(IAAC) Re: Using O III with higher magnifications ?

To: Pro-Am Astronomy List <amastro@egroups.com>, Internet Amateur Astronomers Catalog - Discussion <netastrocatalog-announce@jovian.com>
Subject: (IAAC) Re: Using O III with higher magnifications ?
From: Lew Gramer <dedalus@latrade.com>
Date: Fri, 07 Jan 2000 15:53:47 -0500
Cc: Steve Clougherty <sclough@massed.net>, stevo703@aol.com
In-Reply-To: Your message of "Fri, 07 Jan 2000 12:01:15 GMT." <200001071210.AA09957@pinthas.latrade.com>
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Alister Ling wrote:
>There are some rare exceptions, but straight visual appears to be the best.

I agree with Alister's comments regarding the OIII and extragalactic HIIs.
In exploring the smaller emission regions visible in M33, M101, NGC 2403,
and other targets, I found the OIII rarely gave any noticeable advantage.

But I was surprised to hear Alister feels the same about the UHC! I recall
in particular in M33, being amazed at the result: in a 20" f/5 at 210x with
a UHC, the outer arms of the galaxy were far less prominent, and yet still
I could trace several of them merely by following the subtle arcs of tiny,
nearly-stellar HII regions along them! Such "stellarings" (as Brian Skiff
so nicely called them) were probably still visible without filtering, but
I would have been hard-pressed to ferret many of them out from the ambient
glow of unresolved stars in M33's arms.

Clear skies,
Lew Gramer

Internet Amateur Astronomers Catalog of Deep-Sky Observations:
  http://www.tiac.net/users/lewkaren/netastrocatalog


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