up vs astir

up and astir both are adjectives.

Word	Noun	Adjective	Verb	Adverb
up	No	Yes	Yes	Yes
astir	No	Yes	No	No

As adjectives, up and astir are synonyms defined as:

up (adjective)	astir (adjective)
being or moving higher in position or greater in some value; being above a former position or level	on the move
extending or moving toward a higher place	out of bed
out of bed
used up
(used of computers) operating properly
(usually followed by `on' or `for') in readiness
open
getting higher or more vigorous

up (verb)	astir (verb)
raise

up (adverb)	astir (adverb)
spatially or metaphorically from a lower to a higher position
to a later time
to a more central or a more northerly place
nearer to the speaker
to a higher intensity