HR: 0800h
AN: SH11A-0241    [Abstracts]
TI: RHESSI observations of solar radius
AU: * Fivian, M D
EM: mfivian@ssl.berkeley.edu
AF: SSL/UCB, 7 Gauss Way University of Califoria, Berkeley, CA 94720-7450 United States
AU: Hudson, H S
EM: hhudson@ssl.berkeley.edu
AF: SSL/UCB, 7 Gauss Way University of Califoria, Berkeley, CA 94720-7450 United States
AU: Lin, R P
EM: rlin@ssl.berkeley.edu
AF: SSL/UCB, 7 Gauss Way University of Califoria, Berkeley, CA 94720-7450 United States
AB: The Solar Aspect System (SAS) of the rotating (at 15 rpm) RHESSI spacecraft has three simple solar optical telescopes. Each of these measures the position of the limb by sampling the solar chord profile with a linear CCD using a narrow bandwidth filter at 670 nm. With a resolution of each CCD of 1.7 arcsec/pixel, the precision of each of the 6 limb positions is observed to be better than 50 mas using 4 pixels at each limb. Since the launch of RHESSI early 2002, data have been obtained at a rate of at least 100 samples/sec. This has provided a database of currently 7~×~10⁹ individual measurements. The main function of SAS is to determine the RHESSI pointing relative to Sun center. Using these data we observe the solar oblateness and see signatures of magnetic activity (spots and faculae).
DE: 7504 Celestial mechanics
DE: 7522 Helioseismology
DE: 7529 Photosphere
DE: 7538 Solar irradiance
DE: 7544 Stellar interiors and dynamo theory
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005