CHARM2 measured stellar radii (DO NOT USE WITH NEW STARDB)

ajtribick · Post #1by **ajtribick** » 19.12.2007, 00:17

Please note that this add-on is not compatible with the new stars.dat file available on the SVN. I am developing a new version but this will probably be made available only after Celestia 1.6.0 has been released

It has often been pointed out on these forums that Celestia's handling of stellar radii leaves much to be desired. It has also been pointed out that coming up with a workaround for this is nontrivial.

To get around this I have implemented the CHARM2 catalog in Celestia. This is a catalog of measured angular diameters of stars. The data were extracted using a VB.Net program. Since CHARM2 does not use Hipparcos designations, the HD and SAO cross-indices were used to map the CHARM2 records onto HIP catalog entries. In total, radii for 1944 Hipparcos stars are defined in the output file.

To use this addon, download the zip archive (link at the bottom of this post), extract the file charm2.stc and place it in the extras folder of your Celestia installation.

The script file charm2.celx can be placed in the scripts folder. It will mark all the stars affected by this add-on and provide additional information when these stars are selected.

Information on the generation process from the file header:

Code: Select all

# Celestia star radii revision 1.1 (17/01/2008)
# Generated by Andrew Tribick from:
# CHARM2: an updated Catalog of High Angular Resolution Measurements
# Richichi A., Percheron I., Khristoforva M. - Astronomy and Astrophysics 431, 773 (2005)
#
# RA, Dec, Distance, SpectralType and AppMag from the Hipparcos catalog (stars.txt) and
# Celestia datafiles (revised.stc, extrasolar.stc, nearstars.stc, visualbins.stc, spectbins.stc)
#
# Radii generated from weighted averages of multiple entries in the CHARM2 catalog.
# Where uncertainties on the angular values were not supplied, the average value for
# the error on that type of diameter (limb darkening or uniform disc) were used.
# Where available, radii assuming limb darkening are used in preference to uniform disc.
# The record numbers refer to the entries in the CHARM2 catalog used to compute the radii.
#
# Number of records = 1944

Download (zip, 80KB)

Comments/criticism welcome.

Update: Version 0.2: fixed problem with Right Ascension - I accidentally put it into the [0,24) range instead of [0,360) and then managed to fail to spot such an obvious error.

Update: Version 1.0: release version. Now integrated with default .stc files supplied in the Celestia distribution. Added a script to mark the stars with supplied radii.

Update: Version 1.1: updated script. Now hosted at Celestial Matters.

Update: Version 1.2: fixed Celestia 1.4.1 script crash bug.

Post #2by **chris** » 19.12.2007, 18:50

Thanks for creating this add-on--very nice to have some stellar radii that aren't just inferred from the magnitude and color. I noticed that some of the stars had radii smaller than the Sun. How is it possible to measure such a 'small' object at stellar distances? Are these stars components of binary systems?

--Chris

ajtribick · Post #3by **ajtribick** » 20.12.2007, 19:31

As far as I know, the method is high resolution interferometry, but unfortunately I do not have access to the journal paper to confirm the details.

Current progress is that I am still coding an automatic way of dealing with the various default catalogue files. The next version should incorporate the nearstars.stc file (this one is easiest to handle as it doesn't include stellar rotations, binary orbits, oblateness, non-Hipparcos stars, etc.)

I also plan to include in the next version a script to mark all the affected stars.

Post #4by **t00fri** » 20.12.2007, 19:57

chaos syndrome wrote:As far as I know, the method is high resolution interferometry, but unfortunately I do not have access to the journal paper to confirm the details.

Why don't you quote the journal reference. I most probably have access...

Bye Fridger

ajtribick · Post #5by **ajtribick** » 20.12.2007, 20:02

t00fri wrote:
chaos syndrome wrote:As far as I know, the method is high resolution interferometry, but unfortunately I do not have access to the journal paper to confirm the details.

Why don't you quote the journal reference. I most probably have access...

Bye Fridger

From the ADS:
Richichi, A.; Percheron, I.; Khristoforova, M. - "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, v.431, p.773-777 (2005)

ajtribick · Post #6by **ajtribick** » 30.12.2007, 23:51

*** Release version now out ***

Updated to integrate with .stc files (e.g. binary stars) and added marker script.

Download link is in the first post in this thread.

LordFerret · Post #7by **LordFerret** » 01.01.2008, 03:29

Nice work!

ajtribick · Post #8by **ajtribick** » 19.01.2008, 14:18

Another update... the script is now written in .celx and provides some additional functionality.

