Celestia Forums

Hello!

I'm from Italy, and I've been a user of Celestia since 2009. Don't mind the strange hours of my messages, there should be 9 hours or something of "jet-lag" between the time of this forum and mine (I see mr.green is used here too ). Here now it's 10.40 pm

I'm very interested in extrasolar systems and planets and I downloaded from the Motherload almost everything available about them.
But i saw a great lack of completeness... Yes, Celestia already has 300 exoplanets in its base catalogue, but now they're 700 and also with the cumulated addons made by fans, the catalogues are still full of "holes".

Particularly the CoRoT catalogue... In Celestia's default database only CoRoT-1,2,3,4 and 7 are present, out of 24, and with all of the addons developed 10 are still missing. And a lot of them have been badly encoded... A hot jupiter with a diameter of 2000 km is quite... strange, if you know what I mean A typing error of course, but with a bad result... I don't remember the author now, but i couldn't contact him...

So I decided to make my first addon for Celestia: a complete CoRoT catalogue, with all of the 24 stars and 28 planets publically available.

The addon is almost completed BUT for two little things, two questions that I have for this community of developers... Expecially for those who have experience in this...

1) The stars temperatures. they're making me mad! I read somewhere that there was the tag "Temperature" for the STC catalogue, but it doesn't work... And in Celestia the couple spectrum-temperature is not always equal to the real one... I had to make a table with all of the temperatures that Celestia associates with each spectrum and then insert a spectrum different from the real one, just to fit the given temperature (which is more important in the automatic calculation of luminosity)

Example, CoRoT-23 has a surface temperature of 5900K and a spectrum of G0 V, while for Celestia that temperature is characteristic of a G1 V star... Instead CoRoT-2 does not have this problem, since it's temperature is 5625 K and the actual spectrum is G7 V, like Celestia's one...

Is there a way to force both the temperature and the spectrum to the real measured ones?

2) and this is the worst one. When you build the orbit of the planet you need several parameters. Now the semi-major axis and the eccentricity, along with the argument of perigee, are always given in the public-available data. But these are transiting planets (as for WASP and KEPLER ones), and instead of the Inclination and the Longitude of Ascending Node of the orbit (which correctly position it in the plane of the sky) the TRUE INCLINATION is given, an angle which indicates how much the orbit is inclinated from our point of view (Example: 90° is an edge-on orbit perfectly crossing the star, 0° is a face-on orbit).
Of course this is the most important part. If a planet is found transiting a star as seen from the Earth, then also in Celestia it must do so. I could use random values of AscendingNode and Inclination to make it transit, but i don't like it. Also because the default transiting planets programmed by Celestia's developers have a PERFECT true inclination, exactly the measured one by Corot...
So my question is: how could I make a planet transit exactly like the reality, with the right True inclination?

Thanks for your attention, sorry for the english

Selden sends me ...

Before doing too much work of your own, you should download the current versions of extrasolar.stc and extrasolar.ssc which are maintained on the SVN tree at
http://celestia.svn.sourceforge.net/vie ... c?view=log
and
http://celestia.svn.sourceforge.net/vie ... c?view=log

These files contain >600 extrasolar planets as of last week's update. The CoRoT survey is reasonably well represented - currently it's missing the planets of CoRoT 15, 16, 21, 22 and 24, for which the available data on the Extrasolar Planet Encyclopaedia are too incomplete to generate a proper model.

You need to master a bit of spherical trig to make the conversion from plane-of-sky to Celestia coordinates. If all you want is a quick-and-dirty way to get the correct plane-of-sky orientation portrayed in Celestia, you can use my star orbits converter at
http://www.lns.cornell.edu/~seb/celesti ... ets.html#2

Feed it the correct RA, Declination and plane-of-sky inclination, and read off the Inclination and Ascending Node from the Celestia definition (just ignore the other input and output numbers). Or you can take a peek at the formulae I used, and write your own application.

