Gentlesophonts:
Rick Blackburn [email removed] writes:
> I read with great interest the post on the "Earth/Sirius" subsector.
> I only have one problem. I am pnly a "reader" of Travler, et al,
> and not a player, so, I may be missing something. I do not understand your
> "Jump Destination Table" {reproduced below.}
> On the surface this would "appear to list:
> 1. Galactic Co-ords
> 2. Planet Name
> 3. Starsystem
> 4. Distance in PC
> If this is so, then column 3 does not match up with column 4 in ANY way
> whatsoever. Several different co-ords/distances are listed
> for Procyon.
> Can you please tell be a little more about how THESE figures fit in
> with the Near Star Catalogue from 2300? {Which I accept as being accurate}.
> Your Table reproduced here:
> >Earth/Sirius Jump Destinations Table
> >Destination World Name (Allegiance) Distance (pc)
> >1620.20 Issyk Kul/Procyon (Co) 1
[Rest of the table omitted.]
Ooops! Guess that was a lot of information to digest at one time. The
first problem is that the headers for my table aren't as clear as they
could be. A better header might read like this:
Hex_Location World_Name/Subsector_Name (Allegiance) Distance (pc)
Thus, for example, the world Issyk Kul, located in hex 1620.20 in the
Procyon Subsector, is a member of the Commonwealth of Earth (Co) and
is one parsec away from Earth.
In the Earth Colonies campaign many subsectors are named for
their brightest star. In this Jump Destinations Table for Earth/Sirius
(that is, the world Earth in the Sirius subsector), Procyon,
Fomalhaut, Pollux, Sirius and Vega all refer to *subsectors* rather
than to the stars themselves. Following the Traveller convention the
*system* name is omitted and the main world name is used with the subsector
name instead. Thus, the star names from the 2300AD Near Star List do
not appear in the world/subsector names in the Earth Colonies campaign.
For example, in the example above, the world of Issyk Kul is actually
located in the Alpha Centauri system but appears on star charts and the
like as Issyk Kul/Procyon.
The 2300AD Near Star data lists Cartesian (xyz) coordinates in lightyears
(cyr) for the star systems. These coordinates were converted to parsecs
(pc) and overlayed onto a three-dimensional sector hex map (basically a
`stack' of 36 standard Traveller 2D sector maps to add `depth') centered
on the Sol system (Earth) located at hex 1720.19 (again the conventional
1720 sector hex location but at a `depth' of 19 pc in the `stack').
A Jump Destinations Table like this one for Earth is developed by a
world developer so that jump distances don't have to be continually
calculated for that particular world using the Cartesian formula. These
calculations *can* be made though for any two worlds in a sector if their
hex locations are known. For example, Issyk Kul, at hex 1620.20, is one
parsec from Earth, at hex 1720.19 as follows:
SQRT [ (16-17)^2 + (20-20)^2 + (20-19)^2 ] = SQRT [ (-1)^2 + (0)^2 + (1)^2 ]
= SQRT [ 1 + 0 + 1 ] = SQRT [2] = 1.4 which rounds to 1
Hope that makes the 3D Earth Colonies Sphere a little clearer.
Happy Travelling,
David Johnson
Houston, Texas, USA