The add-on is now hosted at Celestial Matters.

BobHegwood · Post #9by **BobHegwood** » 19.01.2008, 18:25

ajtribick wrote:Another update... the script is now written in .celx and provides some additional functionality.

The add-on is now hosted at Celestial Matters.

Very cool... Thanks a lot for this addition.

Take care, Brain-Dead

cartrite · Post #10by **cartrite** » 19.01.2008, 19:00

ajtribick wrote:Another update... the script is now written in .celx and provides some additional functionality.

The add-on is now hosted at Celestial Matters.

I just tried your addon and I was going to check it out.
But when I started Celestia, I noticed a problem when I opened the celx script. Not sure what to make of it but here is a screen shot.

The markers from the stars show right through the earth. Latest cvs from today using kde version.
cartrite

Post #11by **chris** » 19.01.2008, 19:06

cartrite wrote:
ajtribick wrote:Another update... the script is now written in .celx and provides some additional functionality.

The add-on is now hosted at Celestial Matters.
I just tried your addon and I was going to check it out.
But when I started Celestia, I noticed a problem when I opened the celx script. Not sure what to make of it but here is a screen shot.

The markers from the stars show right through the earth. Latest cvs from today using kde version.
cartrite

This has always been the case with markers. We'll add properly depth sorted markers very soon after 1.5.0, as well as an option to flag a marker as non-depth sorted.

--Chris

BobHegwood · Post #12by **BobHegwood** » 19.01.2008, 19:07

The script also causes MY machine to crash when initiated
under 1.4.1. Works fine in 1.5.5 though. Just FYI.

cartrite · Post #13by **cartrite** » 19.01.2008, 19:16

chris wrote:
cartrite wrote:
ajtribick wrote:Another update... the script is now written in .celx and provides some additional functionality.

The add-on is now hosted at Celestial Matters.
I just tried your addon and I was going to check it out.
But when I started Celestia, I noticed a problem when I opened the celx script. Not sure what to make of it but here is a screen shot.

The markers from the stars show right through the earth. Latest cvs from today using kde version.
cartrite

This has always been the case with markers. We'll add properly depth sorted markers very soon after 1.5.0, as well as an option to flag a marker as non-depth sorted.

--Chris

OK,
I was unaware of this.
cartrite

Cham · Post #14by **Cham** » 19.01.2008, 19:26

BobHegwood wrote:Works fine in 1.5.5 though. Just FYI.

1.5.5 ?? Geez, was I absent for such a long time ? :wink:

BobHegwood · Post #15by **BobHegwood** » 19.01.2008, 23:22

Cham wrote:1.5.5 ?? Geez, was I absent for such a long time ?

Yeah, we seem to be moving at the speed of light now. :lol:

ajtribick · Post #16by **ajtribick** » 20.01.2008, 00:42

By 1.5.5 I presume you mean 1.5.0pre5?

Ok, I've tracked the crash to the use of the # unary operator to get array size. This apparently doesn't play nice with the 1.4.1 parser. It even seems to cause a crash when the code is not executed, for example, the following script will crash under 1.4.1:

Code: Select all

--Title:Crash Celestia 1.4.1

function NotCalled()
local a = {1, 2, 3}
local b = #a
end

wait(0)

For now, do a find and replace on the charm2.celx script:

Find "#charm2" (excluding the quotes) and replace it with "table.getn(charm2)" (again excluding the quotes).

If others confirm this fix works.

Post #17by **chris** » 20.01.2008, 00:57

Celestia 1.5.0 is built with Lua 5.1, while older versions used Lua 5.0. The # array size operator only appeared in Lua 5.1. In addition, Celestia's handling of Lua parsing and run-time errors was not so great in version 1.4.1. That's the reason it just crashes instead of doing something sensible like showing an error dialog. Celestia 1.5.0 is better in this respect.

--Chris

ajtribick · Post #18by **ajtribick** » 20.01.2008, 12:57

Ok, cartrite has confirmed that with the change the add-on now works in 1.4.1. Version 1.2 of this add-on will be available soon...

ajtribick · Post #19by **ajtribick** » 20.01.2008, 14:07

Version 1.2 is released, at Celestial Matters.

Cham · Post #20by **Cham** » 30.01.2008, 23:17

ajtribick,

I tried your addon. The stars don't use any texture at all. There should be something in the STC file so they can use the default textures, as declared in the new config file for 1.5.0. Currently, they are all dull glowing spheres :cry: