Sorry about the date. This should of course be October 7at about 19 UT, in solar longitude around 194.05 (or 194.048) for the 1887 trail.
Esko
>>>
Hi,
There may be some Draconids this year from an old trail or possibly
from two old trails, although the Moon will strongly interfere.
The parent comet 21P/Giacobini-Zinner's earliest observations are
from the return in 1900.
The comet had a close encounter with Jupiter in 1898. It passed Jupiter
within about 0.188 AU . The perihelion distance that is now a little
less than 1 AU was about 1.23AU before this encounter. The uncertainties
in the orbit will grow (in backward time) before this encounter,
but not so very soon at once.
There was another close encounter in 1815 within about 0.17 AU . Before this
the perihelion distance was about 1.6 AU and the uncertainties in the orbit
increase very quickly before this.
The trail from 1887 has an ancounter with the Earth in August 7 at about 19 UT.
There is actually a gap in the basic solution without non-gravitational forces.
This gap, however ends as soon as two days after the Earth reaches the node.
Quite mild non-gravitational forced are cabable of bringing meteoroids to
have an encounter. The da0 is about 0.006 AU. This corresponds
( comparing the beta value or ejection speed, depending on the model )
the Leonids da0 of about 0.08 AU. This is close to the 2001/7-rev value.
This Leonids trail caused the 2001 storm in Americas. So the meteoroids
population may be of the same size.
The Draconids however have an entry velocity of only about 20 km/s whereas the
Leonid entry is at about 71km/s .
So, an enetring Leonid meteoroid has about 13 times the kinetic energy
than a similar size Draconid meteoroid, making the Draconids maybe about
two and a half magnitude more dim. So this trail may cause mainly quite
dim meteors. I have no real ZHR prediction, but I expect it to be about
a dozen or a few dozens maybe. Unfortunately the Moon is two and a half days
before full, making this visually maybe totally invisible.
Video observations may reveal a somewhat more rich display.
I don't know how well these dim and slow meteors are visible in radio
forward-scatter recording. I have some experience with slow bolids.
It is astonishing how weak a reflection, if any, even a very bright
(mag -10 or even brighter) but slow bolid may give.
There may possibly be another encounter with an even earlier trail from 1810.
This would have a very slightly negative da0. The comet motion may be too
uncertain for this prediction to be reliable as to the trail calculation.
Also, at the high perihelion distance of 1.59 AU there may not be ejected a
lot of meteoroids, if any, especially to the required negative da0:s.
However if there will be encounters with this trail meteoroids, these will
probably produce more bright meteors than the trail from 1887 .
The possible outburst from this 1810 trail is predicted to be around the
same time than the other outburt. This older trail has a loop that may
have encouters during several hours, maybe for six hours or even more more,
ie. from about 16 to 22 UT. The comet orbit uncertainty may also make
this time uncertain and as told it is doubtfull if anything can be
observed from this older trail.
Esko