README.md

[BROKEN] Realistic noise version 3.1.1 with MSS1 hitmaps

DO NOT USE this release, found out that I used the total noise curves for each single tube. therefore for some bands there is a factor of 4 less noise in this release. See the relevant issue for more details. Working on a fix, a new version of this release will be made available in the following weeks. In fact, the spectra plots below display the issue, I am comparing the tube-by-tube results to the full mission noise curves.

Tag: mbs-s0010-20200221

Release date 21 Feb 2020

New noise release using version 3.1.1 of the noise curves from so_noise_models.

Compared to previous releases:

• Updated noise spectra which include a fix for the atmosphere parameters
• Includes cross-correlations between the 2 bands in the same dichroic tube
• Uses new hitmaps from the MSS1 time domain simulations
• Supports noise splits
• Variable Nside based on channels
• Released in HEALPix and (later) in CAR

Input components

All maps are in uK_CMB, IQU, single precision (float32)

• For the exact configuration of the noise simulations refer to the noise.toml configuration file available in this repository. For all available options refer to the SONoiseSimulator class in mapsims.

Available maps

Only 1 realizations of the full mission and 1 realization of 4 splits are made available as maps.

Reference frame for noise maps is assumed to be Equatorial.

Location at NERSC:

/project/projectdirs/sobs/v4_sims/mbs/202002_noise

The naming convention is:

{num:04d}/simonsobs_{content}_uKCMB_{tube}_{band}_nside{nside}_{num:04d}_{split}_of_{nsplits}.fits"

where:

• content is noise

• num is the realization number (seed) and currently only 0

• tube is LT0-LT6 or ST0-ST3

• band is one of the available bandpasses (available inside mapsims.so_utils):

    bands = ("LF1", "LF2", "MFF1", "MFF2", "MFS1", "MFS2", "UHF1", "UHF2")
    frequencies = (27, 39, 93, 145, 93, 145, 225, 280)
  

• nsplits is the number of splits, 1 for full mission, 4 for the splits, split is 1 based split ID.

For example: 0000/simonsobs_noise_uKCMB_ST2_MFS2_nside512_0000_1_of_1.fits

Total disk space used is 548 GB for one realization of full mission and splits.

Backed up to tape in ~zonca/sobs/mbs/202002_noise.

Generate other realizations on the fly

More noise realizations should be generated on-the-fly and never written to disk using the mapsims package, check the documentation at https://mapsims.readthedocs.io for installation instructions.

Then check the run_mapsims_onthefly.ipynb notebook. See also an executed version of the notebook on Gist.

The interface of mapsims for on-the-fly simulations is still work in progress, in the next weeks we will also release the capability of running foregrounds + cmb + noise maps and we will also improve the interface to make it easier to only create a single mapsims.MapSim object and loop easily through channels and noise realizations. Please send any feedback to the relevant Github issue.

Hitmaps

Hitmaps are used un-normalized to scale the pixel-by-pixel noise. They are available at NERSC in:

/global/project/projectdirs/sobs/www/so_mapsims_data/v0.2

Or via web through NERSC

Or they can be accessed through the load_hitmaps method of mapsims.SONoiseSimulator.

Software

• The noise component and the runner script are available in the mapsims package, version 2.1.0, see the documentation

Spectra plots

For validation purposes, see a comparison between the input spectra as generated by so_noise_models and a power spectrum (simple anafast with no mask deconvolution).

Spectra were generated with the compute_cl_noise_full.py and compute_cl_noise_splits.py scripts and plotted with plot_cl_noise_full.ipynb and plot_cl_noise_splits.ipynb.

LAT Temperature

LAT Polarization

LAT Temperature splits

LAT Polarization splits