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Comet Lulin and Stellarium

 
Reality420
User ID: 620662
United States
02/22/2009 02:34 PM
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Comet Lulin and Stellarium
Good day.

Those of you who have the freeware planetarium program Stellarium may have noticed that there is no online means to add comet C/2007 N3 (Lulin) to the database.
If you'd like to have Stellarium display Lulin you have to edit the ssystem.ini file and add the orbital elements manually.
Here is the way to do that and the entries required:

SHUT DOWN STELLARIUM WHEN EDITING THE FILE

01) Find the ssystem.ini file in the Stellariumdata folder.

02) Open the ssystem.ini file with a text editor. Your system is probably set up to open *.ini files with Notepad by default; but if it isn't, tell Windows to use notepad to open the file.
You will see a simple text file with entries for the various solar system objects. Stars are handled by star catalog files.

03) Scroll to the last entry which is probably [eris]. Enter 3 blank lines after the last entry and on the 4rth line copy/paste this entry exactly as written.:

[Lulin]
name = C/2007 N3 (Lulin)
parent = Sun
radius = 200
oblateness = 0.0
albedo = 0.8
lighting = true
halo = true
color = 0.6,1.4,1.0
tex_halo = star16x16.png
tex_map = deimos.png
coord_func = comet_orbit
orbit_TimeAtPericenter = 2454842.140898683574
orbit_PericenterDistance = 1.212260812612944
orbit_Eccentricity = .9999939407121265
orbit_ArgOfPericenter = 136.8656286796030
orbit_AscendingNode = 338.5375308345843
orbit_Inclination = 178.3735285648489
orbit_visualization_period = 365.25

04) Save the file in its original location. (Just click FileSave).

05) Close out of ssystem.ini

06) Start Stellarium and advance the time until Saturn has risen nicely above the eastern horizon, about 11:00pm local time.
You should see Lulin displayed near Saturn for 22,23,24,25Feb 2009 and labelled C/2007 N3 (Lulin).

07)The above is for Windows. It may be the same for Linux and OSX.


I've made Lulin much brighter than it really is so it will be brightly displayed therefore the magnitude given by Stellarium is false. Sue me.
You can make Lulin brighter/dimmer by altering the parameters for radius &/or albedo in the above entry.
I haven't tried but albedo ahould be maxed at 1.0 so the program may crash if you go higher than this.
The quickest way to make Lulin more visible is to increase its radius.

I've made Lulin typical comet greenish-blue. You can make it any colour you wish by altering the color parameters of the above entry. The entries are R,G,B in the format shown.

The orbital elements are for Epoch 23Feb 2009 and match the predicted path (J2000) within about an arc-second through the end of March (and probably much longer). For visual observation the accuracy is overkill.

You can download the Stellarium Planetarium here:
[link to www.stellarium.org]

If you want to see Lulin you'd better get on it. It's dim so binoculars and dark skies will be required for a good view.

Have fun and clear skies.


R.
Reality420 (OP)
User ID: 620662
United States
02/22/2009 07:16 PM
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Re: Comet Lulin and Stellarium
The above values are for the latest Stellarium V0.10.1.

For V0.9.x the value above, orbit_visualization_period, is just the orbital period for Stellarium to draw the full orbit.
I think in V0.9.x it is called, orbit_Period = . It is probably just as well to not include it at all since Stellarium apparently has problems drawing parabolic/hyperbolic orbits.
If you include it you can give it any value you wish in days. The larger the number, the larger the calculation and more resources used.

Personally, I'd just not include that entry at all.

Have fun.


R.
Anonymous Coward
User ID: 512611
United States
02/22/2009 07:19 PM
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Re: Comet Lulin and Stellarium
So what is reality of which you speak? In summary......
Reality420 (OP)
User ID: 620662
United States
02/22/2009 07:28 PM
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Re: Comet Lulin and Stellarium
So what is reality of which you speak? In summary......
 Quoting: Anonymous Coward 512611


Reality is that which unsensed or denied, yet it perisists.

Have fun.


R.
Anonymous Coward
User ID: 512611
United States
02/22/2009 07:30 PM
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Re: Comet Lulin and Stellarium
Okay in the Spirit of having fun, what do you think of the possibility of Lulin landing in the Pacific.......

....since the magnetosphere is pretty much non-existent now.
Reality420 (OP)
User ID: 620662
United States
02/22/2009 07:34 PM
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Re: Comet Lulin and Stellarium
Okay in the Spirit of having fun, what do you think of the possibility of Lulin landing in the Pacific.......

....since the magnetosphere is pretty much non-existent now.
 Quoting: Anonymous Coward 512611


Less than the probability that you will win the MegaBall 1000000 times in a row.

(Landing in the Atlantic is a completely different matter.)

Have fun.


R.
SpydrGrl
User ID: 475125
United States
02/22/2009 07:42 PM
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Re: Comet Lulin and Stellarium
Is there a King in Reality420?





It is a joint effort after all, no one goes it alone.

at the Universal Joint.
Anonymous Coward
User ID: 575949
United States
02/22/2009 07:48 PM
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Re: Comet Lulin and Stellarium
wthread





GLP