(meteorobs) Re: Question about radiant drift

[Robert Lunsford]

Bamm and All,

You must also remember that the change in ecliptic longitude per day
slightly exceeds one degree per day in January and slightly less than one
degree in July due to the Earth's varying distance from the sun. This is a
very small amount though, certainly not enough to change the daily rate to
0.9 or 1.1 degree per day. I have a feeling that the differing angles at
which we intercept these streams plays a much more important role in the
varying rates.

Bob Lunsford

----- Original Message ----- 
From: "Bamm Gabriana" <bamm at upastrosoc.org>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: Sunday, June 06, 2004 1:56 AM
Subject: Re: (meteorobs) Question about radiant drift


> > 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