There were 240 days from Nashira (Bringer of Good Tidings), the Western One in the Tail of the Goat (γ Capricorni), up to and including Spica (The Virgin's Girdle), but Porrima (γ Virginis) was close to the equator and also a place where the path forward could be thought of as forked - offering choices (up to heaven, down to hell, or straight 'ahead' to recycling, rebirth):

At ζ (Heze) was the next bifurcation, with some going up and some going down - although not leaving the Middleworld of Mother Earth, the Earth Turtle.

... An iconographic study by Jeff Kowalski suggests a cosmological layout for the Nunnery. The higher placement of the North Building, with its 13 exterior doorways (reflecting the 13 layers of heaven), and the celestial serpents surmounting the huts identify it with the celestial sphere. The iconography of the West Building, with 7 exterior doorways (7 is the mystic number of the earth's surface), and figures of Pawahtun - the earth god as a turtle - indicate this to be the Middleworld, the place of the sun's descent into the Underworld. The East Building has mosaic elements reflecting the old war cult of Teotihuacan, where tradition had it that the sun was born; thus, this may also be Middleworld, the place of the rising sun. Finally, the South Building has 9 exterior doorways (the Underworld or Xibalba had 9 layers), and has the lowest placement in the compex; it thus seems to be associated with death and the nether regions ...

Given how the midnight culmination of Porrima was very close to heliacal Alcyone with Cor Serpentis close to the Full Moon, this place ought to have been essential for those who were building the structure describing the connections between the major stars (and this structural element was not perturbed by the effects of the precession):

*MARCH 7	8	9 (68 = 136 - 68)	10 (*355)
Cb2-4 (420)	Cb2-5 (29)	Cb2-6	Cb2-7
te ua	koia ra	kua tuku ki to mata - ki tona tukuga	e kiore - henua - pa rei
δ Persei (54.7)	Al Thurayya-27 / Krittikā-3		MENKHIB = ζ Persei (57.6) PORRIMA (γ Virginis)
	TAU-ONO (Six Stones) ATIKS = ο Persei, RANA = δ Eridani (55.1), CELAENO (16 Tauri), ELECTRA (17), TAYGETA (19), ν Persei (55.3), MAIA (20), ASTEROPE (21), MEROPE (23) (55.6)	Temennu-3 (Foundation Stone) Hairy Head-18 (Cockerel) ALCYONE (56.1), PLEIONE (28 Tauri), ATLAS (27) (56.3)
May 14 (*54)	15 (500)	16 (136)	17 (*57)
"April 3 (*13)	4 (459)	5 (95 = 136 - 41)	6 (*16)
NAKSHATRA DATES:
6 (249 = 66 + 183)	*SEPTEMBER 7	8	9 (*172 = *240 - *68)
κ Librae (237.2), ι Serpentis (237.4), ψ² Lupi, ρ Oct. (237.5), γ Cor. Borealis, η Librae (237.7),  COR SERPENTIS = α Serpentis (237.9)	π Cor. Borealis, UNUK ELHAIA (Necks of the Serpents) = λ Serpentis (238.1), CHOW = β Serpentis (238.6)	κ Serpentis (239.3), δ Cor. Borealis, TIĀNRŪ = μ Serpentis (239.5), χ Lupi, (239.6), ω Serpentis (239.7), BA = ε Serpentis, χ Herculis (239.8). κ Cor. Borealis, ρ Serpentis (239.9)	λ Librae (240.0), β Tr. Austr. (240.3), κ Tr. Austr. (240.4), ρ Scorpii (240.8)
'October 17 (290)	18 (*211 = *238 - 27)	(292 = 136 + 183 - 27)	20
"October 3 (*196)	4 (277)	5	6

At the time of rongorongo their common star atlas would have documented that Atlas culminated in the night of December 31, which could appear as quite a miracle. However, the ancient clock work had simply worked its way up to a position where all came into order again - because it could be perceived that at the time when Aldebaran had risen with the Sun at 0h the midnight culmination of Atlas would have been connected with day 300:

