Comet 103P Hartley mosaic showing the nebula NGC 1491 , open cluster King 7, and open clusters NGC 1528 , 1513 and 1545 . This was shot from Global Rent a Scope GRAS 14 (stack of 5 black and white images at 60 seconds each for top image and one 60 second image for the bottom image with the comet). You, really, really need to click to embiggen (it's worth it).
Yes, I deliberately made this mosaic, really I did. I didn't mess up my imaging co-ordinates and take 6 images of a completely comet free area before realizing my mistake, no siree.
If you want to see how it is really done, this stunning mosaic from Rolando Ligustri is the way to go.
Chart showing area where images were taken, the field of view of the G14 imager is shown as the large rectangle at the bottom.
The individual FIT images were stacked in Image J using Max Z projection, saved as half scale png's then assembled in the Gimp using layers and difference features.