A Swift TOO request has been issued. Further analysis is ongoing. The points of contact for this burst is Takeshi Uehara : uehara@hep01.hepl.hiroshima-u.ac.jp The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. This message can be cited.
GCN 9936 table
GRB_name GRB090926A
GCN_number 9936
Detection_method Swift-XRT Other
ra 353.4007°
decl -66.3239°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9936 SUBJECT: GRB090926A: UVOT-enhanced XRT position DATE: 09/09/27 00:26:28 GMT FROM: Loredana Vetere at PSU L. Vetere (PSU), P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team: Using 3190 s of XRT Photon Counting mode data and 4 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 =353.40070, -66.32390 which is equivalent to: RA (J2000): 23 33 36.18 Dec (J2000): -66 19 25.9 with an uncertainty of 1.5 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 is an official product of the Swift-XRT team.
GCN 9937 table
GRB_name GRB090926A
GCN_number 9937
Detection_method Swift-XRT Other
ra 353.4001°
decl -66.3240°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9937 SUBJECT: GRB 090926A: Skynet/PROMPT Discovery of the Optical Afterglow DATE: 09/09/27 01:36:29 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 Fermi/LAT localization of GRB 090926A (Uehara et al., GCN 9934) with four of the 16" PROMPT telescopes at CTIO beginning 19.0 hours after the trigger in UBVRI. We detect an optical source within the Swift/XRT localization (Vetre et al., GCN 9936) that is not in the DSS (POSS-II Red), at RA = 23:33:36.02 DEC = -66:19:26.5 Stacking only images that increase the limiting magnitude yields: mean time since cal. trig. tel. exp. fil. magnitude stars (h) (# x s) 19.9 PROMPT-2 22 x 80 V 18.81 +0.10 -0.09 52 NOMAD 20.0 PROMPT-5 22 x 80 I 18.24 +0.04 -0.04 165 USNO B1 20.0 PROMPT-4 24 x 80 R 18.06 +0.03 -0.03 230 USNO B1
GCN 9938 table
GRB_name GRB090926A
GCN_number 9938
Detection_method Swift-UVOT Det
ra 353.4002°
decl -66.3241°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9938 SUBJECT: GRB 090926A: Swift/UVOT detection of an optical afterglow DATE: 09/09/27 02:10:34 GMT FROM: Caryl Gronwall at PSU/Swift-UVOT C. Gronwall (PSU) and L. Vetere (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 090926A approximately 13 hours after the Fermi/GBM trigger (Bissaldi, GCN Circ. 9933). In a 357 sec observation in the white filter, we find a candidate optical afterglow within the XRT error circle (Vetere et al., GCN Circ. 9936) at RA(J2000) = 23:33:36.037 = 353.400154 Dec(J2000) = -66:19:26.64 = 66.324067 with a 90%-confidence error radius of about 0.11 arc sec. This position is 0.99 arc sec. from the center of the XRT error circle and is consistent with the optical afterglow position found by Skynet/PROMPT (Haislip et al., GCN Circ. 9937). The estimated magnitude is 18.78 +/- 0.04. This value is not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).
GCN 9942 table
GRB_name GRB090926A
GCN_number 9942
Detection_method Other
redshift 2.1062
Circular_text TITLE: GCN CIRCULAR NUMBER: 9942 SUBJECT: GRB 090926A: VLT/X-shooter redshift DATE: 09/09/27 06:48:04 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK/NBI), P. Goldoni (APC/Univ. Paris 7 and SAp/CEA), J. P. U. Fynbo (DARK/NBI), V. D'Elia (ASDC and INAF/OAR), S. Covino (INAF/OABr), H. Flores (Paris Obs.), A.J. Levan (Univ. Warwick), S. D. Vergani (APC/Univ. Paris 7), K. Wiersema (Univ. Leicester), report on behalf of the X-shooter GRB collaboration: We observed the afterglow of GRB 090926A (Bissaldi, GCN 9933; Uehara et al., GCN 9934; Vetere et al., GCN 9936; Haislip et al., GCN 9937) with the X-shooter spectrograph mounted on the ESO-VLT UT2. Observations were taken as part of the instrument Science Verification phase. X-shooter is a broad-band single-object spectrograph covering the wavelength range from the UV to the infrared (3300-22000 AA). At the beginning of the observation (22.0 hr after the GRB), the afterglow had R = 17.9 as measured from the acquisition image. Four spectra lasting 1800 s each were secured. The spectrum has high signal to noise and shows a wealth of absorption features, together with a broad depression around 3780 AA, which we interpret as a DLA. We identify CIV 1548 and 1550, Si II 1304 and 1526, SiII* 1533, FeII 1608, MgII 2798 and 2803, and several others, from which we measure a redshift z=2.1062. We caution that the wavelength solution is based on archival calibration data. We thank the ESO observing staff, in particular Joel Vernet, Thomas Bensby, and Stephane Brillant.
