Timing/duration: 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).
Targetting: 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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