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Re: (meteorobs) Taurids and the Telescopic Meteor Observer

How do I follow an introduction like that from the holy GRALE?  Thank
you Lew.

Like the southern showers of July and August, it can be difficult
the discriminate between the competing ecliptic showers of October and
November.  Telescopic and video do offer a way of resolving the
various components.  The better plotting accuracy, especially the
reduced lateral error resulting from the magnification alone, means
that observed weak radiants aren't dispersed into the background as
easily for visual observers, so weaker radiants are detectable.

Now for some caveats.  One has to remember that we are observing
fainter meteors through the telescope, so that the picture we see may
not reflect the radiants present in the visual regime.  Also that the
Taurid shower in particular is old, and hence has fewer faint meteors
than say the delta-Aquarids.  This means the number of Taurids seen
telescopically isn't high (somewhat mitigated by their famed slow long
paths).  As Lew implies we do need more observations at this time.

> What would you recommend as a way to get started with telescopic plotting, for
> those of us who have never had the chance to do it?

Check my notes at the NAMN site 
     http://Web.InfoAvedot net/~meteorobs/guidechap4.html

I'll just mention a few points here.

1) Instrument: Use a low-power, wide-field telescope or binocular.  So a
7-10x50 or 11x80 binocular or an Astroscan would do nicely.  It is vital
that the instrument is mounted.  Commercial binocular mounts aren't
cheap, but many people have made their own for a small outlay.  Even
moderate sized scopes are useable---I've observed the Orionids with a
30cm Newtonian---provided the magnification is no more than twice the
aperture in cm, and the apparent field of view is at least 45 degrees.  
Mixing units in the NASA tradition, a target to aim for is 4x the
aperture in inches and about 60 degrees apparent field.

2) Comfort: Ensure that you can observe for at least 20 minutes in
comfort.  This is often a showstopper.  If you are not comfortable,
you will see very few meteors.  It took me many attempts and
telescopes before I had a setup where I could observe for many hours
during a night.  I use a comet-seeker refractor on an adjustable
tripod and chair.  That way I don't strain to reach the eyepiece.
Since I only use one eye, I have a patch over the other.

If it doesn't work first time, please don't give in.  Find ways to
improve your comfort and so you can concentrate on looking for
meteors.  The meteors are there if you are attuned to them.

3) Charts: For those attempting to watch the Taurids with a small
binocular you can use Uranometria or the IMO A set charts (available
as bulky PostScript from me or by snail mail from Lew or myself).
There are six other sets, not all complete, for a range of common
instruments.

Getting charts out to observers at the last minute or for instruments
we don't have suitable charts, is a nuisance.  Also I don't have
access to the chart-making facilities in Britain any longer.  Thus I'm
working on Java software for observers to create charts tailored to
their instrument from the IMO Website, and sent as GIFs.

> And for those of us who have
> tried it successfully a few times, which of your Telescopic Plotting Charts
> would you recommend for studying the various phases of the Taurid/OAR peak?

As to field centres, that's always tricky because of the long duration
of the Taurids.  For the moment let's just say the first half of
November.  The general principle is to choose a pair of fields so that
a meteor from the radiant seen in each field would intersect at right
angles at the radiant.  Here because of the number radiants that's not
possible.  You might get that configuration for one radiant, but not
all.  If we focussed on the Taurids, it would not be sensible to have
a field north or south of the double Taurid radiant because the
radiants would have the same bearing from the field.  Better to go to
the north-east or north-west.

The way around the number of radiants is to have a set of fields which
straddle the ecliptic around the complex.  This approach minimises
artifacts in the radiant distributions calculated from telescopic
data.  Six fields is typical.  The extra number also aid
identification of the real radiants; if a radiant is `seen' from the
majority of fields, it's unlikely to be an artifact.  However,
I don't expect beginners to use more than three.  The concentration
can be tiring.

The specific IMO charts are: 55, 74, 76 to the north; and 121, 139 or
140, and 141.  For those using their own charts, chooses fields to 10
to 20 degrees north and/or south of the ecliptic spanning RA 20 to 80
degrees.  The fields should have a range of star brightnesses, and no
large areas devoid of stars.  Triangulum and western Auriga are good
in the north, Orion's shield and northern Cetus would do fine in the
south.

Please note that I'm away for the next six days save Monday.  So if
you want telescopic charts, forms, and instructions please mail me
over the weekend.

Malcolm 

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