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Re: (meteorobs) Re Observations Sth Tau, Orionids, Pup Velids 2nd Oct 1997
George, Jim,
> George wrote:
>
> Is this a standard procedure from your local meteor organization? I believe
> Rainer once mentioned something to the effect that you should choose one or
> the other. That is make it your best guess. Anyhow, this is what I do. The
> Taurids are murder for me to determine which radiant any particular meteor
> belongs to. Quite often the meteor and the two radiants line up and it's a
> real guess. Sometimes it becomes a matter of which shower is the most active
> on any particular date that I choose when they line up. Like now the S.
> Taurids are most active. The questionable alignments will favor the S.
> Taurids. Later in the month I will favor N. Taurids if need be. The bottom
> line is, I don't split up shower membership. For meteors that are close to
> the radiants, it becomes a little easier for me to decide. I take into
> consideration how long the meteor path is when it passes thru two radiants.
>
>
> Jim replied:
>
> >From the researcher's point of view, the above method would introduce a
> systematic bias in the data, by having the observer interpret shower
> membership based upon a preconceived notion of what component is most
> active that the time.
>
> If you believe that the Southern Taurids are more active than the Northern
> Taurids on the night that you observe, and you interpret questionable
> alignments as Southern Taurids because of this knowledge, then - presto -
> your data will show the Southern Taurids to be the most active: thus
> proving your preconceived notion.
well, this is a really tricky thing. I think we discussed it several
times. Probably Rainer will also comment on this topic later on.
There is no solution that is 100% perfect:
* if you split the meteors among the showers, you always make a mistake,
since the meteor *can* only belong to one or the other shower.
* if you choose the shower that is supposed to be more active, you data
becomes biased as Jim pointed out.
* if you just call them 'Taurids' it will not help you much either, as
you cannot determine the activity of the single components afterwards.
I agree with George that it is best to decide for one shower according to
all the criteria (backward prolongation, velocity, lengths).
If this seems impossible since both radiants have almost the same
probability, you have to think how you minimize the classification error.
If one shower is certainly much more prominent than the other (for example
ORI at maximum / EGE), you could decide in favour of the richer as George
suggested.
However, if both showers are minor or of comparable strengths, this is
certainly a bad choice. Here I would still use the 3 criteria to decide
for either one or the other.
Sirko
References: