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spatial-transfer-functions.rst

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Spatial Transfer Functions

Date: 2011-07-13 18:54
Author: Adam (adam.g.ginsburg@gmail.com)
tags:googlepost, simulation
slug:spatial-transfer-functions

The majority of the past week has been dedicated to debugging; it looks like cross-scanned simulations finally work. The plot below is a derivation of the spatial transfer function for a number of different intrinsic sky power-law power spectra.

http://2.bp.blogspot.com/-JyAPg0u9uQ8/Th3kuQh1fpI/AAAAAAAAGRs/pP7o3n9_wds/s320/Experiment10_AverageRecoveryFunction.png

Justifying the above plot is essential. First, the very steep power-laws [-3 in the example below] show a recovery fraction >1. This is simply because their S/N was inadequate - the output power spectrum is nearly flat, but at a level higher than the sky.

http://4.bp.blogspot.com/-JPBjsLDfP5M/Th3lw5n1xTI/AAAAAAAAGR0/aDeOmMv5s8w/s320/exp10_ds2_astrosky_arrang45_atmotest_amp1.0E%252B01_sky00_seed00_peak010.00_nosmooth_compare.png

http://3.bp.blogspot.com/-LOCDmoLCcZs/Th3lxfnKVzI/AAAAAAAAGR8/9NCM3OroGoM/s320/exp10_ds2_astrosky_arrang45_atmotest_amp1.0E%252B01_sky00_seed00_peak010.00_nosmooth_psds.png

Second, the most plausible power-laws [-1.5 in the example below] show pretty good recovery (90-95% over the relevant range):

http://1.bp.blogspot.com/-MTZ8WGl3ZRc/Th3mMkvv2II/AAAAAAAAGSE/0OO4Te39fPI/s320/exp10_ds2_astrosky_arrang45_atmotest_amp1.0E%252B01_sky03_seed00_peak010.00_nosmooth_compare.png

http://2.bp.blogspot.com/-5IeTZW-ZTAw/Th3mNHPC8gI/AAAAAAAAGSM/WhIWClGWqbo/s320/exp10_ds2_astrosky_arrang45_atmotest_amp1.0E%252B01_sky03_seed00_peak010.00_nosmooth_psds.png

http://4.bp.blogspot.com/-O6ofm7GaxUI/Th3mNgf29AI/AAAAAAAAGSU/VzQ7aL-yd_E/s320/exp10_ds2_astrosky_arrang45_atmotest_amp1.0E%252B01_sky03_seed00_peak010.00_nosmooth_stf.png

There are some "white" power losses, particularly in the flatter power-spectra. My best guess is that this has something to do with the relative scales being offset from a mean of 1, but so far all tests to show that that is the cause have in fact shown no problems at all. What else could cause a scale-independent power loss? Also, the flat power spectrum (and inverted) aren't quite flat because I impose a "galactic scale height" on them. Should I stop doing that?