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Re: (meteorobs) Bob Lunsford's Suggestions/Help & Nov. 19/20 Correction -Marco V.



>     This topic jogged an old memory in me.  Back in the seventies when I
> first got started serious meteor observing, one of the data points I
> recorded on each meteor seen was a column called DCV.  This stood for
> "Distance from Central Vision".  Haven't seen this term used or recorded in
> a long time.

Quite a few current observers record this parameter.  Lew for one.

As Paul points out, it's not just limiting magnitude.  That's why IMO
uses a "perception factor" for each observer, which is converted to a
shift of the observed LM into an effective LM.  I've had a fellow
observer with a LM 0.8 worse than me, but that was reflected in his
rates compared with mine.  Then I've observed with people with an LM
close to mine, but don't have the good peripheral vision, and see far
fewer meteors than I did.

When I observed visually on a regular basis too many years ago, I
estimated LM much like Mike Linnolt does now, using lots of binocular-
variable-star charts to estimate the LM, not that LMs > +6.5 were
accounted for in the 1970s.  Also after a while, experience just looking
at the general sky impression could give a decent estimate of the LM
to 0.1ish.  There were exceptions.

More recently for telescopic and the odd visual session, I do monitor
the naked-eye LM using the IMO counting method.  As someone in a rural
setting with good sensitivity, I haven't had much difficulty with the
gaps in the sequences.  It's actually having regions with too many stars
to count that's the most inconvenience.  Region to region give
consistent values to 0.1 or better.

Do we need to define a few more regions with plenty of 5.0-6.0 stars
to help avoid those large steps in the LM that the original poster was
bemoaning?

Malcolm Currie
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