It was all skybox matching at first.
IMPORTANT NOTE : I have literally ZERO idea about how the system/planet was found. I just joined Alex in voice who straight told me about CJ's lead, that is all. The skybox match I tried was strictly done once in orbit of the planet.
Really an hit and miss, I circled around the planet several times until I thought of being close enough. Glided down to the surface, straight toward the canyon that was under me. From there just following the canyon's general direction; there was an awful lot of surface POIs on my radar in that area, I aimed at them at first but was only finding System Defense Force vessels every single time, which led me into a circling chase of about 50kms in radius, until I had the Milky Way's bright light contrasting with the surface on the screen (not even talking about the ambient occlusion near fat rocks on the ground that let you think you found something, the deception every time
).
There was an object near a few rocky ridges that was creating some aliasing with the heavy contrast right in the middle, so I headed there, and bam.
I realized long afterward that it wasn't the same as the trailer, I was so focused on the background that I entirely forgot to compare.
Of note, I spent a few thousand hours licking planetary surfaces back during the CoR exploration CG in search for the bases, so had a fair few ideas of how to "enhance" the yoghurting experience already
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About the above : Reduce all your graphic settings to the absolute minimum (planets looks like yoghurt at this stage, hence the term), try to find "contrasty" lighting conditions, and something I like doing : licking the surface upside down with the camera angled straight up your head