ALMA Memo 628 -- High-cadence observations of the Sun

TL;DR

This paper discusses the capabilities and challenges of high-cadence solar observations with ALMA, emphasizing the importance of rapid imaging for understanding solar dynamics and proposing improvements for data processing and observation strategies.

Contribution

It introduces a forward modelling approach to demonstrate the benefits of high-cadence solar imaging with ALMA and offers initial recommendations for enhancing data processing and increasing observation cadence.

Findings

High-cadence imaging improves solar atmospheric diagnostics.

Snapshot imaging limits visibility data, complicating analysis.

Proposed methods can enhance image reliability at sub-second cadences.

Abstract

The Atacama Large Millimeter/submillimeter Array (ALMA) offers new diagnostic capabilities for studying the Sun, providing complementary insights through high spatial and temporal resolution at millimeter wavelengths. ALMA acts as a linear thermometer for atmospheric gas, aiding in understanding the solar atmosphere's structure, dynamics, and energy balance. Given the Sun's complex emission patterns and rapid evolution, high-cadence imaging is essential for solar observations. Snapshot imaging is required, though it limits available visibility data, making full exploitation of ALMA's capabilities non-trivial. Challenges in processing solar ALMA data highlight the need for revising and enhancing the solar observing mode. The ALMA development study High-Cadence Imaging of the Sun demonstrated the potential benefits of high cadence observations through a forward modelling approach. The resulting report provides initial recommendations for improved post-processing solar ALMA data and explores increasing the observing cadence to sub-second intervals to improve image reliability.