The Alien Obelisk Sol-Sirius Network is a network of three alien obelisks built in the Sol system by an unknown civilisation. These obelisks were also connected to a temporal anomaly in the Sirius sector. (Dragon Ball Z vs. Star Trek: The Beginning of Infinity, Dimensional Prophecy of Zohar)
The first obelisk's location was discovered by members of the Catholic Church during Earth's Middle Ages. Unaware of its purpose but believing that it was an object of importance they kept its location a secret. To allow for future generations to locate the obelisk they left clues to its location in a number of mediaeval churches.
It wasn't until the 24th century that the obelisk would be rediscovered. During her pregnancy, Katsuki Farell was covered by a strange light, accompanying this light was a vision of the monolith. The vision indicated that there was a connection between the obelisks and Farell's unborn daughter, Madoka Michael.
Michael would later locate the monolith in the Sahara. An autistic savant, Michael was able to activate the monolith.
To gain more information about the network the Arale supercomputer was built to interface with the alien network.