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Re: (IAAC) prism doubt



Basically any small prism will do. The idea is to hold it up to the
eyepiece and try and see a spectrum. This was a technique pioneered by Ed
Barker in the Webb Society amongst others. It is documented in the WSDSOH
Vol 2. The idea is that a stellar PN will show as a dot when the stars show
as small spectra. The technique is really only useful on bright stellar
PN's because of the absorbtion of light through the prism and the
requirement to split it up into a rainbow. It is also somewhat tricky to do
as you have to have dark skies and look at an angle through the prism. A
small prism is best, usually a 60 deg one. Better results can be obtained
with a direct vision spectroscope or a transmission grating.
At 07:26 22/02/2000 PST, you wrote:
>Hi yan,
>You have used Prism to detect PN in a star field. What kind of Prism is 
>that? What will you see if you use one? I have never used a prism till now 
>to see a PN. Can you pls tell me how to go about it and what are its 
>advantages.
>Vishnu
>India
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