Changes between Version 106 and Version 107 of MD_WSdiffim_photcheck_test20121004

Timestamp:

Feb 26, 2013, 1:39:12 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. 
 
-Two key problems were identified:
+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 (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 (typically y-band) had only order 10-20 inputs, and now have 60-100.
+
+Various other minor issues identified:
  * background binning for photometry on diffims has not been the same as other photometry (~0.1-0.2 offset mag) -- using 128 for now, may need additional/proper tuning
- * coordinate list for determining PSF was a matched+merged list of both the input and reference image rather than just a matched list (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 (typically y-band) had only order 10-20 inputs, and now have 60-100.
-
-Various other minor issues identified:
  * psphot trace level >5 modifies the photometry output -- still to be fixed
  * refConv outputs aren't needed since magic not used -- turning off in gpc1/psphot.config
@@ -31 +31 @@
 
  
-
 = Example: MD10 sequential exposure pair, asteroid (12891) (Peter Vereš) =
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