GRB110731A

This page lists all entries on GRB110731A in GRBweb

Summary Fermi GBM IPN Swift Fermi LAT GCN 12215 GCN 12216 GCN 12217 GCN 12218 GCN 12219 GCN 12220 GCN 12221 GCN 12222 GCN 12223 GCN 12224 GCN 12225 GCN 12226 GCN 12227 GCN 12242 GCN 12244 GCN 12333

Summary table
Variable Value Source
GRB_name_Fermi GRB110731465
T0 11:09:29 UTC Fermi_LAT
ra 280.5041° Swift
decl -28.5372° Swift
pos_error 2.59e-05° Swift
T90 7.485 s Fermi_GBM
T90_error 0.572 s Fermi_GBM
T90_start 11:09:29.957 UTC Fermi_GBM
fluence 2.29e-05 erg/cm² Fermi_GBM
fluence_error 5.70e-08 erg/cm² Fermi_GBM
redshift 2.8300 GCN_circulars,Other
T100 39.8 s
GBM_located False
mjd 55773.46491898148 Fermi_LAT
Fermi GBM table
GRB_name_Fermi GRB110731465
trigger_name bn110731465
ra 280.5042°
decl -28.5372°
pos_error 2.65e+00°
datum 2011-07-31
t_trigger 11:09:29.954 UTC
T90 7.485 s
T90_error 0.572 s
T90_start 11:09:29.957 UTC
fluence 2.29e-05 erg/cm²
fluence_error 5.70e-08 erg/cm²
flux_1024 2.09e+01 erg/cm²/s
flux_1024_error 4.57e-01 erg/cm²/s
flux_1024_time 1.28e-01 erg/cm²/s
flux_64 2.91e+01 erg/cm²/s
flux_64_error 2.11e+00 erg/cm²/s
IPN table
GRB_name GRB110731A
ra 280.5208°
decl -28.5500°
pos_error 5.00e-02°
redshift 2.8300
Swift table
GRB_name GRB110731A
t_trigger 11:09:30 UTC
ra 280.5041°
decl -28.5372°
pos_error 2.59e-05°
T90 38.8 s
fluence 6.00e-06 erg/cm²
redshift 2.8300
Fermi LAT table
GRB_name_Fermi GRB110731465
GRB_name GRB110731A
MET 333803371.0
datum 2011-07-31
t_trigger 11:09:29 UTC
ra 280.5041°
decl -28.5372°
pos_error 1.39e-04°
GCN 12215 table
GRB_name GRB110731A
GCN_number 12215
Detection_method Swift Det
t_trigger 11:09:30 UTC
ra 280.5210°
decl -28.5460°
Circular_text TITLE: GCN CIRCULAR NUMBER: 12215 SUBJECT: GRB 110731A: Swift detection of a burst with an optical counterpart DATE: 11/07/31 11:23:28 GMT FROM: David Palmer at LANL S. R. Oates (UCL-MSSL), A. P. Beardmore (U Leicester), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), A. Melandri (INAF-OAB), C. J. Mountford (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), C. J. Saxton (UCL-MSSL) and T. N. Ukwatta (MSU) report on behalf of the Swift Team: At 11:09:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 110731A (trigger=458448). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 280.521, -28.546 which is RA(J2000) = 18h 42m 05s Dec(J2000) = -28d 32' 44" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multiple-peaked structure with a duration of about 20 sec. The peak count rate was ~20000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 11:10:36.9 UT, 66.4 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 280.5042, -28.5363 which is equivalent to: RA(J2000) = 18h 42m 01.00s Dec(J2000) = -28d 32' 10.6" with an uncertainty of 4.8 arcseconds (radius, 90% containment). This location is 63 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 75 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 18:42:01.01 = 280.50419 DEC(J2000) = -28:32:13.7 = -28.53713 with a 90%-confidence error radius of about 0.61 arc sec. This position is 3.0 arc sec. from the center of the XRT error circle. The estimated magnitude is 15.80 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.17. Burst Advocate for this burst is S. R. Oates (sro 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.)
