## 4. Observational aspectsLet us consider for example that the low limit of LiH abundance could be reached by an appropriate radiotelescope. From (16) and Fig.2 one can see that now if , =30 km/s, . This value of corresponds to the proto-objects at z=200 which can be seen now at =13cm. In order to estimate the observational time for level one should use the standard equation where is a noise temperature . The IRAM observation (de Bernardis at al.,1993) has the =1000 K. At =13cm one can has =100 K. Taking into account 100 times' less here one could see that absolute value of measured in both cases are equal. But the which is predicted at =13 cm is about three order of magnitude more than at = 1.3 mm. There is another problem for observations at low frequency - it is that we need to have a full aperture radiotelescope with an appropriate angular resolution. For proto-objects with size it must be about 600 m diameter. For this case MHz and from (24) is © European Southern Observatory (ESO) 1997 Online publication: May 26, 1998 |