From Canon Lawyer Ed Peters:
A news story out of the Diocese of Fairbanks in Alaska describes an upcoming “priestless Sunday” wherein priests will be away from their parishes to serve remote missions, leaving their parishioners without Sunday Mass that weekend. I can see arguments for and against this unusual action and I don’t think that outsiders are in a position to conclusively support or reject the basic idea.
One point in the news article, however, needs to be corrected: After noting that Communion services will be celebrated in most parishes left without pastors, the article asserts that such services are “not Mass but will satisfy the Catholic obligation to attend Mass.”
That’s wrong. See why: http://www.canonlaw.info/2008/09/priestless-sundays-and-sunday.html