The creators of Avebury are pretty consistent in the way that the megaliths at Avebury Henge were carved to represent stars.
The henge-outward face marks "outer" stars toward the Milky Way, Ecliptic and Celestial Equator. The henge-inward face marks stars toward the center of the starry heavens (i.e. North Ecliptic and North Celestial Poles). Those henge-inward stars are immediately "above" the henge-outward stars in the sky. The narrower "sides" of each stone mark stars to the respective sides of the stars previously identified on the henge-outward and henge-inward faces.
This is also true for Avebury Stone #42, where the henge-outward face marks the stars of Sagittarius. Accordingly, when we "decipher" the remaining sides of that megalith, we already "know" where in the heavens the appropriate stars are, though re-drawing the figures found on stone is not always intuitively obvious, and it takes some work to figure out what the ancients were doing.
The henge-inward face of Avebury Stone #42 thus represents the stars of Aquila, the Eagle. The three images below show a photo clip of our original photograph of Avebury Stone #42, plus a tracing of the most prominent lines and markings on the stone via our zoom-enabled graphic software, and then the corresponding stars to the figures, lines and markings carved in stone, including the entire shape of the megalith itself.
Avebury Stone #42 Henge-Inward Face Our Photograph
Avebury Stone #42 Henge-Inward Face Photo Traced
Avebury Stone #42 Henge-Inward Corresponding Stars Aquila & Scutum
We forgot to circle the face in the lower left hand corner on the sky map.
Do you see it? Compare the stone and the sky map above.