{An angel} (hena aggelon). Like heis in  18:21 , just
"an," not "one." {Standing in the sun} (hest(9374)a en t(9369) h(886c)i(9369)).
Second perfect active participle of hist(886d)i (intransitive).
"Where all the birds of prey would behold him" (Beckwith). For
orneois (birds) see  18:2  and for en mesouran(886d)ati (in mid
heaven) see  18:13  14:6 . {Come and be gathered together}
(Deute sunachth(8874)e). Deute is the adverb deur(935c) (hither),
used when two or more are addressed, possibly from deuro ite
(come here). Asyndeton also without kai (and). First aorist
passive imperative of sunag(935c). The metaphor is drawn from  Eze
39:17 . {Unto the great supper of God} (eis to deipnon to mega
tou theou). The habits of vultures are described by Christ in
 Mt 24:28 . This is a bold and powerful picture of the
battlefield after the victory of the Messiah, "a sacrificial
feast spread on God's table for all the vultures of the sky"
(Swete). Is this battle the same as that of Har Magedon ( 16:16 )
and that of Gog and Magog ( 20:8ff. ) mentioned after the
thousand years? The language in  20:8ff.  seems like this derived
from  Eze 39:17ff. , and "in the Apocalypse priority in the order
of sequence does not always imply priority in time" (Swete).
There seems no way to decide this point save that the end seems
to be at hand.