SkySafari Custom Horizon Panorama Notes for MacOS & iOS

Long wanted to do this and so very happy I finally did, but ran into little snags that I wanted to help other SSP users avoid. First, on iOS and iPadOS, SkySafari Pro won’t recognize correctly sized and placed files ending in “.PNG”, but has no problem with “.png”. That took me a while to figure out. Second, all platforms now support at least 4096 x 2048. Third, my first panorama was off in azimuth. To correct this, I used Google Earth to draw a line between my horizon panorama location and a distant landmark visible in that panorama to get its bearing relative to true north. In my photo editor (Photoshop) I doubled the canvas size laterally to 8192 x 2048 and placed 2 copies of the panorama side by side. Since each column of pixels in a 4096 pixel wide panorama spans 4096/360 = 11.378 pixels, you can determine exactly where to crop the 4096x2048 image from the doubled image so that the outer edges are perfectly aligned with true north. In Photoshop I used rectangular selections of fixed sizes and snapped guides dragged from edge rulers to the sides of those selections for easy and accurate placement. Now that I have a functioning panorama horizon I can plan automated imaging sessions with greater confidence and also know when certain events will require changing locations. I’ll be adding more panorama for those locations, too. Arlo