GCN 12216 table
GRB_name GRB110731A
GCN_number 12216
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 12216 SUBJECT: GRB 110731A: FTN+FTS afterglow observations DATE: 11/07/31 12:17:39 GMT FROM: David Bersier at Liverpool John Moores U David Bersier (LJMU) report on behalf of a larger collaboration: The Faulkes Telescopes North (Hawaii) and South (Australia) both started automatically (110 and 182 seconds after trigger) to observe GRB 110731A, in response to the Swift trigger 458448. The software detected a uncatalogued decaying source that coincides with the position of the UVOT candidate afterglow (GCN 12215). We measure a magnitude mR=16.4 at 28 minutes after the trigger time. Assuming a power law decay, the decay index is about -1. Observations have been obtained with the BVR filters and are continuing on both telescopes.
GCN 12217 table
GRB_name GRB110731A
GCN_number 12217
Detection_method Swift-BAT Det
ra 280.5130°
decl -28.5360°
Circular_text TITLE: GCN CIRCULAR NUMBER: 12217 SUBJECT: GRB 110731A: Swift-BAT refined analysis DATE: 11/07/31 13:58:26 GMT FROM: Scott Barthelmy at NASA/GSFC H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), C. B. Markwardt (GSFC), S. R. Oates (UCL-MSSL), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+402 sec from the recent telemetry downlink, we report further analysis of BAT GRB 110731A (trigger #458448) (Oates, et al., GCN Circ. 12215). The BAT ground-calculated position is RA, Dec = 280.513, -28.536 deg, which is RA(J2000) = 18h 42m 03.1s Dec(J2000) = -28d 32' 10.0" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 98%. The mask-weighted light curve shows many overlapping peaks starting at ~T-1.5 sec, peaking at +T_zero, and ending at ~T+8 sec with a long exponential decay lasting out to ~T+80 sec. T90 (15-350 keV) is 38.8 +- 13.0 sec (estimated error including systematics). The time-averaged spectrum from T-1.3 to T+80.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.15 +- 0.05. The fluence in the 15-150 keV band is 6.0 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.26 sec in the 15-150 keV band is 11.0 +- 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/458448/BA/
GCN 12218 table
GRB_name GRB110731A
GCN_number 12218
Detection_method Fermi LAT Det
ra 280.3900°
decl -28.5300°
Circular_text TITLE: GCN CIRCULAR NUMBER: 12218 SUBJECT: Fermi-LAT Detection of GRB110731A DATE: 11/07/31 18:13:26 GMT FROM: Julie McEnery at NASA/GSFC Johan Bregeon, Julie McEnery and Masanori Ohno report on behalf of the Fermi Large Area Telescope (LAT) collaboration. Based on an on-ground analysis, the Large Area Telescope (LAT), on-board the Fermi Gamma-ray Space Telescope, detected high energy emission above 100 MeV, with greater than 10 sigma significance, from the Swift detected burst GRB 110731A (Oates et al, GCN 12215). The preliminary LAT location of the ground automated analysis is (Ra,Dec) = (280.39,-28.53)+/-0.20 d (68% cont.) which is consistent with the Swift localization and within 0.1d from the optical counterpart position. Further analysis is ongoing. The Fermi LAT point of contact for this burst is Johan Bregeon (johan.bregeon@pi.infn.it). 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.
