Re: ETX-125 and M43

From: Martin Brown (|||newspam|||_at_nezumi.demon.co.uk)
Date: 11/23/04 

Date: Tue, 23 Nov 2004 17:17:50 +0000

Tony Flanders wrote:
> saberscorpx@aol.com (SaberScorpX) wrote in message news:<20041122104353.06367.00000539@mb-m26.aol.com>...
>
>
>>I have no problem discerning m42 from Theta1 and 2.
>
> Wow! We're talking naked-eye, right? At 2' separation between
> the closest components of Theta1 and Theta2, that is genuinely
> extraordinary acuity. Can you separate the components of
> Theta2 as well?

I can't split Theta1 & 2. But on a good night I can split eps Lyrae.

But I do find that the M42 patch is obviously non-stellar in the same
sort of way that M13 appears naked eye fuzzy. It is only the very
brightest square central bit that can possibly show up in urban lit skies.

And I have seen this from central Manchester, UK on the few very clear
nights in a sky that is rarely good to 5th magnitude. In decent dark
skies it is for me obviously diffuse around the star.

>>It's also possible that m42 hadn't brightened and expanded to
>>naked-eye visibility until many decades after it's discovery.
>
> No, not really -- not without a drastic change in our understanding
> of astrophysics. As someone who finds M42 not at all prominent in
> small instruments, at low magnifications, and and in instruments
> with a lot of scattered light, I find it *much* easier to assume
> that it was simply overlooked. In fact, given the quality of
> Galileo's scope, it would have been amazing if he *did* see it.

Are you by any chance partially red-green colour blind? The central
patch of M42 in a small scope seems pretty bright to me.

M1 and other very young SNR are pretty certain to have become dimmer
with time since Messier catalogued them. However, as you say regions
with active star formation and many bright high mass stars in them are
unlikely to have changed very much over a couple of hundred years.

Regards,
Martin Brown

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