GRB 060204A
GCN Circular 4707
Subject
GRB060204a: Swift XRT Source is not GRB Afterglow
Date
2006-02-07T18:22:26Z (20 years ago)
From
David Morris at PSU/Swift-XRT <morris@astro.psu.edu>
D. Morris (PSU), D. Burrows (PSU), N. Gehrels (GSFC) on behalf of the
Swift XRT team:
Further Swift XRT observations of the X-ray source detected within the
INTEGRAL error circle (GCN 4685, Morris et al) have shown that the
source is not fading. This information, together with the coincident,
bright, non-fading source detected in the UVOT (GCN 4698, Cucchiara et
al) and the archival ROSAT pointed observation detection of an X-ray
source consistent with this source position (GCN 4700, Halpern),
indicates that this source is not the afterglow of GRB060204a.
Swift XRT has now collected 24ks of data on this field, producing an
upper limit on the unabsorbed flux of the afterglow in the 0.2-10keV
band of 2e-14 ergs/cm2/s at a mean epoch of T+120ks. This upper limit
assumes an absorbed powerlaw spectrum with photon index of 2 and
galactic absorption of 1e21cm-2. No further observations are planned.
We note that Swift BAT and XRT have previously detected GRBs which have
subsequently become undetectable to a similar limiting flux level in the
XRT on timescales similar to our observation of this field, including
GRB050421, GRB051117b and GRB051210.
This circular is an official product of the Swift XRT Team.
GCN Circular 4700
Subject
GRB 060204A: ROSAT Pointing
Date
2006-02-07T00:34:46Z (20 years ago)
From
Jules Halpern at Columbia U. <jules@astro.columbia.edu>
I note that a faint ROSAT PSPC source was detected in a
pointed observation in 1992 at a position and flux consistent
with the Swift XRT source (Morris et al., GCN 4685) in the
INTEGRAL error circle of GRB 060204A (Mereghetti et al.,
GCN 4654, 4659). This is not the RASS source mentioned
by Kong (GCN 4676).
The source 2RXP J152858.6-392721 has 0.0112+/-0.0023 ct/s,
and its 8" radius error circle is also very near the bright
variable star detected in the Swift UVOT (Cucchiara et al.,
GCN 4698), suggesting that these objects are identical:
R.A.(2000) Dec.(2000) +/-(")
--------------------------------------------------
Swift XRT 15 28 58.4 -39 27 28.5 5
ROSAT PSPC 15 28 58.55 -39 27 20.9 8
USNO B1.0 15 28 58.79 -39 27 30.4
--------------------------------------------------
These results together argue that the Swift candidate is a
variable Galactic source rather than a GRB afterglow.
GCN Circular 4698
Subject
GRB060204A: Swift/UVOT observations
Date
2006-02-06T22:26:26Z (20 years ago)
From
Antonino Cucchiara at PSU <cucchiara@astro.psu.edu>
A. Cucchiara, D. Fox, S. Hunsberger, A. Retter, J. Nousek (PSU),
W. Voges (MPE), N. Gehrels (GSFC), on behalf of the Swift UVOT team.
The Swift/UVOT began observing the field of GRB 060204A,
detected by INTEGRAL (Mereghetti et al., GCN 4654)
at 00:17:07 UT on 2006-02-05, 10.8 hours after the trigger.
Within the XRT error circle reported by Morris et al. (GCN 4685) we found
a DSS/USNO catalogued object (USNO B1 0505-0367492,
B magnitude = 15.48). This is only 2 arcsecond from the XRT position.
A preliminary analysis of this known source shows a fading behaviour
followed by a rebrightening on a timescale of a day. For comparison, our B
magnitude at the beginning of the observation was 14.14 (+/- 0.03),
corrected for galactic extinction (E(B-V)=0.182)). At the moment, we cannot
infer whether this is the optical afterglow of this GRB or a kind of
activity due to
the catalogued object. More XRT observations are ongoing to see if the
XRT source
fades away.
Further analyses are forthcoming.
