LBL Cosmology Visitor Program 
Weak Lensing workshop 
Day 1 discussions 

* Report on IAU Lausanne meeting - no significant new results 

* Plan for discussion of "cherry picking": what is the balance 
between comprehensive, well controlled missions that confidently 
answer weak lensing cosmology questions (but have a 2012 time scale), 
and quick, less complete missions that seek first answers (pre-2011). 

* Plan for "LBL shear comparison" benchmark exercise a la Santa Barbara 
community calculations; given a data set, each group resolves galaxies 
and extracts shear and finally cosmological parameters for comparison 
of algorithms. 

* Cluster finding: several points of discussion such as Hennawi-Spergel  
tomographic matched filter (astro-ph/0404349), cluster finding vs. 
simulations seem to lie below 50% efficiency, projection effects.  We 
plan to make Aug. 9 into "Cluster Finding Day" at the workshop, with 
presentations and focused discussions. 

* Plan for further discussion on combining multicolor images for 
shape extraction. 

* Source redshift distribution: does the exp(-z^1.2) really exist, 
giving galaxies at z>3.5, and are they measurable and useful? 

* sigma8 recent papers by Seljak et al. (astro-ph/0407372) and 
Abazajian (astro-ph/0408003) - very small error bars but incompatible 
with each other.  What lies ahead for WL sigma8 measurements?  At 
what level of detail will we really need to know the true source 
redshift distribution? 

* David Wittman presented an update on DLS.  He is interested in 
looking for new ways to make mass maps.