From the intro:
Being an account of the valiant and mighty deeds, works, and strange fates of those famed Rogue Traders who have writ the history of Koronus, in brief.
What follows is the chronicle of significant events that mark the selected history of the Koronus Expanse, as it is generally known and agreed upon by scholars within the Imperium, with particular reference to the deeds of the Rogue Traders that have forged it. Within are accounts and records of the exploration of the Koronus Expanse, and the strange and wondrous worlds found beyond the Emperor’s Light. Few, however, who compile the chronicles of the Expanse have ever ventured there, and thus they rely on the accounts of others. The sources used by most scholars are the records kept by Rogue Traders and their associates. Such records are prone to inconsistency, embellishment, or outright falsification, and so claims as to the completeness or accuracy of any chronicle are best treated with suspicion.