For the orientation, now I can see why the image in the previous screen shot is tilted. Among all the panels, one is tilted relative to the Galactic plane, and that one happened to be picked by APP as the reference.
My OS is MacOS 10.10.5. The machine is a 3.4GHz i7 iMac with 16GB of RAM. The OS and apps are all stored in a 1TB-SSD*2 RAID0 external enclosure through a Thunderbolt2 connection. It’s not the fastest Mac, but still pretty fast especially for launching apps, because of the RAID0 SSD. To be clear, after I launch APP, its icon appears immediately, but it takes 2 to 3 minutes for the processing window to show up. Yesterday when I entered the license for the first time, it also took this long (or even longer) for the license activation. Because it took so long, I almost thought the activation failed.
Finally, will the equirectangular projection project the 2pi sky into a sphere or a rectangle?
Cheers,
Wei-Hao