GCN 9948 table
GRB_name GRB090926A
GCN_number 9948
Detection_method Swift-UVOT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 9948 SUBJECT: GRB090926A: Swift/UVOT observations DATE: 09/09/27 12:41:56 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) and L. Vetere (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began observerving the field of Fermi GRB 090926A 47ks after the Fermi GBM and LAT trigger (Bissaldi., GCN Circ. 9933; Uehara ., GCN Circ. 9934). We detect a fading optical afterglow in white, v and u filters at the position reported by UVOT (Gronwall et al., GCN Circ. 9938) and Skynet/PROMPT (Haislip et al., GCN Circ 9937). The lightcurve appears to rebrighten from 70ks to the end of current observations. Preliminary magnitudes are reported below. Filter T_start(s) T_stop(s) Exposure Mag Err ------------------------------------------------------- white 46977 47341 358 18.71 +/- 0.04 white 69902 70369 459 19.32 +/- 0.05 v 47348 47712 358 18.45 +/- 0.16 u 46608 46972 358 18.21 +/- 0.07 u 69429 69896 459 18.85 +/- 0.09 u 86050 86613 554 18.52 +/- 0.07 ------------------------------------------------------- The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.02 mag (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT flight system described in Poole et al. (2008, MNRAS, 383,627).
GCN 9951 table
GRB_name GRB090926A
GCN_number 9951
Detection_method Suzaku WAM Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 9951 SUBJECT: GRB 090926A: Suzaku WAM observation of the prompt emission DATE: 09/09/27 14:52:07 GMT FROM: Kazuhiro Noda at Miyazaki U K. Noda, E. Sonoda, N. Ohmori, K. Kono, H. Hayashi, A. Daikyuji, Y. Nishioka, M. Yamauchi (Univ. of Miyazaki), Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa (Hiroshima U.), M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA), 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), K. Yamaoka, S. Sugita (Aoyama Gakuin U.), Y. E. Nakagawa, T. Tamagawa (RIKEN), S. Hong (Nihon U.), N. Vasquez (Tokyo Tech.), on behalf of the Suzaku WAM team, report: The very bright, Fermi-LAT detected GRB 090926A (Fermi-GBM trigger #275631628/ 090926181; Bissaldi, GCN 9933; Uehara et al., GCN 9934) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 04:20:27.168 UT (=T0). The observed light curve shows a multi-peaked structure, lasting from T0-0.5 s to T0+16.5 s, followed by a weak tail seen up to ~T0+34.5s. The total duration (T90) was about 13 s and the fluence in 100 - 1000 keV was 9.71(-0.40, +0.22)x 10-5 erg/cm2. The 1-s peak flux measured from T0+3.5 s was 30.6(-2.3, +1.6) photons/cm2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-0.5 s to T0+34.5 s is well fitted by a GRB Band model as follows. the low-energy photon index alpha: -1.09 (-0.27, +0.37), the high-energy photon index beta: -2.63 (-0.17, +0.11), and the peak energy Epeak: 434 (-30, +32) keV (chi2/d.o.f = 29.7/23). All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included. The light curves for this burst is now available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html
GCN 9953 table
GRB_name GRB090926A
GCN_number 9953
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 9953 SUBJECT: GRB 090926A: Skynet/PROMPT Continued Observations DATE: 09/09/27 18:49:04 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 continued to observe the afterglow (Haislip et al., GCN 9937) of GRB 090926A (Bissaldi, GCN 9933) with four of the 16" PROMPT telescopes at CTIO throughout the night in BVRI. We find that the light curve brightens from the beginning of our observations (about 19 hours after the trigger) to about 1 day after the trigger in all bands, which is consistent with the findings of Oates & Vetere (GCN 9948) in UVOT's u band. Around 1 day, the light curve peaks at R = 17.8 mag (calibrated to 82 USNO B1 stars) and begins to fade. A second, smaller rebrightening begins around 26 hours and peaks at R = 18.0 mag around 27 hours.
