I've just landed at Carstensz Base. I can assure you it's definitely there.
There are 7 planets/moons in the system and two of them are land able.
The planet you want to land on is over 4,000 ls from where you arrive so if you only scanned with a basic or intermediate scanner on arrival it's hardly surprising you didn't find all the planets.
There *are* ways of finding planets/stars with a basic/intermediate scanner at much longer distances but if they in the 100,000 or more range the technique is an exercise in pain.
TL;DR Advanced discovery scanner: don't leave home without it.