ephemerist

noun3

1. •
   One who collects or studies ephemera.

   • The true ephemerist is as committed to the smallest neglected fragment as to the spectacular 'collector's piece'. — 1988
2. •
   One who keeps an ephemeris; a diarist.
3. •
   One who studies the daily motions and positions of the planets.

   • the night immediately before he was discoursing of, and lighting the art of those foolish Astrologers, and Genethliacall Ephemerists — 1640