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SWARP bug with MAP_RMS?
02-09-2009, 13:17
Post: #1
SWARP bug with MAP_RMS?
Hi,

I think I have encountered an odd behaviour(/bug) with SWARP. I have a bunch of images that I wish to combine, for which I also have a good idea of the corresponding uncertainties.

So I chose to combine these using WEIGHT_TYPE=MAP_RMS, (and SUBTRACT_BACK=Y). Using "absolute" uncertainties has the advantage that I can scale the error maps by hand to obtain a seeing-weighted stack (my experiments seem to indicate that this works fine).

Now, if I swarp these individually setting COMBINE=N, I can subsequently rerun swarp with RESAMPLE=N, COMBINE=Y, and the resultant stack is background subtracted and sensible-looking.

However, if I try to run swarp in one go (RESAMPLE=Y, COMBINE=Y) with a list input, it appears that swarp does not attempt any background subtraction (and so the final image is junk with a high pedestal). Using other WEIGHT_TYPEs avoids this problem.

Thought I should point this out.

best regards

Rodrigo Ibata

(Using swarp compiled on OSX 10.5.6)
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