GCN Circular 4685
Subject
GRB060204a: Swift XRT Detection of an Afterglow Candidate
Date
2006-02-06T07:38:45Z (20 years ago)
From
David Morris at PSU/Swift-XRT <morris@astro.psu.edu>
D. Morris (PSU), D. Burrows (PSU), N. Gehrels (GSFC), F. Marshall
(GSFC), M. Chester (PSU) on behalf of the Swift XRT team:
The Swift XRT began observing GRB 060204a, detected by INTEGRAL
(Mereghetti et al., GCN 4654), at 00:08:02 UT on 05 February 2006 (39 ks
after the burst trigger). In 14.5 ks of data, we find a faint,
uncataloged X-ray source within the 2.5 arcminute INTEGRAL error circle at:
RA(J2000): 15:28:58.4
DEC(J2000): -39:27:28.5
with an uncertainty of 5 arcsec (90% containment). This position
includes the latest XRT boresight correction and is 58 arcseconds from
the INTEGRAL reported position in GCN 4654. We calculate an average flux
for this source of 1e-13 ergs/cm2/s (0.2-10keV unabsorbed) assuming a
powerlaw index of 2 and galactic absorption of 1e21 cm^-2. We note that
this source flux is brighter than the 3-sigma upper limit reported in
GCN 4676 (Kong). Due to the small number of counts, we are unable to
determine whether the source is fading at this time. We note, however,
that the detected flux is consistent with typical GRB afterglow flux
levels at T+100ks, which is the mean epoch of this observation.
Observations are continuing and further analysis regarding the fading
nature of this source will be issued as the data become available.
This circular is an officical product of the Swift XRT Team.
GCN Circular 4676
Subject
GRB 060204A: Swift XRT upper limit
Date
2006-02-05T15:23:49Z (20 years ago)
From
Albert Kong at MIT <akong@space.mit.edu>
A. Kong (MIT)
We report a follow-up Swift XRT observation of the INTEGRAL detected
burst GRB 060204A (Mereghetti et al. GCN 4654). The XRT observation
began at 2006 Feb 5 00:08:01 UT, 11 hrs after the burst. The XRT
observation lasted for 5.2 ksec and we found no source within the
2.5 arcmin INTEGRAL error circle. We place a 3 sigma upper limit on
the flux of the afterglow of 4.1e-14 erg cm^-2 s^-1 (0.2-10 keV)
assuming a power-law with a photon index of 2 and a Galactic absorption
of 1e21 cm^-2.
The only X-ray source in the XRT field is 1RXS J152756.5-393155.
GCN Circular 4675
Subject
GRB 060204A: FRAM optical observations
Date
2006-02-05T11:54:49Z (20 years ago)
From
Petr Kubanek at AIO <petr@lascaux.asu.cas.cz>
Petr Kubanek (ASU Ondrejov, Czech Rep. and ISDC Versoix, Switzerland),
Michael Prouza (FZU Praha, Czech Rep.),
Martin Jelinek (IAA Granada, Spain),
Martin Nekola and Rene Hudec (ASU Ondrejov, Czech Rep.)
Report:
The wide field camera of the FRAM telescope, located at Pierre Auger
Observatory in Malargue, Argentina, observed the field of INTEGRAL GRB
060204A (S. Mereghetti et al., GCN 4654, 4659) starting at 2006-02-05
02:40 UT, eg. 13 h 21 m post GRB.
Comparison of combined 47x60 sec exposures (2820 sec total exposure)
with USNO does not reveal any new source within INTEGRAL error box down
to R mag ~ 14.5.
This message can be cited.
GCN Circular 4659
Subject
GRB 060204A: further INTEGRAL results
Date
2006-02-04T17:12:05Z (20 years ago)
From
Sandro Mereghetti at IASF/CNR <sandro@iasf-milano.inaf.it>
S. Mereghetti (IASF, Milano), D.Gotz (CEA, Saclay) on behalf of the IBAS
Localization Team report:
The peak flux of GRB 060204A (GCN 4654) integrated over 1 s is 0.1 ph
(9x10e-9 erg)/cmq/s in the 20-200 keV range. Its fluence in the same
energy band is 4x10e-7 erg/cmq.
A plot of the light curve will be posted at
http://ibas.mi.iasf.cnr.it/IBAS_Results.html
This message can be cited.