GRB 090814A
GCN Circular 9797
Subject
GRB090814A: VLT spectroscopy
Date
2009-08-14T05:07:03Z (16 years ago)
From
Antonio Deugarte at IAA-CSIC <deugarte@iaa.es>
P. Jakobsson (Univ. Iceland), A. de Ugarte Postigo (INAF-OAB),
J. Gorosabel (IAA-CSIC), N. Tanvir (Leicester),
L. Christensen (ESO), J.P.U. Fynbo (DARK/NBI)
report on behalf of a larger collaboration,
We have observed the field of GRB 090814A (Ukwatta et al. GCN 9793)
using FORS2 at the VLT (Paranal observatory) starting at 02:05 UT
(70 minutes after the burst). We detect the object identified by
Updike et
al. (GCN 9794) with a magnitude of R~21.5.
The spectrum shows continuum down to at least 3900 Angstroms.
Non detection of Ly-alpha implies a limit of z < 2.2. We identify a
weak absorption system at z=0.696 through the detection of MgII and
CaII.
This is therefore likely to be the redshift of the GRB but we note that
it could also be produced by an intervening system and thus the strict
redshift range for this GRB would be 0.696 < z < 2.2.
We acknowledge the excelent support from Parnal observatory, in
particular J. Smoker and L. Rivas.
GCN Circular 9799
Subject
GRB 090814A: Swift-BAT refined analysis
Date
2009-08-14T12:55:19Z (16 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC),
T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU),
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 recent telemetry downlinks,
we report further analysis of BAT GRB 090814A (trigger #359951)
(Ukwatta, et al., GCN Circ. 9793). The BAT ground-calculated position is
RA, Dec = 239.613, 25.586 deg which is
RA(J2000) = 15h 58m 27.2s
Dec(J2000) = +25d 35' 09.0"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 37%.
The mask-weighted light curve shows a few semi-overlapping peaks starting
at ~T-18 sec, peaking at ~T-13 sec, peaking at ~T+8 sec, and ending
at ~T+115 sec. There is possible 10-sec precursor peak (3 sigma) at ~T-145 sec.
T90 (15-350 keV) is 80 +- 8 sec (estimated error including systematics).
The time-averaged spectrum from T-16.4 to T+73.6 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.81 +- 0.19. The fluence in the 15-150 keV band is 1.3 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-12.68 sec in the 15-150 keV band
is 0.6 +- 0.2 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/359951/BA/
GCN Circular 9800
Subject
GRB 090814A, RIMOTS optical upper limits
Date
2009-08-14T13:16:44Z (16 years ago)
From
Arata Daikyuji at Miyazaki U <daikyu524@astro.miyazaki-u.ac.jp>
A.Daikyuji, K.Noda, H.hayasi, K.Kono,
N.Ohmori, E.Sonoda, M.Yamauchi
(University of Miyazaki)
We have observed the field covering the error circle of
GRB 090814A (Swift trigger 359951, GCN 9793, T. N. Ukwatta et al.)
with the unfiltered CCD camera on the 30-cm telescope
at University of Miyazaki.
The observation was started 00:59 UT, about 11 hr
after the Swift trigger time.
We have compared our data of 30 sec exposures
with the USNO-A2.0 catalog,
There is no new source at the reported position.
((GCN9794(Adria Updike et al.))
the upper limits are as follows:
--------------------------------------------------------------
Start(UT) End(UT) Num. of frames Limit (mag.)
--------------------------------------------------------------
11:08:33 11:09:03 1 16.2
11:08:33 11:48:08 36 17.3
---------------------------------------------------------------
GCN Circular 9801
Subject
GRB 090814A: Swift-XRT Team Refined Analysis
Date
2009-08-14T13:33:54Z (16 years ago)
From
Kim Page at U.of Leicester <kpa@star.le.ac.uk>
K.L. Page (U. Leicester) & T. N. Ukwatta (GSFC/GWU) report on behalf of
the Swift-XRT team:
We have analysed the first four orbits of data collected for GRB 090814A,
from 165 s to 25.7 ks after the BAT trigger. These data comprise 258 s in
Windowed Timing (WT) mode and 7.8 ks in Photon Counting mode. The enhanced
XRT position for this burst was given by Beardmore et al. in GCN Circ.
9796.
The light curve can be modelled with a series of power-law decays,
starting with alpha1 = 2.60 +/- 0.08 until ~T+830 s, at which point the
decay flattens slightly to alpha2 = 1.91 +/- 0.20. The light curve
flattens again at ~T+5.4 ks, to a slope of alpha3 = 0.51 +/- 0.48. With
the limited data at this time, alpha3 has a relatively large uncertainty.
The spectrum extracted from the WT data can be fitted with an absorbed
power-law, with Gamma = 2.78 +0.12/-0.11, absorbed by the Galactic column
of NH = 4.76 x 10^20 cm^-2 (Kalberla et al. 2005), together with an
intrinsic column (assuming z = 0.696; Jakobsson et al., GCN Circ. 9797) of
(2.0 +/- 0.4) x 10^21 cm^-2. Note, however, that this redshift
determination is uncertain. The total (including Galactic) column at z = 0
would be (1.3 +/- 0.2) x 10^21 cm^-2. Alternatively, the spectrum is
better fitted (at >3 sigma) by a broken power-law with Gamma1 = 0.47
+0.72/-1.59 below a break energy of 0.62 +0.09/-0.08 keV, followed by
Gamma2 = 2.62 +/- 0.09; this fit only requires the Galactic column. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced
from the broken power-law fit is 2.5 x 10^-11 (3.0 x 10^-11) erg cm^-2
count^-1.
