celestial sphere  1-20  21-30

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 From:  BurrMan
7559.1 
So it turns out I would like a model of a Celestial sphere or "Celestial Globe".......

Looks like these Hubbard Scientific types:




I looked around.... If anybody knows where to resource a model (preferably NURBS), let me know please... Found only 2 on sketchup, but they are just sphere's, without any stars mapped out...

probably will just start to model it soon.... :o
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 From:  bemfarmer
7559.2 In reply to 7559.1 
A search for planetarium, stellarium, or constellations might help.
- Brian
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 From:  Michael Gibson
7559.3 In reply to 7559.1 
Hi Burr, it's not quite the exact thing you're looking for but you might search for "orrery" if you want something just kind of generally similar, there are a few models on GrabCAD for that but it has planets going around instead of a star map.

- Michael
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 From:  bemfarmer
7559.4 
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 From:  BurrMan
7559.5 In reply to 7559.3 
Thanks for the reply's... Gonna make it.... :)
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 From:  bemfarmer
7559.6 
This link seems to have very helpful information:

http://www.heavens-above.com/constellation.aspx?lat=0&lng=0&loc=Unspecified&alt=0&tz=UCT

A script to plot Right ascention and Declination, and even spot size for magnitude, translating from Ra, Dec, with spherical coordinates,
to x,y,z might help?

- Brian

Source of above information, and more: http://www.astronomyforum.net/amateur-astronomy-forum/32911-drawing-constellations.html

(http://www.rtgui.com/ links to Cartes du Ciel)
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 From:  BurrMan
7559.7 In reply to 7559.6 
Ah, the "magnitude"... something i wasnt considering. Thanks Brian.... :)
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 From:  BurrMan
7559.8 In reply to 7559.6 
Hey Brian. So i am going to use the pdf's you linked above to map stuff out. I also bought one of the 300 series globes to aid the setup. It will help me with converting hours and minutes to the angles i need and should help with proper scaling..... its about 4 weeks out. Gives me time to polish a few other things.... :)
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 From:  bemfarmer
7559.9 
The celestial math is becoming slightly less opaque.
Some references and thoughts:
http://www.heavens-above.com/constellation.aspx?lat=0&lng=0&loc=Unspecified&alt=0&tz=UCT
https://en.wikipedia.org/wiki/Spherical_coordinate_system
https://en.wikipedia.org/wiki/Celestial_coordinate_system
https://en.wikipedia.org/wiki/Celestial_sphere#Celestial_coordinate_systems

https://en.wikipedia.org/wiki/Equatorial_coordinate_system
https://en.wikipedia.org/wiki/Right_ascension
https://en.wikipedia.org/wiki/Declination

Previously in scripts, points have been plotted in Moi, using spherical coordinates converted to (x, y, z).

Star locations are available in Right Ascension and Declination, Equatorial coordinates.

Right Ascension:
RA is measured in time units of hours, minutes, and seconds.
Convert RA to degrees using 360 degrees = 24 hours.
24 h = 360 deg
1 h = 15 deg, 1 m = 15', 1 s = 15"
1 deg = 4 m, 1' = 4 s
Then convert to radians, 2PI = 360 degrees.
This radian angle is the same as Theta in spherical coordinates, mathematics version, not physics.

Declination:
Dec is measured in angles, i.e. degrees, minutes, seconds.
Dec must be converted to angle Phi in spherical coordinates.
Note that for a negative declination, minutes and seconds are ALSO negative.
Angle Phi in spherical coordinates is equal to (90 degrees minus Dec) [where Dec may be negative.]
Example: Declination of -10 degrees yields Phi of (90 - (-10)) = 100 degrees in spherical coordinates.
Convert Phi to radians.

{Note: Max kept dec, instead of converting to phi, so sin and cos(phi = dec) would be swapped}

Radius of the celestial globe, Theta, and Phi, are converted to (x,y,z) point in Moi:
var x = r * Math.sin(phi) * Math.cos(theta);
var y = r * Math.sin(phi) * Math.sin(theta);
var z = r * Math.cos(phi);

return moi.vectorMath.createPoint( x, y, z );

Point could be made into a small color circle for a large/bright appearing star. What diameter?
Add lines (great circles) connecting constellation stars.
Vernal equinox, time of day...

- Brian

http://spider.seds.org/spider/ScholarX/coords.html

EDITED: 22 Aug 2015 by BEMFARMER

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 From:  Max Smirnov (SMIRNOV)
7559.10 
Hi :)
It's very interesting task. I've wrote ~80% of the script. It took about 30-40 minutes.
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 From:  Max Smirnov (SMIRNOV)
7559.11 
Starmap.v.0.3.2015.08.23

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 From:  BurrMan
7559.12 In reply to 7559.10 
Max,
I would love to see that....
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 From:  Max Smirnov (SMIRNOV)
7559.13 

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 From:  bemfarmer
7559.14 In reply to 7559.11 
Yikes! That was fast.
I see that using dec instead of phi swaps cosine and sine in getting x,y,z.

- Brian

EDITED: 22 Aug 2015 by BEMFARMER

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 From:  BurrMan
7559.15 In reply to 7559.13 
Very cool Max!!! Wow......

If you would like to dig into this a bit, I would be willing to pay you to further customize it..... Let me know if you have time to get into it...

Thanks for the effort!
Burr
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 From:  Max Smirnov (SMIRNOV)
7559.16 
Updated version.
I thought that "mag" value is some kind of distance. I was wrong :) Fixed it.

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 From:  bemfarmer
7559.17 In reply to 7559.16 
.
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 From:  Max Smirnov (SMIRNOV)
7559.18 In reply to 7559.15 
Burr, thank you :)
What do you want to customize?
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 From:  bemfarmer
7559.19 
OK, radius of celestial sphere = distance = 50 units setting.

-Brian
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 From:  Max Smirnov (SMIRNOV)
7559.20 
Starmap + vSeed + ArrayGem :)

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