Index: /trunk/doc/release.2015/ps1.calibration/calibration.tex
===================================================================
--- /trunk/doc/release.2015/ps1.calibration/calibration.tex	(revision 41179)
+++ /trunk/doc/release.2015/ps1.calibration/calibration.tex	(revision 41180)
@@ -1089,4 +1089,5 @@
 rejections do not catch all cases of bad measurements.
 
+\note{justify this outlier rejection process}
 After the initial iterations, we also perform outlier rejections based
 on the consistency of the measurements.  For each star, we use a two
@@ -1114,4 +1115,5 @@
 calibrated based on their overlaps with other images.
 
+\note{justify the choice of a factor of 10}
 We overweight the ubercal measurements in order to tie the relative
 photometry system to the ubercal zero points.  Ubercal images and
@@ -1362,4 +1364,8 @@
 average photometry given the possible presence of non-Gaussian
 outliers even within the best subset of measurements.  
+
+\note{include a reference to IRLS and describe concept more}
+\code{http://users.stat.umn.edu/~sandy/courses/8053/handouts/robust.pdf}
+\code{https://arxiv.org/pdf/0807.0575.pdf}
 
 \subsubsection{Selection of Measurements}