And the answer becomes fairly clear when we realize that Jesus has had the last supper a day before so that he's hanging on the cross during the day of preparation before the beginning of Passover.

At that moment the curtain hanging in the temple was torn in ... who had followed Jesus from Galilee and helped him. Jesus was on the cross from the sixth hour until the ninth hour.

And the answer becomes fairly clear when we realize that Jesus has had the last supper a day before so that he's hanging on the cross during the day of preparation before the beginning of Passover.