Changes between Version 2 and Version 3 of ppSub_vs_Hotpants

Timestamp:

Jan 15, 2010, 5:47:49 PM (17 years ago)

Author:

Paul Price

Comment:

--

ppSub_vs_Hotpants

@@ -95 +95 @@
 == Comparison ==
 
-It is apparent that ppSub (with default ISIS_RADIAL kernels and dual convolution) results in a subtracted image that appears more smoothed (because both images have been convolved, one doesn't see the small-scale pixel-to-pixel noise contributed by one of the images), but the subtraction is of generally of a better quality.  No sources are detected by psphot in 115 of the 136 subtractions.  When sources are detected, it is often about 200, indicating two detections in the wings of each of the stars.  These can be suppressed with slightly different basis function parameters.
+It is apparent that ppSub (with default ISIS_RADIAL kernels and dual convolution) results in a subtracted image that appears more smoothed (because both images have been convolved, one doesn't see the small-scale pixel-to-pixel noise contributed by one of the images), but the subtraction is of generally of a better quality.  No sources are detected by psphot in 115 of the 136 subtractions.  When sources are detected, it is for the wide PSFs, and there are generally about 200, indicating two detections in the wings of each of the stars.  It's possible these could be suppressed with slightly different basis function parameters, and we are trying different distributions of kernel widths in order to do so.
 
 ppSub (without adding photometry) has a running time about twice that of hotpants, but it is performing four times as many convolutions.  This better run time per convolution is probably due to ppSub doing convolutions via Fast Fourier Transforms, rather than directly.
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