(meteorobs) Re: Question about radiant drift

[Bamm Gabriana]

Hi Bob!

Since the ecliptic is slightly inclined from the equator, changes in 
declination is not necessarily a change in ecliptic latitude.

For example, at the Ursids radiant the ecliptic and equatorial 
coordinates are actually perpendicular to each other! This is because 
the ursids are approximately in an equilateral triangle with the 
celestial and ecliptic north poles.

Thus in this case, a change in latitude actually results in a change 
in right ascension instead of declination.

Thanks for all responses, I'm glad there are many as interested as I 
am in this topic. I'll be away for several days, I hope someone can 
refer to me a nice reference on this topic. I am not a physics major 
but I think I have enough background to understand some of them.

Bamm

--- In meteorobs at yahoogroups.com, "Robert Lunsford" 
<lunro.imo.usa at c...> wrote:
> Bamm and All,
> 
> As for the change in celestial latitude (declination), all I can 
add here is
> that a radiant will usually reflect the same change in declination 
as the
> ecliptic located in the same longitude (right ascension). See the 
following
> table for right ascensions and the approximate change in 
declination:
> 
> Right Ascension: 0-30 Change in Declination: +0.3
>                          30-60                                   
+0.2
>                          60-75                                   
+0.1
>                          75-105                                   
0.0
>                        105-120                                  -0.1
>                        120-150                                  -0.2
>                        150-210                                  -0.3
>                        210-240                                  -0.2
>                        240-255                                  -0.1
>                        255-285                                   0.0
>                        285-300                                  +0.1
>                        300-330                                  +0.2
>                        330-360                                  +0.3
> 
> This is off the top of my head so don't expect the figures to be 
exact.
> I really don't have the time to find out where exactly the drift 
shifts from
> 0.1 to 0.2
> 
> There have been some fine responses on this subject, some far beyond
> my capabilities. I just hope my simple contributions help too!
> 
> Bob Lunsford
> 
> 
> ----- Original Message ----- 
> From: "bgarcing" <bgarcing at y...>
> To: "Global Meteor Observing Forum" <meteorobs at m...>
> Sent: Monday, June 07, 2004 1:24 AM
> Subject: Re: (meteorobs) Question about radiant drift
> 
> 
> > Hi Bob and Wayne,
> >
> > I tried plotting the longitude of the radiant against the ecliptic
> > longitude of the sun (which is readily available using different
> > software), and it still does not move at exactly 1 degree per 
degree
> > of sol.
> >
> > Also, theory says that the ecliptic latitude of the radiant 
should be
> > constant, but the data from the tables show that the latitude also
> > changes.
> >
> > What are the factors that affect these? And how to compute these
> > factors using elements unique to each stream? Thanks and clear 
skies.
> >
> > Bamm
> 
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