Obsecratory a. : Expressing, or used in, entreaty; supplicatory.

Example:


Taxonomy
Observatory, the Observatory, Los Angeles, telescope, Griffith Observatory, Planetarium, Astronomy, Leonard Nimoy, Event Horizon, Horizon Theater, Free Admission, Greek Theatre, Samuel Oschin, traffic, Sky, Griffith Observatory Los Angeles, Observatory News, school program.

Defination from the web:
Observatory, a nonprofit educational institution whose purpose is to provide information on astronomy and related sciences to the public.