Thanks for your reply Steve. I'm new to absolute visual
magnitude, but I can appreciate that it's not to be used
as a predictor of observed magnitude without first
applying the conversion you described. Before I do this
however, I have a few questions:
If I apply a conversion from "absolute" to "apparent"
visual magnitude, how often will the calculation lead to
a value that reasonably matches what one would see
through the eyepiece? Does it consistently under or
overestimate?
At first glance this calculation seems like it could be
biased by certain factors:
1. The modeled absorption effects of the intergalactic
medium -- are there debates in this area or is it pretty
nailed down?
2. Error in the measured distance - are there debates
about measurement techniques that significantly affect
the values I would be using?
In other words, for practical purposes I'm trying to
determine the predictive validity and utility of this
calculation for amateur astronomers.
Craig
--- Steve Gottlieb <sgottlieb@No-Spam> wrote:
> In a message dated 9/29/03, Craig Scull writes:
>
> > Seek and yee shall find. Try the 4th entry on a
> Google
> > search for "6946 Globular"
> > http://arxiv.org/abs/astro-ph/0104133
> >
> > Open the PDF and look at the photo of the globular
> near
> > the end of the article. That thing is HUGE! It's
> also
> > relatively bright at Mag 13.2.
>
>
> The listed magnitude in the paper M(V) = -13.2 is the
> "absolute" visual
> magnitude -- its the apparent visual magnitude *if* the
> cluster was located
> at a nearby distance of exactly 10 parsecs or ~33 light
> years. To convert to
> an apparent visual magnitude, you use the distance to
> the galaxy. I'm fairly
> certain the object I observed in N6946 was fainter than
> V = 13.2.
>
> Steve
>
>
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