Sextants with Atlas masters

I'm farming mostly Alva and Jun missions this League but run out regularly and I've been trying to find compasses for them on PoE trade but cannot.

Could someone confirm for me:

1) That they actually exist. Folks talk about them from this and recent leagues so I assume they do. I've never seen one myself though.

2) How I would search for it on PoE Trade?

Thanks frenz!

https://www.pathofexile.com/trade/search/Sentinel/aLDZvvBue

you can filter which master in the dropdown of the filter.

Oh perfect. Thank you so much!