GRB140818A

This page lists all entries on GRB140818A in GRBweb

Summary Fermi GBM IPN GCN 16702 GCN 16703 GCN 16705 GCN 16706 GCN 16708 GCN 16719 GCN 16726

Summary table
Variable Value Source
GRB_name_Fermi GRB140818229
T0 5:30:09.120 UTC GCN_circulars,Fermi GBM Det
ra 199.5125° IPN
decl 6.8000° IPN
pos_error 1.00e+00° IPN
T90 109.25 s Fermi_GBM
T90_error 0.932 s Fermi_GBM
T90_start 5:30:14.306 UTC Fermi_GBM
fluence 2.95e-05 erg/cm² Fermi_GBM
fluence_error 6.46e-08 erg/cm² Fermi_GBM
T100 114.436 s
GBM_located False
mjd 56887.22927222222 GCN_circulars,Fermi GBM Det
Fermi GBM table
GRB_name_Fermi GRB140818229
trigger_name bn140818229
ra 199.5629°
decl 6.9225°
pos_error 4.51e+00°
datum 2014-08-18
t_trigger 5:30:09.122 UTC
T90 109.25 s
T90_error 0.932 s
T90_start 5:30:14.306 UTC
fluence 2.95e-05 erg/cm²
fluence_error 6.46e-08 erg/cm²
flux_1024 8.65e+00 erg/cm²/s
flux_1024_error 2.72e-01 erg/cm²/s
flux_1024_time 9.95e+01 erg/cm²/s
flux_64 1.07e+01 erg/cm²/s
flux_64_error 1.19e+00 erg/cm²/s
IPN table
GRB_name GRB140818A
ra 199.5125°
decl 6.8000°
pos_error 1.00e+00°
GCN 16702 table
GRB_name GRB140818A
GCN_number 16702
Detection_method MAXI Det
t_trigger 8:31:56 UTC
ra 199.5540°
decl 6.8880°
Circular_text TITLE: GCN CIRCULAR NUMBER: 16702 SUBJECT: GRB 140818A: MAXI/GSC detection DATE: 14/08/18 06:29:01 GMT FROM: H. Negoro at Nihon U. F. Honda, K. Suzuki, H. Negoro (Nihon U.), M. Serino (RIKEN), S. Nakahira, S. Ueno, H. Tomida, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA), T. Mihara, M. Sugizaki, M.Morii, J. Sugimoto, T. Takagi, A. Yoshikawa, M. Matsuoka (RIKEN), N. Kawai, T. Yoshii, Y. Tachibana (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, D. Uchida (Osaka U.), Nakajima, K. Fukushima, T. Onodera, T. Namba, M. Fujita (Nihon U.), Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.), Y. Tsuboi, A. Kawagoe (Chuo U.), M. Yamauchi, Y. Morooka (Miyazaki U.), K. Yamaoka (Nagoya U.), report on behalf of the MAXI team: The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 2014-08-18T08:31:56 UT. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (199.554 deg, 6.888 deg) = (13 18 12, +06 53 15) (J2000) with a statistical 90% C.L. statistical error of 0.07 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 1125 +- 62 mCrab mCrab (4-10keV, 1 sigma error). A energy spectrum fit with the absorbed (Nh=2.5e20) power-law model gives a photon index of 1.03 (+0.13/-0.12).
GCN 16703 table
GRB_name GRB140818A
GCN_number 16703
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 16703 SUBJECT: GRB 140818A Tiled Swift observations DATE: 14/08/18 08:38:26 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a series of observations, tiled on the sky, of the MAXI GRB 140818A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00029 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the MAXI event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; and 2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team.
GCN 16705 table
GRB_name GRB140818A
GCN_number 16705
Detection_method MAXI Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 16705 SUBJECT: GRB 140818A: Correction to GCN 16702 DATE: 14/08/18 14:42:40 GMT FROM: H. Negoro at Nihon U. H. Negoro, F. Honda (Nihon U.) report on behalf of the MAXI team: The trigger time of MAXI-GSC detection of GRB 140818A reported in GCN 16702 is incorrect. The correct trigger time is "2014-08-18T05:31:28 UT", and about 79 sec after the Fermi-GBM detection (Triger Number 430032612). The time and the location of Fermi-GBM and MAXI-GSC GRBs suggest that that the bursts are the same origin. We apologize for the mistake.
GCN 16706 table
GRB_name GRB140818A
GCN_number 16706
Detection_method Swift-XRT Other
ra 199.5627°
decl 6.9225°
Circular_text TITLE: GCN CIRCULAR NUMBER: 16706 SUBJECT: GRB 140818A: Swift-XRT and UVOT potential afterglow detection DATE: 14/08/18 15:05:41 GMT FROM: Craig Swenson at PSU/Swift Swenson, C.A. (PSU) and Sbarufatti, B. (INAF-OAB/PSU) report on behalf of the Swift team Swift-XRT has observed the error circle of the MAXI GRB 140818A in a series of observations tiled on the sky. The total exposure time is 2.3 ks spread over 4 fields; the maximum exposure within the sky observed was 1.0 ks. The observations started 10.5 ks after the MAXI trigger (Honda et al., GCN Circ. 16702). Within these data we detect a bright, uncatalogued X-ray source at RA, Dec= 199.56275, 6.92254 which is equivalent to: RA (J2000) = 13h 18m 15.06s Dec (J2000) = +06d 55' 21.1" with an uncertainty of 2.1 arcsec (radius, 90% confidence). This is an enhanced position, determined by using UVOT field stars to determine the astrometry.The exposure at this location was 746 s. This previously uncatalogued source is significantly brighter than the RASS limit, and we thus consider it the likely GRB afterglow. The results of the automatic processing for this source are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00029/index_1.php The Swift/UVOT began settled observations of the field of GRB 140818A 10467 s after the MAXI trigger. A source consistent with the XRT position is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 13:18:15.08 = 199.56285 (deg.) Dec (J2000) = +06:55:22.6 = 6.92295 (deg.) with an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence). Preliminary detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u 10467 11094 617 19.21 0.12 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998). This circular is an official product of the Swift team.
