Thursday, October 19, 2017

Today's Lunar Transit

It was a lovely fall day in Maryland. A perfect day for a lunar transit! Here's an AIA 171 Å image showing the Moon blocking a slice of the Sun.

Wednesday, October 4, 2017

EVE Field of View and AIA/HMI Flatfield Maneuvers today

The wobbling images tell us that another round of calibration maneuvers has started. Today we have the EVE Field of View and AIA/HMI flatfield maneuvers from 1315-1910 UTC (9:15 a.m.-3:10 p.m. ET).
Next Wednesday SDO will perform the EVE cruciform.
On October 19 we will have another lunar transit. A little deeper than the one on August 21, but still not a total eclipse. Here is the movie showing what it will look like.

Wednesday, July 26, 2017

Momentum Management Maneuver #30 today, 1925-2000 UTC

SDO will perform Momentum Management (Delta-H) Maneuver #30 today. From 1925-2000 UTC (3:25-4:00 pm ET), SDO science data may be missing or incomplete. These maneuvers are used to manage the reaction wheel speeds on the spacecraft and are a normal part of our operations.

Thursday, July 6, 2017

Remainder of 2017 Maneuvers and two Lunar Transits

The next set of SDO maneuvers and other niceties has been released.
  • July 5, 1818 UTC 1320-1920 UTC (10:20 am ET - 3:30 pm ET) - EVE FOV and HMI/AIA Flatfield
  • July 12 - HMI Roll Maneuver
  • July 19 - EVE Cruciform Maneuver
  • July 23, 1818 UTC (2:18 pm ET) - Handover Season Starts (HGA +Z slew from storage)
  • July 24, 0449 UTC (00:49 am ET) - First Handover Begins
  • July 26, 1940 UTC (3:40 pm ET) - Momentum Management Maneuver #30
  • August 16, 0709 UTC (3:09 am ET) - Eclipse Season Starts
  • August 21, 1927-1955 UTC (3:27-3:55 pm ET) - Lunar Transit
  • August 30, 2241 UTC (6:41 pm ET) - Station Keeping Maneuver #15
  • September 9, 0650 UTC (2:50 am ET) - Eclipse Season Ends
  • September 25, 1942 UTC (3:42 pm ET) - Handover Season Ends (HGA -Z slew to storage, +Z Active)
  • October 19, 1941-2025 UTC (3:41-4:25 pm ET) - Lunar Transit (26% coverage)
  • December 20, Momentum Management Maneuver #31 (tentative)
The movie for the lunar transit has been updated. It isn't changed very much, but it's a nice finale to the Great American Eclipse taking place across the United States that day. From 1927-1955 UTC (3:37-3:55 pm ET) on August 21 the Moon will block up to 14% of the Sun.

Thursday, June 15, 2017

Measuring the International Sunspot Number

I was in Brussels visiting the Royal Observatory Belgium to talk about improving the accuracy of the International Sunspot Number. The ISN is the most important way we have to judge the Sun’s activity. Measurements from over 200 years ago have recently been found in several observatories and we would like to include them in the sunspot number. We are also looking at new ways to combine the data from the many observers who looked at the Sun since 1610. This would make the sunspot number record more accurate and help us understand the solar cycle.

While at ROB I saw how the ISN is measured. The Solar Influences Data Analysis Center (SIDC) at ROB is the World Data Center for the sunspot number and also measures the ISN as often as possible. Under a white dome sits several telescopes designed to look at the Sun. Every clear day an observer walks up the circular staircase to the floor of the observatory.

The long grey telescope projects a large image of the Sun onto a little table behind the telescope with four little spikes. The other telescopes are also used to study the Sun.

The observer secures a piece of paper on the spikes and draw what they see. There isn’t a lot of space and the back of your head can get very warm when it blocks the light of the Sun.

Here is a picture of what the paper looks like on the table. You can see the only sunspot group near the edge of the Sun by the upper right spike. It is quite small but has three spots in the group. (I was in the dome after the drawing for that day was finished and the telescopes are not centered on the Sun.)

Here is a picture of the actual drawing from that day. There is one small spot group with three visible spots. That makes the ISN, which is 10*number of groups + number of spots, 13 for 14-Jun-2017. This may change a little as other stations report, but the decline of Solar Cycle 24 is continuing.

My thanks to the people at the SIDC for both hosting our meeting and giving me at backstage look at the solar observatory. You can get more information, including more drawings and pictures of the Sun, are the SIDC website.

Thursday, May 25, 2017

Today's Lunar Transit

SDO had another visit from the Moon today, as it passed between SDO and Sun.
Here are two AIA 193 images showing the Moon moving onto and roughly maximum coverage.

Always nice to see another member of the solar system paying a visit. See you again in August!

Tuesday, May 2, 2017

Seven Years of SDO Data!

May 1, 2017 is SDO's 7th birthday of data collection. We launched on February 11, 2010, reached our final orbit, checked out the instruments and spacecraft, and began returning science data on My thanks to the SDO Team for their great work on this mission. My congratulations to the SDO Team for winning a NASA Honor Award for Group Achievement! This award reflects the effort and care the SDO Team has put into the mission.
We have updated a few things on the SDO Website. The kiosk movies will be turned off on May 31. Please migrate to the SDO Dashboard at, which has a lot more flexibility in setting up the 48-hour loop movies. As an added attraction, we have added some higher cadence channels (such as the AIA 171 Å channel shown here). This channel has also been produced with a radial gradient filter that enhances the corona around the edge of the Sun.
Update May 3, 2017: Here's an example of how to embed these html5 videos in a website using the high-cadence AIA 171 Å channel.