Grant

It sounds like you haven't upgraded to Celestia 1.6.1 yet but are using the 1.6.0 datafiles. There are quite a few updates to the data files since 1.6.0, including the extrasolar planets catalogue.

As Grant Hutchison says, for the bleeding-edge updates you must grab the files off the Subversion repository.

About ability to set temperature, this is currently only available in the Subversion trunk builds, this feature will appear in 1.7.0 whenever that will happen.

I thank all of you a lot, you solved all of my doubts!

@granthutchinson
I didn't know that the ssc and stc databases for exoplanets were constantly updated, but Celestia is a real big project and I may have suspected it
I just wanted to make the catalogue on my own, and your starorbs.xls paper is simply perfect! Thanks!!! I am studyng Physics, and then I want to take a master in Astrophysics, but i'm just in the second year and the spherical trig is still an unexplored universe for me Your .xls will be fundamental to understand the basis of the subject!

As far as I understood you must be the one who encoded all the other exoplanets in the default catalogue!
I wanted to speak with you, but I didn't imagine that it could really happen!
To program my planets, infact, I took the extrasolar.ssc and .stc catalogues as examples, and made my own exactly like them. I wanted to do them as possible as the celestia's default ones were. I searched out also for the albedo and surface texture, and made them with the Celestia's parameters, using the work "Sudarsky, Burrows & Pinto Giant Extrasolar Planets"

I indeed found difficulties with those 5 planets. Here is how I solved them, of course just for the representation's sake!
Corot-15 is not in the Extrasolar planet encyclopedia because it is a very massive brown dwarf. From the masses and the period, using kepler's third law, I calculated the two semi-major axes of the star and it's companion, and draw them as a double star (with barycenter)
Corot-16 and 21 have all the data but for the stellar coordinates. I looked in the Simbad astronomical database, but I found nothing. So I put them in the middle of the two zones observed by CoRoT, just to place them...
I didn't find difficulties with corot-22. Instead with corot-23 I had to calculate many things, with the scarcely available data. That was a good revision of the black body's law Just yesterday the corot-23 system was updated on the E.P.E., and now it's complete.
the 24th is still to confirm, so I jumped it!
Thank you very much!! I think I will finish it and submit it for publishing in the Motherload, just for who doesn't know about the Subversion (as me, until now ), until Celestia 1.7 will be relesed

@ajtribick
Thanks, I indeed was with the 1.6.0 version
Can't wait for the 1.7!! The possibility to set the temperature for the stars will be great!! The problem is that Celestia doesn't consider the light extinction due to the interstellar dust... So stars far hotter and brighter than the Sun apppear as "0.172 solar luminosities" Quite annoying

Hi Deepwatcher, if you want run the 1.6.1 exe, you can find it here:
http://fisica.cab.cnea.gov.ar/estadistica/abramson/celestia/
Guillermo host its built versions. Just download the exe, backup the your, replace it with the new and run it. Do substitute even the shaders from the shaders' trunk and replace the old ones.

Thanks Fenerit, i'll try it

Only I'm not really good in this things, it will probably end with a total mess...

All of the problems have been fixed thanks to granthutchinson's excel paper, now the addon is ready!

I know that when the 1.7 version will be published the extrasolar list will be updated for everyone and my work will became useless, but since then i want to make something, also because i didn't know about the existance of a SVN, and like me many people only refers to the Motherload's contents.
Of course both in the readme and in the ssc/stc catalogues I will specify my sources and explain my choices about the "problematic" systems, those where some data was missing and I used the most probable ones

V1.6.1 is already published and available for downloading. It's primarily a bug-fix release, although it has updated data and locale translation files.

Fenerit meant that the Guillermo provides a copy of Celestia.exe for Windows built from source-code, which is as close as you can get to v1.7 right now. It includes Temperature and several other new features. Guillermo's version of Celestia.exe is a drop-in replacement for the Celestia.exe file which comes in v1.6.0 or v1.6.1. It is not an installer, and does not include any updated data files. When you run it, it claims to be v1.6.0, which is wrong and can be confusing.

