Yes, I was right, it was 12 Sept for Rosh Hashanah (Jewish New Year). Thanks to Wikipedia for the following explanation!

Rosh Hashanah (Hebrew: ראש השנה, Biblical: ˈɾoʃ haʃ:ɔˈnɔh, Israeli: ˈroʃ haʃaˈna, Yiddish: ˈroʊʃ hɑˈʃɔnə) is literally translated as "head of the year", and idiomatically refers to the Jewish New Year. The term first appears in the Tanakh, in Ezekiel 40:1.

In fact, Judaism has four "new year" observances which mark various legal "years", much like 1 January marks the "New Year" of the Gregorian calendar while other dates mark fiscal or other "new year" events. Rosh Hashanah is the new year for people, animals, and legal contracts. The Mishnah also sets this day aside as the new year for calculating calendar years and sabbatical (shemitta) and jubilee (yovel) years.

The Torah refers to the day as "The Day of the Blowing of the Shofar" (Yom Terua, Leviticus 23:24), and rabbinic literature and the liturgy itself describe Rosh Hashanah as "The Day of Judgment" (Yom ha-Din) and "The Day of Remembrance" (Yom ha-Zikkaron). Some midrashic descriptions depict God as sitting upon a throne, while books containing the deeds of all humanity are opened for review, and each person passing in front of Him for evaluation of his or her deeds. All of these names are also referenced in the holiday's extensive liturgy.

This holiday is the first of the Yamim Noraim (Hebrew, "Days of Awe"), the most solemn days of the Jewish year; the Yamim Noraim are preceded by the month of Elul, during which Jews are supposed to begin a self-examination and repentance, a process that culminates in the ten days of the Yamim Noraim known as Asseret Yemei Teshuva - The Ten Days of Repentance, beginning with Rosh Hashanah and ending with the holiday of Yom Kippur.

This holiday is characterized by the blowing of the shofar (per Leviticus 23:24), a trumpet made from a ram's horn. In fact, the shofar is blown in traditional communities every morning for the entire month of Elul, the month preceding Rosh Hashanah. The sound of the shofar is intended to awaken the listener from his or her "slumber" and alert them to the coming judgment (Maimonides, Yad, Laws of Repentance 3:4). Orthodox Judaism and some Conservative Judaic communities will not blow the shofar on Shabbat. (There is an exception. Jewish Law permits the Shofar to be blown in the presence of a rabbinical court called the Sanhedrin, which had not existed since ancient times. A recent group of Orthodox rabbis in Israel claiming to constitute a modern Sanhedrin held, for the first time in many years, an Orthodox shofar-blowing on Shabbat for Rosh Hashana in 2006. [1])

In the period leading up to the Yamim Noraim ("Hebrew, "Days of Awe") penitential prayers, called selichot, are recited, and on Rosh Hashanah itself, religious poems, called piyyuttim, are added to the regular services. Special prayer books for Rosh Hashanah and Yom Kippur, called the mahzor (mahzorim pl), have developed over the years. Many poems refer to Psalms 81:3: "Blow the shofar on the [first day of the] month, when the [moon] is covered for our holiday".

Rosh Hashanah has a number of additions to the regular service, most notably an extended repetition of the Amidah prayer for both Shacharit and Mussaf. The Shofar is blown during Mussaf at several intervals. Biblical verses are recited at each point. According to the Mishnah, 10 verses (each) are said regarding kingship, remembrance, and the shofar itself, each accompanied by the blowing of the shofar. A variety of piyyutim, medieval penitential prayers, are recited regarding themes of repentance. The Alenu prayer is recited during the repetition of the Mussaf Amidah.

The traditional greeting on Rosh Hashanah is "Shana Tova" IPA [ʃaˈ na toˈ va], Hebrew for "A Good Year," or "Shana Tova Umetukah" for "A Good and Sweet Year." Because Jews are being judged by God for the coming year, a longer greeting translates as "May You Be Written and Sealed for a Good Year" (ketiva ve-chatima tovah).

During the afternoon of the first day occurs the practice of tashlikh, in which prayers are recited near natural flowing water, and one's sins are symbolically cast into the water. Many also have the custom to throw bread or pebbles into the water, to symbolize the "casting off" of sins. In some communities, if the first day of Rosh Hashanah occurs on Shabbat tashlikh is postponed to the second day. The traditional service for tashlikh is recited individually and includes the prayer "Who is like unto you, O God...And You will cast all their sins into the depths of the sea", and Biblical passages including Isaiah 11:9 ("They will not injure nor destroy in all My holy mountain, for the earth shall be as full of the knowledge of the Lord as the waters cover the sea") and Psalms 118:5-9, 121 and 130, as well as personal prayers.


Rosh Hashanah table set with symbolic foods.Rosh Hashanah meals often include apples and honey, to symbolize a "sweet new year". Various other foods with a symbolic meaning may be served, depending on local minhag (custom), such as tongue or other meat from the head (to symbolise the "head" of the year). Other symbolic foods are dates, black-eyed beans, leek, spinach and gourd, all of which are mentioned in the Talmud. Pomegranates are used in many traditions: the use of apples and honey is a late medieval Ashkenazi addition, though it is now almost universally accepted. Typically, round challah bread is served, to symbolize the cycle of the year. On the second night, new fruits are served to warrant inclusion of the shehecheyanu blessing, the saying of which would otherwise be doubtful (as the second day is part of the "long day" mentioned above).
Yael, if you still pop into this thread - what did you do for Rosh Hashanah?