Alliance/Union star map

[selden]

This is very much a WIP.

It's my second attempt at the start of a map of the inhabited stars described in C.J.Cherryh's series of books about the Company War and its aftermath, which started with Downbelow Station.

One of my self-imposed constraints is that the positions of the real stars be accurate, so what you see at this point is entirely computer generated: I wrote a program which translates the stars' equatorial coordinates into galactic coordinates and which then writes out a script to invoke ImageMagick to create the drawing. As a result, it is not yet very artistic (but I'm also a lousy artist.)

Future enhancements will include the trade routes. I'm also considering drawing in the other (real) stars of the region, but haven't decided how to represent them.

Comments and suggestions will be very welcome.

[töff]

Out of curiosity, what program are you using to determine the star coordinates, and for what era?

[selden]

The 3D coordinates of the real stars (which do not include the Jump Points ) originate from the Hipparcos database.

Since relatively few stars are involved at this point, the table that my program reads was created by hand, so there could be typos. The values were copied-and-pasted from the Simbad astronomical data server. I used their ICRS coordinates (i.e. J2000), and used StarLink subroutines to translate them into l2,b2 galactic coordinates.

When I add the background stars, I suspect I'll write a Lua script to extract their locations from Celestia. Its star positions are based on the most recent reduction of the Hipparcos database and it uses Lua as its scripting language.

p.s. I could have used Simbad's galactic coordinates directly, I suppose, but I didn't even think of it, since I've been using Celestia with equatorial coordinates for so long. I probably should use the Simbad galactic coordinates to verify that the values I'm using are actually right!

[selden]

fwiw, here's a similar viewpoint seen in Celestia, including trade routes. It's not quite the same, so I'll have to figure that out. *sigh*


p.s. the really bright stars are nearby real brown dwarf stars that I added. I was hoping that some might be close enough to the imagined Jump Points to be usable. No such luck
(CJC's Jump Points are brown dwarfs -- masses which drag spacecraft out of "jump space" into normal space. If a spaceship doesn't pass near one soon enough, it won't have enough energy left to make the transition -- or at least that's how I understand it.)

[töff]

Awesome, I love your approach.

If you are using the J2000 epoch data -- well, is this map associated with a story? And, if so, is that story set i the future or the present?

I ask because I'm doing a map based in 15,605 A.D., and the positions of stars & planets are all different. Even the Zodiac will be different. I've decided to rely on the Starry Night proggy for it, although I've found conflicting data from other sources.

[töff]

... It's not quite the same, so I'll have to figure that out. *sigh*

LOL! Amen. I know exactly where you're coming from, there, brother.

[selden]

Awesome, I love your approach.

If you are using the J2000 epoch data -- well, is this map associated with a story?

Yup: Downbelow Station and its sequels.

And, if so, is that story set i the future or the present?

Most CJC's series of A/U books take place between 2350 and 2400, so J2000 positions aren't too far off. By definition, the ICRS coordinate system is fixed and won't precess with time.

I ask because I'm doing a map based in 15,605 A.D., and the positions of stars & planets are all different. Even the Zodiac will be different. I've decided to rely on the Starry Night proggy for it, although I've found conflicting data from other sources.

Unfortunately, Celestia doesn't include proper motions at all, so it wouldn't be any help. I haven't taken them into account, either. I don't have Starry Night, so I don't know how it handles those.

[töff]

Celestia doesn't include proper motions at all, so it wouldn't be any help. I haven't taken them into account, either. I don't have Starry Night, so I don't know how it handles those.

Now that you mention it, neither do I. For all I know, it is simply rotating the entire celestial sphere as a single body of fixed stars. Fortunately, my particular project is just the Solar System, not the individual twinklies.

[selden]

A "minor" update that took most of the afternoon. I verified that the galactic coordinates are correct. I eliminated the uppermost star in an attempt to increase the overall size to make the central labels more readable. It wasn't very successful. I'd rather not make the image gigantic, though.

[selden]

It's now two maps.

The first shows the stars as seen when looking down from galactic North, with the galaxy's center off to the right. The other shows the stars as seen when looking toward the galactic Center. i.e.it shows the stars of the first map as if you were looking at them from the left side of that map.

I've also added background stars so the maps don't look quite so empty. They were drawn using a database of stars closer than 25LY.

I was pleased to see that many of the nearby stars correspond to A/U station stars: a + was drawn in the center of most of the 5-pointed stars which indicate the positions of the Stations.

I think I understand why some of the Station stars don't have a plus mark. There are two causes:
1. I had to make up imaginary closer distances for a few of them, because otherwise they'd be way outside the range of human spacecraft. e.g. Gehenna at ZET Riticuli: the real star is a double which is a long way away.
2. A few of them simply aren't included in the "nearstars" database.

I think that it's now time to try to improve the presentation, since the data isn't going to change any more. I'd greatly appreciate suggestions.