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I wonder if a modelling approach to correcting mechanical (and possible thermal) shits in wave length might be possible. What I have in mind is a similar approach to that pioneered by Patrick Wallace for telescope pointing and implemented on both professional and amateur telescopes. With my Paramoun...

Ivan - I used one with a Lhires III and it worked fine. I only tried with relativly bright stars. Regards Andrew

Interesting Francois, what system did you use to captrue the example above and what R do you feel is necessary to study the system? Thanks Andrew

You do like to test yourself Richard, well done on getting this far. One thought that might help. Given that the LHIRES III just has a doublet it might be worth refocusing it on the slit using a violet light (a violet colour filter would do) but then again it would be off for H alpha etc. Regards An...

Thanks Robin & François - I think I have it now. If you have two independent sources then they add so you need to subtract one to get the other. If one source is being filtered then you divide. In this example we have a mixture of the two.

Please correct if I have it wrong.

Regards Andrew

Interesting work as always Robin. I was just wondering about dividing of one spectrum by the other rather than scaling and subtraction. I think you used the latter when removing telluric line in your previous work. Did you change the approach for a reason? I can see that what you are doing is equiva...

I think a good finderscope aligned with LHIRESIII would be simplest. At the magnitudes available to the LHIRES III it would not need to be large and if you wanted to use it with a webcam that should also be ok. Then it's down to finder charts etc.

Regards Andrew

Hi Robin, if the blurring was due to CA I would have expected the lines in the UV to have been more washed out than they appear to be in François’s spectra. I.e. given the width of the fan I would have expected the spectra to be almost completely washed out in this region. I have a LISA on order, du...

Bernard - Maybe yours are just plain old monochromatic interference within the coverslip? Andrew

Hi Andrew, The source of this particular fringing in high resolution spectra has been traced to interference in the CCD cover glass. The spacing depends on the thickness of the glass. Cheers Robin Hi Robin - That would have been my guess as to the cause but you never know. My MaxCam with E2V chip d...