IRAF: Experience with Analysing CCD Spectra?

[ajclarke]

Hey PF Folkadins =]

DO any of you have an experience with IRAF? I'm currently doing a BSc project on analysing spectral changes during periods of flaring on dMe type stars and I am having some issues extracting my ccd spectra.

In IRAF, I have run apall. And followed the steps of defining an aperature (there is a small issue with the spectrum being slanted, though IRAF seems to have the capabilities to handle this)

However apall seems to be plotting a spectra rather than a pixel count per y direction ,as you would want for analysing which section of the ccd holds the image of the star.

Simply put the x and y-axis are the wrong way around for the apall to work correctly, though why they have spectral dispersion defaulting to y and spatial dispersion to x is beyond me, since virtually all ccd's I have are the other way around.

Any clues on simple ways I can change this to the other way around? Without loading all 200 CCD frames into IDL and then back again?

Cheers.
Adam

 

[mmwave]

Hello Adam,

I am a scientist with experience in using IRAF for analyzing spectral data. I understand the issue you are facing with the apall task and the orientation of the spectra. This can be a common problem when working with CCD data in IRAF.

One solution to this problem is to use the imtranspose task in IRAF. This task allows you to transpose the x and y axes of the image, essentially swapping them. This should help with the incorrect orientation of the spectra in the apall task.

To use imtranspose, you will need to first select the appropriate image and then run the task with the transpose option set to yes. This will create a new image with the axes swapped. You can then use this new image with the apall task and the spectra should be correctly oriented.

Another option is to use the imcopy task to create a new image with the axes swapped. This can be done by specifying the x and y ranges in the task parameters and setting the transpose option to yes.

I hope this helps with your issue and good luck with your project! If you have any further questions or concerns, please don't hesitate to reach out. Best of luck with your research!