GRB 050724
GCN Circular 3892
Subject
Subaru Observations of GRB050724
Date
2005-08-27T14:49:11Z (20 years ago)
From
Elena Pian at ITESRE-CNR,Bologna <pian@ts.astro.it>
A. Pastorello (MPA), K. Kawabata (Hiroshima Univ.), E. Pian, (INAF-OATs),
K. Nomoto (Tokyo Univ.), P. Mazzali (INAF,MPA,Tokyo), T. Hattori, M. Iye,
T. Sasaki (Subaru,NAOJ), on behalf of a larger collaboration, report:
On August 10, 2005, at 07.7 UT we observed the field of GRB050724 with
Subaru+FOCAS and I filter. The exposure time was 2 minutes. The seeing
was 0.4". No object is detected at the position of the optical transient
reported by Berger et al. (submitted to Nature, astro-ph/0508115). The
3-sigma upper limit is I = 23 (this is not corrected for the Galactic
reddening).
This message may be cited.
GCN Circular 3700
Subject
GRB 050724: Secure Host Redshift from Keck
Date
2005-07-29T18:13:53Z (20 years ago)
From
Jason Prochaska at UCO/Lick Obs <xavier@ucolick.org>
J. X. Prochaska (UCO/Lick), J. S. Bloom (UCB), H.-W. Chen (MIT),
B. Hansen (UCLA), J. Kalirai (UCSC), M. Rich (UCLA) and H. Richer (UBC)
report on behalf of the GRAASP collaboration:
"We have obtained LRISb spectroscopy (900s; 2005-07-29 06:31 UT)
of the putative host galaxy of GRB 050724 (Object D in GCN #3672).
We confirm our previously reported redshift (GCN #3679)
based on the identification of Ca H+K, G-band absorption features,
and the 4000Ang break. We report a redshift z=0.258 +/- 0.002.
The velocity dispersion based on CaK appears to exceed 200km/s.
The galaxy shows no [OII] emission in our spectrum suggesting minimal
current star formation.
PAIRITEL imaging of the galaxy from July 29 UT yields a K-band magnitude
of 15.3 +/- 0.2 in a 3" radius aperture. At this redshift,
and including the effects of Galactic extinction, the galaxy
is 1.7 L* based off the 2MASS luminosity function.
The properties of this galaxy -- a massive early-type at
moderate redshift -- are strikingly similar to the probable host
galaxy of GRB 050509b (GCN #3399).
Based on this redshift and the reported fluence in GCN #3667,
the isotropic -equivalent energy release is
E_gamma(iso) = 9.9e49 erg [19-440 keV, comoving], more than 1
order of magnitude brighter than 050509b
(Bloom et al. astro-ph/0505480)."
Figures and imaging can be found at this following site:
http://www.graasp.org/Data/050724
GCN Circular 3699
Subject
GRB 050724: WHT optical observations
Date
2005-07-29T17:58:10Z (20 years ago)
From
Klaas Wiersema at GRACE/U of Amsterdam <kwrsema@science.uva.nl>
K. Wiersema (U. of Amsterdam), E. Rol (U. of Leicester),
R. Starling (U. of Amsterdam), N. Tanvir (U. of Hertfordshire),
D. S. Bloomfield, H. Thompson (Queen's University Belfast)
report:
We have observed the position of the short burst
GRB 050724 (Covino et al. GCN 3665) with the William Herschel
Telescope at the Observatorio del Roque de los Muchachos on
La Palma, using the Aux port Imager.
We observed two epochs, with midpoints 0.424 days and 3.405
after burst. The epoch 1 observations consisted of
4 x 15 + 5 minutes exposure time in R band. Epoch 2
consisted of 4 x 15 minutes in R band.
At the first epoch the weather conditions were good with an
average seeing of 0.8 arcsec. During the second epoch the seeing
was considerably worse, with an average seeing ~1.3 arcsec.
PSF-matched image subtraction of the two epochs using the
ISIS code (Alard et al. 1999) reveals a clearly fading source.
This behaviour is confirmed in a subtraction of the first and
last image from the first epoch. The position of the fading
source matches that described in e.g. GCNs 3690 and 3694,
as well as the radio (GCN 3684) and X-ray afterglow position
(GCN 3683, 3697).
We performed aperture photometry of the host galaxy plus the OT
with respect to two unsaturated USNO stars: 0624-0502999 and
0624-0503050, whose values we take from the USNO-B catalogue.
We find a magnitude difference of approximately 0.2 magnitudes
between the two epochs.
Assuming the contribution of the afterglow to the total flux
at the second epoch to be negligible, we estimate the afterglow to
be approximately R ~22.1 at our first epoch.
A jpg image showing the position of the afterglow and the host
can be found on:
http://remote.science.uva.nl/~kwrsema/grb050724/
We thank the staff of the WHT for outstanding support for these
observations.
GCN Circular 3697
Subject
GRB 050724: Chandra Observations of the X-ray Afterglow
Date
2005-07-28T21:14:02Z (20 years ago)
From
David Burrows at PSU/Swift <dxb15@psu.edu>
D. N. Burrows, D. Grupe (PSU), C. Kouveliotou, S. Patel (MSFC), P. Meszaros
(PSU), B. Zhang (UNLV), and R. A. M. J. Wijers (U. Amsterdam) report:
We observed the X-ray afterglow of the short GRB 050724 (Covino et al., GCN
3665) with the Chandra X-ray observatory from 20:09 UT on 26 July 2005 to
10:45 UT on 27 July 2005. The total exposure time was 50 ks. We find an
uncataloged X-ray source coincident with the VLT source reported by
D'Avanzo et al. (GCN 3690) and the VLA source reported by Cameron and Frail
(GRB 3676) as updated by Soderberg (GCN 3696