>> I have a sneaking suspicion it's a piece of paper with N, E, S, and W marked on it.

Rhiannon, can you come round to my house and clean the coffee off my keyboard and monitor please!?

Hi Rhiannon,
"Ray Seton's Astronomical Signficance Indicator"
is a grand title I've given to an actetate that came with his book 'The Reason for the Stone Circles in Cumbria'.
The acetete is small enough to fit in my notebook and basically is a circle with a north line marked upon it . The circle is approximately the same diameter as a pocket compass. Around the edges of the circle are lines pointing to all of the major solar, lunar and planetary positions during these events throughout the year 2000BC.
For example, I could quickly look at the chart and instantly see where the sun rose and set at the winter solstices,check the moons furthest north or south points or check where a major planet rose or set during a solar event.
I realise that chart being based on 2000BC wouldn't make it 100% accurate but it's close enough and a very simple way to check out approximate allignments in the field.