Re: eShel calibration set-up
Posted: Thu Aug 21, 2025 9:37 pm
Its almost 9 months latter and I've made much progress on getting my eShel functional.
The problem noted in the beginning:"...I should proceed further seeing that the right-side of the frame has such badly trailed Th-Ar light on these orders."
I determined that the eshel's fiber optic collimator on the unit itself was "lose" so I tightened its 4-bolts and all the system's small hexbolts around the spectroscope and my ThAr order lines got much better; the ThAr light on the right hand side were still worse than the left-hand side.
As Joan mentioned in another post, my Vega specto in LA was 240 sec, much too long! This was due to the fact that my fiber light output in the FIGU wasn't aligned with the light cone. I aligned this "fiber-shadow" with the light cone and got a usable Vega spectrum down to 2-sec with the CDK17!
After much adjustment, I got (more of less) the 3 ThAr spots to align as seen in check3 below:
I was able to get orders from 28-58 without any ThAr\zone errors. I took the following spectra of the image response star alpha Del and variable stars R Aqr and WR140 with the CDK17:
These spectra seem radiometrically correct, with typical errors of 0.1-0.3A around Ha and 0.6-1.4A around Hb and bluewards.
The resolution btw orders 28-58 vary btw R 9.5k-10.5k. My usable spectro range seems to be 3850-7995A. While the check3 isn't as good as what I achieved in LA, I think I can proceed with science on this.
Before I place the eShel2 into the "wine-cooler" and arrange the fiber optic agitators, I will do a more exhaustive test on the camera and (x-y)shifts to see if I can get better check3 results, but looks like there is "light at the end of this tunnel."
James
The problem noted in the beginning:"...I should proceed further seeing that the right-side of the frame has such badly trailed Th-Ar light on these orders."
I determined that the eshel's fiber optic collimator on the unit itself was "lose" so I tightened its 4-bolts and all the system's small hexbolts around the spectroscope and my ThAr order lines got much better; the ThAr light on the right hand side were still worse than the left-hand side.
As Joan mentioned in another post, my Vega specto in LA was 240 sec, much too long! This was due to the fact that my fiber light output in the FIGU wasn't aligned with the light cone. I aligned this "fiber-shadow" with the light cone and got a usable Vega spectrum down to 2-sec with the CDK17!
After much adjustment, I got (more of less) the 3 ThAr spots to align as seen in check3 below:
I was able to get orders from 28-58 without any ThAr\zone errors. I took the following spectra of the image response star alpha Del and variable stars R Aqr and WR140 with the CDK17:
These spectra seem radiometrically correct, with typical errors of 0.1-0.3A around Ha and 0.6-1.4A around Hb and bluewards.
The resolution btw orders 28-58 vary btw R 9.5k-10.5k. My usable spectro range seems to be 3850-7995A. While the check3 isn't as good as what I achieved in LA, I think I can proceed with science on this.
Before I place the eShel2 into the "wine-cooler" and arrange the fiber optic agitators, I will do a more exhaustive test on the camera and (x-y)shifts to see if I can get better check3 results, but looks like there is "light at the end of this tunnel."
James
