1. relating to or occurring at the time when a star or constellation rises in the east at sunset or sets in the west at sunrise
Usage: astronomy; technical

Examples

• The acronical rising of Sirius marked an important date in the ancient Egyptian calendar.
• Astronomers observed the acronical setting of the constellation Orion in late spring.
• The acronical position of a star occurs when it is directly opposite the sun in the sky.
• Ancient civilizations tracked acronical events to predict seasonal changes.