If the light curve continues to decay with a power-law decay index of
0.51, the count rate at T+24 hours will be 0.0041 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x 10^-13
(1.2 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00359951.
This circular is an official product of the Swift-XRT team.
GCN Circular 9802
Subject
GRB 090814A: Swift/UVOT Observations
Date
2009-08-14T13:52:07Z (16 years ago)
From
Peter Curran at MSSL <pac@mssl.ucl.ac.uk>
P.A. Curran (MSSL-UCL), T. N. Ukwatta (GSFC/GWU), report on behalf of
the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 090814A
170s after the BAT trigger (Ukwatta et al., GCN 9793). The proposed
optical counterpart (Updike et al. , GCN 9794) is marginally detected in
the u and white UVOT exposures. No optical afterglow consistent with the
enhanced XRT position (Beardmore et al., GCN 9796) is detected in the
other UVOT exposures.
Preliminary magnitudes and 3-sigma upper limits using the UVOT
photometric system (Poole et al. 2008, MNRAS, 383, 627) for for the
first finding charts (FC) and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
u 328 577 246 > 20.16 (FC)
wh 170 319 147 > 20.70 (FC)
u 328 8144 834 21.05 +/- 0.35
b 584 8340 599 > 21.30
v 658 7528 607 > 20.18
w1 708 7939 529 > 20.66
m2 683 7733 529 > 20.5
w2 708 7939 607 > 20.81
wh 170 7117 699 21.54 +/- 0.27
The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.078 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 9809
Subject
GRB090814A: NOT optical follow-ups
Date
2009-08-14T23:02:39Z (16 years ago)
From
Dong Xu at DARK,NBI <dong@astro.ku.dk>
D. Xu, J.P.U. Fynbo (DARK/NBI), P. Jakobsson (Univ. Iceland), Tiina
Liimets (NOT) report on behalf of a larger collaboration:
We observed the field of GRB 090814A (Ukwatta et al. GCN 9793; Updike et
al., GCN 9794) with the Nordic Optical Telescope equipped with ALFOSC.
We obtained 3x600 s R-band frames staring on August 14th, 21:15:11 UT,
20.38 hr after the burst.
The optical afterglow is clearly detected in each frame. The magnitude
is R~22.4 calibrated against the reference star, #1156-0231252 with
R2=19.25, of the USNO B1 catalog.
Compared with the previous measurement of R~21.5 around 70 mins after
the burst (Jakobsson et al., GCN 9797), the afterglow is decaying quite
shallowly, with a power-law slope of ~0.3, being consistent with the
X-ray decaying law during the same period (Page & Ukwatta, GCN 9801).
GCN Circular 9818
Subject
GRB 090814A: optical observations
Date
2009-08-17T11:07:26Z (16 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev (CrAO) and A. Pozanenko (IKI) report on behalf of larger GRB
follow-up collaboration:
We observed the field of GRB 090814A (Ukwatta et al. GCN 9793; Updike et
al., GCN 9794) with Shajn telescope of CrAO on Aug. 14 between (UT)
19:02:44 - 19:56:58 under modarate seeing of about 1.9 arcsec. We detect
afterglow in a stacked image. The coordinates of the afterglow are (J2000)
15 58 26.36 +25 37 52.32 in a full agreement with reported earlier (A.
Updike et al., GCN 9794). The photometry against nearby USNO-B1.0 star 15
58 23.11 +25 39 07.2 16.64 R is following:
T0+ Filter, Exposure, mag., err.
(d) (s)
R 51x60 22.10 +/- 0.08
We confirm the shallow decay of the afterglow (D. Xu et al., GCN 9809) with
power law index ~0.3.
GCN Circular 9903
Subject
GRB 090814A: Skynet/DSO & GORT Observations
Date
2009-09-09T00:41:59Z (16 years ago)
From
Josh Haislip at U.North Carolina <haislip@physics.unc.edu>
J. Haislip, D. Reichart, K. Ivarsen, A. Smith, D. Caton, L. Hawkins, L.
Cominsky, K. McLin, T. Graves, G. Spear, A. LaCluyze, A. Foster, J. Moore,
A. Oza, M. Schubel, J. Styblova, A. Trotter, J. A. Crain, and M. Nysewander
report:
Skynet observed the Swift/BAT localization of GRB 090814A (Ukwatta et al.,
GCN 9793) with the 14" Dark Sky Observatory telescope in North Carolina
beginning 71.1 minutes after the trigger in RI through variable cloud
cover.
Skynet continued observing with the 14" GORT telescope at Hume Observatory
in California beginning 3.3 hours after the the trigger in RI.
We do not detect the afterglow (Updike et al., GCN 9794). Stacking only
images that increase the limiting magnitude yields:
mean
time 3-sigma secondary
since limiting calibration
trigger telescope exposures filter magnitude stars *
75.4 m DSO-14 2 x 160 s I 18.5 13 SDSS 6
+ 1 x 80 s
86.4 m DSO-14 4 x 160 s R 19.2 9 SDSS 6
96.6 m DSO-14 3 x 160 s I 17.8 13 SDSS 6
105.3 m DSO-14 1 x 160 s R 16.9 9 SDSS 6
4.7 h GORT 35 x 80 s I 20.1 8 SDSS 6
5.2 h GORT 40 x 80 s R 20.8 7 SDSS 6
24.9 h DSO-14 11 x 160 s R 20.0 9 SDSS 6
* Transformed using Jester et al., 2005, ApJ, 130, 873.