This is very largely based on an article I originally wrote for the Horizon club's newsletter. It appeared in #28 (May 1992 - bloody hell, that long ago?). Like most analyses of this kind, it relies largely on sifting through all the references and implications in the source material, and then picking the ones that most appeal. Anything that contradicts such preferences is Wrong (and probably written by Allan Prior).
A quick glossary, for the various terms and abbreviations I'll be using throughout this article:
One problem you stand to run into when detailing the B7 universe is the question of ship speed and distance. Speeds are normally given as a multiple of an unspecified 'standard' speed for the Liberator, or as a Time Distort value for Federation and other ships. Distance is normally given in 'spacials', with no indication as to what a spacial actually is. (In Spacefall distance is given in 'subsecs', but this is the only episode to feature this term.)
Tony Attwood, in his Programme Guide, offers a value of 1000c (ie; one thousand times the speed of light) for TD-1, though this value would seem to have been plucked from nowhere. Impressive as 1000c might seem, I feel this is a severe underestimation of just how fast the ships really were. Lets look at some of the evidence from the series.
Like Attwood, I'm forced to pluck a number out of thin air, but I'm opting for TD-1 as 3000c, not 1000. There's a reason for this, namely the relative speeds of Liberator and Federation ships. There are two main references to draw on here.
I'm adopting the 5:3 ratio here, though I freely admit it's hardly the only option. The series just doesn't give enough firm evidence. To keep things simple, I could further assume that TD-1 is a tidy 3000c, and SB-1 an equally neat 5000c. Liberator's standard cruising speed of SB-6 (equivalent to TD-10) would then work out at 30,000c.
However, because of the values I arrived at in determining the value of a spacial, I'm increasing these speeds by a further 25% (near enough), so TD-1 is actually 3,900c and SB-1 is 6,500c. SB-6 is therefore 39,000c.
At first glance this might seem impossibly high (oh, alright, yes, it is impossibly high in real terms) but within the context of the series, it fits in quite neatly. At 30,000 times the speed of light, Liberator could:
This correlates with the premises given in the series, that short inter-system journeys could be made in a matter of hours, that longer voyages could be considerably protracted (eg the eight months 'ship time' haul to Cygnus Alpha), and that the galactic rim and globular clusters are accessible but the Andromeda galaxy is not.
The London left Earth at TD-5, and for want of any other reference we can take this as the standard speed for the voyage (we can reasonably expect an old tub like the London to be slower than a pursuit ship's TD-9). Spacefall gives a journey time of eight months to Cygnus Alpha. There are two problematical dimensions to this. Firstly, the eight months was 'ship time' rather than 'real time' (if there is such a thing), implying (a) that there is some measure of time dilation in FTL travel and (b) that the 'real time' journey presumably took longer than eight months. Secondly, there is the question of Cygnus Alpha being the star Alpha Cygni, which is a mere (!) 1600 ly from Earth.
Leaving aside the unlikelihood of Alpha Cygni having any planets at all (it is a very bright star with a relatively short life span), we can look at the London's voyage in either of two ways.
Which is why I'm forced to the conclusion (no matter how vociferously Judith Proctor might argue to the contrary) that the Cygnus Alpha penal colony is not Alpha Cygni.