*Removing Fourier Modes*

This page presents the results of a new filter which simultaneously fits and removes fourier modes and a secant (airmass) signal from the detector timestreams. The fit is similar to the polysecant removal which is normally used, however the fourier mode filter appears to have less large scale residual signal.
The results of the filter on the timestream are first shown, then the effects on an A520 map are shown. The fouriersecant filtered map has less large scale structure in the final map, however the even/odd and first half second half difference maps have similar features, including a hotspot to the right of the cluster position in the first half-second half difference map.

Figure 1. The original timestream

Figure 2. The Fouriersecant and polysecant fit to the timestream.

Figure 3. The residual timestream after the fouriersecant filter.

Figure 4. The residual timestream after polysecant filter.

Figure 5. The difference between the fouriersecant filtered timestream and the polysecant filtered timestream.

Resulting Maps For these maps I used a 35 order polysecant or fouriersecant, then two iterations of removespatial template.

Polysecant map Figure 6. Using the polysecant.

Figure 7. Even/odd difference map.

Figure 8. First half - second half difference map.

*Fouriersecant map*
Figure 9. Using the fouriersecant filter.

Figure 10. Even/odd difference map.

Figure 11. First half - second half difference map.

Figure 12. Difference map (polysecant map - fouriersecant map)

-- JamesKennedy - 26 Jun 2009

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This topic: APEX_SZ > WebHome > A520 > 2009-06-23 > Test_wiki Topic revision: r1 - 2009-06-26 - JamesKennedy

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