From: Peter Nugent (nugent@panisse.lbl.gov)
Date: Tue Feb 25 2003 - 12:24:51 PST
The only little comment I have concerns the use of the word "slightly"
before "updated K-correction". It was actually a significant change.
Just drop "slightly".
I was interested in the point that Greg made concerning the intrinsic
dispersion in U-B. I therefore did some fits to the Jha data for U-B (at
Bmax) versus B-band stretch (the data came from table 179 as we have
listed it on the web-site).
As Saurabh pointed out in his thesis he thinks that when all the
corrections are done for extinction, there is about a 0.12 magnitude
intrinsic dispersion between U-B and stretch. My fits to the data agree
with this (based on entirely different assumptions on B-V at max and the
relationship between it and stretch). Even if I get rid of the the three
worst outliers it only cuts this down to 0.08. This is bad to do since
there is no way to tell these outliers apart from the other SNe since they
are neither weird in B-V nor have obscenely different stretches than the
others.
I guess about the only thing that is really different than what Rob did,
is that Saurabh's data points to a slightly bluer U-B color of around
-0.5. But this is sensitive to what you think the true value of (B-V) is
as a function of stretch. If you want I can re-run the fits on his data
for a given (B-V) @ B_max versus stretch relationship.
Cheers,
Peter
-- Peter E. Nugent Staff Computational Scientist - Scientific Computing Group - NERSC Lawrence Berkeley National Laboratory M.S. 50F-1650 - 1 Cyclotron Road - Berkeley, CA, 94720-8139 Phone:(510) 486-6942 - Fax:(510) 486-5812 E-mail: penugent@LBL.gov - Web: http://supernova.LBL.gov/~nugent
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