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Hi All,

this is my first post at the Beginners Corners ! About one week ago a new OTA has improved my observatory. It is a used C9.25. I exchange my ex Ed120 with this C9.25 in order to improve the light intensity. I still have the same mount: CG5GT which is a bit under-dimensioned for this important OTA but I am trying to reduce the vibrations with some little trick as installing some weight in the central part of the tripod. Moreover I am waiting a Losmady bar in order to substitute the existent Vixen bar, and I need to install an adaptor in order to be able to install the Losmady on this mount. In the future I will buy a new mount. To guide I am using the beam splitter (micro slide) as per Ken Harrison suggestion. I tested it several time with the ex OTA ED120 and it seems to work very well also with the focal lenght of this new C9.25. Finally the Spectra L200 has been retrofitted with a 20 microns Thorlab fixed slit to improve resolution. I wonder if a focal reducer is a must or I can wait, I have seen that many observers with a C9.25 are using a focal reducer. Any suggestion will be appreciated. Below you can see some pictures: the OTA set up, the spectra processed in Astro Art and IRIS and the spectra profile processed in Vspec, which is very similar to the same class star in the Richard Walker Atlas.

Thanks and Kind Regards,
Marco

Thanks for watching and for any suggestion

Marco,

nice setup ! The C9.25 is a very good choice. Looking forward for more spectra from you...

Cordialement,
Olivier Thizy
Vous ne verrez plus des étoiles comme avant !
http://www.shelyak.com/en/

Hello Marco

I took the same path as you. From ED120 to C9... But not only the diameter is important but also the guiding.
I do not know about the L200, is it a clone of the LHIRESIII ? looks like. With my lhiresIII I do not use any focal reducer, as the LHIRES was designed for this focal ratio of F/10 - So you need to get the specs of yours.
In the past, for my ED120,, I found useful to add a small counter-weight at the entrance of the tube to counter balance the spectrograph/camera.

I'm sure you will have fun !

Valerie

Hello Valerie,
sorry for the late reply. Yes Spectra-L200 is a Littrow spectrometer very similar to LhiresIII. My L200 has 600 l/mm. I have not reflective slit has your LhiresIII, but I have a fixed slit 20 microns. The original design is by Ken Harrison. I will check for a counter-weight at the entrance of the tube to counter balance the spectrograph/camera as per your suggestion.
Cheers,
Marco

Hi Marco, sorry for the very late reply!

Best wishes for the new setup! With Lhires III I do not use any focal reducer, too. With my C9.25 I tried f/6.3 FR but I have checked that efficiency is highest at f/10 ratio. But we speak about Lhires, I don't remember for which ratio L200 is designed. If you need focal reducer to adjust the beam, check for any chromatic aberrations (a possible further problem).

A big "hello" from Italy through France!

Ciao ciao
Paolo