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PostPosted: Sat, 17-09-16, 15:03 GMT 
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t00fri wrote:
CC,

if you have a big, nicely calibrated monitor, then...have a look in the dark:
[click on images by all means and then on the fullscreen button of your browser (FF => F11)]

Just the Milky Way with 2 million (non-GAIA foreground stars). They are available at Motherlode (Grant Hutchison et al., http://www.celestiamotherlode.net/creat ... _1.4.0.zip) and involve assumptions about spectral properties etc. The MilkyWay is the famous one by Nick Risinger sitting on a transparent sphere with the Sun in the center. The MW has the highest resolution he has granted us free of charge ;-) and is very accurate )The 2M stars are numberwise in the same ball park as what we can expect from GAIA in the near future!


Fridger,

I have had Grant's 2M stars for many years now, however you may have perhaps misunderstood the observation I was making ...
... which is that views from within the galaxy (at least anywhere near Sol) are one thing. however views from outside the galaxy are another thing altogether.
Even with the 2 million stars addon, we only have actual stars represented in a rough sphere surrounding Sol. The reasons for this are obvious (I'm sure I don't have to explain to you ;) ), but the net result is that with Galaxy rendering enabled (and Mag Limit WAY up), we see this:
Attachment:
Milky Way Galaxy.jpg
Milky Way Galaxy.jpg [ 127.73 KiB | Viewed 1334 times ]

however with Galaxy Rendering disabled we only see this small sphere of stars (lower left) surrounding SOL:
Attachment:
Milky Way Stars.jpg
Milky Way Stars.jpg [ 39.15 KiB | Viewed 1334 times ]


I was hoping that the GAIA release would give a more complete rendering of actual star distribution in the other arms and further reaches of the galaxy, not just in our vicinity, which might go some way towards a realistic rendering of the structure of the galaxy using the actual distribution of stars, rather than a constructed sprite, however perhaps this is just wishful thinking.

CC

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PostPosted: Sat, 17-09-16, 17:55 GMT 
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t00fri wrote:
Now that we are an active team of FOUR highly competent developers (Andrew, Chris( ELChristou), Dawoon, and myself) you will not have to wait very long anymore for the first beta release of celestia.Sci!.

I would so much love to believe this!
Telling us that
t00fri wrote:
My old Sprite map of the Milky Way in Celestia is retired since a number of years

is only half the truth, right? :)
Anyway, I'm waiting impatiently for some signs of life from .Sci - and I'm not even talking about a release in any way. Just some repository with the sources, even without further explanation, would be welcome!

Steffen


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PostPosted: Sat, 24-09-16, 12:57 GMT 
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Some progress on processing the TGAS result set: here's the view from the vicinity of a certain infamous star. Note that in this case, the spectral type used is a guess based on the B and V magnitudes, uncorrected for reddening - not sure how feasible it will be to correct that. From this region of space, the bright supergiant Deneb appears to be the brightest star in the night sky. HIP stars have proper motions applied to move them to the 2015 positions, to match the Gaia coordinates.

This has revealed a bug in my spectral type parser that also affects my XHIP add-on, I will be releasing a fix in the near future.

Still on the to-do list: build HD and SAO cross-indices. (I'm aware of this catalogue for HD-TYC2 matching, but looks like SAO will require processing). Add TYC-HIP cross index and the relevant code to handle this in Celestia.Sci.


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File comment: View from the vicinity of TYC 3162-665-1
tycho-example.jpg
tycho-example.jpg [ 61.24 KiB | Viewed 1239 times ]
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PostPosted: Mon, 26-09-16, 17:58 GMT 
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To give an indication of the likely size of the star database, my current stars.dat has 1947379 stars from the XHIP and TGAS catalogues that survived the various validation processes. Some further changes I'm planning to incorporate may well result in this number changing. On my machine this does not result in a particularly noticeable drop in performance. Future Gaia releases may be more of a challenge though. :)


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PostPosted: Mon, 26-09-16, 18:11 GMT 
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ajtribick wrote:
To give an indication of the likely size of the star database, my current stars.dat has 1947379 stars from the XHIP and TGAS catalogues that survived the various validation processes. Some further changes I'm planning to incorporate may well result in this number changing. On my machine this does not result in a particularly noticeable drop in performance. Future Gaia releases may be more of a challenge though. :)


Good to know the number of stars we can expect in the near future. From the 2 million stars by Pascal Hartmann and Grant Hutchison (Motherlode) we already have a fair idea about the new amount of "crowdedness" we can expect ;-)

F.

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PostPosted: Fri, 30-09-16, 17:09 GMT 
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http://tapvizier.u-strasbg.fr/adql/?I/337

I/337/tgas ( 2057050 rows ) (positions)
TGAS: Subset of GaiaSource (\originalcolumnnames)

Hipparcos identifier (\original{hip}) => HIP

Tycho 2 identifier (\original{tycho2_id}) => tycho2_id

Code:
-- output format : csv
 SELECT TOP 10 "I/337/tgas".hip,  "I/337/tgas".tycho2_id,  "I/337/tgas".ref_epoch,  "I/337/tgas".ra,  "I/337/tgas".parallax,  "I/337/tgas".phot_g_mean_mag,  "I/337/tgas".phot_variable_flag,
 "I/337/tgas".dec
 FROM "I/337/tgas"



[ run ] => download (csv)

;) admin t00fri


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PostPosted: Fri, 10-02-17, 17:06 GMT 
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The second Gaia Data Release has been postponed until April, 2018. :(

See https://www.cosmos.esa.int/web/gaia/news_20170203

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PostPosted: Fri, 10-02-17, 17:22 GMT 
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Pity, that's going to make the matter of filling in the undersampled regions of DR1 (responsible for the nasty stripe patterns) a bit more of a pressing issue.


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