(meteorobs) On the predicted Perseids outburst
Esko.Lyytinen at MINEDU.FI
Tue Jul 6 04:12:15 EDT 2004
I am leaving to the countryside soon after next weekend for maybe four
weeks. I am there without an internet connection, except when going to
the local library in about 10 km:s distance. I will probably do this
only a few times during this four week period. Then I can see my private
email, but not my work email where I have subscribed the meteorobs
group. I can then look the meteorobs archive, however. My replies to
possible questions etc, will probably come much delayed, possibly before
the outburst, but this may well be left after it. Before leaving, I will
see my work email on thuersday the last time, but will look my private
email on sunday, and probably on monday ..
I will come back home the weekend before the Perseids, and plan to do
some video-observing of the Perseids.
Before going, I have in my mind a few things concerning the predicted
There is no real reason to change our predicted rates of a few hundred.
We could not calibrate the trail-density data with erlier observations.
We had a rough assumption that the amount of meteoroids released (from
the parent comet) during one return is about an order of magnitude
bigger than from the Leonids parent comet.
If this amount were proportional to the parent comet absolute magnitude,
this would be about two orders of magnitude (roughly a hundred times)
bigger than with the Leonids. This would mean (according to our Leonids
type model) a weak storm. I do not like to give too much of optimism,
but I let you know this.
If you do see visually quite a lot of dim meteors (during the outburst
time), testing telescopic observations (near the radiant) might give
Because the one revolution trail will pass a little inside the Earh
orbit, we can get a view tangentially to this trail. There may be some
possibility to observe the one revolution trail in space. With the
Leonids there may have been some level observation of the trail-complex.
The one revolution trail is the most dense individual trail (and this
MAY be more dense than Leonids one revolution trail). The tangential
'point' is now at the distance of about 0.07 AU. At this distance, the
most dense core may appear only some arc-minutes wide (or possibly even
smaller). It probably deserves to try to detect this only under good sky
conditions. A CCD-equipment would best suit for this, but other
photograpy and visual sightings could be tried. Because of the
relatively small apprent size of the densest part, no very wide field
instrument is recommended. I expect equipment that are good for cometary
observations to be good for this purpose.
I tried to derive the apparent location (of the tangential point of the
trail center) from orbital elements of the trails particles around there
and I got RA and dec (J 2000.0):
3h 39.0m +84.86deg. This is valid at the tiome of maximum of the
outburst, that is expected to be the best time to get the trail visible.
The movement is about half a degree in one hour. An hour before the
maximum time, the location is 3h 36.2m 84.33deg and an hour after the
maximum it is 3h 42.5m 85.40deg.
I hope that I got this correctly, I had not much time to check this
carefully. If you find some bad bug, please let me and others know.
Hope you good skies,
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