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November 19, 2016 at 10:33 pm in reply to: GNIRS reduction – Standard star subtraction and telluric lines #1439
At this point you probably have your science and telluric standard in 1D format and wavelength calibrated. In order to remove the telluric features of your science spectrum you have to use the telluric standard spectrum subtracted from the hydrogen lines as well from the continuum.
There is a couple ways to procede to remove the hydrogen lines. You can either use the vega star spectrum as a template for your star or subtract the lines manually by fitting some profile (Lorentzian for example). If you are using IRAF you can open your spectrum and type “k” and “l” in wings of the lines to fit a Lorentzian profile to the lines. With “-” and “-” at the same point you will subtract it. I tip on this is be careful to do remove the line completely. typing “i” you can save the new spectrum.
After that you have to subtract the continuum shape of the telluric star (without the H lines). This can be done with the “continuum” task in IRAF. The result will be your template for the telluric absorption for one specfic object. Note that you should have (ideally) one telluric for each object with different airmasses.
Use this template in the “telluric” task. In the telluric task you can choose the regions where optimize the subtractions. Type “s” and “s” to delimite these regions (type “t” to clean up all the regions). Some times selecte this regions will give you a best result that try to optmize for all spectra. Is up to you choose between a global vs local optmization in the task parameters.
Hope this answer your question and help you with your data reduction.
ps.: I don’t know if you are in the cross-dispersed mode, but I strongly recommend to check the Rachel Manson script for GNIRS data reduction. It is posted in the forum and works wonderfully.
Thanks for sharing your pipeline with us.
I will test in my data to see how it works! :p
I have been using the Felipe Navarete script and works great for my data. I just adapt it to python to make easier (at least for me) to play with it. I will post it here soon.
October 11, 2016 at 7:46 pm in reply to: GMOS IFU data reduction scripts (updated Oct 2016) #1417
- This reply was modified 2 years, 11 months ago by mmarinello.
Is there a “demo data” for GMOS?
I would like to start to reduce GMOS data and a demo data is usually very helpful to learn the steps and tricks of data reduction.