1. First Exploration of MWA Deep Field Point Source Population C. Williams - PhD Thesis J. Hewitt – reporting some analysis

2. Motivation #1: verification of performance of array Compare to existing catalogs – source by source Compare to existing catalogs – statistics Compare multiply observed sources Source injection (uv data)

3. Spectral index distribution for low-frequency-selected and high-frequency-selected sources (De Breuck et al. 2000) “Ultra-Steep-Spectrum” is alpha < -1.3 (between frequencies of 1420 and ~300 MHz) Motivation #2: deeper southern sample of Ultra-Steep Spectrum Sources

4. Motivation #2: new sample of Ultra-Steep Spectrum Sources De Breuck et al. 2004

5. Motivation #3: know your enemy – we want to subtract this foreground

6. Comparison Catalogs Molonglo Reference Catalog (MRC): 408 MHz, southern sky excluding Galactic plan, complete above 1 Jy, goes to 700 mJy, about 3 arc min resolution Culgoora Catalog: 80 and 160 MHz, not really a catalog, rather flux measurements of known sources Parkes-MIT-NRAO 5 GHz survey Source counts from Cambridge 150 MHz surveys

7. Galactic plane Comparison of individual sources

8. Comparison of individual sources: Molonglo-MWA

9. Histogram of differences in source positions Note declination shift

10. Comparison of individual sources: Molonglo-MWA Histogram of differences in source positions, normalized

11. Comparison of individual sources: Molonglo-MWA Differences in source positions Plotted vs. distance from phase center

12. Comparison of individual sources: Molonglo-MWA Differences in source positions, normalized Plotted vs. distance from phase center

13. Comparison of individual sources: Molonglo-MWA Working on comparison of flux densities ( Chris Williams and Fakhri Zahedy, work in progress)

14. Comparison of statistics: Cambridge-MWA source counts MWA sample Flux density vs. distance from phase center

15. Comparison of statistics: Cambridge-MWA source counts MWA sample Choose “complete” region

16. Comparison of statistics: Cambridge-MWA source counts MWA sample (very preliminary) Fits give power law index of -1.75 and -2.12 Cambridge -1.8 (Gower 1966); -1.51 (de Mateo et al. 2002)

17. Comparison of statistics: Distribution of PMN-MWA spectral indices

18. MWA Ultra- Steep Spectrum Sources 128-tile array will be MUCH more capable than this 32-tile array! 5 GHz – 150 MHz spectral indices Deeper sample of Ultra-Steep Spectrum Sources

19. Comparison to other catalogs for verification Positions look good but o Shift o Increased error with distance from phase center Source counts in the right ballpark but o Correction for varying sensitivity across field needed o Careful fitting needed Spectral index distribution looks very plausible Science New sample of Ultra Steep Spectrum sources Learning about the EoR enemy SUMMARY