If you have the chance to obtain an illuminati gobdip, as you mentioned Atlas and not the Antiquated Atlas, you might as well go for the Gordian Astrometer, which is a lot like Deneb. Difference between Deneb and the Gordian astrometer would be crit and det. Deneb having 71 crit with 115 piety and the Gordian astrometer with 68 det and 115 det.

If you weren't talking about the normal Atlas, but about the Antiquated version, you're better off with the Heavensmeter than the Antiquated Atlas, which has crit and piety. Otherwise, even the Atlas Awoken would be better than the Antiquated Atlas. Simply because Spell Speed simply doesn't contribute as much to the Astrologian kit. You can find a more elaborate answer in this topic.