Observatory Charm

Charm

You can use your Observatory to peer into the far corners of “Wildspace” and the “Astral Plane”. After spending a Long Rest in your Observatory, you gain a magical Charm (see ""Supernatural Gifts"" in “chapter 3”) that lasts for 7 days or until you use it. The Charm allows you to cast Contact Other Plane without expending a spell slot. You can’t gain this Charm again while you still have it.

Source: Dungeon Master’s Guide (2024) p. 343