A Measurement of the Angular Power Spectrum of the CMB from l = 100 to 400

TL;DR

This paper measures the CMB's angular power spectrum between multipoles 100 and 400, confirming a peak near l≈200 and matching the spectrum of the CMB at that scale.

Contribution

First measurement of the CMB angular spectrum in the range l=100 to 400 from Cerro Toco, combining new data with previous observations to localize the peak.

Findings

Peak in the spectrum at l≈200 with δT_l≈85 μK

Spectrum at l≈200 matches the CMB spectrum

Confirmed fall in anisotropy at l>300

Abstract

We report on a measurement of the angular spectrum of the CMB between $l\approx 100$ and $l\approx 400$ made at 144 GHz from Cerro Toco in the Chilean altiplano. When the new data are combined with previous data at 30 and 40 GHz, taken with the same instrument observing the same section of sky, we find: 1) a rise in the angular spectrum to a maximum with $\delta T_l \approx 85~\mu$K at $l\approx 200$ and a fall at $l>300$, thereby localizing the peak near $l\approx 200$; and 2) that the anisotropy at $l\approx 200$ has the spectrum of the CMB.