GCN 9959 table
GRB_name GRB090926A
GCN_number 9959
Detection_method Konus-Wind Det
t_trigger 4:20:28.683 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 9959 SUBJECT: Konus-Wind and Konus-RF observations of GRB 090926A DATE: 09/09/28 16:42:28 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, M. Ulanov, and D. Svinkin on behalf of the Konus-Wind and Konus-RF teams, and T. Cline on behalf of the Konus-Wind team, report: The long bright GRB 090926A (Fermi-GBM trigger 275631628 / 090926181: Bissaldi, GCN 9933) localized by Fermi-LAT (Uehara et al., GCN 9934) triggered Konus-Wind at T0=15628.683 s UT (04:20:28.683). It was also detected by Konus-RF instrument onboard CORONAS-PHOTON s/c in the waiting mode while being at high latitudes. The burst light curve shows a multipeaked structure with a total duration of ~16 s, followed by a weak tail seen up to ~T0+50 s. As observed by Konus-Wind the burst had a fluence of 1.80(-0.07, +0.08)x10^-4 erg/cm2, and a 16-ms peak flux measured from T0+8.944 s of 2.91(-0.54, +0.56)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+26.880 s) can be fitted (in the 20 keV - 10 MeV range) by GRB (Band) model for which: the low-energy photon index alpha = -0.76 +/- 0.03, the high energy photon index beta = -2.59(-0.13, +0.10), the peak energy Ep = 321 +/- 12 keV (chi2 = 106.0/84 dof). The emission is clearly seen up to ~10 MeV. All the quoted errors are at the 90% confidence level. Assuming z = 2.1062 (Malesani et al., GCN 9942) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, Omega_\Lambda = 0.73, the isotropic energy release E_iso ~2.0x10^54 erg, the peak luminosity (L_iso)_max ~ 1.0x10^54 erg/s, and Ep_rest ~1000 keV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB090926_T15628/
GCN 9961 table
GRB_name GRB090926A
GCN_number 9961
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 9961 SUBJECT: GRB090926A: Swift-XRT refined analysis DATE: 09/09/28 21:59:52 GMT FROM: Loredana Vetere at PSU L. Vetere (PSU) reports on behalf of the Swift-XRT team: We have analyzed the first 21.8 ks of Swift-XRT data of FERMI GRB090926A (Bissaldi et al., GCN Circ. 9933). The UVOT-enhanced XRT position for this burst was given in GCN Circ.9936 (Vetere et al.). The data are entirely in Photon Counting (PC) mode from T+46.7 ks to T+203 ks. The light curve shows a decaying behaviour with some flaring activity. It is best fitted by a power-law with decay index 1.29+/-0.2. Assuming the X-ray emission from the burst continues to decline at the present rate, the predicted count rate at T+3d is 0.009 cts/s. The average spectrum is best fit by an absorbed power-law model with a photon spectral index of 2.6 (+0.3,-0.2) and an absorption column density of 1.0 (+0.5,-0.3)e21 cm-2 in excess of the Galactic value of 2.7e20 cm-2 (Kalberla et al. 2005). The counts-to-observed 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5e-11 erg cm-2 count-1. The average observed (unabsorbed) fluxes are 1.3 (1.9)E-12 ergs cm-2 s-1. Errors are given at the 90% confidence level. This circular is an official product of the Swift-XRT team.
