Convergence Maps

Stefan's 4x4 deg convergence maps are now available, on request. Each map can be read in as a kappamap object, which includes a method for looking up convergence values at specified sky positions. Here is what Stefan's first map looks like, when reformatted to FITS and viewed in ds9:

![Example convergence map from Stefan Hilbert] (http://www.slac.stanford.edu/~pjm/H0/lightcones/GGL_los_8_0_0_N_4096_ang_4_rays_to_plane_37_f.ds9.jpg)

Pixel 0,0 is in the bottom left hand corner in the ds9 view, and the physical coordinate system is used for connecting the image pixel numbers to the coordinates in Stefan's catalogs. Here is some test output from kappamap.py - Stefan confirmed that the physical coordinates are correct for 2184, 2263 (see below). The map is the one in GGL_los_8_0_0_N_4096_ang_4_rays_to_plane_37_f.kappa.

Looking up kappa value at position 2184 , 2263 in the image coordinate system

• physical coordinates: 0.00232653752829 0.00367303177544 (radians)
• approximate world coordinates: 359.867675781 0.21044921875 (degrees)
• ds9 image coordinates: 2185 2264
• Value of kappa = 0.0169250555336
• Compare with expected value: 0.0169251

Note that these physical coordinates a) are right-handed, b) lie parallel to the image coordinate system axis, c) are the same as pos_rad in Stefan's catalog, and d) assume a flat, not spherical, sky.