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Hi Evgenya,
I'm copying the STScI helpdesk (help@stsci.edu) in case they have
any other suggestions. You can use the standard tasks like EPIX to simply
zero pixels in the FFT image but otherwise I'm not aware of a way to take
out a specific frequency using existing tasks. The addition of the 'r'
to the filename in the INVERSE task is, I believe, intentional. ST may
comment on whether/how that can be changed. Hope this helps.Cheers,
Mike Fitzpatrick
On Tue, 22 Nov 2005, Evgenya Shkolnik wrote:> Dear IRAF Experts,
>
> I'd like to "pre-whiten" some data, i.e. take out a low-frequency
> sine-wave from some residual spectra (due to fringing.) I tried using the
> "powerspec" routine and "bwfilter" which don't quite do what I need. I
> just want to remove one frequency at a time.
>
> Can you tell me the best way(s) to do that with IRAF?
>
> Also, a strange thing occurs in the "inverse" routine. The routine
> automatically adds an 'r' to the input filename and then I get an error
> (see below)
> ------------------
> fo> inverse sine.fits
> Output data file (test_inverse):
> ERROR: Cannot open image (siner.fits)
> -----------------
> Is this a bug or is it fixable?
>
> Thank you!
>
> Evgenya
>
> -------------------------------------------------
> Evgenya Shkolnik Tel: 808-956-8800
> NRC Postdoctoral Fellow Fax: 808-956-7264
> NASA Astrobiology Institute
> University of Hawaii - Manoa
>
>