You can install and run several different versions of Celestia at the same time. You just have to make sure that you tell the installer to install the software into separate directories.

Deepwatcher: glad to have been of assistance.
My star orbits spreadsheet isn't ideal for your purpose because it uses some parameters that are standard for binary stars but not for transiting exoplanets.
Spherical trig isn't a major problem: like planar trig, there are only a few simple rules, and the only trick is to be able to string them together in the right order to get to the answer you need. 3D visualization is just a bit harder than 2D, so you'll probably find yourself waving your hands a lot.
Any basic mathematical astronomy textbook will have a chapter on coordinate conversion using spherical trig. It will tell you about interconverting ecliptic, equatorial and horizon coordinates; probably galactic coordinates, too. Once you've got the idea, it's easy to generalize: think of plane-of-sky orbital elements as a coordinate system in which the "equator" lies in the plane of the sky, the "north pole" points away from your eye, and the longitude system goes counterclockwise from your point of view.

Grant

@Selden Thanks, I think i'll try Guillermo's .exe. Installing in different directories you say? that sounds pretty easy, ideal for me

@Grant

granthutchinson wrote:waving your hand a lot

this one is fantastic

and awfully true, just to understand the orbital parameters (that until 2 months ago were completely obscure to me) I "waved" a lot hands, papers, pencils and...plastic orbits! (taken from one of my old "Science & Game" sets, in Italy there is a line of games produced by Clementoni which is fantastic, sets such as "the Solar System", "Satellites", "Energy and Sun", this last even with a little solar panel and electric motor to play with )

Your excel paper have been very precious to me, it gave me the first "hints" of planar conversion in the spherical system. No problem with the fact that is thought for binaries, I was able to use it fantastically for my planets! I also found out that the ArgofPeriaxis given by Extrasolar Planets Encyclopaedia must be converted too, but I expected that. Can't wait to study this things properly! I know a couple of places in the campus where I could get some very good dispenses about this!

thank you all for help!

Clear Skies! (a wish from an astronomy amateur! )

I finally managed to upload my add-on, I hope it will receive a positive judgment from the administrators

Also Kepler catalogue is ready, but I wait for this to be valued first :

Thanks to you all who helped me a lot with this!

it's been two weeks since I uploaded my work and I still have not received any answer... Is it normal? Am I worrying for nothing?

--- edit ---

That's a pity, I didn't have the celestia version 1.6.1 but the 1.6.0... They even told me that in this same topic, but I was really sure that I had the last version... So in the default catalog I had to modify only Corot-1,2,3,4 (in fact you have no errors with them)... That makes 50% of my add-on useless

I'll fix it for the new version as soon as I can!

About the other problem: I used the textures from theory (the article linked in the sources of the original extrasolar.ssc) and statistic from other planets in Celestia itself. And since I didn't have those other planets, I had to guess what texture I had to use, from temperature. In the first 4 planets, by the way, I just used celestia parameters.

Anyway, why didn't was I noticed of the failure of my add-on to the check? Have I given a wrong e-mail or something like that?

Thanks!

J.T.K. wrote:Hi deepwatcher,

... linux users (few ridiculous percent).

Actually, most professional scientists are using Linux (why? ). Among the Celestia Developers
Andrew, myself, Pat Suwalsky and Christophe Teyssier are using Linux.

Active forum members like John VV, -- known e.g. for vast image manipulation work -- is also a Linux enthusiast.

They may --after all- constitute only a few percent of the Windows users, but it remains debatable whether they are a ridiculous minority . It is true though that Win/Mac operating systems are more friendly to ignorant users.

Here is some statistics (worldwide) from log entries of a big global server, as of Jan 2012:

Win 7 (47.1 %), WinXP (31.4 %), Mac (9.0 %) and Linux (4.9 %)

In the US the Linux fraction is considerably lower, though.

