Hoshana Rabbah
Sefarim describe Hoshana Rabbah as a day of judgment, comparable to Rosh Hashanah and Yom Kippur. It acts as a final seal, finalizing the judgments initially determined on Rosh Hashanah and Yom Kippur.
Rabbi Daniel Glatstein, in an online shiur, quoted the Chasam Sofer, who, in turn, quoted the Rama Mipano, saying that forgiveness on Hoshana Rabbah occurs six hours into the night (approximately chatzos).
Many have the minhag to remain awake for the whole night of Hoshana Rabbah learning Torah and reciting Tehillim. Some have the custom to read the whole Sefer Devarim before Chatzos and to read the whole Sefer Tehilim after Chatzos.
Forgiveness and Mitzvos 