[AZ-Observing] Re: Comet Holmes second look (Oct 27.1 UT)

I'm surprised the OIII did not enhance the comet's outer halo for you  
Brian as it did for me and a couple others.  I haven't observed the  
comet tonight, though.  Looking at the spectra Keith posted, could  
the absorption at 4300A be the reason for the increased contrast?  If  
I'm correct, that's close to an OIII absorption, but my better  
judgement tells me that shouldn't matter since the narrow band filter  
is supposed to only transmit at 496 and 501nm.  Or, maybe it's just  
me PNe imagination.

-FRANK


On Oct 26, 2007, at 8:11 PM, Brian Skiff wrote:

>      I now have my 70mm Pronto out, and for the first time have
> had a look with an optically sharp telescope without scattered light.
> The comet is still rather low, but I tried all three of my filters
> (UHC, [OIII], old Lumicon 'Deep Sky').  The UHC and [OIII] were
> much worse.  The Deep Sky filter (a mild light-pollution filter,
> mainly cutting out the mercury, sodium, and natural night-sky emission
> lines, but passing H-beta, [OIII], and H-alpha in the red) was
> actually useful in enhancing the contrast on the very large outer
> halo.  It is well visible without the filter at 30x, but the contrast
> is better for that feature; not useful for the bright inner stuff.
>
> \Brian
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