Miyakawa Koji-DKIST intern

Koji was born on the island of Oahu but grew up in Japan. He is currently a junior studying astronomy and physics at the University of Hawaii at Hilo. Koji’s passion for space exploration led him to participate in the NASA Hawaii Space Grant Consortium Research Internship during the Spring 2023 semester. In his free time, Koji enjoys watching movies. Upon graduation, he hopes to pursue a Ph.D. and contribute to the field of astronomy. Koji’s multicultural background and interest in space exploration make him a valuable asset to the scientific community.

Home Island: Oahu

High School: 

Institution when accepted: University of Hawaii at Hilo

Deriving a Sky-Brightness Model to Establish Good Coronal Observing Conditions 

Project Site: Daniel K. Inouye Solar Telescope, Pukalani, HI

Mentors: Andre Fehlmann & Tom Schad

Project Abstract:

The Daniel K. Inouye Solar Telescope (DKIST) on Haleakala, Maui, is the world’s largest solar telescope. With its capability to observe the solar disk and the much fainter solar corona, DKIST plays a crucial role in solar research.  Accurate knowledge of the sky brightness near the sun is vital for determining the feasibility of coronal observations on a given day.  The primary goal of this project is to utilize a Cimel Electronique CE318-T automated multispectral atmospheric photometer and develop a model to estimate the sky brightness as close to the solar limb as possible, which will provide near real-time data to assist telescope operators in decision-making.  The CE318-T is able to measure and calculate atmospheric parameters such as aerosol optical depth (AOD) and water-vapor content. However, the CE318-T has limitations in measuring pure sky brightness close to the sun due to its large field of view.  Therefore, we pursued two potential approaches to achieve this goal. One avenue involves using custom observing modes of the CE318-T to disentangle the sun’s brightness from the surrounding sky brightness, necessitating data collection and subsequent analysis. Using a cross-sun arrangement of pointings, photometry of the sun, solar limb, and sky were collected to create a simple model of sky brightness.  Another approach we explored is incorporating AErosol RObotic NETwork (AERONET) aerosol properties as inputs to a parametric model of the sky brightness.  The available atmospheric modeling software, Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS), aided in this endeavor by computing clear-sky spectral irradiances, including direct-beam and circumsolar for specified atmospheric conditions.  Successful implementation of the proposed model provided valuable insights into estimating sky brightness near the solar limb, further enhancing DKIST’s capabilities for coronal observations.