Complex sentence: Astronomers estimate that the Milky Way experiences roughly 30 to 60 novae per year, but a recent examination has found the likely improved rate of about 50 ± 27.
Split into simpler sentences: Astronomers estimate that the Milky Way experiences roughly 30 to 60 novae per year. A recent examination has found the rate to be with a likely rate of about 50 ± 27.