My Orion GIF was created using PixInsight's BLINK process to create PNG files which I then turned into a GIF using the PS  Timeline window.  The mpg4 that I also made with PS  was flawless, but rendering the GIF I found that if I dithered I lost all tonal and contrast control  of the image.  The un-dithered image I posted   shows obvious  intensity banding, which is what dithering is supposed to fix.

What tools and settings have others used to make high quality GIFs?