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Re: (meteorobs) Geminids from China (Dec. 14/15 ZHUJI)
Jin>>>>>For those which could be traced back geometrically to the GEM radiant, but
be far from radiant with too short trail and too slow speed, I usually recorded
them as SPOs.
Let me guess, Jin, that many of these meteors you are describing were at or
near the horizon...? My (limited) understanding
is that (a) a meteor can never have too short a trail to be associated with its
shower (but can be too long) and (b) a meteor moving from overhead down to the
horizon will appear to slow (and dim) somewhat near the horizon. I had exactly
the same experience during the Geminids. I saw MANY meteors with short path
lengths near the horizon moving at, say, a speed of two (slow) but I knew that
most likely they were Geminids because they were traceable back to the radiant
and the Geminids were at near-peak intensity. So given your other descriptions, I
would say it's safe to assume that many of your sporadics were Geminids. It would
be good to have an experienced observer give us both his/her slant on this.
Bob Lunsford recently reitierated the reverse for me in a posting... that a
slower meteor, when moving overhead of the observer, will appear to speed up!
I had the same experience with the XORs that you had with the HYDs, that is,
I was not confidant enough of the radiant so I labeled potential XOR's as SPO's
and quit worrying. As a new observer, I didn't need the added confusion.
Kim Youmans
Jin Zhu wrote:
> Kim,
>
> Thanks for your message.
>
> > It would appear you had a very impressive night of observing during
> > the Geminids. I have a very honest curiosity (rather than an obtuse,
> > one-line question of doubt) as to your sporadic totals. You have listed 175
> > Geminids vs 163 sporadics. That is a high number of sporadics, even given
> > that many will be HYDs and what-not. What is your impression of the
> > sporadic totals?
>
> Yes, I agree that it seemed that the sporadic seemed too much from my
> observations. :) And it also looked strange that the variation of SPO
> numbers seems relavent to that of GEM! I don't think that that was from
> the weathere variation. It's a great pity that I didn't use plotting -
> I'm not familar enough to those fainter stars for a reliable plotting.
> There should be some HYDs inside my SPOs, but may not be so much as those
> of XORs and MONs - the reason for my not including HYD as one of my
> observing showers was that I made a wrong radiant position for that
> during the first half of observation... We also saw some HYDs during
> the previous night.
>
> I used not wide radiant radius - about 3 degrees (?) - for shower
> determination. Meteors far from radiant may have wider close-distance.
> For those which could be traced back geometrically to the GEM radiant,
> but be far from radiant with too short trail and too slow speed, I
> usually recorded them as SPOs. However, these may not happened too
> much - I mean that those SPOs with obvious different directions
> may probably the large part of my recorded SPOs. Perhaps I need to
> record something about the start/end points of the trails of each
> SPOs next time.
>
> I just checked my Leonids observations this year, I saw 37 LEOs, 6 LINs,
> and 59 SPOs during 2.72 hours on Nov. 17/18. It seems to me that some
> new observers tends to include some SPOs to shower members, some may
> even don't know exact radiant position before observation. For the
> Leonids observation in 1998, I heard that some observer regarded
> all meteors which could be traced back to the LEO constellation to
> the LEOs. For this year's observation, we have more communications
> and sometimes we observe together, which made our shower determination
> standard closer - and I always found that new observers may easy to gave
> more shower members (from SPOs) when they observe.
>
> This rises to another question about the XORs and MONs during the GEM
> maximum. It seems that the XOR members I observed are more than the
> one listed in IMO canlendar. I think that it might be possible that
> the real XOR, MON, HYD members are underestimated because of the GEMs.
> GEM is very good for new observers to start their first meteor
> observations, however, because of the close distance of these four
> radiants, new observers may not be able to distinguish between the
> four, and may easily include all of those to GEMs. I myself am too
> busy recently to check whether this could be possible from different
> observations reported here, both from 'experienced' observers and
> 'new' observers, and it's a pity that I didn't have time one week
> before the Geminids (the maximum) to get some observation for the
> SPO background. But those should be find out from IMO database?
>
> > By the way, I have enjoyed reading your observations this past year. You
> > and your observing collegues in China have been quite busy, it would appear,
> > please keep us informed of your observations!
>
> It was a great pity that I'm too busy now, so I could only send out
> those reports in data format, without any description. We did have
> some funny things happened during observations, and saw some quite
> interesting meteors which worths to be said in some words. Anyway,
> I have some friends now who can observe with me together, and I wish
> that some of them could write something when they have time later.
> And I'm thinking about to establish a Meteor Society under Beijing
> Astronomical Society (functioned as Chinese Meteor Society?), and
> I already know many meteor observers in China now.
>
> Merry Christmas to all of you, and Happy New Years!
>
> It seems that our meteor observations would be even better for the coming
> years.
>
> Best, Jin
>
> > > -----------------------------------------------------------------------
> > > OBSERVING PERIODS: 0=none seen; /=shower not watched
> > > -----------------------------------------------------------------------
> > > PERIOD (UT) FIELD TEFF F LM GEM MON XOR SPO
> > > 13:26-13:30 E,90 0.08 1.05 6.0 4 0 1 4
> > > 13:46-14:00 E,90 0.25 1.05 5.5 7 2 3 3
> > > 14:01-14:15 E,90 0.25 1.05 5.9 5 0 0 9
> > > 14:16-14:30 E,90 0.25 1.05 5.9 3 1 4 7
> > > 14:31-14:45 E,90 0.25 1.05 5.9 10 0 1 14
> > > 14:46-14:59 E,90 0.23 1.05 6.0 8 2 8 6
> > > 15:00-15:14 E,90 0.25 1.05 6.0 11 0 3 14
> > > 15:15-15:30 E,90 0.26 1.05 5.5 5 3 4 11
> > > 15:31-15:45 E,90 0.25 1.05 5.5 13 2 1 12
> > > 15:46-15:59 E,90 0.23 1.05 6.0 8 3 4 5
> > > 16:00-16:14 E,90 0.25 1.05 6.0 13 1 4 6
> > > 16:15-16:21 E,90 0.12 1.05 6.0 7 0 1 4
> > > 16:24-16:44 S,80 0.35 1.05 6.0 16 2 4 10
> > > 16:45-16:59 S,80 0.25 1.05 6.0 15 1 2 7
> > > 17:00-17:14 S,80 0.25 1.05 6.2 5 2 2 9
> > > 17:15-17:33 S,80 0.32 1.05 6.2 18 0 4 17
> > > 17:34-17:45 S,90 0.20 1.05 6.2 9 1 1 9
> > > 17:46-17:59 S,90 0.23 1.05 6.2 16 0 0 10
> > > 18:00-18:04 S,90 0.08 1.05 6.2 2 0 0 6
> > > -----------------------------------------------------------------------
> > > TOTALS 4.35 175 20 47 163
> > > -----------------------------------------------------------------------
>
> ========================================================================
> Jin Zhu | Tel.: +86-10-62759888, 62756612 (O)
> Beijing Astronomical Observatory | +86-10-62579689 (H)
> Chinese Academy of Sciences | +86-314-5054767 (Schmidt dome)
> P. R. China | Fax : +86-10-62765031 or 64888731
> ------------------------------------------------------------------------
> email: zj@bac.pkudot edu.cn or jinzhu@sun.ihep.ac.cn
> WWW Home Page: http://vega.bac.pkudot edu.cn/~zj
> Pager: zhu_jin@263dot net (only Sub. line) OR +86-10-64256688 PIN 82333
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