Find the moment and viewpoint
Check the date, local time, place label, coordinates, and timezone context first. Those are the inputs that define the observation.
Read the horizon and direction system
Altitude and azimuth describe positions relative to the observer’s horizon. Directional marks and horizon geometry tell you how the celestial scene is oriented locally.
Sources: U.S. Naval Observatory — Computing Altitude and Azimuth
Then read the bodies and layers
Stars, planets, constellation geometry, annotations, and optional visual systems are layered onto the same calculated moment. Different presets can reveal or suppress information without changing the underlying sky.
Finish with provenance
The technical footer and source surfaces tell you what data, render identity, or edition produced the object. That is where the chart becomes a record rather than only an image.