(meteorobs) Question about radiant drift

Bamm Gabriana bamm at upastrosoc.org
Sun Jun 6 04:56:49 EDT 2004


> This is a fact of our orbit. Any radiant that does not move 1 
> degree per day along the ecliptic cannot be real, unless an 
extrordinary 
> explanation is available.

Hi Wayne,

Is this exact? I took a look at the data in Table 6 of the IMO 
calendar, converted the RA and Dec into ecliptic coordinates, and 
plotted them in a graph.

I expect that the change in ecliptic longitude is exactly 5 degrees 
because the table is given every 5 days, but it doesn't seem to be 
that way.

The rate of change in longitude seems to be slightly different for 
each shower. In some cases the increase doesn't even seem to be 
linear; the perseid radiant for example seemed to be gaining in speed 
as the shower progresses.

I hope this is merely because the figures in the table are rounded 
off to the nearest degree (and nearest day too, because they are in 
terms of calendar days instead of sol). I wish I could have more data 
so I can verify if this is indeed exact or if there is indeed a 
numeric factor that depends on the shower.

Thanks and clear skies!

Bamm




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