ball1.gif BAM

Tucker et al. use 3.1-9.2 cm$^{-1}$ data from the balloon-borne BAM (Balloon-borne Anisotropy Measurement) experiment to constrain CMBR anisotropy.

The FWHM of the beam, assumed to be gaussian, is $\sigma_{\rm FWHM} =
0.7^\circ$. The zero-lag window function of the two-beam experiment is

W_\ell = e^{-\sigma_{\rm G}{}^2 (\ell + 0.5)^2}
[2 - 2 P_\ell ({\rm cos}(2\Phi_0))] ,

where $\sigma_{\rm G} = \sigma_{\rm FWHM}/\sqrt{8 {\rm ln} 2}$, $P_\ell$ is a Legendre polynomial of order $\ell$, and $\Phi_0 = 3.6^\circ$ is half of the peak-to-peak chop angle.

The first column in the window function file is $\ell$, which runs from 2 to 600. The second column is $W_\ell$.

Table: BAM zero-lag Window Function Parameters
$\ell_{e^{-0.5}}$ $\ell_{\rm e}$ $\ell_{\rm m}$ $\ell_{e^{-0.5}}$ $\sqrt{I(W_\ell)}$
16 58.2 30 92 2.36

The quoted bandtemperature values are from Tucker et al., with 20% added in quadrature to their statistical 1 $\sigma$ error bars to account for the BAM 1 $\sigma$ calibration uncertainty.

Fig.: BAM zero-lag window functions. (Postscript version here.) win_BAM.gif


ball23.gifLink to the experiment webpage.

G.S. Tucker, H.P. Gush, M. Halpern, I. Shinkoda, and W. Towlson, ``Anisotropy in the Microwave Sky: Results from the First Flight of the Balloon-Borne Anisotropy Measurement (BAM)", Astrophys. J. Lett. 475, L73 (1997).

Bharat Ratra and Tarun Souradeep
Department of Physics, Kansas State University
Last updated: 2000-08-31