Continuous Solar Observations from the Ground -- Assessing Duty Cycle from GONG Observations

TL;DR

This study evaluates the duty cycle of ground-based solar observations from the GONG network over 18 years, demonstrating a high mean duty cycle of 93% and analyzing factors affecting observational coverage.

Contribution

It provides a detailed assessment of the GONG network's duty cycle, including site-specific analysis and implications for future ground-based solar observation planning.

Findings

Mean duty cycle of 93% for the network

Duty cycle reduces by 5% after quality checks

Standard deviations of duty cycle are 1.9% monthly and 2.2% yearly

Abstract

Continuous observations play an important role in the studies of solar variability. While such observations can be achieved from space with almost 100% duty cycle, it is difficult to accomplish very high duty cycle from the ground. In this context, we assess the duty cycle that has been achieved from the ground by analyzing the observations of a six station network of identical instruments, Global Oscillation Network Group (GONG). We provide a detailed analysis of the duty cycle using GONG observations spanning over 18 years. We also discuss duty cycle of individual sites and point out various factors that may impact individual site or network duty cycle. The mean duty cycle of the network is 93%, however it reduces by about 5% after all images pass through the stringent quality-control checks. The standard deviations in monthly and yearly duty cycle values are found to be 1.9% and 2.2%, respectively. These results provide a baseline that can be used in the planning of future ground-based networks.