Abstract: A celestial navigation device. A full-featured embodiment is useful as a sundial and planisphere and for measuring, among other things, latitude, longitude, and for time to angle conversions. The device may have one or more rings and is based on a transparent circular tube having a gravity indicator, typically a ball or bubble, in the circular tube, which locates the lowest or highest point in the tube to indicate time or angle measurements against a corresponding scale. The device may have a 24-hour time scale, a calendar scale, and/or an angle scale. One embodiment includes a split analemma with separate north and south portions. Each analemma portion is used with a corresponding gnomon of a pair of gnomons, each on opposite sides of the tubular ring. A two-ring embodiment has an inner ring and outer ring rotatably slidable relative to one another. Two additional gnomons and star position marks may be provided for star sighting observations.