Moving back a bit to planet ranges on the barcode, I found something interesting, that shows quite well how much of a leeway the FSS gives you to setting the slider incorrectly.
Take a look at this tiny ammonia moon, specifically, where I set the slider to to resolve it and where its signal actually is:

Quite a lot of leeway there. Meanwhile, in the bottom right corner, you'll only get the correct planet type if you set the center of the slider to precisely the middle of the signal. Most of the time, this doesn't make a difference, but if you look up
@Frillop Freyraum 's earlier picture
here, you'll notice that it's just slightly off the middle of the signal and giving a wrong type already.
As a fun aside, to better visualise the range in which you have to be correct to be able to click the scan, compare this (taken before resolving the AW):
to this:
(Apologies for amateur 'shopping.)
And this is why there's an overlap on the arrows displayed above, because the signal can be anywhere within this bar to be able to successfully resolve the blob.