Asteroid-magnitude fix for KStars
I submitted a patch today on the mailing list, to fix magnitudes of asteroids. It was a trivial patch, but involved quite some research to learn the correct formula.
I was trying to find out how I would use the “orbital” elements H (Abs. Magnitude) and G (Slope Parameter) to find the magnitude of a asteroid / comet. After many many futile attempts, Google finally put me at Seichii Yoshida’s (the well known comet researcher) website:
http://www.aerith.net/astro/Encke-nucleus.html
It didn’t take me long to get KStars to use that formula. Now, there’s some agreement between KStars and SB What’s Observable. Vesta was good with KStars showing 7.9 and SBWObs showing 7.97
but I wasn’t so happy with Ceres (KStars = 8.3, SBWObs = 7.95) – but it is far better than the case earlier, which was setting the magnitude to H!!!!
The patch is available here. Ignore the extension and open it with any text editor.
akarshsimha 7:10 pm on December 26, 2007 Permalink | Log in to Reply
This patch is now commited to the SVN.
Jason Harris, the original author of KStars, who is still the major player in the game is an amazing genius, IMO. He found that with the above patch applied, KStars always showed a magnitude tad higher than that on the JPL SB What’s Observable site. He rightly made an educated guess that this was probably a bug in the calculation of the earth-planet distance in KSPlanetBase::Rearth() and he swatted the bug dead in the next commit!
Now, as Dr. Suresh Govindarajan, our faculty advisor and Physics teacher rightly said, an eye for detail is something that Indians lack, while their intuitive abilities are better. I would have never even compared the magnitudes of more than 2 objects (Yes… I compared them for two objects – Vesta and Ceres – and stopped there). But Jason made a detailed study of the error and even swatted some other, unexpected bug! Isn’t that amazing?
I ^:-)^ to him.
Kumar Appaiah 4:51 pm on December 27, 2007 Permalink | Log in to Reply
Great going, and continue this effort!
Kumar
akarshsimha 6:37 pm on December 27, 2007 Permalink | Log in to Reply
Thank you Kumar.
I will continue…