Board Thread:Warhammer 40k General Discussion/@comment-71.91.63.134-20150907060405/@comment-8881468-20151206075154

astronomicon existed before emperor was interned in the golden throne so that is debateable (novel: the outcast dead mentions the "hollow mountian" where psykers are stripped off their lives to be of use)

and warp travel can be done without the astronomicon, by warp nodes  mentioned in anthology "thge primarchs" short story "the lion"