• Judaism.SE/How was Rosh Chodesh determined, if a New Moon Cannot be Seen?
• Calculating months and weeks in the Mosaic Law
• Astronomy.SE/How Soon Could a Waxing Crescent Moon Be Seen?
Apart from Rabbinical commentary, (in the Talmud) - is there any Scriptural or literary evidence explaining how a New Moon was determined - especially since it is not visible?
Or, was it the case that the Waxing Crescent Moon was taken "As and For" the New Moon?
2. The Text/Context:
NASB, 1 Samuel 20:18 - Then Jonathan said to him, “Tomorrow is the new moon, and you will be missed because your seat will be empty.
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?).