(meteorobs) Re: Circular IAU C22 Pro-Amat WG: Possible meteors from comet, P/2005 JQ5 (Catalina) (Mikhail Maslov)

Fri Jul 1 12:47:10 EDT 2005

Hello Mikhail, and others,

This is copletely true what you say about the comet motion. There is no 
hope of a prediction of a real encounter with some old trail.

The modeling that we made, had the purpose to tell somethig more general 
on the meteoroids spread from the comet orbit. The parent comet orbit 
did not have (could not have) any real close encounters with Jupiter and 
not even very close encounters with the Earth (for many ceturies or even 
much more). So we can tell something general on the orbit precessisons 
and (hopefully) also something how much the meteoroids orbits can differ 
from the comet orbit by means of (more or less) randomlike perturbing 
effects of the planets. In the text ":.the trails 1302, 1350, 1403, and 
1500 A.D." does not mean that the perihelia reallly occurred in those 
years. One only considers and models the approximate time-span from 
these years, how the meteoroids deviate from the parent comet orbit.
For example this modeling seems to tell that the meteoroids (to produce 
meteors now) need to have ejected several centuries ago but there MAY be 
meteoroids near the Earth orbit from about six centuries ago, and 
earlier. If there may be or have been enough to get observed, can only 
be resolved by means of observations.

I also think that this level of modeling also tells that the number of 
meteors (if any) from this radiant will increase in the coming decades, 
independent of  if the parent comet is nearby in its orbit or not. When 
the comet orbit gets really more close to the Earth orbit as especially 
in 2085, this will be different and there may become the possiblity of 
real stoms (maybe weak) from fresh trails.
IF anything was observed now in June, this may mean that this can become 
even an  important shower that deserves attention every year from this on.

The comet P/2005 JQ5 has in its orbit the difference to 
21P/Giacobini-Zinner orbit, that the orbit (of P2005 JQ5) does not reach 
to the orbit of Jupiter and there may not be as quick sudden changes in 
the orbit. This means that the meteoroids stream, as a whole can stay 
more compact and even a lesser number of meteoroids may give a 
comparable or stronger annual display (not storms) than that form comet 21P.

Best regards,
Esko Lyytinen

 >>>

 >Hello, Peter and all,

 >Many thanks for your two letters and for your study with Esko
 >Lyytinen. I'm sorry, I'm quite busy these days, so just now I make
 >comments on P/2005 JQ5 Catalina. Some time later I'll try to respond
 >to other messages.
 >As I understand, the comet P/2005 JQ5 Catalina was not known before
 >its apparition in 2005 (or it was?, under some other designation,
 >for example?). And, as we know, comets and meteor particles are
 >subjected to non-gravitationnal forces. Some of them are quite
 >regular, for example radiation pressure. But comet's trajectory is
 >also influensed by non-regular reactive forces due to dust and vapor
 >jets they release when they are not very far from the Sum. A given
 >comet have to be observed at least at several apparitions before some
 >approximate characteristics of these jet forces can be defined. So
 >far, we can't compute comet movement during many centures on the base
 >of only one apparition, as in P/2005 JQ5 Catalina case. In meteor
 >computations accurate orbital elements of parent comet are extremely
 >important. Say, an error in perihelion date even of several days can
 >completely crash the results and lead to totally wrong conclusions. If
 >we don't know the influence of non-gravitational forces, such an error
 >can easily appear in the computation of secular comet movement.
 >About future evolution of P/2005 JQ5 Catalina. As follows from the
 >latest orbit, obtained on the broader observed arc, during the period
 >of 1901-2100 minimal distance between comet and Earth orbit is to be
 >gradually decreasing from 0.05 AU in the beginning of 20 century to
 >0.0244 AU in 2005 and to 0.01 AU to the end of 21 century. Perhaps in
 >22 century these orbits will intersect each other. In 2005 the minimal
 >distance corresponds to sol.long=82.207 deg. (13.06.2005 4:37 UT).
 >During 21 century longitude of min. dist will also decrease from 79-83
 >deg. in its first half to 76-81 deg. in the second.
 >And the last on this comet. It is very small. For example, if comet
 >21P Giacobiny-Zinner had such size, in 1946 instead of storm of many
 >thousands meteors per hour the world would see no more than several
 >dozens meteors per hour. I think, it decreases meteor abilities of
 >P/2005 JQ5 Catalina very much. Say, if in case of Draconid activity we
 >could see an outburst of 100 meteors per hour or lower, the same dust
 >trails geometry with P/2005 JQ5 Catalina as a parent comet gives
 >almost nothing, below visual recognizing. If it was on the place of 7P
 >Pons-Winnecke, we would see nothing in 2004 and nothing or almost 
nothing in
 >1998. But, maybe this a comet produces relatively high number of
 >very small particles and can be the source of radio-shower. Some
 >radioreports on meteorobs inform about increased number of signals
 >on 12 June. This is very interesting On the other hand, slow meteors,
 >as I know, are difficult to observe on radiowaves.

