P70

Presentation Title:

The FOXSI-4 instrument

Author(s):

Kris Cooper, Athanasios Pantazides, Yixian Zhang, Shunsaku Nagasawa, Takahiro Minami, Savannah Piel, Riko Shimizu, Sota Kashima, Yoshiaki Sato, Koki Sakuta, Kazuki Ampuku, Ryuto Fujii, Tetsuo Kano, Naoki Ishida, Wayne Baumgartner, Stephen Bongiorno, Milo Buitrago-Casas, Patrick Champey, Steven Christe, Sasha Courtade, Jessie Duncan, Lindsay Glesener, Hunter Kanniainen, Säm Krucker, Ikuyuki Mitsuishi, Sophie Musset, Noriyuki Narukage, Juan Carlos Martinez Oliveros, Subramania Athiray Panchapakesan, Eliad Peretz, Taro Sakao, Tadayuki Takahashi, Juliana Vievering, Shin Watanabe

Abstract:

We present an overview of the Focusing Optics Solar X-ray Imager (FOXSI-4) sounding rocket instrumentation and the capabilities that are enabled by its novel observation. The FOXSI sounding rocket utilises direct-focusing optics and has observed the quiet Sun, active region emission, and microflares in hard X-rays (HXRs) during three previous flights. Direct imaging HXR telescopes are used regularly to observe astrophysical sources and, even though not solar-optimised, are occasionally able to observe the Sun if conditions are sufficiently quiet (e.g., with NuSTAR). Using direct-focusing optics allows for greater image quality achieving higher sensitivity and dynamic range when compared to indirect imaging techniques; therefore, detailed simultaneous measurements become possible between relatively weak and bright sources. FOXSI is the first solar-optimised direct-focusing HXR instrument capable of observing emission from a range of solar phenomena at different scales. FOXSI-4, the fourth sounding rocket mission flown on 2024 April 17 from Poker Flat in Alaska, took part in NASA's first solar flare campaign with Hi-C Flare where an M1 GOES class flare was near-simultaneously observed by both experiments. Throughout the flight, in addition to the M1 flare, FOXSI-4 also observed weaker flares within its field of view as well as quiescent active region emission. The FOXSI-4 instrument incorporated new hardware compared to previous flights with upgrades including high-resolution Wolter-I optics from Nagoya University and Marshall Space Flight Center, improved CMOS soft X-ray detectors, a new Timepix detector, and variable-pitch double-sided CdTe HXR strip detectors. Additionally, two microfabricated pixelated attenuators from Goddard Space Flight Center were also included. Using the improved hardware, observations from FOXSI-4 will provide an unprecedented view into energy deposition throughout the solar atmosphere and flare particle acceleration via high-resolution images and spectra.

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