The Hercules Text
Republished as Hello Out There (along with the novel A Talent for War). This is a straightforward hard science fiction novel about first contact. What happens when SETI actually finds an alien message? The version I read is the original 1985 version which has apparently been rewritten and reissued since then. Even though I have read the former, I think I can safely recommend it since the decoding of the alien message and the reactions of the characters are what fascinated me.