heliac vs heliacal

heliac and heliacal both are adjectives.

Word	Noun	Adjective	Verb	Adverb
heliac	No	Yes	No	No
heliacal	No	Yes	No	No

As adjectives, heliac and heliacal are synonyms defined as:

heliac and heliacal: pertaining to or near the sun; especially the first rising of a star after and last setting before its invisibility owing to its conjunction with the sun

heliac (adjective)	heliacal (adjective)
pertaining to or near the sun; especially the first rising of a star after and last setting before its invisibility owing to its conjunction with the sun	pertaining to or near the sun; especially the first rising of a star after and last setting before its invisibility owing to its conjunction with the sun