The dates in the Julian and Gregorian calendars were defined from the cardinal points of the Sun, not from the positions of the stars. But to determine the cardinal points of the Sun it was useful to look at the phase (face) of the Full Moon - who always was half a year away.

Alternatively one could look at the culminations (at 21h in the epoch of rongorongo) of the leading stars, in which case April 25 would be found at the thirsty Mouth of the Fish - Fom-al-Ha(u)t:

... Horapollo, the grammarian of Alexandria, about AD 400, tells us that the crane was the symbol of a star-observer in Egypt ...

... Grus has as an alternative name Flamingo (a name which sounds quite similar to that of the bird Phoenix) which obviously is based on 'flame'. Phoenicopterus (the Flamingo) is characterized by its red feathers. Wikipedia: ... from Greek φοινικόπτερος meaning 'purple wing'. Purple is the colour for kings and 'phoenix' should therefore mean 'purple, the colour of the king' ...

The position of the very bright star Canopus far down in the south was unique for it was like a 'navel' (for navigating at sea, for determining time). On Easter Island a line should not be drawn towards Alcor and the north pole but instead towards the south and Canopus.

... The Arabs in the desert regarded it as a test of penetrating vision; and they were accustomed to oppose 'Suhel' to 'Suha' (Canopus to Alcor) as occupying respectively the highest and lowest posts in the celestial family. So that Vidit Alcor, et non lunam plenum, came to be a proverbial description of one keenly alive to trifles, but dull of apprehension for broad facts ...

1		23			13		166		15
	Ga2-1 (31)		Ga2-25 (55)	Ga2-26		Ga3-11 (70)		Gb1-8 (237)		Gb1-24 (253)
	ST JOHN'S DAY		July 18 (199)	19 (200)		Aug 2 (214)		Jan 16 (381)		Febr 1 (32)
	CANOPUS		DRUS (*119)	*120		*134		*301		ε Equulei (*317)
	*278		*302	*303		ε Equulei (*317)		DRUS (*484)		ACUBENS (*135)
	CHRISTMAS EVE		Jan 17 (382)	18		Febr 1 (397)		July 18 (2 * 282)		Aug 3 (580)
	'May 28 (148)		SOLSTICE	'June 22 (173)		'July 6 (187)		'Dec 20 (354)		'Jan 5 (370)
	'Nov 27 (331)		SOLSTICE	'Dec 22 (356)		'Jan 5 (370)		'June 20 (171)		'July 6 (187)
	'May 14 (134)		"June 7 (158)	8 (*79)		"June 22 (173)		"Dec 6 (*260)		"Dec 22 (356)
	"Nov 13 (*237)		"Dec 7 (*261)	8 (342)		"Dec 22 (*276)		"June 6 (*77)		"June 22 (173)

... In the inscriptions of Dendera, published by Dümichen, the goddess Hathor is called 'lady of every joy'. For once, Dümichen adds: Literally ... 'the lady of every heart circuit'. This is not to say that the Egyptians had discovered the circulation of the blood. But the determinative sign for 'heart' often figures as the plumb bob at the end of a plumb line coming from a well-known astronomical or surveying device, the merkhet. Evidently, 'heart' is something very specific, as it were the 'center of gravity' ... See Aeg.Wb. 2, pp. 55f. for sign of the heart (ib) as expressing generally 'the middle, the center'. And this may lead in quite another direction. The Arabs preserved a name for Canopus - besides calling the star Kalb at-tai-man ('heart of the south') ... Suhail el-wezn, 'Canopus Ponderosus', the heavy-weighing Canopus, a name promptly declared meaningless by the experts, but which could well have belonged to an archaic system in which Canopus was the weight at the end of the plumb line, as befitted its important position as a heavy star at the South Pole of the 'waters below'. Here is a chain of inferences which might or might not be valid, but it is allowable to test it, and no inference at all would come from the 'lady of every joy'. The line seems to state that Hathor (= Ha[u]t Hor, 'House of Horus') 'rules' the revolution of a specific celestial body - whether or not Canopus is alluded to - or, if we can trust the translation 'every', the revolution of all celestial bodies. As concerns the identity of the ruling lady, the greater possibility speaks for Sirius, but Venus cannot be excluded; in Mexico, too, Venus is called 'heart of the earth'. The reader is invited to imagine for himself what many thousands of such pseudo-primitive or poetic interpretations must lead to: a disfigured interpretation of Egyptian intellectual life ...

... it is not too much to assume that the Egyptians observed, and taught people to observe, the sun on the horizon. This being so, the chances are that at first they would observe the stars on the horizon too, both stars rising and stars setting; this indeed is rendered more probable by the very careful way in which early astronomers defined the various conditions under which a star can rise or set, always, be it remembered, in relation to the sun ... Although the Egyptians knew nothing about telescopes, it would seem that they had the same problem before them which we solve by a special arrangement in the modern telescope - they wanted to keep the light pure, and to lead it into their sanctuary as we lead it to the eyepiece. To keep the light that passes into the eyepiece of a modern telescope pure, we have between the object-glass and the eyepiece a series of what are called diaphragms; that is, a series of rings right along the tube, the inner diameter of the rings being greatest close to the object-glass, and smallest close to the eyepiece; these diaphragms must so be made that all the light from the object-glass shall fall upon the eyepiece, without loss or reflection by the tube. These apertures in the pylons and separating walls of Egyptian temples exactly represent the diaphragms in the modern telescope ...