## Planck 2015 CMB temperature variance

Tracey Friday
Posts: 2
Joined: January 25 2018
Affiliation: University of Central Lancashire

### Planck 2015 CMB temperature variance

I'm using Planck 2015 CMB temperature (intensity) SMICA pipeline maps and am trying to determine the temperature variance of each pixel. Variance and hit-count were provided with the 2013 CMB maps (there were 3 columns: intensity, hit-count and variance) but they aren't in the 2015 maps (there is only an intensity column).

So I've tried to determine the variance from the half-difference of the half-mission maps but my results look dodgy. I'll try the half-ring maps next but I'm not optimistic.

If anyone else has either found the variances somewhere or managed to determine them themselves I would be very grateful if you could point me in the right direction please!

Thank you :)

Tracey Friday
Posts: 2
Joined: January 25 2018
Affiliation: University of Central Lancashire

### Planck 2015 CMB temperature variance

After much gnashing of teeth (and much help from the IRSA and PLA folks - thank you!) I have a couple of solutions that have worked for me (all I'm doing is weighting a few pixels). Here they are in case they help anyone else out:

(1) the II covariances in the 143 & 217 GHz maps give good enough estimates of noise for weighting.
(2) the HMHD maps do work if you smooth them (which I hadn't previously).