On-The-Fly Observing System of the Nobeyama 45-m and ASTE 10-m Telescopes

TL;DR

This paper introduces an On-The-Fly spectral line observing mode for two radio telescopes, significantly improving efficiency and accuracy in mapping regions by continuous antenna movement and optimized data processing.

Contribution

Development and verification of an OTF observing system for Nobeyama 45-m and ASTE 10-m telescopes, enhancing efficiency over traditional methods.

Findings

OTF mode doubles observing efficiency compared to traditional methods.

System improvements include software, hardware, and data reduction processes.

Optimal parameters are identified for maximum efficiency.

Abstract

We have developed spectral line On-The-Fly (OTF) observing mode for the Nobeyama Radio Observatory 45-m and the Atacama Submillimeter Telescope Experiment 10-m telescopes. Sets of digital autocorrelation spectrometers are available for OTF with heterodyne receivers mounted on the telescopes, including the focal-plane 5 x 5 array receiver, BEARS, on the 45-m. During OTF observations, the antenna is continuously driven to cover the mapped region rapidly, resulting in high observing efficiency and accuracy. Pointing of the antenna and readouts from the spectrometer are recorded as fast as 0.1 second. In this paper we report improvements made on software and instruments, requirements and optimization of observing parameters, data reduction process, and verification of the system. It is confirmed that, using optimal parameters, the OTF is about twice as efficient as conventional position-switch observing method.