The Plummet determines New Moon Day

2Kings 21:13  And I will stretch over Jerusalem the lineH6957 of Samaria, and the plummetH4949 of the house of Ahab: and I will wipe Jerusalem as a man wipeth a dish, wiping it, and turning it upside down.

Isaiah 28:17  Judgment also will I lay to the line,H6957 and righteousness to the plummet:H4949 and the hail shall sweep away the refuge of lies, and the waters shall overflow the hiding place.H5643

Zechariah 4:10  For who hath despised the day of small things? for they shall rejoice, and shall see the plummetH68 H913 in the hand of Zerubbabel with those seven; they are the eyes of Yehovah,H3068 which run to and fro through the whole earth.

Amos 7:7  Thus he shewed me: and, behold, AdonaiH136 stood upon a wallH2346 made by a plumbline,H594 with a plumblineH594 in his hand.

Amos 7:8  And Yehovah3068 said unto me, Amos,  what seest thou? And I said, A plumbline.H594 Then said Adonai,H136 Behold, I will set a plumblineH594 in the midst of my people Israel: I will not again pass by them any more:

After His professed people reject His Name and the calendar endorsed with His Name, depicting His New Moon Day with her four quarterly 7th day Sabbaths, then:

Amo 8:3  And the songs of the temple shall be howlings in that day, saith Adonai Yehovah: there shall be many dead bodies in every place; they shall cast them forth with silence.

S.D.A. Bible Commentary Vol. 7-CN- REV14-CT- Revelation-PR- 07-PG- 977
(Ch. 7:2, 3). The Question Before Us Now. –The Sabbath question is to be the issue in the great final conflict, in which all the world will act a part. Men have honored Satan’s principles above the principles that rule in the heavens.(see Gen. 1:14) They have accepted the spurious sabbath, which Satan has exalted as the sign of his authority. But YHVH Elohim has set His Seal upon His Royal Requirement. Each Sabbath institution, both true and false, bears the name of its author, an ineffaceable mark that shows the authority of each.
(The Lunar Calendar is embedded in Leviticus 1:1, The Four Letters of His Name stands each one in succession at the beginning of the four Lunar Weeks, click this link to see Leviticus 1:1 illustrated)