This is OK and very quick.
This is not a direct alternative to s_region however: resulting contours are much larger, can't be included in a table. But we can either have precomputed MOC stored somewhere (for datasets?) or compute them on the fly when required.
• Then: test intersections with something else.
How do we do that? Is it scheduled under the Logical operations menu item in Aladin (currently not used)?
Image above was drawn before the inversion of longitudes in s_region from Mars craters service, so they plot correctly (inverted both in original s_region and in Aladin)