When it comes to real work on the computer (coding and hi-end calculating, server applications) then UNIX type architectures (Linux) are usually far superior to the other OS. I am working in parallel with Win 7, Win XP and with Linux. So I do have a qualified basis for comparison.

Fridger

J.T.K. wrote:Hi deepwatcher,

Do you have PC under MS or linux or MAC ?

I know from bdfd's experience that the updates asked by John are for linux users (few ridiculous percent).
But you must do it if you want see your job on ML.

Be accurate, it's a exercice (good or bad...)

Can you be more precise? What should I do? bdfd?
I am working with Windows, like most of the world, but I don't want to discuss here which OS is better. I thought my add-on could fit any OS, it's just a STC and a SSC file... (should I save them in caps lock, like .SSC, or normal, like .ssc? I know they are different for Linux...)

J.T.K. wrote:

t00fri wrote:

J.T.K. wrote:Hi deepwatcher,

... linux users (few ridiculous percent).

MS 47.1 + 31.4 %, Mac (9.0 %) and Linux (4.9 %)

I was right but can you tell us little thing...

47.1 + 31.4 + 9 + 4.9 = 92.4

Where are the missing 7,6 % ?

Please verify your calculations !

Note my point was NOT do discuss which OS is better. It was rather to point out that despite small total percentage, Linux is used by lots of professionals. Hence your wording implying that Linux users represent a ridiculous minority sounded misplaced to me. Hence my intervention.

Concerning your attempts to teach a theoretical physicist the percentage calculus , you forgot that
the only consistency requirement is that the given partial sum is NOT > 100%. Of course I simply have left out "other OS" that I felt were not so relevant in the present context, The unspecified "other OS" included e.g.

Vista(4.7%) Win2003 (0.7%) Mobile OS (1.3%)

The numbers were copied from w3schools.com, a large web development site.
http://www.w3schools.com/browsers/browsers_os.asp

Fridger

--- edit ---

J.T.K. wrote:
Please, verify the informations before circulation, without this it's not credible.

I had hoped you had understood the underlying philosophy about such numbers: the >>> DISPLAYED <<< percentages need not add up to 100%!! Just call the small missing part "other"...

As is written on that w3schools.com site, the data were extracted from log file entries. There is always a small fraction of entries that is either not worth displaying or invalid / missing for some technical reason. Since the total number of logins is precisely known they can always derive a reliable percentage value for the types of OS they are interested in, provided they were SUCCESSFULLY logged. The only relevant consistency constraint in such a standard procedure is that the sum of quoted percentages must NOT EXCEED 100%.

Here is a trivial explicit example that hopefully teaches you what percentages really mean:

Suppose in Jan 2012 a Web site had 10000 logins in total. Imagine moreover that the site operator writes a small shell script whose ONLY purpose is to count the login entries from Linux OS machines! The script ignores any other possible OS. JUST looks for Linux. Suppose, among the 10000 logins, the script counts 490 from Linux machines. Then the operator calculates CORRECTLY and RELIABLY:

Percentage of Linux OS: 490 / 10000 * 100 % = 4.9 %

Hence he was able to extract the correct percentage of Linux OS without even bothering about how many computers used Win XP, Win 7, Vista, Mac OS, etc... Suppose there was a bug in the shell script such that instead of 490 it counts e.g. 10005 Linux machines, then the operator would know for sure that the script cannot be right

Before I loose my good humor in this ridiculous discussion, I suggest we stop it NOW.

Fridger

This is a qestion for John (BTW, great virtual texture add-ons!! Have almost all of them!).

In my reply I exposed where the problem were born from. Now a question: if someone that downloads my add-on (which I will fix with those "Modify" or "Replace") and has NOT the 1.6.1 version but the 1.6.0, will he still have my add-on working?
I mean, I know that if you use the command "Modify" and in the default fle there is nothing to modify, then the planet will not be displayed. What if with command "Replace"? Does it allow to display my planets even if you don't have them in a default file?

Thanks for attention far here!

--- edit ---