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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0282

Coordinated active region DEM investigations with NuSTAR

plan term


@ @


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

contact person in HINODE team

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

 abstract of observational proposal
The proposed Hinode observations are in support of NuSTAR investigations of the temperature structure and heating source of active regions. Active region differential emission measures (DEMs) are of interest both because (1) presence of hightemperature plasma could indicate the coronal heating source (waves vs nanoflares); and (2) previous studies do not agree on whether hot (>6-8 MK) plasma exists in quiescent, nonflaring active regions. While EUV and soft X-ray observations provide a good estimate of the several-million-degree plasma, hard X-ray observations are uniquely suited to observe the hottest plasma. Additionally, hard X-rays from nonthermal electrons would indicate the presence of nanoflares even during quiescent times. We ask for supporting observations from EIS and XRT to characterize the fewmillion- degree plasma.

 request to SOT
-- Context magnetograms, not high priority.

 request to XRT
-- Multiple filters for quiescent active region DEM analysis, e.g. thin-Be, med-Be, med- Al, thick-Al and thick-Be. 384hx384h FOV, long exposure times for the thick filters. Low cadence is OK.

-- If possible, include a full-disk synoptic in 1-2 filters, outside of the NuSTAR observation window within 2 hours of the observation start or stop. This is useful for characterizing hot plasma outside NuSTARfs field of view.

 request to EIS
--- Study to run: HPW021_VEL_120x512v1

-- May include full-disk synoptic (FULL_SUN_SLOT_SCAN_1) Can be outside of NuSTAR observing time. This will be requested only if NuSTAR is also performing a full-Sun mosaic.

 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).

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, quiescent, nonflaring active regions that are not large/hot/active have successfully been observed by NuSTAR with excellent sensitivity and spatial and energy resolutions. NuSTAR has a field of view of ~12x12 arcmin, allowing entire and multiple active regions to be observed at a time. The optimal target for a NuSTAR / Hinode combined study of active-region temperatures is one or more active regions that are not too bright within a 12x12 arcmin area (NuSTARfs FOV), and no bright active regions within about 10 arcmin of the edges of this FOV (to reduce ghost-ray background).

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