Changes between Version 134 and Version 135 of MD_WSdiffim_photcheck_test20121004

Timestamp:

Mar 4, 2013, 6:03:33 PM (13 years ago)

Author:

Mark Huber

Comment:

--

MD_WSdiffim_photcheck_test20121004

@@ -16 +16 @@
 The MD10 sequential exposure pair, asteroid (12891) example was used to trace through the code to identify problems. The camera SMF exposure photometry was taken as the "true" target photometry to achieve from the diffim photometry. Offset of exposure photometry to some predicted/expected magnitude is a different problem altogether. 
 
-Key problem -- coordinate list for determining PSF was a matched+merged list of both the input and reference image rather than just a matched list (poor PSF resulting in 0.3+ irregular mag). When the list is sorted by inst_flux and the top hardcoded 500 sources are used, ones that are not in the input warp from masking etc reduce the available "good" sources. Normally that is only a small fraction, but when a deeper refstack is used the missing sources have a much higher inst_flux and begin to dominate the set for determining the PSF making for a poor solution. Newer MD refstacks have been much deeper, some fields before (and typically in y-band) had only order 10-20 inputs, and now have 60-100. (see [wiki:MD_WSdiffim_photcheck_test20121004#Largesamplediffimphotometryfory-band])
+Key problem -- coordinate list for determining PSF was a matched+merged list of both the input and reference image rather than just a matched list (poor PSF resulting in 0.3+ irregular mag). When the list is sorted by inst_flux and the top hardcoded 500 sources are used, ones that are not in the input warp from masking etc reduce the available "good" sources. Normally that is only a small fraction, but when a deeper refstack is used the missing sources have a much higher inst_flux and begin to dominate the set for determining the PSF making for a poor solution. Newer MD refstacks have been much deeper, some fields before (and typically in y-band) had only order 10-20 inputs, and now have 60-100. 
  * however, there was a specific routine (pmSourceMatchMerge) added for ppSub to make the merged list. Really the specific input list should be used and not a mix (match/merge) of both, even for the stamp selection, but the input source lists are combined into a master detection list.
 
@@ -29 +29 @@
  * is convolved refstack really necessary here or would the unconvolved stack be better (basically the refstack is just sky for moving objects but for other transient science may want unconvolved) as the unconvolved stack is typically of better FWHM and requires less deconvolution to the warp seeing -- needs to be investigated further
  * psphot run on diffim compared to ppSub photometry does not necessarily agree -- unclear still if config/setup or actual problem/bug
+
+For results using only a matched list and a background binning, see [wiki:MD_WSdiffim_photcheck_test20121004#Largesamplediffimphotometryfory-band]