GRB090927A

This page lists all entries on GRB090927A in GRBweb

Summary Fermi GBM IPN Swift GCN 9945 GCN 9946 GCN 9950 GCN 9952 GCN 9954 GCN 9955 GCN 9956 GCN 9958 GCN 9960 GCN 9974 GCN 10021

Summary table
Variable Value Source
GRB_name_Fermi GRB090927422
T0 10:07:16 UTC GCN_circulars,Swift Det
ra 343.9725° Swift
decl -70.9804° Swift
pos_error 8.15e-05° Swift
T90 0.512 s Fermi_GBM
T90_error 0.231 s Fermi_GBM
T90_start 10:07:17.022 UTC Fermi_GBM
fluence 3.03e-07 erg/cm² Fermi_GBM
fluence_error 1.83e-08 erg/cm² Fermi_GBM
redshift 1.3700
T100 2.2 s
GBM_located False
mjd 55101.42171296296 GCN_circulars,Swift Det
Fermi GBM table
GRB_name_Fermi GRB090927422
trigger_name bn090927422
ra 343.9500°
decl -70.9800°
pos_error 8.04e+00°
datum 2009-09-27
t_trigger 10:07:17.214 UTC
T90 0.512 s
T90_error 0.231 s
T90_start 10:07:17.022 UTC
fluence 3.03e-07 erg/cm²
fluence_error 1.83e-08 erg/cm²
flux_1024 3.32e+00 erg/cm²/s
flux_1024_error 2.45e-01 erg/cm²/s
flux_1024_time -2.56e-01 erg/cm²/s
flux_64 6.54e+00 erg/cm²/s
flux_64_error 1.09e+00 erg/cm²/s
IPN table
GRB_name GRB090927A
ra 343.9542°
decl -70.9833°
pos_error 5.00e-02°
redshift 1.3700
Swift table
GRB_name GRB090927A
t_trigger 10:07:16 UTC
ra 343.9725°
decl -70.9804°
pos_error 8.15e-05°
T90 2.2 s
fluence 2.00e-07 erg/cm²
redshift 1.3700
GCN 9945 table
GRB_name GRB090927A
GCN_number 9945
Detection_method Swift Det
t_trigger 10:07:16 UTC
ra 343.9530°
decl -70.9780°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9945 SUBJECT: GRB 090927: Swift detection of a short burst DATE: 09/09/27 10:19:48 GMT FROM: David Palmer at LANL D. Grupe (PSU), J. R. Cummings (NASA/UMBC), C. Gronwall (PSU), C. Guidorzi (U Ferrara), C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), M. H. Siegel (PSU), T. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the Swift Team: At 10:07:16 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090927 (trigger=370846). The BAT on-board calculated location is RA, Dec 343.953, -70.978 which is RA(J2000) = 22h 55m 49s Dec(J2000) = -70d 58' 38" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak structure with a duration of about 1.5 sec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~1 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+33.8 minutes. There will be no XRT or UVOT data until this time. 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 9946 table
GRB_name GRB090927A
GCN_number 9946
Detection_method Swift-UVOT Det
ra 343.9725°
decl -70.9804°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9946 SUBJECT: GRB 090927: Swift/UVOT detection of an optical afterglow DATE: 09/09/27 10:58:19 GMT FROM: Caryl Gronwall at PSU/Swift-UVOT C. Gronwall and D. Grupe (PSU) report on behalf of the Swift/UVOT team: In response to GRB090927 (Swift/BAT trigger 370846) at 10:07:16 UT, UVOT took a finding chart exposure of 150 seconds with the White filter starting 2141 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 22:55:53.41 = 343.97255 DEC(J2000) = -70:58:49.3 = -70.98037 with a 90%-confidence error radius of about 0.63 arc sec. This position is 7.2 arc sec. from the center of the XRT error circle. The estimated magnitude is 19.10 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03.
