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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0283

Coordinated observations with NuSTAR of high coronal sources

plan term


@ @


 name : Glesener, Smith @  e-mail : glesener[at]ssl.berkeley.edu

contact person in HINODE team

 name : Reeves @  e-mail : kreeves[at]cfa.harvard.edu

 abstract of observational proposal
The proposed Hinode observations are in support of NuSTAR investigations of hot plasma and accelerated electrons in the high corona in partly occulted flares. Hard Xray observations of electron acceleration sites in the corona can investigate the mechanisms that accelerate particles up to the extraordinarily high energies observed. Previous instruments such as the RHESSI spacecraft have rarely been able to image faint sources in the corona due to insufficient sensitivity and constraints in imaging dynamic range caused by indirect imaging. The improved sensitivity of NuSTAR will allow the systematic observation of coronal acceleration sites, but due to the instrumentfs limited count rate, this investigation will best be performed in occulted flares. In addition to coronal electron acceleration sites, other observations may include pseudostreamers and the study of escaping electron beams responsible for Type III radio emission.

 request to SOT
No request.

 request to XRT
-- CME Watch program (2048hx2048h FOV, binned 4x4) using the thin-Be filter with a ~1 minute cadence

 request to EIS
-- EIS observations are not high-priority for this study, but a program designed for flares would be appropriate.

 other participating instruments
The Nuclear Spectroscopic Array (NuSTAR) is a soft/hard X-ray instrument producing direct focused images and spectra of faint astrophysical targets from 2 to 80 keV. While not a heliophysics mission, NuSTAR occasionally observes the Sun as a target of opportunity.

NuSTAR quiet-Sun solar pointings are called as ToOfs on a 3-4 day time scale. Solar observations are 1-4 orbits (~1 to 6 hours).

NuSTAR has a field of view of ~12x12 arcmin. Because it was not designed/optimized for bright solar sources, NuSTAR has a limited count rate of 800 counts per second over the entire energy range. Therefore, the best opportunities to take advantage of NuSTARfs high sensitivity and straightforward imaging come during times of low solar activity. While medium/large flares (GOES class C and higher) are probably too bright, flares that are partly occulted (i.e the base of the flare is obscured by the solar disk) offer the opportunity to observe faint sources of accelerated electrons high in the corona without the high deadtime that would be induced by the brightest part of the flare. The ideal target for this coordinated study is a region just above the solar limb at a time when a frequently-flaring active region has recently rotated off of the visible solar disk (giving a high probability of occulted flares), with its base occulted for at least one day (to avoid high deadtime due to the bright, hot thermal active-region plasma.) For studies of pseudostreamers, the target may be different.

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