heliacal (adj.)

"pertaining to the sun" (but used especially of stars, in reference to their becoming visible out of the sun's glare), c. 1600, with -al (1) and Latinized form of Greek heliakos "of the sun," from helios "sun" (from PIE root *sawel- "the sun"). The heliacal year (used in ancient Egypt) is reckoned from the heliacal rising of Sirius; thus it also is known as the canicular year. Related: Heliacally (1580s).