GCN 9972 table
GRB_name GRB090926A
GCN_number 9972
Detection_method Fermi LAT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 9972 SUBJECT: GRB 090926A: Fermi LAT and GBM refined analysis DATE: 09/09/29 21:20:20 GMT FROM: Elisabetta Bissaldi at MPE Elisabetta Bissaldi (MPE), Michael S. Briggs (UA Huntsville), Frederic Piron (IN2P3/LPTA), Hiromitsu Takahashi and Takeshi Uehara (Hiroshima University) report on behalf of the Fermi LAT and GBM teams: Further analysis of GRB 090926A (Bissaldi GCN 9933, Uehara et al. GCN 99934, Vetere et al. GCN 9336) reveals it is detected in the Fermi Large Area Telescope (LAT) at least until 300 s after the Fermi Gamma-Ray Burst Monitor (GBM) trigger time, T0=04:20:26.99 UT, with some indication for very extended emission up to a few kilo-seconds. Spectral analysis of the main emission episode, from T0 to T0+20.7 s, is well-fit by a Band function with Epeak = 268 +/- 4 keV, alpha = -0.693 +/ 0.009 and beta = -2.342 +/- 0.011 (C-STAT 1277 for 699 d.o.f.). Additionally, an effective area correction of 0.8 and 0.85 is applied to both BGO detectors with respect to the NaI detectors and LAT. The brightest interval, i.e. from T0+8.5 s to T0+10.5 s, includes a bright, narrow spike that is present from ~10 keV to >100 MeV. It shows a deviation from the Band function. The parameters for this multi-component fit (C-STAT = 781 for 697 d.o.f.) are Band_Epeak = 233 +/- 8, Band_alpha = -0.43 +/- 0.06, Band_beta = -3.00 +/- 0.13, and a power-law index of -1.845 +/- 0.019 for the additional component. In this case, the effective area correction applied to both BGOs is 0.76. The fluence between 10 keV and 10 GeV is (2.47 +/- 0.03)E-04 erg/cm^2 within the 21 seconds (the GBM T90) following the GBM trigger. The points of contact for this burst are: Takeshi Uehara (uehara@hep01.hepl.hiroshima-u.ac.jp) and Elisabetta Bissaldi (ebs@mpe.mpg.de). The Fermi LAT is a pair conversion telescope designed to cover the Energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. This message can be cited.
GCN 9982 table
GRB_name GRB090926A
GCN_number 9982
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 9982 SUBJECT: GRB 090926A: Skynet/PROMPT Observations of Post-Peak Fading DATE: 09/10/01 04:36:16 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 has continued to observe the afterglow (Haislip et al., GCN 9937) of GRB 090926A (Bissaldi, GCN 9933) with four of the 16" PROMPT telescopes at CTIO in BVRI. Since peaking in brightness approximately 1 day after the trigger (Haislip et al., GCN 9953), the afterglow has been fading with a power-law index of approximately -1.4. At 4.1 days after the trigger, it's magnitude is R = 20.09 +0.10 -0.09 (statistical) 0.57 (systematic; calibrated to 172 USNO B1 stars). Skynet's most recent BVRI light curve, calibrated to USNO B1 and NOMAD stars, can be found here: http://skynet.unc.edu/grb/grb090926a.jpg
GCN 9984 table
GRB_name GRB090926A
GCN_number 9984
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 9984 SUBJECT: GRB 090926A: Skynet/PROMPT Observations of Day 4 - 6 Fading Rate DATE: 09/10/03 20:49:13 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 has continued to observe the afterglow (Haislip et al., GCN 9937) of GRB 090926A (Bissaldi, GCN 9933) with four of the 16" PROMPT telescopes at CTIO in BVRI. After peaking in brightness approximately 1 day after the trigger (Haislip et al., GCN 9953), the afterglow had been fading with a power-law index of approximately -1.4 until approximately 4 days after the trigger (Haislip, et al., GCN 9982). Between 4 and 6 days after the trigger, the afterglow has been fading with a shallower power-law index of approximately -0.8. At 6.1 days after the trigger, its magnitude is R = 20.40 +0.11 -0.10 (statistical) +/- 0.57 (systematic; calibrated to 172 USNO B1 stars). Skynet's most recent BVRI light curve, calibrated to USNO B1 and NOMAD stars, can be found here: http://skynet.unc.edu/grb/grb090926a.jpg
