Ragnar

Ragnar is a gas giant planet, and the location of the Ragnar Anchorage munitions station located in the outer reaches of the Twelve Colonies. After the Fall of the Twelve Colonies, Commander Adama, assuming command of the Colonial Fleet (RDM) after Admiral Nagala's death, orders all ships to Ragnar; President Laura Roslin's fleet is the only known assemblage of ships to make this rendezvous.

The atmosphere of the planet, in keeping with some gas giants, is wracked by violent storms. Ragnar Anchorage station appears to be located in an area of relative calm within the very tenuous upper atmosphere.

The storms themselves create a high level of electromagnetic interference in the upper atmosphere of the planet, which interferes with a range of systems, including a ship's ability to plot FTL jumps. While this effectively hides Ragnar Anchorage from enemy scans, it also means that a ship must cross the "EM threshold" above the main bulk of the atmosphere before attempting a jump. This problem requires Commander Adama to place Galactica directly between the planet and an opposing force of Cylon basestars to provide the necessary protection for the civilian Fleet to jump away from Colonial space.

Another side effect of the storm is the emission of a form of radiation that adversely affected the Cylons' silica pathways, technology integrated into humanoid Cylons. When Leoben Conoy appears to fall sick while trapped on the station with Adama, it gives the commander his first clue that Conoy is a Cylon construct (Miniseries).

Notes

The name of the planet is an allusion to the tale of Ragnarok, the apocalyptic battle of the gods of Norse mythology.
It is possible that the deleterious effects on the Cylon technology became known to the Colonials during the Cylon War, prompting them to place the Anchorage within the planet's atmosphere.