The fifteenth day of the first month is February 5, 2023.

The first month of the year is the month of "Jianzheng". In the era of observing the signs of the times, the handle of the dipper back to the Yin is the spring, and the month in which the spring is located is the first month of the year. Calendar Jianzheng, the original is the concept of Regent's discipline in December built. Later it evolved and was also used to refer to the first month of other calendars. Now usually refers to the first month of the lunar calendar.

Summer calendar to spring January as the first month, equivalent to the month of the dry calendar Jian Yin; Shang calendar to winter December as the first month, equivalent to the month of the dry calendar Jian ugly; Zhou calendar to winter November as the first month, equivalent to the month of the dry calendar Jian Zi.

The Qin calendar takes the tenth month of winter as the first month, which is the equivalent of the month in which the dry-branch calendar is built. This is the origin of the saying that the summer calendar builds the Yin, the Shang calendar builds the Ugly, the Zhou calendar builds the Zi, and the Qin calendar builds the Hai, in fact, they belong to different calendars, which is a correspondence relationship.

Lunar Calendar:

Lunar Calendar is a modern calendar in China, which belongs to Lunar-Yang calendar, that is to say, the combination of Lunar Calendar and Solar Calendar. It is based on the cycle of the moon phases, with each lunation being one month, and referring to the solar return year as the length of a year, and adding the twenty-four festivals and setting up the intercalary month in order to make the average calendar year compatible with the return year. and intercalary months are added to make the average calendar year compatible with the solar return year.

The Lunar Calendar is a combination of the lunar and solar calendars, and was known as the Summer Calendar in ancient times because of its use of the "Xia Zheng".

The Lunar Calendar is a new calendar used after 1970, and its years are divided into equal years and leap years, with twelve months in equal years and thirteen months in leap years, and the months are divided into large and small months, with a large month of thirty days and a small month of twenty-nine days, and the average calendar month is equal to the month of the first lunar month.

Reference: Baidu Encyclopedia - The First Month of the Chinese Lunar Calendar

Reference: Baidu Encyclopedia - China's current modern calendar