Tuesday, April 8, 2014

HMI Roll Tonight

Tonight, April 9, 2014, from 0519-1200 UTC (1:19 am - 8:00 am ET). SDO will execute the HMI Roll maneuver. The spacecraft will spin 360 degrees about the line to the Sun center. It stops along the way to collect a few images at each of the points. Usually the near-realtime images that are served from the SDO website are "de-rotated", but sometimes we get the watch the Sun spin around.

This data is used to study how the instruments change while they are on orbit. The most important science that comes out is whether the Sun is round or bulges a little bit at the waist. So far, it appears that the Sun bulges less than we expect and that bulge does not change very much as sunspots come and go. The only way to check is to redo the measurements at different times in the solar cycle. This set of points will be made at the maximum of Solar Cycle 24.

Thursday, April 3, 2014

EVE Cruciform on April 2, 2014

Yesterday, between 1730 and 2230 UTC (1:30 pm to 6:30 pm ET) SDO did the EVE cruciform maneuver. SDO nods back and forth and up and down. Here is an example of an AIA image taken while SDO was moving, blurred by that motion. These maneuvers allow the EVE science team to maintain the accuracy of their measurements. Accurate measurements allow them to study how much energy is released in late-phase flares and other solar events.

Monday, March 31, 2014

X-1 Flare Yesterday with a Nice Coronal Dimming


The X-1 flare on Saturday produced a very nice example of coronal dimming. Here is a short movie showing five hours of the Sun in the AIA 193 passband. After the flare happens in the upper right quadrant at 1755 UTC on March 29, 2014, a dark region spreads over the north pole. This is a coronal dimming event. There are many ways to interpret these dimming events. Are they the edges of the coronal mass ejection that left the Sun at the time of the flare? Are they waves moving past magnetic field lines and making them sway? Whatever it is, it moves fast. Active Region 12017 is at 10°N 48°W. If something moves from there to the north pole of the Sun (90°N) in 45 minutes it had to move at about 360 km/s (800,000 mph). I only see the dimming moving north.

Wherever coronal dimmings come from, they look pretty cool.

Wednesday, March 26, 2014

Momentum Management Maneuver Today

Today at 1840 UTC (2:40 pm ET) SDO will execute a momentum management maneuver. For about 45 minutes from 1815 to 1900 UTC SDO data may be unavailable.

Wednesday, March 12, 2014

SDO on the Astronomy Picture of the Day

An very nice animation of SDO images for the month of January 2014 is featured on the Astronomy Picture of the Day for March 12, 2014. The images show the brighter active latitudes on either side of the equator, a coronal hole in the northern hemisphere, and filaments covering the disk of the Sun. In the HMI visible light image in the six-image montage you can see the sunspots that make up the active regions. The image is too small to see the faculae that go along with sunspots, but the latest HMI flattened image shows them quite well.

January's 31 days are a little longer than one solar rotation of 27.27 days. That means you see a part of the Sun that is just off limb at the beginning of the month a second time as that part of the Sun rotates back into view. Active region 11944 is present throughout the month in the southern hemisphere and reappears as AR 11967 at the end of the movie. AR 11946 grows in the northern hemisphere and will reappear as AR 11968. AR 11944 will also return as AR 11990 in late February. On February 25 it will be the location of an X-4.9 flare as it rotates back into view.

Long-lived active regions are a sign that solar maximum is here and starting to fade.

Check it out!

Wednesday, March 5, 2014

Stationkeeping Maneuver Today

Today at 2035 UTC (5:35 pm ET) SDO will execute a stationkeeping maneuver. For about 45 minutes from 2015 to 2100 UTC SDO data will be unavailable.

Thursday, February 27, 2014

2014 Spring Eclipse Season has Begun

The SDO 2014 Spring Eclipse Season has begun! For the next 3 weeks the Earth will pass between SDO and the Sun around 0730 UTC each morning. They start short and last up to 72 minutes before tapering back to short.

Here is an image from our first eclipse. It is always nice to see the ragged edge of the Earth's atmosphere as the bright spots on the Sun shine through while the dimmer regions disappear. Here we can see AR 11988 near the edge of the Earth, with a coronal hole just to the right. Active regions 11981-11984 are further to the right and are hardly affected by the Earth, although they soon disappear behind the Earth.

When SDO can't see the Sun we don't get data. Eclipses are one of our largest data holes. But the orbit gives us 24/7 access to the data flow. So far we have received 98% of the data, so the eclipses aren't a problem but they are pretty!