GCN 10003 table
GRB_name GRB090926A
GCN_number 10003
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 10003 SUBJECT: GRB 090926A: Skynet/PROMPT Observations of Day 6 - 11 Fading DATE: 09/10/09 17:24:40 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 has continued to observe the afterglow (Haislip et al., GCN 9937) of GRB 090926A (Bissaldi, GCN 9933) with two of the 16" PROMPT telescopes at CTIO in RI. After peaking in brightness approximately 1 day after the trigger (Haislip et al., GCN 9953) and fading with a power-law index of around -1.4 until approximately 4 days after the trigger (Haislip, et al., GCN 9982), the afterglow faded with a shallower power-law index of around -0.8 until approximately 6 days after the trigger (Haislip et al., GCN 9984). Between 6 and 11 days after the trigger, the afterglow has been fading with a steeper power-law index of around -1.7. At 11.1 days after the trigger, its magnitude is R = 21.45 +0.22 -0.18 (statistical) +/- 0.57 (systematic; calibrated to 172 USNO B1 stars). Skynet's most recent BVRI light curve, calibrated to USNO B1 and NOMAD stars, can be found here: http://skynet.unc.edu/grb/grb090926a.jpg Continued observations with larger telescopes are encouraged.
GCN 10009 table
GRB_name GRB090926A
GCN_number 10009
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 10009 SUBJECT: RT-2 observation of the bright GRB 090926A DATE: 09/10/11 06:48:11 GMT FROM: Sandip K. Chakrabarti at S.N. Bose Nat. Centre for Basic Sci. S. K. Chakrabarti, A. Nandi, D. Debnath, T. C. Kotoch (ICSP, Kolkata, India), A. R. Rao, J. P. Malkar, M. K. Hingar, V. K. Agrawal (TIFR, Mumbai, India), T. R. Chidambaram, P. Vinod, S. Sreekumar (VSSC, Thiruvananthapuram, India), Y. D. Kotov, A. S. Buslov, V. N. Yurov, V. G. Tyshkevich, A. I. Arkhangelskij, R. A.Zyatkov (MephI, Moscow, Russia) report: The very bright GRB 090926A (FERMI-GBM trigger 275631628 / 090926181; Bissaldi, GCN 9933) is detected by RT-2 Experiment onboard CORONAS-PHOTON satellite at T0 = 04h 20m 27s (UT). The satellite was in LIGHT mode (pointing towards the SUN) for a short duration at a high latitude in its orbit. During this time, the GOOD time (away from the polar and SAA regions) observation was for 348 sec starting at 04h 16m 55sec (UT) and ending at 04h 22m 43sec (UT). The burst light curve consists of multiple peaks of total duration of ~ 17 sec, followed by a weak tail ending at ~ T0+30 sec. The strongest peak count rate is ~ 1200 cts/sec. This burst is also independently detected by KONUS-RF, another instrument onboard CORONAS-PHOTON satellite (Golenetskii et al., 2009, GCN 9959). Both RT-2/S and RT-2/G detectors have registered the burst profile of this bright GRB in the energy band of 15 ~1000 keV with strongest emission in the energy band of 60 215 keV. The light curve is available at the web-site: http://csp.res.in/rt2_files/grb090926-lc.html
GCN 10020 table
GRB_name GRB090926A
GCN_number 10020
Detection_method Fermi LAT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 10020 SUBJECT: Radio observation of GRB090926a with ATCA DATE: 09/10/13 09:10:17 GMT FROM: Aquib Moin at CIRA/ATNF Aquib Moin (Curtin Institute of Radio Astronomy / Australia Telescope National Facility), Dale A. Frail (National Radio Astronomy Observatory), Steven Tingay (Curtin Institute of Radio Astronomy), Jean-Pierre Macquart (Curtin Institute of Radio Astronomy) report: We observed the UVOT-enhanced XRT position (GCN 9936) of the Fermi LAT/GBM burst GRB090926a (GCN 9933, 9972) at 5.5 GHz with the Australia Telescope Compact Array (ATCA) between 05:00:00 UT and 10:00:00 UT on October 01, 2009. The ATCA was in its most compact configuration giving a synthesized beam of 138 x 78 arcsec. We did not detect a radio source at the XRT position of the GRB090926a (GCN 9936). The radio flux density at the GRB position found out to be -0.271 0.727 mJy/beam. No further observations are planned. The Australia Telescope Compact Array (/ Parkes telescope / Mopra telescope / Long Baseline Array) is part of the Australia Telescope which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. See the GRB field image at: http://cira.ivec.org/dokuwiki/doku.php/grb/grb090926a_field_image