OCTOBER 26	27 (300)	28	29	30	31 (*224)
*OCTOBER 22	23 (*216)	24	25	26	27 (300)
Ga8-16	Ga8-17 (220)	Ga8-18	Ga8-19	Ga8-20	Ga8-21
ζ Pavonis (283.4), λ Cor. Austr. (283.6), DOUBLE DOUBLE = ε Lyrae (283.7), ζ Lyrae (283.8)	South Dipper-8 Φ SAGITTARII (284.0), μ Cor. Austr. (284.6), η Cor. Austr., θ Pavonis (284.8)	SHELIAK = β Lyrae, ν Lyrae (285.1), ο Draconis (285.5). λ Pavonis (285.7) ATLAS (27 Tauri)	χ Oct. (286.0), AIN AL RAMI (Eye of the Archer) = ν Sagittarii (286.2), υ Draconis (286.4), δ Lyrae (286.3), κ Pavonis (286.5), ALYA (Serpent) = θ Serpentis (286.6)	ξ Sagittarii (287.1), ω Pavonis (287.3), ε Aquilae, ε Cor. Austr., SULAPHAT = γ Lyrae (287.4), λ Lyrae (287.7), ASCELLA = ζ Sagittarii, BERED = i Aquilae (Ant.) (287.9)	Al Na'ām-18 / Uttara Ashadha-21 NUNKI = σ Sagittarii (288.4), ζ Cor. Austr. (288.5), MANUBRIUM = ο Sagittarii (288.8), ζ Aquilae (288.9)
December 29	30 (*284)	31	January 1	2	3 (368)
Ca10-28	Ca10-29 (284)	Ca11-1	Ca11-2	Ca11-3	Ca11-4
te inoino	te tagata	E inoino	te inoino	kua haga	tupu te raau i te vai
SIRIUS = α Canis Majoris (101.2), ψ5 Aurigae (101.4), ν Gemini (101.6), ψ6 Aurigae (101.7)	τ Puppis (102.2), ψ7 Aurigae (102.4)	Mash-mashu-sha-Risū-9 (Twins of the Shepherd ?) θ Gemini (103.0), ψ8 Aurigae (103.2), ALHENA = γ Gemini (103.8), ψ9 Aurigae (103.9)	ADARA (Virgins) = ε Canis Majoris (104.8)	ω Gemini (105.4), ALZIRR (Button) = ξ Gemini (105.7), MULIPHEIN = γ Canis Majoris (105.8), MEKBUDA (Contracted) = ζ Gemini (105.9)	7h (106.5) no star listed (106)

This was the place for the Mad Hatter's T-party, where the Door-mouse had told of the 3 little sisters down in the well with treacle in the South Dipper, with Tillie marking its end and with the March Hare having just upset the Milk Jug into his plate. Nunki announced the beginning of the Sea and it could have been a sea of milk.

NOVEMBER 1	2 (306)	3 (*227)	4	5
*OCTOBER 28 (301)	29	30	31 (*224)	*NOVEMBER 1
Ga8-22	Ga8-23	Ga8-24 (227)	Ga8-25	Ga8-26
19h (289.2) λ Aquilae (Ant.) (289.1), γ Cor. Austr (289.3), τ SAGITTARII (Tillie) (289.4), ι Lyrae (289.5), δ Cor. Austr. (289.8)	Al Baldah-19 AL BALDAH = π Sagittarii, ALPHEKKA MERIDIANA = α Cor. Austr. (290.1), β Cor. Austr. (290.2)	ALADFAR = η Lyrae (291.1), NODUS II = δ Draconis (291.5), ψ Sagittarii (291.6), τ Draconis (291.7), θ Lyrae (291.8)	ω Aquilae (292.1), ρ Sagittarii (292.6), υ Sagittarii (292.7)	π Draconis, ARKAB PRIOR = β¹ Sagittarii (293.0), ARKAB POSTERIOR = β² Sagittarii, ALRAMI = α Sagittarii (293.2), χ Sagittariii (293.6)
January 4	5 (*290)	6	7 (372)	8
°December 31	°January 1	2 (*287)	3 (368)	4
'December 8	9	10 (*264)	11 (345)	12
"November 24	25 (329)	26 (*250)	27	28
NAKSHATRA DATES:
MAY 3 (123)	4	5 (*45)	6	7
*APRIL 29	30	*MAY 1 (*41)	2	3 (123)
WEZEN (Weight) = δ Canis Majoris (107.1), τ Gemini (107.7), δ Monocerotis (107.9)	no star listed (108)	λ Gemini (109.4), WASAT (Middle) = δ Gemini (109.8)	no star listed (110)	ALUDRA = η Canis Majoris (111.1), PROPUS = ι Gemini (111.4),  GOMEISA = β Canis Minoris (111.6)
July 6 (*107)	7	8	9 (190)	10 (*111)
°July 2	3 (184)	4	5	6 (*107)
'June 9	10 (161)	11	12	13 (*84)
"May 26	27	28 (148)	29	30 (*70)
Ga2-13	Ga2-14	Ga2-15 (45)	Ga2-16	Ga2-17

The inversion depicted at °December 31, after the end of 4 * 91 = 364 days, coincided with Tillie (τ Sagittarii).

 

125	*MARCH 7	8	9 (68 = 136 - 68)	10 (*355)
	Cb2-4 (420)	Cb2-5 (29)	Cb2-6	Cb2-7
	te ua	koia ra	kua tuku ki to mata - ki tona tukuga	e kiore - henua - pa rei
	May 14 (*54)	15 (500)	16 (136)	17 (*57)