Definition: Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.
Input: The Feast of the Sacred Heart has been a Solemnity in the Roman Catholic liturgical calendar since 1856, and is celebrated 19 days after Pentecost.

Since 1856 The Feast of the Sacred Heart has been important to the Roman Catholic calendar. It is celebrated 19 days after Pentecost.