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Hello:

Apologies if this is not the right place to submit questions and if so, can someone please explain how to post a new question in a forum?

I noticed that fxcor can do fourier filtering in the course of doing cross-correlations for rv determinations. I'm interested in something far simpler. Can the fourier filtering routine in fxcor be used as a stand-alone? in other words, is there a way to out put the filtered object spectrum?

thanks,
Sally

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Unforutnately, there is no way to save the filtered spectrum from FXCOR. However, the BWILTER task in STSDAS.PLAYPEN is essentially the same algorithm depending on your filter parameters. You can also do "cl\$this->_split2($m[0]) refer filter" to find other tasks that do image filtering which may help, likewise see the smoothing (boxcar) functions in tasks like SPLOT.

Hi Mike,

Thanks so much for the tip on BWFILTER -- I think that's what I'm looking for!

Except that it seems to have a bug or something. It seems to work ok non-interactively, but when trying to run interactively, it doesn't seem to respond when I hit return (or anything else) to mark the filter threshold frequency. Or, when it finally bombs, it says, "frequency out of range" or "frequency must be positive". I've set a nominal value of 0.1 for the paramter "freq" which isn't supposed to be relevant unless it's run non-interactively. I'm just running with this very simple set of parameters:

playpen\$this->_split2($m[0]) lpar bwfilter
input = "test.fits" input
output = "test3.fits" output
(interactive = yes) interactive mode?
(freq = 0.1) frequency where signal is comparable to noise
(device = "stdgraph") graphics device
(cursor = "") graphics cursor input
(Version = "19August1994") date of installation
(mode = "al")


The input file is just a plain old 1D spectrum:

playpen\$this->_split2($m[0]) imhead test
test[34701][real]: 75689

Any more suggestions?

thanks again,
Sally

The cursor read problem is an incompatibility between the 32-bit only STSDAS binaries linked against an older IRAF, and the 64-bit CL (linux64 or macintel) binary from a newer IRAF version I'm guessing you are using. This can be fixed by using a 32-bit CL binary, and if you installed both the 32- and 64-bit binaries then you can do this by simply changing your IRAFARCH, otherwise let me know which platform you are using and I can provide one.

The good news is that the STSDAS v3.17 system that came out today appears to have fixed this. If you are running IRAF v2.16 then doing a "make stsdas" in your iraf$extern directory will update the package and the problem should be fixed. The new system was linked against v2.14, v2.15 or v2.16 depending on which release doc you read, but at least on 64-bit Mac the cursor read correctly.

Great, I think we can fix that then -- thanks again!

S.