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Bad efficiency of the eShel from shelyak

PostPosted: Wed May 08, 2019 6:13 pm
by Berthold Stober
Bonjour à tous

I have for some time ( perhaps the last 6 months) big problems with the efficiency of the shelyak eShel . I sent it to shelyak but no effect could realized. The bad efficiency is still to see. I have changed all fibers -> nothing. In 2015 I had with KAF 3200 after 10 seconds using the tungsten lamp oft the calibration unit about 50.000 ADU and now I have since about 6 months 50.000 too but I need now 25 seconds. I don't know what I could do to solve this problem.

The efficiency of an eShel is high depending of the correct amount of the angle alpha , 63 degree. How can I find out if this angle is correct on my eShel?

So how it is, I cannot use the expensive device.


Re: Bad efficiency of the eShel from shelyak

PostPosted: Wed Jun 12, 2019 9:47 pm
by James Foster
To: Berthold,

I don't have an eShel, but have you gone through Shelyak manual and Christian's extensive notes on how to set-up the
instrument and process data using Isis? Here are some links:

Shelyak Manual:

Device use:

Isis data processing:

Remember, Spectroscopy is on the bleeding edge of what Amateur astronomers do and, as such, we must research techniques
and theory more than any other portion of amateur astronomy. The only harder pursuits in amateur astronomy maybe radio astronomy and/or
spectropolarimetry where you need both spectroscopic expertise and knowledge of magnetic-electrical fields to interrupt the data.


p.s. Once you get eShel running, remember that Shelyak has a modification for eShel that improves its near UV efficiency and increases the orders you
can get usable data from.