COMETS (ssc from MPEC updates)

[jogad]

Hello,

Obviously, these comets should not all have tails and they are not supposed to be lined up in a nice circle around the sun like this. ????

For the tails, I don't know.

For the alignment, here is another point of vue of the same group of comets.



All those "comets" are fragments of a single comet that disintegrated.
A quick search gave me this link.
http://en.wikipedia.org/wiki/73P/Schwassmann-Wachmann

The "alignment" is a very demonstrative consequence of the laws of gravitation. The fragments that are closer to the sun are quicker than those that are farther. By the time, this gives this kind of aligment.

[fsgregs]

Jogad:

Thanks for the info. I had no idea a comet had some many fragments with each fragment given its own designation.

I stand corrected.

Frank

[jogad]

Hi,

After near 3 years and a period out of this forum, I had completely forgotten all that when I posted recently to announce a new addon here:
More comets for Celestia

The goal was to keep the comet base as up to date as possible by adding the new comets and updating the old ones.
I wrote a script (perl script) for that which examined the DIRL addon and the standard comets.ssc from Celestia.

Rediscovering this thread, I realize that the Cham's Comets_936.ssc file is a better candidate than DIRL's addon.

So my final installation is this:

--> install the Cham's Comets_936.ssc file in the datas directory of Celestia (to force it to be read before the updatded file)
--> Tell celestia to use it by adding a line in the celestia.cfg file:

Code: Select all

SolarSystemCatalogs        [    "data/solarsys.ssc"
                        "data/asteroids.ssc"
                        "data/comets.ssc"
                        "data/Comets_936.ssc" # <-- line to add
                                ...

--> copy the files attached to this post in a celestia/extras subdirectory (e.g. celestia/extra/more_comets)

You have a file "morecomets.ssc" which contains the updated comets and the new ones, and a perl script "buildcomets.pl" to update the "morecomets.ssc" file from time to time.

To update the ssc file

--> download this file from the Minor Planet Center:
http://www.minorplanetcenter.net/iau/Ep ... t00Cmt.txt
--> copy it to the addon directory (e.g. celestia/extra/more_comets)
--> rename it as "comets.txt"
--> launch the buildcomets.pl perl script from the same directory and the update will be performed in less than one second!.

I have adapted the script to mimic the naming of comets in the Cham's ssc file.

Applying the sript on the source file from http://www.minorplanetcenter.net/ Minor Planet Center leads to update 91 comets of the files comets.ssc from Celestia and comets_936.ssc by Cham, and add 138 new comets.
The result is now 1075 comets in Celestia