Index: /trunk/Ohana/src/relastro/doc/notes.txt
===================================================================
--- /trunk/Ohana/src/relastro/doc/notes.txt	(revision 17042)
+++ /trunk/Ohana/src/relastro/doc/notes.txt	(revision 17043)
@@ -1,2 +1,16 @@
+
+2008.03.01
+
+  relastro (and relphot for that matter) needs to have a somewhat
+  flexible error model for the detections.  Some data have an accurate
+  astrometric error; some have a reported error, but it is either
+  insufficient (eg, only from poisson error), or inaccurate.  A
+  complete error model would be something like this:
+
+  dR_total^2 =  dR_sys^2 + AS * dR_obs^2 + MS * dM_obs^2
+
+  dR_sys : systematicAstrometryError
+  AS     : astrometryErrorScale
+  MS     : astrometryErrorMagScale
 
 2007.11.12