Use the map to align your direction with them, and see if it aligns with stellar objects like planets, moons, etc. They might just be visible but out of grid-range and thus not something the game lets you ‘interact’ with until you’re on grid with them.
Edit: The more I look at the screenshots, the more convinced I am that this is the case. An alt used to live in a structure and used a bookmark at a celestial directly from the undock for… well, sneaky purposes, and it showed a little dot like that in that direction, which turned out to be the celestial in question when warped to. Not interactable at range.