GCN 12219 table
GRB_name GRB110731A
GCN_number 12219
Detection_method Swift-XRT Det
ra 280.5042°
decl -28.5375°
Circular_text TITLE: GCN CIRCULAR NUMBER: 12219 SUBJECT: GRB 110731A: Enhanced Swift-XRT position DATE: 11/07/31 18:18:07 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 1566 s of XRT Photon Counting mode data and 4 UVOT images for GRB 110731A, 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 = 280.50417, -28.53748 which is equivalent to: RA (J2000): 18h 42m 1.00s Dec (J2000): -28d 32' 14.9" with an uncertainty of 1.4 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 12220 table
GRB_name GRB110731A
GCN_number 12220
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 12220 SUBJECT: GRB 110731A: NOT photometry DATE: 11/07/31 23:11:39 GMT FROM: Giorgos Leloudas at Dark Cosmology Centre D. Malesani, G. Leloudas (DARK/NBI), Dong Xu (WIS), A. de Ugarte Postigo, J. Hjorth (DARK/NBI), P. Jakobsson (U. Iceland), and M. B. Nielsen (NOT), report on behalf of a larger collaboration. We used the Nordic Optical Telescope (La Palma, Spain) equipped with ALFOSC to observe the field of GRB 110731A (Oates et al., GCN 12215). Observations started at 21:22 UT, i.e. 10.22 hr after the trigger. We obtained 3x300 s in R under bad (1.7") seeing conditions. The afterglow has faded considerably with respect to the report by Bersier (GCN 12216). Photometry is made difficult by the crowding of the field, and we estimate a tentative magnitude for the transient R = 22.2 +- 0.3 mag.
GCN 12221 table
GRB_name GRB110731A
GCN_number 12221
Detection_method Fermi GBM Det
t_trigger 11:09:29.940 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 12221 SUBJECT: GRB 110731A: Fermi GBM observation DATE: 11/08/01 06:29:38 GMT FROM: David Gruber at MPE David Gruber (MPE) reports on behalf of the Fermi GBM Team: "At 11:09:29.94 UT on 31 July 2011, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 110731A (trigger 333803371 / 110731465) which which was also detected by Fermi LAT (Bregeon et al. 2011, GCN 12218) and Swift (Oates et al. 2011, GCN 12215). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 6 degrees. Moreover, this burst was bright enough to result in a Fermi spacecraft autonomous rapid repoint (ARR) maneuver. The GBM light curve consists of one pulse with a duration (T90) of about 7.3 +/- 0.3 s (50-300 keV). The time-averaged spectrum from T0 s to T0+7.3 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.82 +/- 0.03 and the cutoff energy, parameterized as Epeak, is 317 +/- 10 keV. The event fluence (10-1000 keV) in this time interval is (2.218 +/- 0.006)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.128 s in the 10-1000 keV band is 20.9 +/- 0.5 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak= 304 +/- 13 keV, alpha = -0.80 +/- 0.03 and beta = -2.98 +/- 0.30. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN 12222 table
GRB_name GRB110731A
GCN_number 12222
Detection_method Swift-UVOT Det
ra 280.5041°
decl -28.5372°
Circular_text TITLE: GCN CIRCULAR NUMBER: 12222 SUBJECT: GRB110731A: Swift/UVOT Observations DATE: 11/08/01 12:17:25 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) reports on behalf of the Swift-UVOT team The Swift/UVOT began settled observations of the field of GRB 110731A 75s after the trigger (Oates et al., GCN Circ. 12215). We detect a fading source in the white, v, b and u filters at a refined position of RA(J2000), DEC(J2000)= 280.50413 deg, -28.537167 deg. This is equivalent to: RA (J2000) 18:42:00.99 Dec (J2000) -28:32:13.8 with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence). This is consistent with the UVOT position reported in Oates et al. (GCN Circ. 12215) and with the enhanced position of the X-ray afterglow (Beardmore et al., GCN Circ. 12219). The non-detection in the uv filters is consistent with a redshift of between 2 and 3. Preliminary magnitudes using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the finding chart (FC) and summed exposures at the location of the optical afterglow are: Filter T_start(s) T_stop(s) Exp(s) Mag ##################################################### wh (FC) 75 225 147 15.85+/-0.02 wh 567 587 19 17.64+/-0.11 v 790 810 19 16.90+/-0.23 b 542 562 19 17.87+/-0.23 u (FC) 287 537 246 17.71+/-0.08 u 1118 1138 19 18.37+/-0.44 uvw1 666 1286 78 >18.88 uvm2 642 1261 78 >18.77 uvw2 592 1385 97 >19.24 ##################################################### We note that photometry is difficult due to the field being crowded and the presence of a faint contaminating source in the source region. The values quoted above are not corrected for the non-negliable Galactic extinction due to the reddening of E(B-V) = 0.18 in the direction of the burst (Schlegel et al. 1998).
