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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0221

Co-ordinated Observations with FOXSI: a Rocket-launched Hard X-ray telescope -

plan term


@ @


 name : Krucker @  e-mail : krucker[at]ssl.berkeley.edu

contact person in HINODE team

 name : Williams, Brooks, Rainnie @  e-mail : drw[at]mssl.ucl.ac.uk

 abstract of observational proposal
The proposed observations are in support of the upcoming launch of NASAfs FOXSI (Focusing Optics X-ray Solar Imager) sounding rocket. FOXSI will provide hard X-ray imaging observations in the 5 – 15 keV range at a 50 times improved sensitivity compared to RHESSI. This will allow us to investigate the low-level hard X-ray emission that is predicted in some coronal heating scenarios.

The current launch data is confirmed for November 2; the exact launch time is TBC in the next weeks. During the 6-minute FOXSI flight, two different targets will be observed. 1) The first minute will be spent on observing a non-flaring active region (the FOXSI field-of-few is 10x10 arcmin). This will ensure that we will get enough counts to test if the hard X-ray focusing optic works properly. Additionally, it will also allow us to study non-flaring hard X-ray emissions from active regions. 2) During the remaining 5 minutes, FOXSI will point to the quiet Sun and polar region to search for hard X-ray emissions from so-called enetwork flaresf (e.g. Krucker et al. 1996).

Scientific objectives:  
Coronal heating is one of the main unsolved problems in Heliophysics. Low-level energy releases at high occurrence rates (so-called nanoflares) are one of the proposed mechanisms to heat the corona (e.g. Hannah et al. 2012). While large flares are known to be an insufficient energy input to heat the solar corona, low-level events are a hot topic discussed in many studies providing different, often controversial results. For active region, Schmelz et al 2009 reported the existence a hot (~8 MK) component, while Warren et al. 2011 does not observe such a signature. While EUV and soft X-ray observations are providing a good estimate of the several-million-degree plasma, hard X-ray observations are uniquely suited to observe hot plasma (typically above ~6 MK). Additionally, non-thermal bremsstrahlung emissions can be efficiently detected. The science objectives for the two different points of FOXSI are as following:

For the active region observations, we will be able to search for a non-flaring hot component (a component such as reported in Schmelz et al. would produce a clear signal in the FOXSI data), or at least find a new upper limit. We ask for supporting observations from EIS and XRT to characterize the few-million-degree plasma.

For the quiet Sun, FOXSI will be able to search for a non-thermal signature of network flares. The absence of such a signature would clearly show that the quiet Sun network flares do not accelerate electrons in the same way as regular flares. We ask for supporting observations from EIS and XRT to observe the thermal emissions associated with network flares.

Furthermore, we ask for SOT observations to provide magnetic context observations. In particular for the quiet Sun it is important to see if the observed hard X-ray events are indeed associated with the strongest magnetic fields.

 request to SOT
context magnetograms (within part of the FOXSI field of view)

 request to XRT
AR observations: Similar or equal run as Schmelz et al.; run to be performed before the FOXSI launch and after (preferably repeated a few times to get an idea on the long-term time evolution).
QS observations: adaptation of polar region run

 request to EIS
AR observations: Final choice TBD, but AR run to be performed before the FOXSI launch and after (preferably repeated a few times to get an idea on the long-term time evolution).
QS observations: fast time cadence with 15-30 second exposures with a slit width of 2 arcsec. The step size of 10 arcsec is proposed to roughly match the FOXSI spatial resolution; slit lengths of 512 arcsec. This will provide a 512hx100h or 512hx200h fov in 5 minutes of observations depending on exposure time.

 other participating instruments

Dear David,

the second FOXSI launch is coming up on December 9 with a launch window
between 18:15-19:15 UT. Nominally we will launch at 18:15UT and start
observing about 2 minutes later for about 7 minutes (same procedure as
for first FOXSI launch). Could we run again the same HOP as last time?


the only addition that would be favorable from our side is to have a few
full disk XRT images before the FOXSI flight for reference, if possible.

Can you arrange again with the HINODE team? Or let me know who to
contact. Thank you.

Regards, Sa"m

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