Indeed a nice pice of work done by shri sasiekaran_pti..well sh. ayush, sun is in cancer from 14th jul to 14th august...so first hint is here.. then saturn remains in a rashi for 2.5 years..so by hit and trial method, we can find out that saturn was in virgo from 27th july 1980 till starting of october 1982...this was the second hint...jupiter stays in a rashi for 13 months approx...and rahu and ketu are there in a rashi for 1 year 7 months approx...so by these hit and trial methods one can find out but yes its a long procedure and may be very confusing too....