From: Alex Conley (aconley@panisse.lbl.gov)
Date: Tue May 20 2003 - 15:10:52 PDT
Hi Rob,
What was decided about the SNe that I thought were poorly behaved
(that is, the SNMINUIT fits were unstable to initial conditions) when
I refit all of them? There were three in the 42 sample that were
exceedingly bad, and I thought were not suitable for cosmology fits.
Two of them no longer appear to be used, but one of them (1997aj = 9794)
is still present.
There was a message thread about this
http://panisse.lbl.gov/collab/archive/hstpaper/0121.html
which ended up with you tossing all SNe with NO color information
(which took care of the other two that I had problems with), but didn't
affect sn1997aj.
The reason I thought that sn1997aj was bad is that there were two
solutions with the same chisquare but very different fit values.
The first one had s=0.954, mR=22.587, and the second had
s=1.504, mR=22.859. The both had chisquare of 120/70. Admittedly
I am more inclined to believe in the s=0.954 fit, but this is a prior
that probably shouldn't be implicitly included.
I think we could use this as a formal critereon: If it was found that
changing the initial conditions of the fit produced more than one solution
with similar chisquare but fit parameters that varied by more than x sigma
(where x could be 5 or more), the supernova was excluded. This would
eliminate only 97aj from the currently existing 42 sample.
Alex
This archive was generated by hypermail 2.1.4 : Tue May 20 2003 - 15:10:53 PDT