AMiBA: System Performance

TL;DR

This paper details the optimization and performance measurement of the AMiBA system for detecting the Sunyaev-Zel'dovich effect in galaxy clusters, demonstrating high sensitivity and stability in observations.

Contribution

It presents the system performance optimization, calibration methods, and measurement results of the AMiBA array for galaxy cluster observations.

Findings

Achieved a point source sensitivity of 63±7 mJy in 1 hour.

Demonstrated good phase and power stability over hours.

Measured Saturn's disk brightness temperature as 149+5-12 K.

Abstract

The Y.T. Lee Array for Microwave Background Anisotropy (AMiBA) started scientific operation in early 2007. This work describes the optimization of the system performance for the measurements of the Sunyaev-Zel'dovich effect for six massive galaxy clusters at redshifts $0.09 - 0.32$. We achieved a point source sensitivity of $63\pm 7$ mJy with the seven 0.6m dishes in 1 hour of on-source integration in 2-patch differencing observations. We measured and compensated for the delays between the antennas of our platform-mounted interferometer. Beam switching was used to cancel instrumental instabilities and ground pick up. Total power and phase stability were good on time scales of hours, and the system was shown to integrate down on equivalent timescales of 300 hours per baseline/correlation, or about 10 hours for the entire array. While the broadband correlator leads to good sensitivity, the small number of lags in the correlator resulted in poorly measured bandpass response. We corrected for this by using external calibrators (Jupiter and Saturn). Using Jupiter as the flux standard, we measured the disk brightness temperature of Saturn to be $149^{+5}_{-12}$ K.