Coptic calendar and difference from Jewish calendar

We read Coptic new year Psalms 65-11 & 81:1 (also 2-7) They are about the new year and the Jewish Feasts of Trumpets and Tabernacles
Our Coptic Calendar started with the year when Diocletian became an Emperor in the year 284, which is the difference between 2011 AD in the Julian and 1727 AM in the Coptic Calendar which ended Sunday 9/11.

Both calendars have leap year every time the year is divisible by 4
In the current Gregorian Calendar, a correction approved by Pope Gregory XII reflects the fact that the Solar year is actually 11 minutes shorter (365 days “5 hours and 49 minutes” and not exactly 6 hours).

Therefor a centennial year is not a leap year unless it is divisible by 400, so 1900 is not a leap year in Gregorian Calendar but is a leap year in Julian and Coptic Calendars. This is why our Christmas in now January 7 instead of December 25.

Jews follow a lunar calendar which is only 354 days(like Muslim calendars) but they adjust it to match Solar calendar by accumulating the difference and have a year with 13 month every time the difference adds up to a full month. Thus Jewish Feasts move in cycles while Muslim Calender which does not apply that correction keeps shifting.

That is why both Jewish Passover and our Good Friday, Easter, and Pentecost move forward every year and then move way back about a month every few years.
Example Easter from 2001 to 2011 was April 15, May 5, April 27, April 11, May 1, April 23, April 8, April 27, April 19, April 4, April 24.

Coptic New Year (Rass El Sanna) comes in either September 11 or 12, Jewish Rosh_Hashanah comes in September or October.
Here are information about both celebrations

http://en.wikipedia.org/wiki/Coptic_calendar

http://en.wikipedia.org/wiki/Rosh_Hashanah