Only because of the mention of an annual feast. Out of all of the new moons Trumpets is the only one named as a Sabbath and has the biggest celebration of all the new moon days:
Leviticus 23:23-25
23 The LORD said to Moses, 24 “Say to the Israelites: ‘On the first day of the seventh month you are to have a day of sabbath rest, a sacred assembly commemorated with trumpet blasts. 25 Do no regular work, but present a food offering to the LORD.’ ”
However, until Hillel II instituted a permanent calendar based on calculations (ca. 360), the fixing of the new moon was determined by observation and the evidence of witnesses.
During the earlier period, the practice of adding a second day to festivals … was introduced for communities lying at a distance from Palestine, because it was doubtful on precisely which of the two days the new moon occurred.” (Encyclopedia of the Jewish Religion, p. 78; Massada-P.E.C. Press Ltd, 1965., based on talmudic tradition)
https://en.wikibooks.org/wiki/Hebrew_Roots/New_Moon