Unique opportunity to purchase an observatory class Barr Associates Ca K filter

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christian viladrich
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Unique opportunity to purchase an observatory class Barr Associates Ca K filter

Post by christian viladrich »

I’m selling my Ca K Barr Associates filter.

This is a two-cavity 2.6 A FWHM filter. DayStar or Lunt Ca K filters are only one cavity (meaning less blocking of photospheric light).

Measurements of the filter are presented here :
http://astrosurf.com/viladrich/astro/in ... ilter.html

Outside diameter is about 30 mm, and free aperture about 28 mm. Lunt Ca K 1800 is only 18 mm in free aperture.

The thermal stability of the filter is excellent at 0.001 nm/°C.

A number of images taken with this filter are presented in Solar Astronomy Book. More are presented in my website. For example :

http://www.astrosurf.com/viladrich/astr ... il2019.htm
http://www.astrosurf.com/viladrich/astr ... ASI290.jpg
http://www.astrosurf.com/viladrich/astr ... ASI290.jpg
http://www.astrosurf.com/viladrich/astr ... 90-CaK.jpg

Drop me a PM for more information and price.

Clear skies !

Christian Viladrich


Christian Viladrich
Co-author of "Planetary Astronomy"
http://planetary-astronomy.com/
Editor of "Solar Astronomy"
http://www.astronomiesolaire.com/
Dennissloane
The Sun?
The Sun?
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Joined: Fri Jul 17, 2020 12:45 pm

Re: Unique opportunity to purchase an observatory class Barr Associates Ca K filter

Post by Dennissloane »

Greetings Christian
I’m interested in the Barr CaK filter is still available.
Thanks
Dennis


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