Sep 21 – 23, 2015
Royal Observatory of Belgium
Europe/Brussels timezone

Measurements of the Solar Oblateness during the SDO Mission

Sep 22, 2015, 10:45 AM
Meridian Room (Royal Observatory of Belgium)

Meridian Room

Royal Observatory of Belgium

Avenue Circulaire - 3 - Ringlaan 1180 Brussels
3-Results from recent space missions


Dr Rock Bush (Stanford University)


During the five plus years of the Solar Dynamics Observatory (SDO) spacecraft on-orbit operation, the Helioseismic and Magnetic Imager (HMI) instrument has been measuring the shape of the Sun. To date, twelve roll maneuvers have been performed by the SDO spacecraft during which the spacecraft is rotated 360 degrees around the Sun-spacecraft line. HMI observations taken during these roll maneuvers enable the instrument distortion to be separated from the solar shape. The mean equator to pole radius difference over the five years of observations is approximately 6.0 milli-arcseconds. The long term trend of the solar oblateness, however, does not show a correlation with the current solar sunspot cycle. Details on the HMI instrument thermal variation during the roll maneuvers will be discussed. In particular, the thermal control of the HMI optical bench was modified in 2013 after which there was a statistically significant decrease in the solar oblateness determined from the HMI observations.

Primary author

Dr Rock Bush (Stanford University)


Isabelle Scholl (University of Hawaii) Jeff Kuhn (University of Hawaii) Marcelo Emilio (Universidade Estadual de Ponta Grossa, Parana, Brazil)

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