Information about STEREO-A close approach to Earth, August 2023

Comparison with GONG and HMI farside maps.

Shown here is a side-by-side comparison between the latest SECCHI beacon images and the most recent calibrated farside maps from the Global Oscillation Network Group (GONG), and the Solar Dynamic Observatory (SDO) Helioseismic and Magnetic Imager (HMI).

EUVI image revised: Sunday, 20-Apr-2025 00:05:12 UTC

Image courtesy GONG project.

The farside maps are based on an analysis of sound wave travel time variations, with locations of shorter travel times appearing darker. These darker regions indicate locations where there is an accumulation of magnetic field on the far surface (farside information and references). Candidates with a probability of 70% or higher are highlighted in red (more information).

For comparison, here is a similar analysis of SDO/HMI farside data, in a somewhat different format. The black and white areas show magnetic field strength and polarity, while the orange regions show the helioseismology results for the far side. (Note also that a different map projection is used, evenly spaced by latitude instead of by sine latitude.)

Image courtesy SDO/HMI project.

Last Revised: Tuesday, 27-Apr-2021 20:47:25 UTC
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