No need to look to the stars for Astrologian help in Bravely Second, just this guide!
Astrologian is a very good support Job in Bravely Second. This mostly comes from the Job's specialty, which makes support abilities activate at the start of their turn. They also cover a wide array of support magic, go beyond the stat limit, and even makes them last longer!
If you want a support magic Job, Astrologian should be at the top of your list, no matter what you plan to do.
You unlock Astrologian after defeating Norzen in Al-Khampis in chapter 1.
Prescience makes Astrologian the ideal magic support Job, even if you aren't selecting it as your main Job. You will want to use whichever support spells you want as soon as you can, since they activate at the start of the turn.
They have a decent INT and MND and can use Rods or Staves well, so it is a good idea to pick this as your main Job if you plan to use it all. The reason being that you won't have to use up 2 slots for their support ability.
You will want to save at least 1 extra BP whenever you can so you can add the Blast spellcraft effect to your spells. Adding your effects to all party members really helps, and lets you use certain spells on multiple people that you wouldn't be able to usually.
That does it for my Bravely Second Astrologian Job guide. Let me know if you have any questions and visit by Beginner Tips and Tricks for more help with this game!