GCN 16708 table
GRB_name GRB140818A
GCN_number 16708
Detection_method Fermi GBM Det
t_trigger 5:30:09.120 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 16708 SUBJECT: GRB 140818A - Fermi GBM Detection DATE: 14/08/18 18:08:23 GMT FROM: Oliver Roberts at UCD/Fermi Oliver Roberts (UCD) reports on behalf of the Fermi GBM Team: "At 05:30:09.12 UT on the 18th of August 2014, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 140818A (trigger 430032612 / 140818229), which was also detected by MAXI/GSC (H. Negoro et al. GCN 16702 and GCN 16705). A possible afterglow has also been reported by Swift-XRT and UVOT (C. Swenson et al. GCN 16706) The GBM on-ground location is consistent with the MAXI/GSC and Swift positions. The angle from the Fermi LAT boresight is 35 degrees. The GBM light curve consists of two peaks, with the second peak at T~50s being brighter than the first. The duration (T90) of the burst is about 109 s (50-300 keV). The time-averaged spectrum from T0+25s to T0+135 s is adequately fit by a BAND function. The power law index alpha is -0.69 +/- 0.04 . The power law index beta is -2.39 +/- 0.10 . The cutoff energy, parameterised as Epeak, is 181 +/- 8 keV. The event fluence (10-1000 keV) in this time interval is (2.95 +/- 0.06)E-05 erg/cm^2. The 1.024-sec peak photon flux was measured starting from T0+99.5 s in the 10-1000 keV band is 8.6 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN 16719 table
GRB_name GRB140818A
GCN_number 16719
Detection_method Konus-Wind Det
t_trigger 5:31:20.472 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 16719 SUBJECT: Konus-Wind observation of GRB 140818A DATE: 14/08/19 14:37:57 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R. Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report: A long duration GRB 140818A (MAXI/GSC detection: Honda et al., GCN 16702, 16705; Fermi-GBM detection: Roberts, GCN 16708) triggered Konus-Wind at T0=19880.472 s UT (05:31:20.472). The burst light curve shows a rather weak pulse at ~T0-83 s followed by the main emission episode at ~T0-15 s. The total duration of the burst is ~126 s. The emission is seen up to ~2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB140818_T19880/ As observed by Konus-Wind, the burst had a fluence of 3.68(-0.21,+0.22)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+24.304 s, of (2.29+/-0.49)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+41.216 s) is best fit in the 20 keV - 3 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.11 (-0.13,+0.14) and Ep = 219 (-21,+26) keV (chi2 = 68/68 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.7 (chi2 = 68/67 dof) All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN 16726 table
GRB_name GRB140818A
GCN_number 16726
Detection_method GROND
Circular_text TITLE: GCN CIRCULAR NUMBER: 16726 SUBJECT: GRB 140818A: GROND confirmation of afterglow candidate DATE: 14/08/20 13:22:12 GMT FROM: Fabian Knust at MPE/GROND GRB 140818A: GROND confirmation of afterglow candidate F. Knust, K. Varela, and J. Greiner (all MPE Garching) report on behalf of the GROND team: We observed the field of GRB 140818A (MAXI/GSC nova alert; Honda et al., GCN 16702) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile). Observations started at 23:15 UT on 2014-08-18, 15 hours after the GRB trigger. They were performed at an average seeing of 2.7" and at an average airmass of 1.9. We detect an optical/NIR counterpart at the position of the Swift-XRT and UVOT afterglow candidate reported by Swenson et al. (GCN 16706) with magnitudes g' = 22.4 +/- 0.2 mag, r' = 21.7 +/- 0.1 mag, i' = 22.0 +/- 0.2 mag, z' > 21.9 mag, J > 20.7mag, H > 20.2 mag, and K > 17.7 mag all in AB system. GROND photometry indicates that the UVOT source (Swenson et al., GCN 16706) has faded, confirming it as the afterglow. The given magnitudes are derived based on calibrating the images against SDSS zeropoints and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.036 mag in the direction of the burst (Schlegel et al. 1998). [GCN OPS NOTE(20aug14): Per author's request, the "draft" language was removed.]