GCN 10049 table
GRB_name GRB090926A
GCN_number 10049
Detection_method Konus-Wind Det
redshift 2.1000
Circular_text TITLE: GCN CIRCULAR NUMBER: 10049 SUBJECT: GRB 090926A: Late-time Gemini South Observations and Possible Jet Break DATE: 09/10/20 22:10:04 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko, D. A. Perley, B. E. Cobb, J. S. Bloom, and N. R. Butler (UC Berkeley) report on behalf of a larger collaboration: We have imaged the field of the Fermi GRB090926A (Bissaldi et al., GCN 9933; Uehara et al., GCN 9934) with the Gemini Multi-Object Spectrograph mounted on the 8-m Gemini South telescope. Observations were taken in the Sloan g', r', and i' filters beginning at 2:28 UT on 19 October 2009 (~ 22.9 d after the GBM trigger). We detect a faint source in all filters at the location of the optical afterglow (Haislip et al., GCN 9937, Gronwall et al., GCN 9938). Using several unsaturated USNO-B objects in the field of view, along with the filter transformations of Jordi, Grebel, and Ammon (2006 A&A 460, 339), we measure a magnitude of r' ~ 23.7 for this source. Along with its relatively blue color (g' - i' ~ 0), the object appears marginally extended, suggesting it is likely dominated by emission from the host galaxy of GRB090926A. We caution, however, that the host candidate is partially blended with a nearby object (~ 1.5" in the SW direction, just outside the optical and X-ray afterglow error circle) of comparable magnitude, which likely affects the photometry. Comparing with the last reported R-band detection (R ~ 21.5 at t ~ 11.1 d; Haislip et al., GCN 10003), the optical decay must have significantly steepened from previous measurements (power-law index alpha >~ 2.5). A similar steepening is hinted at in the latest XRT observations of this source (see http://astro.berkeley.edu/~nat/swift/00020113/bat_xrt.jpg), suggesting a possible jet break. Using the measured redshift of z = 2.1 (Malesani et al., GCN 9942), the isotropic gamma-ray energy derived from the Konus-Wind instrument (E_iso ~ 2e54 erg; Golenetskii et al., GCN 9959), and assuming expansion into a constant density medium (n ~ 1 cm^-3) with a gamma-ray efficiency ~ 20%, we infer an opening angle ~ 0.1 rad. The collimation-corrected prompt energy release would therefore be large, E ~ 1e52 erg.
GCN 10113 table
GRB_name GRB090926A
GCN_number 10113
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 10113 SUBJECT: GRB 090926a, SMARTS optical/IR afterglow observations DATE: 09/10/30 07:27:25 GMT FROM: Bethany Cobb at UC Berkeley B. E. Cobb (UC Berkeley) reports: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 090926a (GCN 9933, Bissaldi et al.) over several epochs. For each epoch, total summed exposure times amounted to 36 minutes in I and 30 minutes in J. The afterglow of GRB 090926a (e.g. GCN 9937, Haislip et al.; GCN 9938, Gronwall et al.) is detected in our images with the following magnitudes (calibrated using Landolt standard stars in the optical and 2MASS stars in the IR): time post-burst I mag J mag 20.60 hrs 18.17+/-0.06 17.28+/-0.07 71.74 hrs 19.53+/-0.07 18.35+/-0.09 119.18 hrs 20.33+/-0.10 19.16+/-0.13 Between ~21 and 119 hours post-burst, the afterglow fades with a rate of alpha ~ -1.1+/-0.1 (where afterglow flux is proportional to t^alpha).