Differences

This shows you the differences between two versions of the page.

--- 20180420_pysm_smooth [2018/04/20 11:36] – pryke
+++ 20180420_pysm_smooth [2018/04/20 11:51] (current) – pryke
@@ Line 4: / Line 4: @@
 (See [https://arxiv.org/abs/1608.02841 PySM paper] and [https://github.com/bthorne93/PySM_public git repo].)
-PySM can be run at any nside up to 512. What it does internally I have not investigated. It can also be told to smooth the output maps to a given beam size.
+PySM can be run at any nside up to 512. What it does internally when asked for <512 I have not investigated. I suspect it downgrades the templates with which it is working. It can also be told to smooth the output maps to a given beam size.
 To be realistic we would generate PICO maps with the resolution varying by band as per [[imageroptions]].
@@ Line 14: / Line 14: @@
 {{:20180420_fig1.gif}}
-Now I smooth the above with 120 arcmin beam and take the difference of smoothed minus unsmoothed:
+Now I turn on smoothing with 120 arcmin kernel and take the difference of smoothed minus unsmoothed:
 {{:20180420_fig2.gif}}
+We see severe artifacts which results from the harmonic space manipulation of a map which has bright galactic plane.
+The dynamic range is smaller in polarization but there is still a problem.
+We need to decide how to deal with this. Some options
+) The galactic plane will always get masked in post analysis anyway - we could just pre-mask it before smoothing (this is what I did for CMB-S4 sims concerned only with small patch at high latitude.
+) We could do some preliminary nside=16 sims with no smoothing at all.
+) We could implement a map space smoothing which will not suffer from such artifacts.
+There must be knowledge from Planck on how to deal with smoothing a map with large dynamic range - since this is true for the real maps?!

User Tools

Differences

Page Tools