Since Guide uses MPCORB and the data provided from the MPC "only" contains H and G as far as brightness parameters, it would seem reasonable Guide does not utilize a separate albedo parameter for calculating apparent magnitude.

The MPCORB format is documented here: http://minorplanetcenter.org/iau/info/MPOrbitFormat.html


I'm afraid Bill will have to inform us if phase angle is factored into the Guide magnitudes - I'm not sure how much of an effect this has on most observable minor planets, as the phase will be closer to 100% than to 0%.

--Grant

--- In guide-user@yahoogroups.com, Pierre Laporte <solideogloria@...> wrote:
>
>
>
> Does somebody (Bill or others) can explain how Guide 9.0 estimate
> the magnitude of the asteroid ?
>
>
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> I would like to know which parameters and equation Guide use for it
> estimation. I made precise estimation of asteroides via a ccd images and I
> would like to compare it to the theoritical estimation.
>
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> Does just the distance to sun-asteroid and asteroid earth are use ? Does
> Guide use and aldebo factor ?
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> Is there any useful reference that I can consult ?
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> Thank you
>
>
>
> Pierre Laporte
>
> C.O.A.M.N.D.
>
> Centre d'Observation Astronomique Des Monts Notre-Dame
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>
> [Non-text portions of this message have been removed]
>