Is it always a mortal sin to miss Mass on Sunday?

Hi. I was invited to go for a church camp though the church is not catholic. The problem is that I might not go for mass on one Sunday. In this case will it be a mortal sin if I miss it?

The following link should assist you in better understanding the Catholic Church’s teaching regarding attending Mass while on vacation. If you have any further questions or concerns that are not answered by this link, please contact Catholic Answers directly.Recommended Reading:
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*]Is there a dispensation from the Sunday obligation while traveling?
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