I am one of those people that likes realism in his space campaign.
In regards to that I like the idea of a 3D starmap and I use the 2300AD
map, but of course, I have wanted a larger 3D map. I am in the process
of converting the "Machine Readable Version of the Catalogue of Stars
within 25 Parsecs" to use in a database.
For those of you not familar with the catalogue, its on finet somewhere in
Finland. There are 2150 records, each 135 bytes long, containing up to 44
pieces of information on stars within a sphere around our sun , 25 parsecs
in radius.
I have put the file into Excel and exploded each 135 byte record to tis
its components. I have then set up a database (Access) to receive the
information. My own goal is to have a file containing the coordinates
(preferably cartesian for simplicity) for display in other programs, and a
file containing information like magnitude , type of star , etc. This
would be inthe same format as the 2300AD starmap, Near Star List"
The database will allow users to look at stars in a particular area of
space, or a type of star, or whatever information you put on it.. ie,
something to store campaign information in . One possibility would be to
store political allegiencies, navy sizes, trade types.
This is being done on a PC, in Windows, and I will make it available to
everyone onthe group, but I have a problem. I want to make a starmap that
would give an accurate location for a star at the time of my campaign (2203
AD). I don't know how to use some of the data. It gives declination, and
right assencsion for each star, but there is such things as:annual proper
motion, radial velocity, U component fo space velocity relative to Sun, V,
and W components, Box orbit parameters w, e, and i.
Its fairly obvious to me that all I need to do is use one set of these
numbers, specifically the velocities to determine the star's position in
2203. However, I have a few questions:
1) How do the U,V, and W components relate to the declination?
2) What re the box orbit parameters relation to U,V,W and the
RA/declination?
3) How does parallax play a role in these numbers?
I am aware that parsecs (3.34 ly per parsec ) are the recipricol of
parallax, and the error in parallax increases the farther out you go.
What I need advice on is which of these sets of numbers to use, if more
than one set is given for a particular star? Also, do I need to worry
about the orientation of the dec with respect to the sign of the number when
I convert to spherical coordinates? The data is given is positive or
negative numbers, and I am wondering how this relates to the other
parameters given? Since this is not that difficult to calculate and
compare numbers on my own, I would like to know what other people know
about this subject or whether they have done their own calculations. It
wouldn't matter if I just used RA and decl, since I can arbitrarily set my
axis anywhere, but I want to know for consistency , how the other parametsr
relate to this.
Secondly, I want to know if I need to modify this data with regards to:
precession, geocentric parallax correction on RA/DEC and atmospheric
refraction?
If so , what are the equations?
There is not that much data in the file on each star, and once I have the
information it would not be that difficult to plot all the points, or have
the database select a section of the sphere and just plot that.
I would really appreciate it if someone would take one set of numbers,
whether real or not, and show me the relationship between them.
Hopefully I can get this done fairly quickly, post it, and go on to other
things. By the way, anyone use the database ability of Excel? What do
you think of it?
Steven B. Fellows
[email removed]
PS: The current size of the Excel file is about 4.5 megs up from 300 k from
the original datafile. The database sits at about 580 K, but that is just
a table of the data, with no forms yet. The ultimate goal, is to have:
1) Star number (field index)
2) X coordinate
3) Y coordinate
4) Z coordinate
5) Luminosity
6) Magnitude
7) Spectral type
There is also something called B-V color and U-B color. I would assume
this is either related to redshift, or spectral type.. any ideas?
PPS: If Jack Dietz is reading this list... ( can 't remember if my
correspondence on this subject is from here, or from NetNews), how are you
doing on your project related to this?