(meteorobs) re Next meteor shower and call for observation of comet 209P

Wed Oct 3 22:26:33 EDT 2012

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Jay Salsburg

-----Original Message-----
From: meteorobs-bounces at meteorobs.org
[mailto:meteorobs-bounces at meteorobs.org] On Behalf Of
grs_longs at Safe-mail.net
Sent: Wednesday, October 03, 2012 1:11 PM
To: meteorobs at meteorobs.org
Subject: (meteorobs) re Next meteor shower and call for observation of comet
209P

First of all, just in case, I'm pretty sure a typo has crept into Mikhail
Maslov's emails, and I think he means May 24th not May 21st when he mentions
this shower, double checked against other email and his webpage.

Secondly I have to thank him very much for his reference to the Japanese
comet orbit site!  A marvellous site.  I was going to have to try yet again
to get an old piece of dos to run on my system in order to try to work 209P
back in time via numerical integration (this program's not been happy since
I first upgraded to 32bit, which was a long time ago).  Using
http://jcometobs.web.fc2.com/pcmtn/0209p.htm I was able to see that as I'd
expected from the comments being made that 209P had been a little too
intimate with Jupiter from time to time, and all without me having to worry
about whether I had done the analysis properly even if I managed to get
those results on my own!

Anyway, MM commented "It is difficult to estimate expected intensity of the
outburst due to the lack of past observed cases of activity from the given
comet meteor shower,"

Well, using the 1898 to 1914 orbits, considering them to be essentially the
same, and prior to an interaction with Jupiter, I've had a look through the
various IAU and other meteor orbit databases that have been available over
the aeons.

These orbits give a radiant in Lynx in early June, and interestingly enough
an exact phrase search on "June Lyncids" in the now legendary google gives
this short hit :-

"P/2004 CB (LINEAR) is a possible source of future June Lyncids. As a result
of infrequent shallow close encounters with Jupiter, the inclination of the
orbit of this ..."

from Jenniskens' Meteor Showers and their Parent Bodies book, apparently.
Looks like another Jovian interaction last time around changed things a bit,
so there'll be no June Lyncids...

Anyway, June Lyncid candidates can be found in the archives, albeit never
more than one a year, several years apart, so reality is a bit worrying.
Except it has to be remembered that past surveys were very short run,
infrequent within in each run season, and probably not looking much in
Northern Summers (short nights, Northern academic Summer vacation, etc).

MetRad gives RA and Dec 115d, 60d, roughly, on June 6th, for the 1898 orbit,
V about 16km/s as best fits with D Criterion about 0.05.  I say "V" because
the following data are a mix of Vgeo (photographic) and Vinf(radio).

( http://biko.home.xs4all.nl/dmsweb/publications/MetRad.ps )

The 1898 209P orbit was tested against meteor orbits using D criterion with
threshold level of 0.1.

One "classical" photographic one from 

http://adsabs.harvard.edu/abs/1961SCoA....4...97J

No 173, Date 5.26538/6/1954  RA 105.2d  dec +58.6d  15.98km/s

Three Harvard radio meteors also match :-

Harvard1 7862 Date  7.007/6/1963 RA 116d Dec 59d, 19 km/s
Harvard2 6035 Date  2.319/6/1969 RA 126d Dec 58d, 18 km/s
Harvard2 7389 Date 21.013/6/1969 RA 122d Dec 55d, 21 km/s

and 2 Sonotaco ones

Date_Time and ID 20080527_030159 RA 108d Dec 73d 14 km/s Date_time and ID
20080610_224347 RA 116d Dec 60d 17 km/s

With only the first Harvard radio meteor having a good D criterion value of
around 0.03, and the first Sonotaco one appearing doubtful despite passing
the 0.1 threshold.

So, 209P may have produced meteors detected in the past, though with such
sparcity (somewhat a function of observing regime, though), it is difficult
to be sure.

I surmise the expected future outburst is based on proximity of the comet
rather than anything else?

One problem with a small number of such widely spaced single matches can be
shown in that using D Criterion searches of the databases for the 2014 orbit
another 5 meteors with values < 0.1 (but none better than 0.07) and ranging
in date from 1959 to 2009 can be matched with the 2014 orbit and radiant...
...which is all well and good, but that orbit has only existed since 209P
had an encounter with Jupiter in 2012! That is, it hasn't been able to
provide any such objects yet! ;)

So, nothing definite in the archive re past 209P meteors, despite the past
orbits having a had a chance of producing meteors (for example, Harvard1
7862 matches orbits contemporaneous to it less well than the 1898 one).

Cheers

John G.
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