{When all the people were baptised} (en t(9369) baptisth(886e)ai
hapanta ton laon). The use of the articular aorist infinitive
here with en bothers some grammarians and commentators. There
is no element of time in the aorist infinitive. It is simply
punctiliar action, literally "in the being baptized as to all the
people." Luke does not say that all the people were baptized
before Jesus came or were baptized at the same time. It is merely
a general statement that Jesus was baptized in connexion with or
at the time of the baptizing of the people as a whole. {Jesus
also having been baptized} (kai I(8873)ou baptisthentos). Genitive
absolute construction, first aorist passive participle. In Luke's
sentence the baptism of Jesus is merely introductory to the
descent of the Holy Spirit and the voice of the Father. For the
narrative of the baptism see  Mr 1:9  Mt 3:13-16 . {And praying}
(kai proseuchomenou). Alone in Luke who so often mentions the
praying of Jesus. Present participle and so naturally meaning
that the heaven was opened while Jesus was praying though not
necessarily in answer to his prayer. {The heaven was opened}
(ane(9369)chth(886e)ai ton ouranon). First aorist passive infinitive
with double augment, whereas the infinitive is not supposed to
have any augment. The regular form would be anoichth(886e)ai as in
D (Codex Bezae). So the augment appears in the future indicative
kateaxei ( Mt 12:20 ) and the second aorist passive subjunctive
kateag(9373)in ( Joh 19:31 ). Such unusual forms appear in the
_Koin(825f). This infinitive here with the accusative of general
reference is the subject of egeneto (it came to pass).  Mt
3:16  uses the same verb, but  Mr 1:10  has schizomenous, rent
asunder.