Changes between Version 4 and Version 5 of stacking_coverage.20130307

Timestamp:

Apr 16, 2013, 4:09:40 PM (13 years ago)

Author:

watersc1

Comment:

--

stacking_coverage.20130307

@@ -1 +1 @@
 == 2013-04-16 ==
 
-While testing the input FWHM cut, I discovered that an image that appeared valid by eye was being flagged during the PSF matching stage as having a overly deviant chi^2 value.  A study of the code revealed that the chi^2 value used is calculated in the following way:
+While testing the input FWHM cut, I discovered that an image that appeared valid by eye was being flagged during the PSF matching stage as having a overly deviant chi!^2 value.  A study of the code revealed that the chi!^2 value used is calculated in the following way:
 
- 1. For all valid stamps in the PSF match, the flux and squared residual are fit with a quadratic function (x0 + x1 * flux + x2 * flux^2).
+ 1. For all valid stamps in the PSF match, the flux and squared residual are fit with a quadratic function (x0 + x1 * flux + x2 * flux!^2).
  2. This quadratic function is subtracted from the squared residual, providing a flux-neutral measurement of the squared residuals.
- 3. The RMS scatter of these remaining residuals is saved as the chi^2 value for the PSF match (there's a sum over all used kernels, but the example case has only a single kernel).
+ 3. The RMS scatter of these remaining residuals is saved as the chi!^2 value for the PSF match (there's a sum over all used kernels, but the example case has only a single kernel).
 
-The following table shows the set of PSF match values, along with the parameters of the quadratic function:
+The following table shows the set of PSF match values, along with the parameters of the quadratic function.  This table shows that we seem to be needlessly matching PSFs for images already rejected at the input stage.  In addition, there appear to be 2 iterations of this function (pmSubtractionRejectStamps) being called for images 7+.
 
 || Nstamp || mean   || rms     || x0      || x1           || x2           || Image || Rejected? ||
@@ -29 +29 @@
 
 
+We can now plot up the data and quadratic fits to validate their quality:
+
+||Image || Plot ||
+|| 0    || [[Image(fit.0.png)]] ||
+|| 1    || [[Image(fit.1.png)]] ||
+|| 2    || [[Image(fit.2.png)]] ||
+|| 3    || [[Image(fit.3.png)]] ||
+|| 4    || [[Image(fit.4.png)]] ||
+|| 5    || [[Image(fit.5.png)]] ||
+|| 6    || [[Image(fit.6.png)]] ||
+|| 7a   || [[Image(fit.7.png)]] ||
+|| 7b   || [[Image(fit.8.png)]] ||
+|| 8a   || [[Image(fit.9.png)]] ||
+|| 8b   || [[Image(fit.10.png)]] ||
+|| 9a   || [[Image(fit.11.png)]] ||
+|| 9b   || [[Image(fit.12.png)]] ||
+|| 10a   || [[Image(fit.13.png)]] ||
+|| 10b   || [[Image(fit.14.png)]] ||
+|| 11a   || [[Image(fit.15.png)]] ||
+|| 11b   || [[Image(fit.16.png)]] ||
 == 2013-04-08 ==