Yesterday I attempted to extract E and B mode maps from the

*Planck*Q and U stokes maps. I tried this in HEALPy first, later we did the same with the IDL implementation of HEALPix.

I'm using the latest version of healpy, 1.8.6. I'm using the 2015 datarelease of Planck, with the smica pipeline (

**COM_CMB_IQU-smica_1024_R2.02_full.fits**)

As a test, we wanted to make a quick plot of the E and B power spectra. To this end, we first read in the maps such that 'IQU' below is a tuple of the three relevant maps.

Code: Select all

`Cls = hp.anafast(IQU,pol=True)`

EBpowspec.png

Comparing this to CAMB output, the EE spectrum (cyan) looked quite fine in shape and amplitude; the BB spectrum however seems to have the expected

*shape*of a lensing-induced B mode spectrum, but a couple of orders of magnitude too big!

What am I doing wrong, or what am I missing?

Thanks in advance!!