GCN 12223 table
GRB_name GRB110731A
GCN_number 12223
Detection_method Konus-Wind Det
t_trigger 11:09:34.604 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 12223 SUBJECT: Konus-Wind observation of GRB 110731A DATE: 11/08/01 12:53:47 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The long GRB 110731A (Swift-BAT trigger #458448: Oates, et al., GCN 12215; Krimm et al., GCN 12217; also detected by Fermi-LAT: McEnery, GCN 12218, and Fermi-GBM: Gruber, GCN 12221) triggered Konus-Wind at T0=40174.604 s UT (11:09:34.604). The burst light curve shows a multipeaked structure with a duration of ~7 s. There is a low-level emission seen in the G2 band (~80-360 keV) up to ~T0+40 s. As observed by Konus-Wind the burst had a fluence of 1.63(-0.10,+0.11)x10^-5 erg/cm2, and a 64-ms peak flux measured from T0+4.304 s of (6.0 +/- 1.3)x10^-6 erg/cm2/s (both in the 20 keV - 6 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+8.448 s) can be fitted (in the 20 keV - 6 MeV range) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), with alpha = -0.74(-0.15, +0.16), and Ep = 288(-25, +30) keV (chi2 = 98.2/76 dof). Fitting by GRB (Band) model yields the same alpha and Ep, and only an upper limit on the high energy photon index: beta < -2.92 (chi2 = 98.1/75 dof). 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/GRB110731_T40174/
GCN 12224 table
GRB_name GRB110731A
GCN_number 12224
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 12224 SUBJECT: GRB 110731A: Swift-XRT refined Analysis DATE: 11/08/01 12:54:32 GMT FROM: Owen Littlejohns at U of Leicester O. M. Littlejohns, P. A. Evans, A. P. Beardmore (U. Leicester) and S. R. Oates (UCL-MSSL) report on behalf of the Swift-XRT team: We have analysed 8.1 ks of XRT data for GRB 110731A (Oates et al. GCN Circ. 12215), from 56 s to 36.0 ks after the BAT trigger. The data comprise 607 s in Windowed Timing (WT) mode (the first 8 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 Beardmore et al. (GCN. Circ 12219). The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=1.04 (+0.05, -0.10). At T+502 s the decay steepens to an alpha of 1.183 (+0.027, -0.024) before breaking again at T+29.0 ks to a final decay with index alpha=4.2 (+5.8, -2.0). We note that the uncertainty in this final decay is large due to the small number of data points after the final break. A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.08 (+/-0.05). The best-fitting absorption column is 2.05 (+0.14, -0.13) x 10^21 cm^-2, in excess of the Galactic value of 1.0 x 10^21 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 1.92 (+/-0.12) and a best-fitting absorption column of 1.7 (+0.4, -0.3) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (5.5 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.7 (+0.4, -0.3) x 10^21 cm^-2 Galactic foreground: 1.0 x 10^21 cm^-2 Excess significance: 8.4 sigma Photon index: 1.92 (+/-0.12) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00458448. This circular is an official product of the Swift-XRT team.
GCN 12225 table
GRB_name GRB110731A
GCN_number 12225
Detection_method Other
redshift 2.8300
Circular_text TITLE: GCN CIRCULAR NUMBER: 12225 SUBJECT: GRB 110731A Gemini-N redshift DATE: 11/08/01 13:23:44 GMT FROM: Nial Tanvir at U.Leicester N. R. Tanvir, K. Wiersema (U. Leicester), A. J. Levan (U. Warwick), S. B. Cenko (U. Berkeley) and T. Geballe (Gemini) report on behalf of a larger collaboration: We observed the location of GRB 110731A (Oates et al. GCN12215) with the GMOS-N instrument on Gemini-North (Mauna Kea), beginning at 1 Aug 2011 09:07 UT. Spectroscopic observations totalling 3600s were obtained in good conditions using the B600 grating (spanning approximately 3800 A to 6650 A). We identify a broad Ly-alpha absorption feature and several absorption lines of O, C, Si and Al at a common redshift of z=2.83. This includes fine structure lines of O, C and Si, as seen in other GRB sight-lines, confirming that this is the redshift of the burst. Provisional calibration of the acquisition image gives a magnitude of R=22.0 for the afterglow (uncorrected for foreground extinction of A_R ~ 0.5), suggesting a fairly shallow rate of decay since the NOT epoch (Malesani et al. GCN12220).
