Added view:moon_azimuth and view:moon_elevation

[m-mohr]

e.g. for nighttime lights surface radiance

[m-mohr]

Any thoughts @jlaura?
The new fields are arrays as I thought non-Earth data may provide angles for multiple moons?

[jlaura]

I don't think it need to. My thinking echos. a discuss with @matthewhanson. Basically, a STAC item references a single spatial entity. So, an observation with two moons in it should be represented by two different STAC items with the backing data being singletons.

I think that the one-to-one mapping (spatial entity to STAC item) is really consistent then across extensions such that we do not have to propagate arrays everywhere when two singletons might be desirable (e.g., two view geometries, two AI/ML derived labels from different target body specific training data sets, etc.)

More discussion here: stac-extensions/ssys#9 on my thinking for moving in this direction and credit to @matthewhanson for starting me down this road.

[m-mohr]

@jlaura Thanks. I think I did not make my point clear enough and there was a misunderstanding, sorry. This is meant for a single capture, not necessarily on a moon:

These fields are, comparable to the sun angles, about potential influences on a capture of a single Planet. On Earth there's a single moon that "shines" on the Earth during the nigth, which might influence the image, similar to the sun during the day. Thus we have a single value here for sun related angles.
I have not really a clue, but I assumed that on other Planets there could be multiple moons that "shine" on the Planet, no? Thus I made this an array. Does this make more sense? Is this reasonable or is there only always one moon per Planet that may influence the captures on Planets?

[jlaura]

Ohhh!!! I understand. in theory yes, in practice I am not aware of any tracking like this. I do know that some folks work on lunar South Pole data where scattered light (photons bouncing off higher slope areas and then illuminating permanently shadowed regions) is a thing, but secondary reflectance from a moon onto a surface, I'm not aware of. For the outer planets, the moons are numerous, small, and far away, so I don't know that secondary illumination from those is meaningful / measurable with what instrumentation we have.

That said, I don't know that this is a bad idea as it might future proof something we aren't aware of.