DISPCOR and echele spectra
Karsten Brogaard wrote on Apr 02, 2007
Hi,
I am reducing echelle spectra with simultaneous thorium argon next to each target order. The problem is that some of the thorium argon lines are so bright that they interfere with the taget spectra. Therefore I need to know where in wavelength space this happens. It is easy on the one side where the thorium argon spectrum has the same wavelength coverage as the target. But on the other side the wavelength range is different so I somehow need to calculate back to pixels and then to the other wavelength range. I cannot see how to do this since when I linearize I loose the pixel to wavelength relation. Maybe it is just me who do not understand it well enough but please help. Thanks in advance.
Karsten
I am reducing echelle spectra with simultaneous thorium argon next to each target order. The problem is that some of the thorium argon lines are so bright that they interfere with the taget spectra. Therefore I need to know where in wavelength space this happens. It is easy on the one side where the thorium argon spectrum has the same wavelength coverage as the target. But on the other side the wavelength range is different so I somehow need to calculate back to pixels and then to the other wavelength range. I cannot see how to do this since when I linearize I loose the pixel to wavelength relation. Maybe it is just me who do not understand it well enough but please help. Thanks in advance.
Karsten
Francisco Valdes wrote on Apr 02, 2007
Hi Karsten,
I'm not sure I understand the situation. "A picture is worth many emails" in this case. One thought is that when you define apertures for the target order. Then you extract the target spectra with those definition. Then use the same orders but with a shift of all the apertures to place them on top of the arc spectra. Extract this. This will then have done the two fairly equivalently and may be able to then match the two to solve the problem you have.
Yours,
Frank Valdes
I'm not sure I understand the situation. "A picture is worth many emails" in this case. One thought is that when you define apertures for the target order. Then you extract the target spectra with those definition. Then use the same orders but with a shift of all the apertures to place them on top of the arc spectra. Extract this. This will then have done the two fairly equivalently and may be able to then match the two to solve the problem you have.
Yours,
Frank Valdes
Last post on Apr 02, 2007