GCN 9950 table
GRB_name GRB090927A
GCN_number 9950
Detection_method Swift-XRT Det
ra 343.9729°
decl -70.9803°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9950 SUBJECT: GRB 090927: Enhanced Swift-XRT position DATE: 09/09/27 13:41:20 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 1424 s of XRT Photon Counting mode data and 3 UVOT images for GRB 090927, 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 = 343.97291, -70.98032 which is equivalent to: RA (J2000): 22h 55m 53.50s Dec (J2000): -70d 58' 49.2" with an uncertainty of 2.0 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 9952 table
GRB_name GRB090927A
GCN_number 9952
Detection_method Swift Other
ra 343.9729°
decl -70.9803°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9952 SUBJECT: GRB 090927: Swift XRT refined analysis DATE: 09/09/27 15:13:01 GMT FROM: Dirk Grupe at PSU/Swift-XRT D. Grupe and L. Vetere (PSU) report on behalf of the Swift-XRT team: Due to an observing constraint, the Swift XRT started observing the field of GRB 090927 Grupe et al., GCN Circ. 9945) delayed at 10:43:03 UT, 2147s after the BAT trigger. XRT found a faint, fading, uncatalogued X-ray source at RA (J2000): 22h 55m 53.50s Dec (J2000): -70d 58' 49.2" with an uncertainty of 2.0 arcsec (radius, 90% confidence) as given in Evens et al. (GCN Circular 9950). This location is 24.8" from the BAT on-board calculated location (Grupe et al., GCN Circular 9945), inside the BAT error circle, and 0.5" from the UVOT position given in Gronwall & Grupe (GCN Circular 9946). Based on the Photon Counting mode (pc) mode data of the first orbit with an exposure time of 1421s we extracted a spectrum which can be fitted with a single absorbed power law model with Gamma = 1.64+/-0.49 and an absorption column density consistent with the Galactic value of 2.92 x 10^20 cm^-2 (Kalberla et al. 2005). The light curve can be modelled with a single power-law decay with an index of alpha=1.76+2.05/-0.96. If the afterglow continues to decay with this slope the predicted count rate 24 hours after the trigger is 2.5e-4 counts s^-1 or 1.3e-14 ergs s^-1 cm^-2. This circular is an official product of the Swift-XRT team.
GCN 9954 table
GRB_name GRB090927A
GCN_number 9954
Detection_method Swift-UVOT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 9954 SUBJECT: Swift/UVOT observations of GRB 090927 DATE: 09/09/27 18:58:12 GMT FROM: Paul Kuin at MSSL N.P.M. Kuin (MSSL-UCL) and D. Grupe (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began a delayed observing the field of GRB 090927 2121s after the trigger due to an observing constraint (Grupe, GCN Circ. 9945). We detect a fading optical afterglow in white, v,b, and u filters at the position reported by UVOT (Gronwall et al., GCN Circ. 9946). Preliminary magnitudes are reported below. Filter T_start(s) T_stop(s) Exposure(s) Magnitude =================================================== white(FC) 2141 2291 147.4 19.13 +/- 0.09 white 2372 2920 235.6 19.40 +/- 0.09 v 2121 2617 48.6 19.0 +/- 0.37 v 3131 3331 196.6 19.37 +/- 0.25 b 2348 2542 38.9 19.50 +/- 0.31 b 2696 2716 19.5 19.09 +/- 0.34 u 2323 2517 38.9 18.77 +/- 0.26 u 2671 2691 19.5 >18.89 uvw1 2299 3576 92.8 >19.63 uvm2 2446 3536 235.6 >19.89 uvw2 2397 2592 38.9 >18.84 ==================================================== The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.03 mag (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383,627).
GCN 9955 table
GRB_name GRB090927A
GCN_number 9955
Detection_method Swift-BAT Det
ra 343.9290°
decl -70.9730°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9955 SUBJECT: GRB 090927, Swift-BAT refined analysis of the possibly short burst DATE: 09/09/27 19:36:02 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift M. Stamatikos (OSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), D. Grupe (PSU), 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), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090927 (trigger #370846) (Grupe, et al., GCN Circ. 9945). The BAT ground-calculated position is RA, Dec = 343.929, -70.973 deg which is RA(J2000) = 22h 55m 42.9s Dec(J2000) = -70d 58' 24.2" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 55%. The mask-weighted light curve shows a single irregular peak with an overall roughly FRED shape. T90 (15-350 keV) is 2.2 +- 0.4 sec (estimated error including systematics). The time-averaged spectrum from T+0.0 to T+2.4 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.80 +- 0.20. The fluence in the 15-150 keV band is 2.0 +- 0.3 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-0.01 sec in the 15-150 keV band is 2.0 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The classification of this burst as short or long is not clear. The burst appears to have significant lag between energy bands, and moreover is not particularly hard. We expect to perform a more quantitative lag analysis and report the results in an additional circular. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/370846/BA/
GCN 9956 table
GRB_name GRB090927A
GCN_number 9956
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 9956 SUBJECT: GRB 090927: Zadko Telescope observations DATE: 09/09/27 20:29:05 GMT FROM: Alain Klotz at CESR-CNRS A. Klotz, T.P. Vaalsta, Liang Yan, and J. Zadko report on behalf of the Zadko Telescope Team. A. Klotz (CESR, OHP), T.P. Vaalsta, Liang Yan, J. Zadko, H. Miao, J. Moore, K. Frost, D. Coward, A. Imerito, D. Blair, R. Burman, P. Luckas, S. Gordon, A. Fletcher, A. Ahmet, (University of Western Australia) M. Todd, M. Zadnik (Curtin University) M. Boer, M. Laas (OHP), P. Thierry (Airbus) The 1.0m F/4 Zadko telescope started imaging the field of GRB 090927 (trigger=370846, Grupe et al., GCN 9945) 110 minutes after the Swift trigger. A fading source was found within the XRT error circle (GCN 9946, Gronwall et al.). The field was observed for 50 minutes using a preliminary version of a robotic observation mode. Preliminary photometry of unfiltered images taken with an iKon DW436BV camera show the following initial magnitudes of the optical afterglow: tmid(min) Exp. Time R Magnitude ------------------------------------- 110 42s >16 126 540s 19.8 +/- 0.5 158 360s 20.0 +/- 0.5 The fading seems to have low decay which is encouraging to perform spectrocopy in the next hours.
