Monday, July 22, 2013

EVE Cruciform on July 17, Other Maneuvers this week

When you see the Sun zipping through the SDO movies you know its time for a calibration maneuver. Last Wednesday we did an EVE cruciform, nodding SDO up, down, back, and forth to allow EVE to look at how the instrument is behaving. The blurry frame on at left is an example of what happens when you take an AIA 171 image during one of the moves. This Wednesday we will do an EVE field of view and HMI/AIA flatfield. Although we can't maintain our 24/7 observing schedule during these maneuvers, they allow us to keep the instruments in excellent shape.

Sunday, July 14, 2013

Which Way is North?

Compasses tell us which way is North on the Earth. It's easy, the needle with the big N points toward the North Pole of the Earth. Other directions can be read off the dial, like a primitive GPS!
Compasses work because the Earth has a simple magnetic field with the magnetic poles in almost the same place as the rotation poles. And the compass needle points along only the part of the magnetic field that is horizontal.
The Sun also rotates and has North and South poles. But compasses aren't very useful on the Sun. The solar magnetic field is very complicated and is usually vertical rather than horizontal. Now North and South refer to magnetic fields pointing out of and into the surface.
In an HMI magnetogram (such as one from July 15, 2013 on the left) we color the outward pointing fields as white and inward as black. The weak fields are grey.
So it is probably better to think of the solar field as outward (+) and inward (-) rather than North and South. That way you won't use the magnetic field to give directions on the surface of the Sun.
On the Sun it isn’t which way is North, but which way is up!

Monday, July 8, 2013

Space Weather on Brewster Rockit

Check out the July 7 Brewster Rockit, a comic at A nice little illustration about space weather effects in the heliosphere. A bit of a preview is at left.

Thursday, July 4, 2013

LMSAL JSOC Computers Shutting Down Today

Maintenance on the chillers in the building hosting the SDO JSOC computers at LMSAL means those computers have been turned off. The main JSOC archives at Stanford are unaffected and this temporary shutdown should not affect users.

Tuesday, July 2, 2013

So Long Camilla

Little SDO is looking a little sad today. His long time partner in EPO, Camilla Corona SDO has retired as the SDO mascot. Camilla had an great career as a mascot, traveling to the stratosphere and many other places to bring the excitement of science to audiences of all ages. She made young children understand that science starts when you ask questions.
Good luck in your new life as Camilla Corona the Space Chicken!