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(meteorobs) re P/2000 G1 & Vought
Cheers to Jim Richardson for sorting out a tricky taxonomy!
There's nothing like astronomy for tricky taxonomy!
I was also glad of the quantification of the additional component from
Earth's rotation : I'd been wondering what sort of value that'd amount to.
Paul Johnson's contribution helped my poor little brain too! I'd a feeling
that "speeds" could get all the way down to zero.
And Lew, we weren't both right and both wrong, we were just talking about
different things!
Basically, if somebody double station photos or videos any Camelopardalids,
they'll end up calculating the speed as Vgeo = 6 to 8 km/s, a radar person
will say they've Vinf of about 13 or 14 km/s, whilst a visual observer will
just say they are very slow!
Hopefully, Lew, in tandem with what Jim Richardson said, the following
should help.
I found 3 pretty good Camelopardalids [reference RA, Dec, Sol.Long and
_Vgeo_ taken from the vmdrad.dat list at the IMO webpages] in photographic
databases. They have Vgeo of 6.4, 7.2 and 8.0 km/s : two were on 14/3/53,
one on 23/3/54 [ie probably the legendary McCroskey et al!]
I found several pretty good Camelopardalid candidates in the radar
databases, which list Vinf ["infinite velocity"] as opposed to Vgeo, and
the Vinf values are 13 to 14 km/s. Just about all of them were from the
second Harvard survey and for 1969. So, using Jim R's info re Va=Vinf, and
putting it in terms you [Lew] prefer, Camelopardalids most likely have a
"speed" of 13 km/s.
And if you use Jim R's sums, 6.8^2 + 124.9 all square rooted gives 13 !!!
The CAMid orbits are generally 0.99 to 1 AU for q, an eccentricity about
0.35 to 0.4, and an inclination clustering around 9 degrees. Asc. Node is
near 360 = 0, and Arg Peri usually about 190.
This is pretty damn circular and "flat" for an orbit that doesn't belong to
one of the major planets! In tandem with q occuring more or less at the
node, which occurs when we're there, it is no great surprise they are so
"slow"! [NB no suitable comets tallied, nor any NEOs to speak of].
I personally have a sneaking suspiscion that the "Camelopardalids" are
either a McCroskey invention, from photographic work, or a Sekanina
invention from radar work, as both tended to use traditional stream naming.
Lindblat, on the other hand, tended to give streams a number. However,
most of these authors' works came out in obscure conference series or
observatory annals or the like, and I've never been able to get hold of
copies, so I'm guessing. Also, folk keep mentioning Cook, a name that means
nothing to me.
So, the software I'm using is probably chucking out Vgeo proper, but I've
no documentation, so I'm not sure. It only really matters for these v.slow
objects, I think, as I've seen data with both Vgeo & Vinf listed, and
there's usually not much between them when you get to 40 km/s plus.
Using Jim R's sums, we should be able to convert 11 km/s Vgeo for P/2000 G1
meteoroids into Vinf=Va [I'll stick to Vinf: I'd never heard of Va till
today], = 15-16 km/s.
Finally, Lew, in this context, the Compton Gamma Ray Observatory is
probably a better parallel than the shuttle, not to mention an iridium
satellite or two... :-)
Cheers
John
JG, UK
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