http://www.fivedoves.com/letters/june2022/derrickd65.htm

Dear Derrick & Fellow Watchers,

I apologize for not being more precise.  

Ascension Thursday is not on the Jewish Calendar but is generated from the Jewish Calendar. The difference being that the Day of the Rapture, since it is part of the Mystery Gospel revealed only to Paul, is significant outside the "Significant" days on the Jewish Calendar.

Hope that makes sense.

All the Best,
Mike P