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5 added 42 characters in body

# 1. Question / Issue :

Since a New Moon cannot be seenIf a New Moon cannot be seen, then it seems that the first visible confirmation of a New Moon is actually the Waxing Crescent Moon, which can only be observed from after the New Moon - minimally - after 12.1 tohours with a telescope, and 15.5 hours after the New Moon,without. (See Astronomy.SE/How Soon Could a Waxing Crescent Moon Be Seen?).

According to Judaism 101, the Jewish Calendar:

Used to be calculated by observation

Calculated mathematically since 4th century

In view of this, is there any Rabbinical commentary that helps explain how the 1st of the Month / New Moon was determined during the Temple Period?

2. Or, was it determined "After-the-fact" and the calendar day was set to the first, retroactively?

I am hoping for references that can be cited, thank you.

# 1. Question / Issue :

Since a New Moon cannot be seen, then it seems that the first visible confirmation of a New Moon is actually the Waxing Crescent Moon, which can only be observed from after 12.1 to 15.5 hours after the New Moon, (See Astronomy.SE/How Soon Could a Waxing Crescent Moon Be Seen?).

According to Judaism 101, the Jewish Calendar:

Used to be calculated by observation

Calculated mathematically since 4th century

In view of this, is there any Rabbinical commentary that helps explain how the 1st of the Month / New Moon was determined during the Temple Period?

2. Or, was it determined "After-the-fact" and the calendar day was set to the first, retroactively?

I am hoping for references that can be cited, thank you.

# 1. Question / Issue :

If a New Moon cannot be seen, then it seems that the first visible confirmation of a New Moon is actually the Waxing Crescent Moon, which can only be observed after the New Moon - minimally - after 12.1 hours with a telescope, and 15.5 hours without. (See Astronomy.SE/How Soon Could a Waxing Crescent Moon Be Seen?).

According to Judaism 101, the Jewish Calendar:

Used to be calculated by observation

Calculated mathematically since 4th century

In view of this, is there any Rabbinical commentary that helps explain how the 1st of the Month / New Moon was determined during the Temple Period?

2. Or, was it determined "After-the-fact" and the calendar day was set to the first, retroactively?

I am hoping for references that can be cited, thank you.

4 Clarified question, added citation from Astronomy.SE regarding the Waxing Crescent Moon.

# 1. Question / Issue :

According to Judaism 101 Since a New Moon cannot be seen, then it seems that the Jewish Calendar:first visible confirmation of a New Moon is actually the Waxing Crescent Moon, which can only be observed from after 12.1 to 15.5 hours after the New Moon, (See Astronomy.SE/How Soon Could a Waxing Crescent Moon Be Seen?).

According to Judaism 101, the Jewish Calendar:

Used to be calculated by observation

Calculated mathematically since 4th century

IsIn view of this, is there any documentationRabbinical commentary that helps explain how Rosh Chodeshthe 1st of the Month / New Moon was determined during the Temple Period?

2. Or, was it determined "After-the-fact" and the calendar day was set to the first, retroactively?

I am hoping for references that can be cited, thank you.

# How was Rosh Chodesh determined, during the Temple Period?

According to Judaism 101, the Jewish Calendar:

Used to be calculated by observation

Calculated mathematically since 4th century

Is there any documentation how Rosh Chodesh was determined during the Temple Period?

2. Or, was it determined "After-the-fact" and the calendar day was set to the first, retroactively?

I am hoping for references that can be cited, thank you.

# 1. Question / Issue :

Since a New Moon cannot be seen, then it seems that the first visible confirmation of a New Moon is actually the Waxing Crescent Moon, which can only be observed from after 12.1 to 15.5 hours after the New Moon, (See Astronomy.SE/How Soon Could a Waxing Crescent Moon Be Seen?).

According to Judaism 101, the Jewish Calendar:

Used to be calculated by observation

Calculated mathematically since 4th century

In view of this, is there any Rabbinical commentary that helps explain how the 1st of the Month / New Moon was determined during the Temple Period?

2. Or, was it determined "After-the-fact" and the calendar day was set to the first, retroactively?

I am hoping for references that can be cited, thank you.

Post Reopened by MTL, kouty, Danny Schoemann, DonielF, msh210
3 no need for a numbered title when there's only one section, IMO

# 1. Question - a Request for Citable Reference

According to Judaism 101, the Jewish Calendar , the Jewish Calendar:

Used to be calculated by observation

Calculated mathematically since 4th century

Is there any documentation how Rosh Chodesh was determined during the Temple Period?

2. Or, was it determined "After-the-fact" and the calendar day was set to the first, retroactively?

I am hoping for references that can be cited, thank you.

# 1. Question - a Request for Citable Reference

Used to be calculated by observation

Calculated mathematically since 4th century

Is there any documentation how Rosh Chodesh was determined during the Temple Period?

2. Or, was it determined "After-the-fact" and the calendar day was set to the first, retroactively?

I am hoping for references that can be cited, thank you.

According to Judaism 101, the Jewish Calendar:

Used to be calculated by observation

Calculated mathematically since 4th century

Is there any documentation how Rosh Chodesh was determined during the Temple Period?