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RHESSI Observations of the Quiet Sun View all project descriptions by submitter

Iain Hannah Submitted: 27-Apr-2006 13:47

Description: We are using RHESSI's excellent sensitivity in 3-100 keV to determine the X-ray spectrum of the non-flaring, spotless, active-region-free Sun, i.e. the quiet Sun. RHESSI's normal imaging method is not suited to measuring signals that are potentially widely distributed across the Sun, so instead we have had to adopt a novel offpointing technique. By making RHESSI point slightly away from the Sun the quiet Sun signal is modulated against the background allowing it to be measured directly. However the quiet Sun signal is still weak and we need to accumulate a lot of data to determine whether we have an actual signal or only noise upper limits. We have been able to put RHESSI into this offpointing mode 4 times so far (up to April-2006) during periods of low activity and have determined that the technique works and have preliminary quiet Sun spectra. These spectra are not of the quietest possible times however, and so this work is an ongoing investigation, with us planning further offpointing periods as we pass through Solar minimum. See for more information.

Participants: Hannah, I.G., Hurford, G.J, Hudson H.S, Lin, R.P

Project Status: Go to main RHESSI project descriptions page  Multi-wavelength Study of Seismically Active Solar Flares  Edit Entry  Submitter's Homepage

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