We report simultaneous observations at 1.2 and 2 mm , with a double channel photometer on the SEST Telescope , of the X-ray cluster RXJ0658-5557 in search for the Sunyaev-Zel ’ dovich ( S-Z ) .
The S-Z data were analyzed using the relativistically correct expression for the Comptonizationand we find from the detected decrement ( 2.60 \pm 0.79 ) ~ { } 10 ^ { -4 } , which is consistent with that computed using the X-ray ( ROSAT and ASCA ) observations .
The uncertainty includes contributions due to statistical uncertainty in the detection and systematics and calibration .
The 1.2 mm channel data alone gives rise to a larger Comptonization parameter and this result is discussed in terms of contamination from foreground sources and/or dust in the cluster or from a possible systematic effect .
We then make use of the combined analysis of the ROSAT and ASCA X-ray satellite observations to determine an isothermal model for the S-Z surface brightness .
Since the cluster is asymmetrical and probably in a merging process , models are only approximate .
The associated uncertainty can , however , be estimated by exploring a set of alternative models .
We then find as the global uncertainty on the Comptonization parameter a factor of 1.3 .
Combining the S-Z and the X-ray measurements , we determine a value for the Hubble constant .
The 2 mm data are consistent with H _ { 0 } ( q _ { 0 } = \frac { 1 } { 2 } ) = 53 ^ { +38 } _ { -28 } { kms } ^ { -1 } { Mpc } ^ { -1 } , where the uncertainty is dominated by the uncertainty in models of the X-ray plasma halo .