  Fr 2-30 = PN? G126.8-15.5 is a faint emission nebula, hosting a 14th-mag
central star that we identify here for the first time. Deep Halpha and [O III]
images reveal a roughly elliptical nebula with dimensions of at least 22'x14',
fading into a surrounding network of even fainter emission. Optical
spectrograms of the central star show it to have a subdwarf O spectral type,
with a Gaia parallax distance of 890 pc. A model-atmosphere analysis gives
parameters of Teff = 60,000 K, log g = 6.0, and a low helium content of nHe/nH
= 0.0017. The location of the central star in the log g -- Teff plane is
inconsistent with a post-asymptotic-giant-branch evolutionary status. Two
alternatives are that it is a helium-burning post-extreme-horizontal-branch
object, or a hydrogen-burning post-red-giant-branch star. In either case the
evolutionary ages are so long that a detectable planetary nebula (PN) should
not be present. We find evidence for a variable radial velocity (RV),
suggesting that the star is a close binary. However, there are no photometric
variations, and the spectral-energy distribution rules out a companion earlier
than M2 V. The RVs of the star and surrounding nebula are discordant, and the
nebula lacks typical PN morphology. We suggest that Fr 2-30 is a "PN mimic" --
the result of a chance encounter between the hot sdO star and an interstellar
cloud. However, we note the puzzling fact that there are several nuclei of
genuine PNe that are known to be in evolutionary states similar to that of the
Fr 2-30 central star.
