- GCN/BACODINE POSITION NOTICE
TITLE: GCN/MAXI NOTICE
NOTICE_DATE: Mon 18 Aug 14 05:45:00 UT
NOTICE_TYPE: MAXI Unknown Source Position
EVENT_ID_NUM: 887151727
EVENT_RA: 199.51d {+13h 18m 03s} (J2000),
199.70d {+13h 18m 48s} (current),
198.88d {+13h 15m 32s} (1950)
EVENT_DEC: +6.80d {+06d 48' 07"} (J2000),
+6.73d {+06d 43' 31"} (current),
+7.06d {+07d 03' 53"} (1950)
EVENT_ERROR: 1.0 [deg radius, stat+sys, 90% containment]
EVENT_FLUX: 2448.0 +- 0.0 [mCrab]
EVENT_DATE: 16887 TJD; 230 DOY; 14/08/18
EVENT_TIME: 19916.00 SOD {05:31:56.00} UT
EVENT_TSCALE: 1day
EVENT_EBAND: High, 10-20 keV
SUN_POSTN: 147.50d {+09h 50m 00s} +13.11d {+13d 06' 45"}
SUN_DIST: 51.73 [deg]
MOON_POSTN: 62.52d {+04h 10m 04s} +17.53d {+17d 32' 06"}
MOON_DIST: 131.25 [deg]
MOON_ILLUM: 43 [%]
GAL_COORDS: 321.41, 68.71 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 195.37, 13.92 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: MAXI Unknown Source Position. GRB or unknown X-ray Transient.
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/MAXI NOTICE
NOTICE_DATE: Mon 18 Aug 14 06:04:40 UT
NOTICE_TYPE: MAXI Unknown Source Position
EVENT_ID_NUM: 887151727
EVENT_RA: 199.55d {+13h 18m 13s} (J2000),
199.74d {+13h 18m 57s} (current),
198.92d {+13h 15m 42s} (1950)
EVENT_DEC: +6.89d {+06d 53' 16"} (J2000),
+6.81d {+06d 48' 40"} (current),
+7.15d {+07d 09' 03"} (1950)
EVENT_ERROR: 1.0 [deg radius, stat+sys, 90% containment]
EVENT_FLUX: 1125.0 +- 0.0 [mCrab]
EVENT_DATE: 16887 TJD; 230 DOY; 14/08/18
EVENT_TIME: 19916.00 SOD {05:31:56.00} UT
EVENT_TSCALE: 1day
EVENT_EBAND: High, 10-20 keV
SUN_POSTN: 147.51d {+09h 50m 03s} +13.11d {+13d 06' 29"}
SUN_DIST: 51.74 [deg]
MOON_POSTN: 62.69d {+04h 10m 47s} +17.55d {+17d 33' 17"}
MOON_DIST: 131.08 [deg]
MOON_ILLUM: 42 [%]
GAL_COORDS: 321.58, 68.78 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 195.37, 14.02 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: MAXI Unknown Source Position. GRB or unknown X-ray Transient.
- GCN Circular #16702
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 Circular #16703
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 Circular #16705
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 Circular #16706
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 (Hond=
a
et al., GCN Circ. 16702). Within these data we detect a bright,=20
uncatalogued
X-ray source at RA, Dec=3D 199.56275, 6.92254 which is equivalent to:
RA (J2000.0) = 13h 18m 15.06s
Dec (J2000.0) = +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) =3D 13:18:15.08 =3D 199.56285 (deg.)
Dec (J2000) =3D +06:55:22.6 =3D 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=20
exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
u 10467 11094 617 19.21 =B1 0.12
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) =3D 0.04 in the direction of the burst
(Schlegel et al. 1998).
This circular is an official product of the Swift team.
- GCN Circular #16708
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 Circular #16719
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 Circular #16726
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).
Previous IAU Circulars 