heliacal

[hi-lahy-uh-kuh l] /hɪˈlaɪ ə kəl/
adjective, Astronomy
1.
pertaining to or occurring near the sun, especially applied to such risings and settings of a star as are most nearly coincident with those of the sun while yet visible.
Also, heliac
[hee-lee-ak] /ˈhi liˌæk/ (Show IPA).
Origin
1600-10; < Late Latin hēliac(us) (< Greek hēliakós; see heli-1, -ac) + -al1
Related forms
heliacally, adverb
Word Origin and History for heliacal
adj.

"pertaining to the sun," c.1600, with -al (1) and Greek heliakos "of the sun," from helios "sun" (see sol). The heliacal year is reckoned from the heliacal rising of Sirius; thus it also is known as the canicular year.