Hi Chin-Lin,

Your plan sounds good. A couple comments:

- Your 1) and 2) are the same thing except for deprojection being on/off. That's fine, but I just want to point out that doing deprojection is just a matter of running reduc_coaddpairmaps multiple times per realization (to do dp=0000, dp=0100, dp=0111, etc.) as opposed to just once (dp=0000). Once you've done the simulation and have your pairmaps, as long as you set mapopt.deproj=true, you pretty much get dprojected and undeprojected maps for free.

- We talked about this on the telecon, but unless we have a way to turn off A/B offsets, what we're going to see is leakage from A/B offsets and nothing more. After deprojection we will see residual leakage from A/B offsets and nothing more. It will still be interesting to add noise to the beam maps and see what happens, and once you proceed to real beam maps, it is possible we will see more than just residual A/B offsets, which would imply an undeprojected residual that is strong enough to affect us. If we don't see anything, we can be glad that undeprojected residuals are below what we care about.

And it might be interesting to be able to see beamwidth / ellipticity deprojection do something when you simulate real beam maps.

I'm in favor doing one more sim, which is with beam maps that have no A/B centroid mismatch, and running with simopt.diffpoint='ideal'. I don't see the downside to doing this and I think it gives is more information about our beams. Without doing it, even if there are weak undeprojected residuals in our beams that we have a shot at seeing via these sims, we'd make ourselves blind to them by always including A/B offsets. Yes, the fact that we'd be blind to them would mean that they're so weak we don't care about them, but if they're there it'd be nice to know.

What do people think? It seemed to me like you guys were opposed.

-Chris

On Wed, Jun 12, 2013 at 2:13 PM, Chin Lin Wong <clwong@physics.harvard.edu> wrote:

Hi

I was tasked to propose the immediate next steps for using the beam maps that I've constructed and convolving it with the flat sky to quantify T->P leakage.

Immediate plan of work:

1. Tag subset, TnoPol, timestream deproj off for
    (a) set of noiseless input beam maps with AB offsets in the beam map
    (b) Stefan's multigauss implementation

Make T,Q,U maps and power spectrum, compare T->P leakage. Is (a) the same as (b) and the same as what Chris has in his posting? This would check that I've gotten the simulation to run correctly. Start with 1 realization, and if that goes easily, do 10 realizations.

2. Tag subset, TnoPol, timestream deproj on for:
    (a) set of noiseless input beam maps with Ab offsets in the beam map
    (b) Stefan's multigauss implementation
Did I use the deproj correctly? Translate the recovered deproj coefficients into beam parameters and compare vs input.

3. Tag subset TnoPol, timestream deproj on for a set of input beam maps w uber-chopper noise levels.
Make T,Q,U maps and power spectrum. It would be informative to see at what level we can quantify the T->P leakage with uber chopper noise in the beam maps.

Next, I think we want to use real beam maps. I plan to first make composite uber-chopper maps, using uber chopper maps at 4 different dk angles. I will mask out the ground to make these maps, and hopefully, this will result in nice, clean maps with no ground/MAPO contamination in them. The uber chopper maps are our least noisy maps, and it would be interesting to see in test (3) how well we can quantify the T->P leakage in the presence of noise.

Feedback will be really welcome.

Thanks!

Chin Lin

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Christopher Sheehy - Ph.D. candidate - University of Chicago
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