 >Best regards, Mikhail Maslov

PJ> CIRCULAR FROM THE PRO-AMAT WORKING GROUP OF IAU C-22
PJ> June 16,2005
PJ> ==============================================================

PJ> POSSIBLE METEORS FROM COMET P/2005 JQ5 (CATALINA)

PJ> It was first pointed out by Mikhail Maslov (meteorobs)
PJ> that comet
PJ> P/2005 JQ5 does not pass far from Earth orbit and may
PJ> cause meteor
PJ> activity. He found that the current elements put the
PJ> radiant at
PJ> RA=242 deg, Dec=-09 deg, and any meteors from this radiant
PJ> would
PJ> be very slow (Vg=16 km/s).

PJ> A study by Esko Lyytinen and Peter Jenniskens now shows
PJ> that
PJ> most recent dust trails from this comet (particularly
PJ> those of 2005
PJ> and 1948) are well within Earth orbit and are not
PJ> expected to cause
PJ> noticeable activity. However, dust ejected around
PJ> 1300-1400 A.D.
PJ> may have wandered in Earth's path as a very dispersed
PJ> stream
PJ> between June 14 and June 24. In particular, Esko evaluated
PJ> the
PJ> trails 1302, 1350, 1403, and 1500 A.D. to find that all
PJ> accumulate
PJ> at around the same range of solar longitude, with the
PJ> comet orbit
PJ> not changing much over that timeframe.

PJ> For the period June 14 - June 24, a low level of activity
PJ> may radiate
PJ> from (for June 17.0) RA = 244.3, Decl. = -9.9 (J2000.0)
PJ> with
PJ> Vinf = 19.05 km/s (or Vg = 15.44 km/s).

PJ> This is near the star psi-Scorpii, just above the ecliptic
PJ> plane
PJ> and near the antihelion source direction. To discriminate
PJ> from sporadic
PJ> meteors, orbits may need to be determined. A test
PJ> particles from
PJ> the 1302 trail near Earth orbit at the current Epoch was
PJ> found to
PJ> have orbital elements:

PJ> a = 2.76 AU
PJ> q = 0.8417 AU
PJ> Node = 86.067 degrees (J2000.0)
PJ> w = 233.79 degrees
PJ> i = 4.94 degrees

PJ> It is not known if this comet was active that long ago,
PJ> nor how much
PJ> dust it may have ejected. Hence, any predictions of meteor
PJ> activity
PJ> will be unreliable. We surmise that the activity will be
PJ> low and dispersed
PJ> over a ten-day period.

PJ> When the comet is near Earth in 2085, the dust ejected in
PJ> the
PJ> return of 2005 will also be close to Earth path that year
PJ> and the
PJ> shower may be more prominent.

PJ> -Peter Jenniskens