White noise levels for high cadence scan at elevation of 40 degrees

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Summary

In this posting provides noise levels for a high cadence scan strategy at an elevation of 40 degrees, with az=[20,160] and az=[200, 340], and with a base scan rate of 1 deg/s.

Depth maps

Depth maps for 10 days of observation provided by Reijo for 1 optics tube for the LF bands, and 1/8th of an optics tube for the MF and HF bands can currently be found here

/global/cscratch1/sd/keskital/s4sim/reference_tool/out_v1/00000000

The simulations provide noise covariance matrices for TQU (as well as inverse covariance matrices, hits maps, and one realization). Here we show the depth maps in temperature

Depth maps el 40.png


The underlying NETs and detector counts can be found in this spreadsheet. The efficiency of the simulations is 91.7%, with 8.3% spent in turn-arounds. The noise levels shown below are scaled to an overall efficiency of 25% (to match the estimates made by the NTT) and observing time of 7 years. In addition, the map level depths presented below assume a yield of 80%, correlation factors and number of tubes taken from the same spreadsheet.

Noise characteristics for elevation of 40 degrees

Frequency band LF MF HF
Sky fraction (in %) 68.6 67.8 67.0
Effective sky fraction for signal (in %) 61.6 63.7 63.8
Effective sky fraction for noise (in %) 66.0 66.2 65.9


Frequency (GHz) 27 39 93 145 225 278
white noise level TT (uK-arcmin) 21.34 11.67 1.89 2.09 6.90 16.88
ell knee TT 415 391 1932 3917 6740 6792
1/f exponent TT (uK-arcmin) -3.5 -3.5 -3.5 -3.5 -3.5 -3.5
white noise level E/B (uK-arcmin) 30.23 16.53 2.68 2.96 9.78 23.93
ell knee E/B 700 700 700 700 700 700
1/f exponent E/B (uK-arcmin) -1.4 -1.4 -1.4 -1.4 -1.4 -1.4

The simulations provide information both about white noise levels and the atmospheric 1/f contribution. For MF and HF, the behavior in polarization is similar to the previous estimates with lknee between 500 and 700 although with a somewhat shallower rise (between -1.06 to -1.2). For LF the simulations suggest significantly lower atmospheric noise. Since this is preliminary, the table uses the noise model inferred from the WAFTT work.