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re: (meteorobs) QUERY: Limits of IMO LM charts?
Hello Lew, you make me sick!!:-)
I'm lucky to get off of the bottom of those charts some nights. I have
written down what the 5.0 threshold is so I know if it's worth going out to
observe.
Exactly what is the magnitude when limiting magnitude area zero (the whole
sky) count is 5 stars....and one of them is Jupiter :-)
Wayne
-------------
Original Text
From Lew Gramer <dedalus@latradedot com>, on 8/19/96 2:35 PM:
To: "Meteor Observing Mailing List" <meteorobs@latradedot com>
Cc: "International Meteor Organization News" <imo-news@tu-chemnitzdot de>
I promise to provide a summary of my observations around the Perseid max,
as
soon as the data I laboriously transcribed from tape to paper can be
laboriously
transcribed from paper to electrons (hopefully tonight). I also hope to
provide
a juicy, detailed account of the wonder of observing from a pitch-black
beach in
the subtropics, with a southern ocean horizon letting me glimpse
constellations
I had never even identified before... Not to mention sharks and sea
turtles. :)
Meantime, however, I have a very specific QUESTION about the IMO Limiting
Magnitude Chart #8, in Taurus. The question is, what do I do with a star
count
which significantly exceeds the published limit of 32 stars??
To my utter amazement, and in spite of no less than *four* recounts of this
region on the morning of the Perseid max, I still was forced to conclude
that I
was seeing *38+* stars in this field! This in spite of the obvious zodiacal
band, and the close-to-the-horizon crescent moon.
The only explanation I could come up with (barring an error in the
published
chart) was that this area of the sky was just under 7.5 lm, and that there
were
a PROFUSION of stars in the magnitude decile between 7.5 and 7.6 (or 7.7?).
This leads to a more general question (although I won't be under these
skies
again for some time... ignore my gentle weeping): Is there any published
"extension" to the LM chart tables put out by the IMO, listing star counts
and
limiting magnitudes below the IMO's arbitrary limit of 7.5?
As a MORE GENERAL question, is the AAVSO-chart method of determining
limiting
magnitudes still advocated by IMO for experienced observers under very dark
skies? It's discussed in my old copy of the IMO Handbook, but I haven't
seen it
mentioned in any of the emails or Web pages I've read. I ask, because one
of the
few downers of going out to these eye-bending dark sites is the endless,
mind-numbing 50 and 60 star counts which have to be made every half hour...
Thanks in advance,
Lew Gramer, sunburnished meteor observer ;>