GCN 12226 table
GRB_name GRB110731A
GCN_number 12226
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 12226 SUBJECT: GRB110731A: MITSuME Ishigakijima Optical Upper Limits DATE: 11/08/01 14:10:02 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 110731A (Oates et al., GCNC 12215) 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 13:02:23 UT (~1.9 h after the burst). We did not find any new point source within the enhanced XRT error circle (Beardmore et al., GCNC 12219) in all the three bands. We could not detect the previously reported afterglow (Bersier, GCNC 12216; Malesani et al., GCNC 12220). Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Ic ---------------------------------------------------- 0.12025 14:02:40 6180.0 >21.8 >20.6 >20.1 ---------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]
GCN 12227 table
GRB_name GRB110731A
GCN_number 12227
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 12227 SUBJECT: GRB 110731A / EVLA upper limits DATE: 11/08/01 19:02:55 GMT FROM: Ashley Zauderer at CfA A. Zauderer, E. Berger (Harvard), and D.A. Frail (NRAO) report on behalf of a larger collaboration: "We observed the Swift burst GRB 110731A (GCN 12215) with the EVLA beginning on 2011 Aug 1.15 UT (0.68 days after the burst). Observations were performed at 5.75 and 22 GHz for about 30 min at each frequency. No radio source is detected in coincidence with the optical afterglow (GCN 12215), to a 3-sigma limit of ~50 microJy at 5.75 GHz. Additional observations are planned."
GCN 12242 table
GRB_name GRB110731A
GCN_number 12242
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 12242 SUBJECT: GRB110731A: MOA optical observations of the steeply fading afterglow DATE: 11/08/03 11:49:40 GMT FROM: Akihiko Fukui at Nagoya U/MOA P. J. Tristram (MJUO), A. Fukui (Nagoya U.), K. Ohnishi (Nagano NCT) and T. Sako (Nagoya U.) report on behalf of the MOA collaboration. We began prompt observations of the afterglow of GRB110731A (Oates et al., GCN 12215) at July 31 11:12:47 UT responding to the Swift trigger 458448 (3.3 min after the trigger) using the 61 cm B&C telescope at the Mt John University Observatory in New Zealand. We obtained a series of I and V band images with 60 sec exposure times followed by some 120 sec exposures until 12:56 UT (105 min after the trigger). The total number of I and V images are 39 and 35, respectively. Although the first image had a poor psf, the following images had well-shaped psf's and we confirmed the steeply fading afterglow, which is consistent with the previous reports (e.g. Bersier et al. GCN 12216), on these images in both the I and V bands. The afterglow is located within the error circle reported by Oates et al. GCN 12222. The magnitude of the afterglow on the second and on the last images in the I band obtained by psf-fitting photometry with the DoPHOT package (Schechter et al. 1993) and calibrated to the USNO-B1.0 N magnitude (similar to I magnitude) follow. ------------------------------------------ Filter mid_JD-2450000 exptime[sec] dT[min] Nmag error I 5773.96831 60 4.86 14.75 0.20 I 5774.03807 120 105.31 20.2 2.7 ------------------------------------------ Here dT denotes the difference between the mid_JD (mid time of exposure) and the trigger time. The large error in the magnitude of the last image resulted from the calibration relying on extrapolation.
