Thursday, January 30, 2014

A Lunar Transit

Today the Moon passed between SDO and the Sun from 1331-1556 UTC (8:31-1056 am ET). At 2.5 hours in length, it was the longest lunar transit so far in the SDO mission.
You can watch the transit using the browse data option on our website. Use the times 2014-01-30 00:00:00 and 2014-01-30 17:00:00 and your favorite wavelength to enjoy the show.

Here is an image from 2014-01-30 14:29:12 in the AIA 171 passband. If you watch the movie you will see the Sun move a little bit during the transit. This transit covers a lot of the solar disk and blocks the sunlight from SDO. The fine guidance systems on AIA and HMI can't work because they need to see the whole Sun to keep the images centered from exposure to exposure. Once the transit is over the fine guidance systems started back up, giving us steady images of Sun.

And, as the Moon left SDO's field of view, an M8 flare erupted in AR 11967.