2026-03-03 理化学研究所,東京理科大学,京都大学,広島大学,千葉大学
パルサーから放射されるX線パルスを利用して測位を行うNinjaSat（想像図）
©RIKEN、NASA/CXC/SAO、気象庁（図を改変）
＜関連情報＞
- https://www.riken.jp/press/2026/20260303_2/index.html
- https://www.spiedigitallibrary.org/journals/Journal-of-Astronomical-Telescopes-Instruments-and-Systems/volume-12/issue-01/018002/In-orbit-demonstration-of-X-ray-pulsar-navigation-with-NinjaSat/10.1117/1.JATIS.12.1.018002.full
NinjaSatによるX線パルサー航法の軌道上実証 In-orbit demonstration of X-ray pulsar navigation with NinjaSat
Naoyuki Ota, Takuya Takahashi, Toru Tamagawa, Tomoshi Takeda, Teruaki Enoto, Takao Kitaguchi, Wataru Buz Iwakiri, Yo Kato, Masaki Numazawa, Tatehiro Mihara, Hiromitsu Takahashi, Chin-Ping Hu, Yuanhui Zhou, Keisuke Uchiyama, Yuto Yoshida, Syoki Hayashi, Arata Jujo, Sota Watanabe, Amira Aoyama, Satoko Iwata, Kaede Yamasaki, Soma Tsuchiya, Yosuke Nakano, Takayuki Kita, Mayu Ichibakase, Hiroki Sato, Hirokazu Odaka, Tsubasa Tamba, Kentaro Taniguchi
Journal of Astronomical Telescopes, Instruments, and Systems Published:17 February 2026
DOI:https://doi.org/10.1117/1.JATIS.12.1.018002
Abstract
We demonstrate the pulsar navigation capability of a CubeSat X-ray observatory, NinjaSat, equipped with two sets of gas multiplier counters (GMCs). GMCs are sensitive to the 2 to 50 keV band with an effective area of 16cm2 per module at 6 keV. We verified the timing accuracy by observing Crab Pulsar and confirmed that a stable timing measurement performance is stable within 100μs. To demonstrate the pulsar navigation, we applied a method that optimizes orbital parameters to maximize the significance of the pulse profile of X-rays from a pulsar using “Significance Enhancement of Pulse-profile with Orbit-dynamics (SEPO).” We observed Crab Pulsar with an exposure time of ∼100ks at different epochs and analyzed the data downlinked to the ground. By comparing the optimized orbit with the satellite position derived from Global Positioning System data, we quantitatively evaluated the pulsar navigation performance. The results showed that the position component along the Crab line of sight was consistently constrained within ∼40km, and the range of three-dimensional error varied between 27 and 370 km depending on the observation epoch. We demonstrate the feasibility of applying a CubeSat-class X-ray observatory to pulsar navigation and also provide the first experimental verification that the accuracy of the SEPO method depends on the seasonal geometry between the orbital plane and the pulsar direction.
