How to get a list of stars around some target?

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Topic author
captain_picard
Posts: 6
Joined: 11.08.2010
With us: 9 years 2 months

How to get a list of stars around some target?

Post #1by captain_picard » 09.02.2013, 14:23

Hi all,
I have the following question:
Is it possible to use Celestia and via a script or addon, to get a list of stars inside a radius of x lightyears around the currently selected object and highlight them, say with a colored reticule or something?

An example would be the following: Select a star, say Sirius, and then run the script in order to highlight all the stars in a 200ly radius. I understand that would mean a hell lot of stars (~200^3/3^3~10^5 in this case), but perhaps one could add further criteria like star type or brightness etc.

So, is this possible? BTW, I know that going to Navigation > Star Browser, I can do something similar, but it is not exactly what I want, ie to highlight them all at the same time. From a quick search that I did, I didn't find anything helpful.

An idea would be to do the selection and calculation a priori in some other program and then modify Celestia's star catalog to contain only these stars, but it would be nice to do it in real time.

Thanks for any pointers/help!

Cheers
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jogad
Posts: 458
Joined: 17.09.2008
With us: 11 years
Location: Paris France

Re: How to get a list of stars around some target?

Post #2by jogad » 09.02.2013, 19:02

Hi,

Have a look here
http://en.wikibooks.org/wiki/Celestia/C ... stia#stars

In the given example stars are selected by spectral type but you can choose the distance from a target or any creterion you want.

:mrgreen:

Topic author
captain_picard
Posts: 6
Joined: 11.08.2010
With us: 9 years 2 months

Re: How to get a list of stars around some target?

Post #3by captain_picard » 09.02.2013, 19:10

Awesome!!! It seems to be exactly what I am looking for!!! Many thanks dude :D

Cheers
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Marco Klunder
Posts: 180
Joined: 20.02.2008
Age: 57
With us: 11 years 7 months
Location: The Netherlands

Re: How to get a list of stars around some target?

Post #4by Marco Klunder » 09.02.2013, 19:18

Although already cross-posted by Jogad, here is an example code to mark stars from the actual selected star within a given distance of 100 LY
You can of course adjust the distance.

Code: Select all

obs = celestia:getobserver()
obs:setframe(celestia:newframe("universal"))
celestia:unmarkall()
celestia:setrenderflags{markers = true}

-- Set distance in Lightyears
distance = 100

i=0
number_of_stars = celestia:getstarcount()

actual_selection = celestia:getselection()
if actual_selection:type() == "star" then
   pos_actual_star = actual_selection:getposition()
   for star in celestia:stars() do
      distance_to = pos_actual_star:distanceto(star:getposition()) / 9460730472580.8
      if distance_to <= distance then
         label_string = string.format("%4.1f", distance_to)
         star:mark("gold" , "square", 4, 1, "" .. label_string, false)
      end
      i=i+1
      if math.fmod (i, 1000) == 0 then
         celestia:print("Starcount: " .. i .. " of total: " .. number_of_stars, 10, -1, -1, 2, 4)
         wait(0)
      end
   end
   celestia:print("Stars marked with distance to " .. actual_selection:name() .. " < " .. distance .. " LY.", 10.0, -1, -1, 2, 4)
   wait(10.0)
else
   celestia:print("Actual selection is NOT a star", 3.0, -1, -1, 2, 4)
   wait(3.0)
end


Marco
Last edited by Marco Klunder on 09.02.2013, 22:39, edited 2 times in total.
Marco Klunder
email: marco.klunder@hccnet.nl
Windows7 Ultimate, PD 3.0 GHz, 2 GB of RAM, Nvidia GeForce 6700 XL
Celestia161 / SVN + Lua Edu Tools v1.2 Beta9 and Celestia160-ED

Topic author
captain_picard
Posts: 6
Joined: 11.08.2010
With us: 9 years 2 months

Re: How to get a list of stars around some target?

Post #5by captain_picard » 09.02.2013, 19:34

Many thanks dude, you rock!!!!

I will give it a try asap :)

Cheers
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Avatar
Marco Klunder
Posts: 180
Joined: 20.02.2008
Age: 57
With us: 11 years 7 months
Location: The Netherlands

Re: How to get a list of stars around some target?

Post #6by Marco Klunder » 09.02.2013, 22:41

Small edits to the code in the above post.
Because the script was far, FAR, FAR to slow....

Marco
Marco Klunder
email: marco.klunder@hccnet.nl
Windows7 Ultimate, PD 3.0 GHz, 2 GB of RAM, Nvidia GeForce 6700 XL
Celestia161 / SVN + Lua Edu Tools v1.2 Beta9 and Celestia160-ED

Topic author
captain_picard
Posts: 6
Joined: 11.08.2010
With us: 9 years 2 months

Re: How to get a list of stars around some target?

Post #7by captain_picard » 10.02.2013, 10:32

Thanks for the update on the script! I have just tried it and it works beautifully :)

Cheers
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