HR: 0800h
AN: SH11A-0242    [Abstracts]
TI: A Search for Hard X-Ray Emission from the Quiet Spotless Sun
AU: * Hannah, I G
EM: hannah@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 United States
AU: Hurford, G J
EM: ghurford@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 United States
AU: Hudson, H S
EM: hhudson@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 United States
AB: RHESSI observations often show hard x-ray emission from non-flaring active regions. The objective of this work is to search for hard x-ray emission that is not associated with active regions. There are a number of potential sources for such emission, some of which are relevant to coronal heating. With its shutters open RHESSI has greater sensitivity in the 5-25 keV range than previous missions. It uses a set of 9 rotating modulation collimators to image sources with size scales from 2 arcseconds to 3 arcminutes. However, since the quiet Sun sources may be well-dispersed spatially across the disk, RHESSI's normal imaging technique is not well suited to the task. An alternate observational technique involves pointing RHESSI slightly away from the Sun. Then the time-dependent transmission of the thick individual grids (whose field of view is 1 degree) chops the integrated solar signal at ~0.5 Hz to provide effective background suppression. This paper describes the technique and initial results from a period of offpointing observations (19-July-05 to 25-July-05) acquired when the GOES background level dropped to below A2 and there were no active regions visible on the disk.
DE: 7500 SOLAR PHYSICS, ASTROPHYSICS, AND ASTRONOMY
DE: 7554 X-rays, gamma rays, and neutrinos
DE: 7594 Instruments and techniques
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005