True. What canon law does not say, though, is when the Ascension falls for the purposes of obligation. In the EF, Ascension is always Thursday. In the OF, it may or may not be transferred depending on the diocese in which you live.
My periodic traveling got me thinking about this.
**Scenario #1: **
In my home diocese the celebration of Ascension is transferred to Sunday. But what would be my obligation if I was on an out-of town trip that week, and unknowingly visiting in a diocese where the obligation had not been transferred?
My home parish announces Ascension will be celebrated the following Sunday.
On Monday morning I catch an airplane to another city (perhaps Boston, New York or Philadelphia), located in a diocese where Ascension is celebrated on Thursday.
I don’t go to mass on Thursday because I am unaware of the non-shift.
The following Sunday, before I get on the airplane to return home, I attend Sunday mass. But the readings are for the Sunday after Ascension. Oops.
Did I just commit a sin?
Scenario #2:
Some countries celebrate different Holy Days of Obligation than the United States. If I am planning to travel outside the US, do I have an obligation to check the local rules at my destination and find out whether they have a Holy Day of Obligation during my trip? (This came up in the opposite way when I was visiting Canada on Assumption and discovered the churches only offered daily mass.)
I am traveling outside the United States.
I am visiting England on June 29th, which is the Feast of Sts. Peter and Paul and a Holy Day of Obligation in England.
The United States doesn’t list June 29th as a Holy Day of Obligation so I go about my ordinary business not thinking about attending mass.
Did I just commit a sin?
In both cases I am following the norms for attending mass as celebrated in my home parish, and in both cases if I were at home there would be no question of sin. But since I am visiting away from home am I obliged to follow the local rules at my destination?