That it is, although only god and little green apples know when the place was colonized originally. I believe I mentioned the time-and-space shenanigans, so this might not even be our galaxy. No matches on star charts, in any case.

[Which is, says Bones' expression, completely ridiculous and should never have happened without consulting him first.]

There's a sister planet, Antiqua, that comes into a close convergence around the time of the solstice. Interplanetary war between the two of them is apparently what led to the domes going up to begin with, but there's no sign of current hostilities.