asterismal vs asterism

asterismal is not a noun while asterism is a noun.

Word	Noun	Adjective	Verb	Adverb
asterismal	No	Yes	No	No
asterism	Yes	No	No	No

asterismal (noun)	asterism (noun)
	(astronomy) a cluster of stars (or a small constellation)
	(mineralogy) a star-shaped figure with six rays that is seen in some crystal structures under reflected or transmitted light

asterismal (adjective)	asterism (adjective)
relating to asterisms or constellations