In a manner relating to or occurring at the rising or setting of a star at sunrise or sunset.
From acronical (Greek akron peak + -ical) combined with the adverbial suffix -ly, modifying verbs or adjectives in astronomical contexts.
This adverb is now mostly extinct from modern astronomy, replaced by clearer positional terms, but it's a beautiful reminder of how older scientists poetically described celestial movements.
Complete word intelligence in one call. Free tier — 50 lookups/day.