GCN 9958 table
GRB_name GRB090927A
GCN_number 9958
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 9958 SUBJECT: GRB 090927: VLT redshift DATE: 09/09/28 07:44:23 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst Andrew J. Levan (Univ. Warwick), Johan P.U. Fynbo (DARK/NBI), Jens Hjorth (DARK/NBI), Daniele Malesani (DARK/NBI), Paolo D'Avanzo (INAF/OABr), Valerio D'Elia (INAF/OAR), report on behalf of a larger collaboration: We observed the afterglow of GRB 090927 (Grupe et al., GCN 9945; Gronwall et al., GCN 9946), possibly short (Stamatikos et al., GCN 9955). Using FORS2 on the Very Large Telescope, we have obtained 3x30 min spectra (300V grism) of the optical afterglow (Gronwall & Grupe, GCN 9946; Klotz et al., GCN 9956). Observations started on Sep 27.11 UT, about 16.5 hr after the burst. The afterglow had a magnitude R ~ 21.7 as measured from the acquisition images. The obtained spectrum shows Mg II and Fe II absorption lines corresponding to z = 1.37. There is no evidence for higher redshift systems or a Lyman-alpha and hence z = 1.37 is the likely redshift of GRB 090927. We acknowledge excellent support from the ESO observing staff, in particular Yuri Beletsky and Stephane Brillant.
GCN 9960 table
GRB_name GRB090927A
GCN_number 9960
Detection_method Other
ra 22.0000°
decl -70.0000°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9960 SUBJECT: GRB 090927: Faulkes Telescope South Detection of the Optical Afterglow DATE: 09/09/28 16:42:32 GMT FROM: Zach Cano at ARI/John Moores Liverpool Z. Cano, A. Melandri, C. Mundell, D. Bersier, R.J. Smith, I. A. Steele, S. Kobayashi, C.J. Mottram (Liverpool JMU), A. Gomboc (U. Ljubljana) report, on behalf of the Liverpool GRB group: The Faulkes Telescope South (Australia) observed the field of GRB 090927 (Swift trigger=370846, Grupe et al., GCN 9945) on 2009 September 27 and 28. The afterglow candidate reported by Gronwell & Grupe (GCN 9946) is clearly visible and fading at position: RA(J2000): 22 55 53.42 Dec(J2000): -70 58 49.54 with the following magnitudes calibrated wrt USNO-B1 objects in the field: I = 19.4 +/- 0.1 @ 3.66 hrs I = 21.3 +/- 0.2 @ 27.23 hrs R = 19.9 +/- 0.1 @ 4.21 hrs Observations are on-going, but we derive preliminary decay rates using the above FTS measurements and the R-band magnitude reported by Levan et al. (GCN 9958) to be: alpha_I=0.9+/-0.2, alpha_R=1.2+/-0.2.
GCN 9974 table
GRB_name GRB090927A
GCN_number 9974
Detection_method Fermi GBM Det
t_trigger 10:07:17.210 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 9974 SUBJECT: GRB 090927: Fermi GBM observation DATE: 09/09/30 13:01:46 GMT FROM: David Gruber at MPE D. Gruber (MPE), E. Bissaldi (MPE) and S. McBreen (UCD/MPE) report on behalf of the Fermi GBM Team: "At 10:07:17.21 UT on 27 September 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090927 (trigger 275738839 / 090927422), which was also detected by the Swift-BAT (Grupe al. 2009, GCN 9945). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 85 degrees. The GBM light curve consists of one weak pulse with a duration of about 2 seconds. The time-averaged spectrum from T0-0.256 s to T0+0.896 s is adequately fit by a simple power law function with index -1.47 +/- 0.06 (C-stat 330 for 239 d.o.f.). The event fluence (8-1000 keV) in this time interval is (6.1 +/- 0.5)E-07 erg/cm^2. The 128-msec peak photon flux measured starting from T0-0.128 s in the 8-1000 keV band is 7.2 +/- 0.9 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN 10021 table
GRB_name GRB090927A
GCN_number 10021
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 10021 SUBJECT: Radio observation of GRB090927 with ATCA DATE: 09/10/13 09:12:09 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 enhanced Swift-XRT position of the GRB090927 (GCN 9950) 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 126 x 76 arcsec. We did not detect a radio source at the XRT position of the GRB090926a (GCN 9950). The radio flux density at the GRB position found out to be 0.036 0.172 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/grb090927_field_image