(meteorobs) Two questions for meteorobs members

[Marco Langbroek]

Op 28-7-2010 16:30, Skywayinc at aol.com schreef:

> QUESTION 2:
> Are the V(infinity) speeds  of meteors corrected for the Earth’s gravity?
> The speed would be, by the time we see the shooting  star have a downward
> component of 11km/s due to falling by  gravity.

This is the difference between Vinf and Vgeo. Vgeo is the velocity minus the 
Earth Gravity induced vector (hence why it is always lower). Vinf is the 
observed velocity (Vgeo + a gravity factor). In terms of orbit determination, 
Vgeo (along with the geocentric radiant RA geo and Dec geo) is important as it 
are those which determine the orbital vector.

Now, confusingly, in orbital mechanics outside meteor astronomy, Vinf is 
actually the real velicity (that what is valled Vgeo in meteor astronomy) and 
Vgeo is the real velocity plus a gravity factor. Yep: that is eaxctly the other 
way around as we use it in meteor astronomyh!!! This disparate use of terms in 
meteor astronomy versus other orbital astronomies (e.g. asteroids) is 
unfortunate and very confusing.

- Marco

-----
Dr Marco (asteroid 183294) Langbroek
Dutch Meteor Society (DMS)

e-mail: dms at marcolangbroek.nl
http://www.dmsweb.org
http://www.marcolangbroek.nl
-----