Somewhere around her center is the 'shoreline'. Once she was located earlier in the year, but precession has moved spring equinox (north of the equator) to a place where nothing of the modern constellation is now down in the water. Flamsteed has managed, however, to draw the last part of the monster's tail at 0h.

Flamsteed was born in 1646 and he died in 1719. From his time and up to the present the precession has moved equinox about 4 days forward, or stated in right ascension ca ¼ of an hour forward.

In the Marduk chapter I presented the sea-monster in Babylonian times, at that time named Tiamat:

... Once upon a time, in Babylon, Marduk was the name for Spring Sun. He cut Tiamat, the great 'ocean monster' in half by a slash. Below I quote from Peter Jensen's Die Kosmologie der Babylonier:

'... Marduk, die Frühsonne des Tages und des Jahres, wurde eben wegen dieses seines Charakters der Lichtbringer am Weltmorgen. Marduk, der die leblose, chaotische Nacht, die keine Gestaltungen erkennen lässt, besiegt, der den Winter mit seinem Wasserfluten, den Feind des Naturlebens, überwindet, wurde der Schöpfer des Lebens und der Bewegung, der Ordner des Regellosen, der Gestalter des Unförmlichen am Weltmorgen ...

Die Sonne, die des Morgens das Weltmeer durchschreitet und besiegt und das Licht bringt, lässt aus dem Chaos der Nacht zuerst den Himmel, dann erst die Erde hervortreten, spaltet das gestaltlose Reich der Nacht in die zwei Hälften, den Himmel und die Erde ...'

Marduk was the early Sun of the day and the year ('die Frühsonne des Tages und des Jahres'). He was the bringer of light in the morning of the world (der Lichtbringer am Weltmorgen). He defeated winter, with its 'floods of water', enemy of life in nature. And he was the creator of life and movement, the one who brought order where there had been none. He was the creator of forms in the morning of the world.

The Spring Sun, who comes out through the 'world ocean' in the morning and defeats it, and who brings light, first allowed the sky and then the earth to come out, and he divided the shapeless domain of night into two halves, the Sky and the Earth.

Marduk divided the 'night' (the winter season) in half. Winter is divided in half by the birth of Spring Sun at winter solstice. And then, of course, it must be reflected on the cycle of day and night, in which a new day will be 'born' at midnight ...

"... in all delineations, it [Cetus] has been a strange and ferocious marine creature, in later times associated with the story of Andromeda, and at first, perhaps, was the Euphratean Tiāmat ..." (Allen)

In Babylonian times Cetus rose heliacally earlier than today. If we consider the constellation is stretching for say 3h, then half of it would be at her center. It means ca 90 / 1440 * 26000 = 1625 years. If we wished to move her completely through a cardinal point it would thus take about 3250 years.

"It [Cetus] occupies a space of 50º in length by 20º in breadth, and so is one of the most extended of the sky figures ..." (Allen)

Maybe the feat of Marduk was to cut off her head, I guess so.