Up: ASCA observations of massive
Table 3 summarizes the ASCA observations. The GIS data were
obtained with the normal PH mode, and the SIS data using the BRIGHT2 1
CCD mode. The targets were centered at the nominal position of the 1
CCD mode, which causes a slight position offset on the GIS images.
All the subsequent analysis has been carried out
with the XSPEC_8.5 and FTOOLS_3.5 packages using the screened data
provided by the ASCA Standard Analysis from NASA/GSFC.
Table 3:
Journal of observations
The countrates have been integrated within a radius of 500'' in
the [0.7-10] keV band for the GIS images and within a radius of 250''
in the [0.4-10] keV band for the SIS. |
The ROSAT images
of A 1300 and A 1732, filtered by a wavelet multi-resolution algorithm
with a rigorous treatment of photon noise (Starck & Pierre
1998), are shown in Lémonon et al. (1997) and
Pierre et al. (1996) respectively.
At the ASCA angular resolution, A 1732 does not show significant structure
as already inferred from the 30 ks HRI pointing which revealed a very
regular morphology and a moderate cooling flow of
/year. A 1300, on the other hand, is clearly elongated, in good
agreement with the PSPC observation that was used to infer the post-merger state of the cluster; no HRI image is available for this cluster.
An elliptical region has been selected for extracting the SIS/GIS
spectra of A 1300 and an circular region for A 1732; this is shown in
Fig. 1 and Fig. 2. For both objects, the background area
was selected in the vicinity of the source but excluding the cluster
outskirts (beyond 8' from the source center). In an attempt to improve
signal-to-noise, we have also used background spectra from blank-sky fields,
since both clusters are in the direction of moderate
. This did
not lead to a significant improvement in the spectral fit accuracy (see
Table 4). Note, also, that blank-sky observations are presently
available only for the GIS detector and not for the SIS in the BRIGHT2 1 CCD
mode.
In addition, we made use of our 8.6 ks ROSAT PSPC observation of A 1300
to complement the spectral analysis.
Table 4:
Results from the spectral analysis; errors are
given for a 90% confidence interval. Rest frame absorption corrected luminosities have been
calculated from the GIS countrate using the temperatures and metallicities
obtained by ASCA (this table) and
values listed in
Table 2
* Indicates that the GIS spectra were extracted using a background
from blank-sky observations, otherwise the background has been routinely estimated from our images using regions free of sources. |
 |
Figure 1:
SIS image of A 1300 in the [0.4-10] keV band. The pixel size is 6.3''
and the image has been filtered by a Gaussian having a of 1.5
pixel. Contours levels are 1.0, 2.0, 3.0... counts/pixel. The region
extracted for the spectrum is indicated by an ellipse |
 |
Figure 2:
SIS image of A 1732; otherwise as for Fig. 1 |
Up: ASCA observations of massive
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