In Chapters 4-17, the author descibes in great detail, the images on a celestial map. Most people think it was some kind of vision but it was a celestial map. How do we know this? In Chapter 17, he writes:

"I saw a woman sit upon a scarlet coloured beast, full of names of blasphemy..."

How could he see a beast full of names unless if was on a chart and the names were labels? He is describing a particular constellation with the names of the stars composing it spelled out.

Then he writes:

[4] And the woman was arrayed in purple and scarlet colour, and decked with gold and precious stones and pearls, having a golden cup in her hand full of abominations and filthiness of her fornication:
[5] And upon her forehead was a name written, MYSTERY, BABYLON THE GREAT, THE MOTHER OF HARLOTS AND ABOMINATIONS OF THE EARTH.

Now how could you fit all that on someone's forehead and be able to read it? Because it was a label that overlapped her forehead because she is another constellation drawn on a chart.