Tried starting with the audio and I get 47 which changes your 81.59 to 78.4 or thereabouts. But then for the 30 degree I get 31 which brings 78.4 back up to 79.4 so still a few degrees off. What's the explanation for the 60 degree line?
Edit: Added the most important statement: Thank you for checking! [up] This could mean the lines are for Meriope 5C after all, and that could mean the location identified on the map at Time-0 is significant. It might be of benefit to test a UP at the location at that exact time. The exact location (where the grids on the sphere make 90 degrees) slightly to the right of the intersection point when using the 30 degree line, and more to the left when using the 60 degree line... which sort of indicates the location is quite precise in relation to the intersection - the UP may want to be in a precise location on Merope 5C, relative to the intersection at Time-0. There is a faint circle slightly off-centre, which I think is the dotted circle of Merope 5 when viewed though Merope 5C. So when approaching Merope 5C, the Merope 5 circle needs to be off centre, not exact centre. This would move you maybe up to a degree in lat and long, which is about 3km?
To explain the 60 degree line:
The 60 degree line is the Merope 5C orbital plane from the reverse side. The rings and orbital plane intersect at two places Time 0 and Time 3.3 (Merope 5C has a 6.6 day rotational period, tidal locked) so on Time 0, the 30 degree line matches when the rings are on the 45 degree line. At time 3.3, the approach is from the reverse side of Merope 5, so to keep the map consistent (ie: always up) you have to invert your ship. At that inversion the 60 degree line lines up.
You can try it yourself to see it as it is much clearer when doing rather than my poor explanations. If you fly to Merope 5C in SC (target Merope 5C to get its orbit ring) fly along its orbital line with Merope 5 visible in your side window view. The rings will appear as rings, but keep flying and the rings will become a line. If you also position yourself so the Merope 5C orbit ellipse is also a line, slow down to 30km/s and turn to face Merope 5, and the rings are at 45 degrees. Depending on which side of Merope 5 you are in the Merope 5c orbit, the 30 degree line or the 60 degree line will match. I call the 30 Degree line Time-0 as the 30 degree line touches the circle. The 60 degree line has a gap, so I am assuming it might be secondary... but that is an assumption which needs to be tested. In any case, when you have lined up one way and matched the orbit to the rings, fly toward and past Merope 5 until you reach the other side of the Merope 5C orbit ring. Turn around and the other line will now line up.
It is this matching of the lines from opposite sides of the Merope 5C orbit, and still corresponding to the same location on Merope 5C that tells me this is the correct reading for those lines. It is very unlikely they could fit so well for identifying specific locations on the body, and not be for that purpose.
I hope that helps - I really should not be typing this now, but my boss is in a meeting at the moment.
