Reference point (song):
Map ref.: __°N __°W
Latitude (songs):
Offset: C - E - F + A + (B * 1,590477) / (C * D)
A B yrs
S.O. C
D hrs
E while F
Longitude (albums):
Offset: - (N * P + 2 * N + 2 * P - 5 * M - Q + (M * Q * 0,847523) / (N * P))
M = *#*# ←
N =Z̶Z̶Z̶
P = XXX
Q = ✋✋←☼
The cache can hold travellers and it contains a pen.
Note: this mystery works only in English. All answers involve English post-punk from late 70s and early 80s. By the way, I like the darker stuff... Be brave!
Hot points: #1: map ref point, #2: bogus point. The following hot points can be applied to check whether you have correct ideas for some of the latitude or longitude letters: #4: add C to latitude to the bogus coordinates, #5: add M to longitude of the bogus coordinates, #6: add D to the latitude of the bogus coordinates, #7: add P to the longitude of the bogus coordinates. (#3 is obsolete.)
Bonus cache: The caches of my three music mysteries contain numeric codes X, Y and Z. You need the values to be able to find the bonus cache. The caches are this one (X), Synth-pop mystery (Y) and Prog rock mystery (Z). If you already have found some of these caches but don't have the codes, just ask me and I'll send them to you. (I added the codes to the log books of the caches 10.9.2017.)