CamSpec 2020 Public Release

This page details our 2020 CamSpec release, associated with the paper arXiv:1910.00483, "A Detailed Description of the CamSpec Likelihood Pipeline and a Reanalysis of the Planck High Frequency Maps" by George Efstathiou and Steven Gratton. Please cite this paper if you use CamSpec in your work.

The code for CamSpec, by George Efstathiou, Steven Gratton and Antony Lewis, is now incorporated into CosmoMC, available at github here. Use:

git clone --recursive 

Please add the line:

export NONCLIKLIKE=cliklike_CamSpec

to your .bashrc file (or similar) before compiling CosmoMC in order to use CamSpec functionality.

The likelihood data is contained in the following file:


(Nb. this is a 1.3GB file that unpacks to a 2.2GB directory.) Click and save this in your downloads directory. Then copy and unpack this file to a suitable data location, schematically /your/data/ say. From your downloads directory, do:

mkdir /your/data/
cp camspec2020.tgz /your/data/
cd /your/data/
tar xzf camspec2020.tgz

Alternatively, use wget:

mkdir /your/data/
cd /your/data/ 
wget ""
tar xzf camspec2020.tgz

Then create a symbolic link in the CosmoMC data/ directory to the camspec/ directory. So in CosmoMC/data/, run the command:

ln -s  /your/data/camspec camspec

The data file provided is for the most powerful likelihood discussed in our paper, the "v12.5HMcln" one. "Ini" files in CosmoMC/batch3/ are given for running TT, TTTEEE, TE, EE and TEEE analyses with our default multipole ranges. Note that some of the settings applied in the ini files to get the analyses to be performed correctly are non-intuitive; we do not recommend changing settings. Please consult us if you have a specific run in mind and would like advice on how to configure this. Please also get in touch if you would like to use any of the other likelihoods discussed in the paper for some reason (note that the 12.1 likelihoods are very similar to the camspec likelihoods provided in the Planck Legacy Archive for the 2018 release).

A sample grid settings file is provided, in python/, illustrating use of the likelihoods.

The likelihoods are then used as standard in CosmoMC, and are naturally used in conjunction with the Planck "lowl" and "lowE" likelihoods available via the Planck Legacy Archive.

We will be providing a native python Cobaya version of the likelihood in the near future.

We are indebted to the Planck Collaboraton for their enormous efforts in producing such a wonderful set of data.