GRB 081105
GCN Circular 8484
Subject
GRB 081105 Swift/BAT and IPN Localization
Date
2008-11-06T01:00:17Z (17 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <jayc@milkyway.gsfc.nasa.gov>
J. Cummings, S. Barthelmy, N. Gehrels, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
K. Hurley, and T. Cline on behalf of the Konus-Wind team,
K. Yamaoka, M. Ohno, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada,
T. Murakami, and K. Makishima on behalf of the Suzaku WAM team
A. von Kienlin, G. Lichti, and A. Rau, on behalf of the
INTEGRAL SPI-ACS GRB team,
and M. Marisaldi, F. Fuschino, M. Galli, C. Labanti,
E. Del Monte, F. Lazzarotto, L. Pacciani, and P. Soffitta
on behalf of the AGILE team
At 2008-11-05 T0=48372.403 s UT (13:26:12.403), a long soft GRB,
GRB 081105 triggered Konus/Wind. The IPN was informed, and Swift/BAT,
AGILE-MCAL, Suzaku/WAM, and INTEGRAL/SPI-ACS reported coincident
rate increases. Ground analysis of BAT data (trigger #333811) yielded
a significant image peak that was found to be coincident with the IPN
timing triangulation annulus. The location of the burst was
RA, Dec 3.966, 3.454, uncertainty radius of 2.5 arcmin, which is
RA(J2000) = 00h 15m 51.8s
Dec(J2000) = +03d 27' 14"
The source was found onboard, but not with high enough significance
to trigger an automatic burst response. The partial coding was only
2.5%.
The burst was a single peak, about 10 seconds long.
A Swift TOO has been requested and approved. The Swift narrow-field
instruments should begin observing the burst at about 04:30 UT, 15
hours after the burst.
GCN Circular 8487
Subject
Swift-XRT observations of GRB 081105
Date
2008-11-06T15:41:23Z (17 years ago)
From
Andy Beardmore at U Leicester <apb@star.le.ac.uk>
A.P. Beardmore (U. Leicester) and J. Cummings (GSFC/UMBC)
report on behalf of the Swift-XRT team.
The Swift-XRT started observing the field of the Swift-BAT and IPN
localization GRB 081105 (Cummings et al., GCN 8484) at
2008-11-06 05:18:07(UT), 15.8 hours after the trigger.
In an exposure of 5ks we detect an X-ray source within the BAT error
circle at RA, Dec = 3.95224, 3.47098, which is
RA (J2000) = 00:15:48.5
Dec (J2000) = +03:28:15.5
with an uncertainty of 4.8 arcsec (radius, 90 percent confidence).
The observed count rate is (7.6+/-2.0)e-3 count/s. At this stage we cannot
tell whether the source is fading. Further Swift observations are planned.
This circular is an official product of the Swift-XRT team.
GCN Circular 8488
Subject
UVOT/Swift observations of GRB081105
Date
2008-11-06T16:07:53Z (17 years ago)
From
Patricia Schady at MSSL/Swift <ps@mssl.ucl.ac.uk>
P.A. Curran (UCL-MSSL), P. Schady (UCL-MSSL) and J. Cummings (GSFC/UMBC),
on behalf of the Swift/UVOT team.
The Swift Ultra-Violet/Optical Telescope (UVOT) began settled observations
of the Swift-BAT and IPN localization GRB 081105 (#333811; Cummings et
al., GCN 8484) ~16 hours after the BAT trigger. No afterglow is detected
at the XRT position (Beardmore et al., GCN 8487) in any filter. The
3-sigma limiting magnitudes in each of the observed UVOT filters are as
follows:
Filter T_start(dys) Exp(s) Mag UL (3sig)
white 0.67 159 > 20.76
v 0.81 630 > 19.92
b 0.66 885 > 21.05
u 0.74 224 > 19.92
uvw1 0.73 886 > 20.75
uvw2 0.89 886 > 21.02
The values quoted above are in the UVOT photometric system (Poole et al.
2008, MNRAS, 383, 627). They are not corrected for the expected Galactic
extinction corresponding to a reddening of E(B-V)=0.03 mag in the
direction of the burst (Schlegel et al. 1998).
