Not really my area but I clicked on this because I was bored and now I'm annoyed because it's actually interesting and I have work in the morning.
The astronomical alignment thing gets thrown at every ancient site going - Stonehenge, the pyramids, whatever - so I'm always a bit sceptical when someone rolls it out again. But the Nazca stuff does feel different because the scale of it makes no sense if it was just art. Like you wouldn't carve a hummingbird the size of a football pitch just for the lads to admire from ground level would you.
What calculations did you find exactly? Because I've seen people claim alignments before and then it turns out its only accurate if you squint and pick the right date. Would be good to see the actual working rather than just the conclusion.