Filtering and re-gridding large scale HI data

Tom Kuiper (JPL) presented a project to fully automate radio astronomy in the Deep Space Network (DSN). The main purpose of the DSN is to communicate with all the NASA spacecrafts, but there is plenty of idle time in which the 34m and 70m dishes could be used for radio astronomy. We’ll soon have the possibility to propose for that time, which would be very well-suited for long-term monitoring of e.g. pulsars or Jupiter’s synchrotron emission.

After lunch, Michael Troxel from Ohio State spoke about the Dark Energy Survey Year 1 results. He emphasized the great agreement between the different probes (cosmic shear, galaxy clustering, galaxy-galaxy lensing), the very thorough (and blind!) analysis of the systematics, and the fact that so far, there is no tension with other probes. The Year 3 and finally Year 5 results will allow us to put much tighter constraints on w and sigma8, while at the same time preparing us for the LSST era.

I finally got the chance to play some more with the recently release GALFA DR2 HI data (data, paper) and used cygrid to re-grid the data from FITS images to HEALPix, which is very useful for analyses of large-scales and is the quasi-standard in CMB science. The map can be found here.

Lastly, I went back to the HI4PI data and worked on a low-pass filter in harmonic space. We’re using this to remove the small scales, where we don’t have a reliable beam model. Moreover, we’ll be using this to generate dust foreground maps. By cutting the small scales, we can ensure that the HI does not mimic the CIB signal through chance correlations.

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