eShel problem with V6.0.0

[Bernard Heathcote]

I believe there is a bug in V6.0.0 affecting eShel spectra.

Using the same data and parameters the final spectra produced by V6.0.0. have many absorption spikes which are not present in V5.9.6 or earlier versions.
See attached example.

I have not check if a similar problem exists when reducing single order spectra.

[Christian Buil]

Look the eShel setting panel and adjust the Rejection coefficient to 100 (at the Botton of the panel, "Optimal extraction" section). Try also a zero value gain.

Christian

[Bernard Heathcote]

Christian,

Thanks for your suggestion to change the Rejection Coefficient to 1000 as this did work. I also tested with the value 10, which also worked, compared to the original value 3 which did not work.

I am puzzled about what has changed between version 5.9.6 and 6.0.0 as the rejection coefficient=3 works with the earlier version but not with 6.0.0 (both using same data and xml files).

Cheers,
Bernard

[Bernard Heathcote]

Christian,

I have just noticed that one difference between V5.9.6 and V6.0.0 is that in the latest version the 'optimal extraction' setup has an entry for camera RON, which is not in V5.9.6.
As my QHY22 camera has a RON=5.0 I used that value (default =1.7) but that did not remove the noise. I assume there must be some other difference between the two versions on how optimal extraction is implemented.

Bernard

[James Foster]

Nice discussion on the eShel! I'm still trying to figure out my DEF_ORDER. LST file. One confusing thing I notice is
when Isis displays the 2d .fits image, it displays it with a vertical mirror image; I noticed this with Alpy and LISA processing previously.
Hopefully I'll be able to process my 1st eShel spectrum before Halloween......maybe!

James