A new analysis of velocity distribution , optical photometry and X-ray surface brightness from ROSAT PSPC data of the galaxy cluster A 2319 is presented .
The temperature profile derived from ASCA data ( [ Markevitch 1996 ] ) is taken into account .
A method to check the hydrostatic model in the presence of a temperature gradient is proposed .
Consistency of the hydrostatic isothermal model and the explanation of the ” \beta -discrepancy ” are discussed .
Galaxy and gas density profiles of the main component A 2319 A are derived , allowing for the effect of the secondary component A 2319 B .
The inadequacy of a polytropic model , which would produce a binding mass decrease with respect to the isothermal \beta -model , is discussed .
A simple interpolation of the temperature profile provides instead an increase of the binding mass and a lower baryon fraction thus mitigating the “ baryon catastrophe ” .
Assuming as typical the value f _ { b } \approx 0.2 , a comparison with the most recent estimate of \Omega _ { b } ^ { nucl } implies for the cosmological parameter \Omega _ { o } \raise - 2.0 pt \hbox { \hbox to 0.0 pt { \hbox { $ \sim$ } } \raise 5.0 pt \hbox { $% < $ } } 0.4 .