GCN Circular 8489
Subject
GRB 081105: Observations from OSN
Date
2008-11-06T21:59:26Z (17 years ago)
From
Antonio Deugarte at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (ESO, Santiago), F. Aceituno &
A. J. Castro-Tirado (IAA-CSIC, Granada) report on
behalf of a larger collaboration:
We have observed the field of GRB 081105
(Cummings et al. GCNC 8484) with the 1.5m OSN
telescope in R and I bands. We do not detect any
source within the XRT error box (Beardmore et
al. GCNC 8487). The mean times and 3-sigma
limits of the observations are the following:
t-t0(days) Band Limit
1.2454 R > 21.3
1.2499 I > 20.7
Photometry is based on the star 0934-0003777 of
USNO-B1.0 catalogue (R.A.: 3.953112, Dec.:
+3.463859), assuming R=17.11 and I=16.54.
GCN Circular 8492
Subject
GRB 081105: GROND Upper Limits
Date
2008-11-07T07:53:48Z (17 years ago)
From
Christian Clemens at MPE <cclemens@mpe.mpg.de>
C. Clemens, R. Filgas, J. Greiner, T. Kruehler, A. Yoldas (all MPE Garching),
A. Kupcu Yoldas (ESO) and G. Szokoly (Eoetvoes Univ., Budapest) report on
behalf of the GROND team:
We observed the field of GRB 081105 (Swift trigger #333811; Cummings et al.,
GCN #8484) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory
(Chile).
Observations started at 02:01 UT on November 6th, 2008, 12.6 hr after the GRB
trigger with 23.0 min of total exposures in g'r'i'z' and 24.0 min in JHK.
They were performed at an average seeing of 1.4" and at an average airmass of
1.2.
As Ugarte Postigo et al. (GCN #8489), we do not detect any object within the
4.8'' Swift-XRT error circle reported by Beardmore et al. (GCN #8487) down to
the following upper limits (all in AB system) of:
g' > 23.3 mag,
r' > 23.2 mag,
i' > 22.5 mag,
z' > 22.3 mag,
J > 21.6 mag,
H > 21.0 mag and
K > 20.0 mag.
These upper limits are derived based on calibrating the images against the
GROND zeropoints as well as 2MASS field stars.
GCN Circular 8522
Subject
Further Swift-XRT observations of the probable GRB 081105.
Date
2008-11-16T01:15:46Z (17 years ago)
From
Andy Beardmore at U Leicester <apb@star.le.ac.uk>
A.P. Beardmore (U. Leicester), D.N. Burrows (PSU), J.R. Cummings (NASA/UMBC)
report on behalf of the Swift-XRT team.
The Swift-XRT reobserved the field of the Swift-BAT and IPN localisation
GRB 081105 (Cummings et al., GCN 8484) for a further 9.8 ks starting at
2008-11-12T04:15:51(UT), 6.62 days after the trigger.
Using a 10 pixel radius extraction region we detect 9 counts at the
position of the XRT source reported in GCN 8487 (Beardmore & Cummings)
compared with 1.28+/-0.20 estimated background counts. The Bayesian method
of Kraft et al. (1991 ApJ 374 344) produces a 3 sigma confidence level on
the expected source counts of S_min = 1.40 to S_max = 20.08, suggesting
the source is detected. (The lower limit on the expected source counts,
S_min, approaches zero when the confidence level reaches 4.4 sigma.) The
estimated source count rate is (1.07+/-0.40)e-3 count/s (where the quoted
error is 1 sigma), compared with a value of 0.0065 +/-0.0015 count/s from
the earlier observation.
By fitting the low counts per bin data using Cash statistics, we find
the source has faded with a decay slope of 1.01 +0.38-0.32. Both the
source intensity and decay is comparable to those seen in other long GRBs
at this stage of their outburst (e.g. see
http://www.swift.ac.uk/xrt_curves/allcurves.php).
We suggest the X-ray source reported in GCN 8487 was the counterpart to
the BAT/IPN localisation and its decaying nature gives further weight to a
GRB interpretation.
This circular is an official product of the Swift-XRT team.