aka 'Operation quadripoint'
Mission & vision System info
History log Carrier Crew
The quest to find the quadripoint
The cartographic survey near the "cross-shaped" border of the four regions Izanami, Newton's Vault, Arcadian Stream and Ryker's Hope shows that there exists no real 'quadripoint'!
There are two "3-region-confluences" about 50ly apart from each other: Newton's Vault and Ryker's Hope share a common border, while Izanami and Arcadian Stream do not.

The following schematic illustrates the situation:

There can be only one
When drawing a line between the two confluence points located at
[3509 | 0 | 39901] and [3559 | 0 | 39901], any system located near the "midpoint" at [3534 / 0 / 39901] must be in minimum distance to all four regions.

Luckily, there is one system nearly exactly on these coordinates, only -13,7 below the galactic pane:
PLOEA AUSCS ZA-A c16 at [3534.4375 | -13.6875 | 39901.0625]

..and here we shall raise a monument!
The system is located at the very "north-west" edge of Ryker's Hope region, you can reach the three other sectors via a short jump (less than 30ly each):
Newton's Vault = Ploea Auscs AC-A b6 6,98 ly
Arcadian Stream = Ploea Auscs NA-A d110 27,94 ly
Izanami = Ploea Auscs YB-A b8 29,80 ly