I want to make a better skybox.

[WhiteWeasel]

Seeing as my endeavors in the modding section have been fruitless, I have to ask here for help now. Anyone good with GIMP? I'm trying to modify a texture for the sky box in ksp, I got Raredens' high res one, but wanted to add some flair to it by adding a nebula. Thing is I want to kinda make it (a little) transparent around the edges so the stars blend better and get rid of ugly "cut offs" (really noticeable in the in game view). The nebula should probably be scaled up a bit more, so its' stars are the same size/density as the background texture. What I managed so far:

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