GCN 12244 table
GRB_name GRB110731A
GCN_number 12244
Detection_method Suzaku WAM Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 12244 SUBJECT: GRB 110731A : Suzaku WAM observation of the prompt emission DATE: 11/08/04 02:12:35 GMT FROM: Yoshitaka Hanabata at Hiroshima U Y. Hanabata, T. Uehara, T. Takahashi, M. Mizuno, M. Ohno, Y. Fukazawa (Hiroshima U.), T. Yasuda, Y. Terada, M. Tashiro, W. Iwakiri, K. Takahara (Saitama U.), S. Sugita (Nagoya U.), K. Yamaoka (Aoyama Gakuin U.), M. Kokubun, T. Takahashi (ISAS/JAXA), Y. E. Nakagawa (Waseda U.), N. Ohmori, M. Akiyama, M. Yamauchi (Univ. of Miyazaki), Y. Urata, P. Tsai, C-J. Chuang (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo), on behalf of the Suzaku WAM team, report: The bright long GRB110731A (Swift/BAT trigger #458448: Oates et al. GCN 12215, also detected by Fermi-LAT: Bregeon et al. GCN 12218) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 11:09:30.211 UT (=T0). The observed light curve shows multiple peaks starting at T0-1.5 s, ending at T0+7.5 s, with a duration (T90) of about 6.56 seconds. The fluence in 100 - 1000 keV was 1.31 (-0.12, +0.08) x 10^-5 erg/cm^2. The 1-s peak flux measured from T0+3.5 s was 5.20 (-0.70, +0.57) photons/cm^2/s in the same range. Preliminary result shows that the time-averaged spectrum from T0-1.5 s to T0+7.5 s is well fitted by a power-law with exponential cutoff model: dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with alpha 0.93 (-0.66, +0.57), and Epeak 339 (-51, +40) keV (chi^2/d.o.f. = 11.2/12). 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 12333 table
GRB_name GRB110731A
GCN_number 12333
Detection_method correction
ra 280.5030°
decl -28.5375°
Circular_text TITLE: GCN CIRCULAR NUMBER: 12333 SUBJECT: GRB 110731A: SAO RAS and Terskol observations DATE: 11/09/09 08:30:16 GMT FROM: Vladimir Sokolov at SAO RAS A. S. Moskvitin, V. V. Sokolov, O. I. Spiridonova (SAO RAS, Russia), M. V. Andreev, A. V. Sergeev, N. A. Parakhin (Terskol Branch of Institute of Astronomy, Russia) We observed the field of GRB 110731A (Oates et al., GCN 12215) on July, 31 with 0.6-m Zeiss-600 (Terskol Branch of Institute of Astronomy, Russia) equipped with the PixelVision Vienna CCD (1024 x 1024, bin 2 x 2) + R filter, and 1-m Zeiss-1000 (SAO RAS, Russia) equipped with the E2V 42-40 CCD (2048 x 2048, bin 2 x 2) + B and Rc filters. In both cases the observations carried out at a high airmass and with the seeing ~4". At all stacked images we did not detect any source within the Swift/UVOT error circle (Oates., GCN 12222). Close to the error circle are visible two objects which are also present in the USNO-B.1 catalogue: S1: USNO-B.1 0614-0802286 (R.A.=18:42:00.72, Dec.=-28:32:14.9, E.=2000.0) & S2: USNO-B.1 0614-0802328 (R.A.=18:42:01.24, Dec.=-28:32:11.6, E.=2000.0). Our astrometric calibration and photometry of S1 object showed that it can contain flux from OT but due to large seeing we can not distinguish bright S1 and faint OT. All three co-added images are shown at ftp://ftp.sao.ru/pub/grb/GRB110731A/GRB110731A.jpg Upper limits are shown at the following table. _________________________________________________________ mid. time, UT filter exp., sec 3-sigma lim. telescope _________________________________________________________ 19:15 R 53 x 200 19.9 Zeiss-600 19:24 Rc 31 x 60 21.7 Zeiss-1000 19:38 B 22 x 60 20.8 Zeiss-1000 _________________________________________________________ We use USNO-B.1 star 0614-0802353 (R.A.=18:42:01.83, Dec.-28:32:23.9, E.=2000.0, B2 = 15.77, R2 = 14.29) as a standard, and did not apply Galaxy extinction correction. This message can be cited.