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Vol. 53, No. 6 Cosmological parametersD NARASIMHATata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, IndiaAbstract. There is some consensus emerging on the values of the basic parameters of classical cosmology. The baryon number density estimated from the light element abundance or X-ray gas in galaxy clusters tends towards 5% of closure density; the dark matter content based on a number of independent methods appears to be somewhat less than half the closure density; Hubble constant obtained from local measurements, gravitational lens or Sunyaev Zeldovich method are all probably centred around 60 km/sec/Mpc and the age of the Universe is generally agreed to be around 14 Gyr - all specified with bearable error bars. The supernova projects and CMBR anisotropy together favour a finite cosmological constant, and gravitational lens statistics support the same conclusion. Keywords Cosmology; Hubble constant; cosmological constant; critical density. Pacs 2.0 |