ball1.gif Python I - III

Dragovan et al. (Python I), Ruhl et al. (Python II), and Platt et al. (Python III) use 90 GHz data from the ground-based Python experiments at the South Pole to constrain CMBR anisotropy. Rocha et al. summarize these Python experiments.

Python I and II data were taken at a single telescope elevation. Python III data were taken at this fiducial elevation as well as two additional elevations offset above and below the fiducial elevation. The chopper throw and azimuthal telescope beam switching were both $2.75^\circ$ on the sky for the Python I and II observations. The first series of Python III measurements, hereafter IIIL, also used these chopper and beam switch parameters. The second series of Python III measurements, hereafter IIIS, were made with both the chopper throw and telescope beam switch reduced to $2.75/3^\circ$ on the sky.

The FWHM of the beam, assumed to be gaussian, is $\sigma_{\rm FWHM} =
(0.75 \pm 0.05)^\circ$ (one standard deviation uncertainty). As discussed in Platt et al. and Rocha et al., the Python III beam was smeared to a FWHM of $\sigma_{\rm FWHM} = (0.82 \pm 0.05)^\circ$ (one standard deviation uncertainty). The zero-lag window function of the four-beam experiment is

\begin{displaymath}
W_\ell = e^{-\sigma_{\rm G}{}^2 (\ell + 0.5)^2}
[1.25 - 1....
... t})) - 0.125 P_\ell ({\rm cos}(3\theta_{\rm t}))] ,
\eqno(1)
\end{displaymath}

where $\sigma_{\rm G} = \sigma_{\rm FWHM}/\sqrt{8 {\rm ln} 2}$, $P_\ell$ is a Legendre polynomial of order $\ell$, and the throw $\theta_{\rm t}$ is $2.75^\circ$ or $2.75/3^\circ$.

The first column in the window function file is $\ell$, which runs from 2 to 750. The second, third, and fourth columns are zero-lag $W_\ell$'s for Python I/II, IIIL, and IIIS, respectively.


Table: Python I - III zero-lag Window Function Parameters
  $\ell_{e^{-0.5}}$ $\ell_{\rm e}$ $\ell_{\rm m}$ $\ell_{e^{-0.5}}$ $\sqrt{I(W_\ell)}$
Python I/II 53 91.7 73 99 1.34
Python IIIL 52 87.7 72 98 1.30
Python IIIS 128 171 176 230 0.623

The quoted bandtemperature values are from Rocha et al.. They were computed assuming a flat bandpower spectrum, and account for the Python absolute calibration uncertainty of 20%, as well as the beamwidth uncertainty, following Ganga et al. (see discussion in Rocha et al.).

Rocha et al. also use the Python I, II, and III data to constrain cosmological parameters.

Fig.: Python I-III zero-lag window functions. (Postscript version here.) win_PythonI-III.gif

REFERENCES

ball23.gifLink to the experiment webpage.

M. Dragovan, J.E. Ruhl, G. Novak, S.R. Platt, B. Crone, R. Pernic, and J.B. Peterson, ``Anisotropy in the Microwave Sky at Intermediate Angular Scales", Astrophys. J. Lett. 427, L67 (1994).

K. Ganga, B. Ratra, J.O. Gundersen, and N. Sugiyama, ``UCSB South Pole 1994 Cosmic Microwave Background Anisotropy Measurement Constraints on Open and Flat-$\Lambda$ Cold Dark Matter Cosmogonies",Astrophys. J. 484, 7 (1997).

S.R. Platt, J. Kovac, M. Dragovan, J.B. Peterson, and J.E. Ruhl, ``Anisotropy in the Microwave Sky at 90 GHz: Results from Python III", Astrophys. J. Lett. 475, L1 (1997).

G. Rocha, R. Stompor, K. Ganga, B. Ratra, S.R. Platt, N. Sugiyama, and K.M. Górski, ``Python I, II, and III Cosmic Microwave Background Anisotropy Measurement Constraints on Open and Flat-$\Lambda$ Cold Dark Matter Cosmogonies", Astrophys. J. 525, 1 (1999).

J.E. Ruhl, M. Dragovan, S.R. Platt, J. Kovac, and G. Novak, ``Anisotropy in the Microwave Sky at 90 GHz: Results from Python II", Astrophys. J. Lett. 453, L1 (1995).


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