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The sierra mountains area in California is indeed an interesting place! If you can stay long enough, I suggest you to drive from the Death Valley up to the Mono Lake (there are a few places you may want to stop and take photos on your way), and then turn left toward the Yosemite. I will keep my fingers crossed for your planned trip to U.S.A.!
By the way, my teenaged son and I just started night-sky photography and your photos are truly amazing!!!