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Re: (meteorobs) Iridium flares and meteor photography

-- [ From: Robert Lunsford * EMC.Ver #2.5.3 ] --

David,

Thanks for your reply to the list. I agree that flares can be a useful
tool in estimating fireballs as bright as -7. As David stated it is very
important to use your precise geographical coordinates or the
predictions verses what you actually see may be off be several
magnitudes. 

David, I hope to see more of your contributions to the list!

Bob Lunsford
> 
> I've been watching Iridium Flares since mid-April using predictions
from
> www2.gsoc.dlrdot de/satvis .  I have found that the timings are very
precise, in
> fact you could set your watch by them to WWV accuracy.  This is of
course
> dependent on the precision with which your site coordinates are known.
 I have
> seen several web links to sites that supposedly give the Lat/Long for
any site
> on Earth, but they usually give one coordinate for an entire city,
which is not
> accurate enough.  You have to get out a good map, ruler, and
calculator and do
> it yourself.
>     The predicted sky location is also very accurate, and known flares
could be
> avoided by meteor photographers by choosing a different area of the
sky to
> monitor.
>     Also, Iridium flares are symmetrical so there should be a
gradually
> brightening/dimming trail on both sides of the maximum flare, not just
before
> the flare, as most often occurs with photographed meteor trails. They
should be
> easy to distinguish from meteor trails on photographs.
>     Lastly, if this isn't heresy, I'd like to suggest that Iridium
flares make
> a useful training tool for visual meteor observers.  Meteor magnitude
estimates
> brighter than -4 are usually not much more than guesses since we have
nothing
> in the sky to compare the meteor with. These predicted flares allow
anyone with
> clear or partially clear skies to step outside at the right time and
see a
> magnitude sample as bright as -7.  I've seen enough of them that I'm
beginning
> to develop a magnitude memory for brighter than -4 events.
> 
> David Holman
> 
> 
> 

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