Near Star weirdness

General physics and astronomy discussions not directly related to Celestia
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Evil Dr Ganymede
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Post #21by Evil Dr Ganymede » 07.03.2004, 18:03

Cormoran wrote:Dr. G,
Very nice work, and it has increased my confidence in my own star maps, as a direct point for point comparison shows that our figures agree to within rather fine tolerances :D . How far does your map extend, btw?

Only up to about 7 pc from Sol, unfortunately - that's all the RECONS list covered.

Only one point, can you confirm that the galaxy rotates clockwise in the view both are databases use, because I rather like the 'coreward, spinward' naming convention (though in deference to my pagan wife, I think I might use 'Widdershins' instead of trailing :lol: )


I quite like spinward/trailing myself, though technically the opposite of 'trailing' is 'leading' (as in trailing/leading hemispheres of tidelocked moons). And I see Grant's confirmed that the Traveller folks did at least get the spinward direction right ;).

Cormoran
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Post #22by Cormoran » 07.03.2004, 18:17

Grant and Dr. G.

Okay, I Like spinward. It's evocative. So is coreward and rimward.

Trailing isn't :lol:

Any other suggestions as to what to call it? (Not antispinward please :D )

As for the reach of your star list, Dr. G, it'd be a fairly simple matter to glue on more far-reaching databases. Obviously the further we go from home, the less accurate we get due to the number of decimal places most star lists go down to, and the greater margin of error in distances.

However, the available data is out there (and in my lil box o' tricks here too hehehe).

Let me know if you want some raw datasets I have lying about. I have an Access database with 31000 stars in it, with coordinates (not derived using your methods, but agreeing with your results). It also has RA and Dec info for the stars so you could run your own conversion method on them. Its a shame that many stars will make CHview explode :lol:

I wish I was a good enough coder to write my own version.

Anyways, let me know, and happy mapping :D

Regards,

Cormoran
'...Gold planets, Platinum Planets, Soft rubber planets with lots of earthquakes....' The HitchHikers Guide to the Galaxy, Page 634784, Section 5a. Entry: Magrathea

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Evil Dr Ganymede
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Post #23by Evil Dr Ganymede » 07.03.2004, 19:09

Cormoran wrote:Grant and Dr. G.
Trailing isn't :lol:

Any other suggestions as to what to call it? (Not antispinward please :D )

Trailing works though - plus it's better than "The Other Way" ;). It's "the direction that the galaxy is rotating around from" - and I sure can't think of a better word of that.

As for the reach of your star list, Dr. G, it'd be a fairly simple matter to glue on more far-reaching databases. Obviously the further we go from home, the less accurate we get due to the number of decimal places most star lists go down to, and the greater margin of error in distances.

However, the available data is out there (and in my lil box o' tricks here too hehehe).



Oh, I know that. I've got the entire Hipparcos dataset available via the search page there, only problem is that it's not listed in as nice a way as the RECONS list is. Plus I now have the means, thanks to my equatorial to galactic coordinates conversion spreadsheet made with the help of everyone here, to convert any star coordinates that I find into something more meaningful for Traveller. So I can at least locate the other named stars (Vega, Arcturus, Aldebaran, etc) pretty easily now.

Only problem is that I've had to figure all this out by hand (as in "plug into spreadsheet, then make up subsector maps by hand from the X/Y/Z coordinate I get from that), and I don't fancy doing that for a few more thousand stars 8O ;).

Incidentally, Cormoran - you are probably already aware of this, but a lot of the canonical star systems in Traveller don't match up with the real locations of the stars - and that's not just because for some reasons MWM decided that "coreward" on the Solomani Rim maps was actually toward the top left corner of my realistic map instead of toward the middle of the top edge.

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Post #24by Spaceman Spiff » 07.03.2004, 20:04

"Trailward"? :)

Oh look, :o all the G type stars are to one side of Sol as you approach from the galactic core... (Trailward, ahem) :)

You know what might be a challenge for long range starmaps? In all the plots of known stars centred on the sun I've ever seen, I've never seen one that shows up the spiral arms of our galaxy.

Even the 2.5million star database used in Celestia merely shows a disc of stars fading out as Hipparcos fails to detect ever more remote stars. Yet, I would have thought we have at least one major spiral arm coursing through the database. Where are these Orion and Sagittarius arms?

I believe it might be because all stars older than tyical OB associations live long enough to drift out of their birthplaces along spiral arms and smear out.

If someone can accentuate the O and B stars, I think the arms would start to show up. I think Celestia fails to show this because the dynamic range of star brightness is constrained too much to show up the arms properly.

Spiff.

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selden
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Post #25by selden » 07.03.2004, 20:21

Marc Griffith has written an SQL addon for the Windows version of Celestia that should be able to select particular stellar types. See http://mostlyharmless.sourceforge.net/sqladdon/mh_readme.html
Selden


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