[Kstars-devel] Trouble with comet magnitudes

[Jason Harris]

Hi Akarsh,

Thanks for submitting a patch earlier for the asteroids.  I'd like to apply it 
immediately, but I think it's better to wait for the end of the feature 
freeze, which should be in mid-January.  Please feel free to continue to 
develop your improvements in your local copy, and keep submitting your 
patches to the list.  We can apply them to our local copies and give you 
feedback.  I just want you to know that we won't be able to commit them until 
the freeze is over.

On Tuesday 18 December 2007 01:19:43 pm Akarsh Simha wrote:
> Hello
>
> Using the same formula which was used in the patch attached to my
> previous mail for comets turns out to be a difficult thing, because
> the H and G parameters are not present in our comets.dat nor is the
> albedo present.
>
> In order to be able to include the calculation of comet magnitudes,
> we must expand our comets.dat database. May I know which particular
> format we are using? Is it one of the formats supported by the IAU
> MPC site:
> http://cfa-www.harvard.edu/iau/Ephemerides/Comets/SoftwareComets.html
>
The comets.dat format is the one used by the website from which we get the 
ephemerides: http://ssd.jpl.nasa.gov/?sb_elem

Actually, they recently modified their column formatting a little bit, which 
means we can no longer import their files directly.  One of the TODO items 
for 4.1 is to make the code which parses the asteroid and comet ephemerides 
more robust to simple format changes like this.  In any case, we really 
shouldn't import the comet ephemerides directly, because there are a lot 
of "disappeared" comets in that file that need to be removed.

> Is it wise to add two columns into the current comets.dat file indicating
> the H and G parameters?
>
The ephemerides published at the above JPL site do not include G and H for the 
comets.  We can consider using a different source for our ephemerides; do you 
have an alternative in mind?  Maybe the IAU ephemerides you linked to?

> PS: A small documentation patch is attached.
>
Thanks!  This one I can apply immediately.

> Regards
> Akarsh.



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