Unistellar citizen astronomer Hiroaki Tsuchiyama and his eVscope
The Unistellar Network had its first successful citizen science results from Japan! Congratulations to Hiroshi Matsushita and Hiroaki Tsuchiyama for making the first positive detections from the Unistellar community in the Japanese islands! This is an amazing first step from the already vibrant community of Japanese citizen astronomers using their Unistellar eVscopes.
On May 22, 2021, Unistellar citizen astronomer Hiroshi Matsushita successfully detected a main-belt asteroid known as 895 Helio near Mount Fuji, and helped assess its size more accurately. He traveled there to record this 10 second event, observing the disappearance of a bright star as Helio occulted (passed in front of) it.
Hiroshi’s result suggests a size of 80 miles (128 kilometers) for asteroid Helio. This estimated diameter is very close to the published size of Helio, estimated from the NEOWISE space telescope (68-93 miles/ 110-150 kilometers), but significantly more accurate.
2021年5月22日、Unistellarの市民天文学者であるMatsushita Hiroshiさんは、富士山付近にあるヘリオ（小惑星）として知られている小惑星帯の小惑星の観測に成功し、より正確なサイズの判定に貢献しました。彼はこの10秒間を記録するためにそこまで足を運び、ヘリオが明るい星の前を通過することでその星が消えるところを観察しました。
Matsushitaさんの観測の結果は、小惑星ヘイロのサイズは128kmであることを示唆しています。この直径の予測はNEOWISE（NASA開発の広域赤外線探査衛星）による宇宙望遠鏡による観測から公表されているヘリオのサイズ、110-150kmに非常に近いだけでなく、より正確なものとなっています。
Hiroshi’s eVscope observation of 895 Helio occulting a star. What you see here is the star disappearing and reappearing, as 895 Helio passes in front of it. The graph shows the brightness of the star dramatically dropping when Helio passes in front of it, and increasing again afterwards.
On March 25, 2021, Unistellar citizen astronomer Hiroaki Tsuchiyama successfully detected the transit of an exoplanet candidate that we have dubbed UE4 (for Unistellar Exoplanet number 4) to keep certain details private. An exoplanet candidate is a potential planet outside our solar system! This one was discovered over 300 light-years away by the NASA TESS space telescope, but not yet definitively proven to be a planet. From this observation and others, Unistellar/SETI Institute astronomers believe that UE4 is a “Warm Jupiter” candidate that orbits its star in about 10-100 days. Warm Jupiters are in between “Hot Jupiters,” which orbit their star in 1-10 days, and colder Jupiter analogues, which take hundreds of days to orbit their star.
Unistellar citizen astronomer Hiroaki Tsuchiyama successfully detected the transit of exoplanet candidate UE4.
Hiroaki describes his observation of UE4:
“The UE4 (Unistellar Exoplanet Number 4) campaign was my second exoplanet transit challenge. The observation was done at my home. Tokyo, where I live, is strongly affected by light pollution, and even in the suburbs of the city, the Bortle scale is 7, which is not a good environment.
On the day of the UE4 campaign, there were many clouds until the evening, and UE4 could not be caught for about 30 minutes from the start of observation. However, after that, it gradually cleared up and it became a very clear night sky. Unfortunately, the light curve missed the beginning of the transit, but I was fortunate to be able to observe most of it.
The eVscope is a wonderful platform that not only allows you to easily shoot deep sky, but also allows you to engage in space research through Citizen Science.”
「UE4キャンペーンは私の系外惑星トランジットの2度目のチャレンジでした。
観測は私の自宅で行いました。
私が住む東京は光害の影響が強く、都市の郊外でもボートルスケールは7であり、良い環境とは言えません。
UE4キャンペーンの当日は夕方まで雲が多く、観測開始から30分ほどはUE4は捉えることができませんでした。しかし、その後、次第に雲が去りとてもクリアな夜空になりました。eVscopeのライブビューでUE4を捉えた時はとても興奮したことを覚えています。残念ながら、ライトカーブ（高度曲線）はトランジットの始まりを逃しましたが、その大部分を観測出来たことは幸運でした。
eVscopeは手軽に深宇宙を撮影できるだけでなく、市民科学を通して宇宙の研究に携わることができる素晴らしいプラットフォームです」
The graph below is a transit light curve, which shows the apparent brightness (“relative flux”) of exoplanet candidate UE4’s host star from Hiroaki’s data. The star is initially 1% fainter than normal as the planet crosses in front of it and then returns to its full intensity.
Hiroaki also performed his own analysis of his data, using the AstroImageJ open source software, and his measurements agree with those made by Unistellar/SETI Institute astronomers and with predictions based on the NASA TESS data.
Transit light curves like this one are used to visualize an exoplanet transit from collected data. This light curve shows the transit of UE4 as it passed in front of its star, which caused the flux (brightness) of its host star to dim and then return to normal. The depth of the dip tells us about the planet’s size as compared to the star. The gray circles and blue squares on the large graph indicate the brightness of the star over time, which were compared to astronomical models, indicated by the red line. This shows that the star’s brightness dimmed by about 0.8% (the dip along the plot’s vertical axis) as UE4 crossed the star. The smaller plot below shows residuals, or how well the data matched the astronomical models.
For the Japanese translation of this post, visit 日本の市民科学者による初めての天文学的快挙
