1 4 GHz Source Counts Melanie Gendre Walter

1. 4 GHz Source Counts Melanie Gendre Walter Max-Moerbeck Mitch Mickaliger Katie Rabidoux Under the supervision of Brian Mason and Jim Condon

Overview Used GBT to measure continuum emission in a random patch of sky Calculated source counts Distribution of sources as function of flux density Large GBT beam size (9') can cause confusion Detection of a group of sources as one source

Observations Used GBT (L-Band) 1410 MHz Continuum Mapped 10º x 1º area 9' beam, Nyquist sampled Bonn 1420 MHz Survey Reich, 1982, A&AS 48, 219. Reich and Reich, 1986, A&AS 63, 205.

Parameters Calibration source 3 C 286 Tsys = 14. 5 K G = 1. 69 K/Jy With an integration time FWHM = 9 arcmin of 0. 2 s, and bandwidth of Effective Area = 4664 m^2 50 MHz we get Aperture efficiency = 0. 59 Tnoise = 4. 6 m. K antenna solid angle = 9. 84 10^-6 srad Snoise = 2. 71 m. Jy mean beam solid angle = 5. 46 10^-6 srad mean beam efficiency = 0. 55

Reduction

Results For a distribution of sources at a given flux density, the number of sources can be described by the power law n(S) = k * S-γ where k is a normalization constant and γ is the power law coefficient

Results: Source Count {gamma, k} {{1. 7, 1895. 64}, {1. 9, 1002. 79}, {2. 1, 449. 769}, {2. 3, 174. 458}} {S^2. 5 n(s)} {2. 23693, 2. 22059, 2. 13258, 1. 98149}