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SDO Mission Blog

This is the Solar Dynamics Observatory Mission blog. It will consist of mission status, news, and event updates.

Today is the Summer Solstice, the longest day in the Northern hemisphere and the shortest day in the Southern. That officially happens at 20:50 UTC (4:50 pm ET). This solstice is the first day of summer in the USA.

But it has nothing to do with the Sun. The solstice is caused by the tilt of the Earth’s rotation axis to its orbit. On the other hand, we are in the maximum of Solar Cycle 25. Active region 13664 was an excellent example of how an active region should behave during a solar maximum. During the 16 days that AR 13664 was visible from the Earth in May, it produced 99 flares, including 12 X-class flares.

I produced a video of AR 13664 to celebrate the solstice. I downloaded three-color AIA images from the SDO website AIA and GOES XRS fluxes from the GOES website for days between 01 May 2024 and 16 May 2024. After removing the blank and offset images taken during an EVE cruciform, there were 1522 valid images in those 16 days (99% of the possible 15-min images). The XRS flux had 21616 points that were greater than zero.

Using the JythonMusic synthesizer, the XRS fluxes were converted to MIDI percussion sounds and then into a mp4 file. There’s a lot of different drums and cymbals in the soundtrack. XRS fluxes below a C-class flare were made into rests. When the video is quiet the Sun’s activity level is low.

The AIA images and audio file were combined to give the Solstice Celebration Video shown here.

The video starts with sporadic flares and some visible activity. Once AR 13664 starts generating flares the sound and images quickly start to resemble a fireworks finale! As AR 13664 rotates out of view the activity level drops, even though new active regions have appeared. You can also see a few non-solar things, such as the apparent rotation during a calibration roll maneuver. The flare sounds and flares in the images are not exactly in synch as the images are not frequent enough.

The solar fireworks were only the beginning. The largest geomagnetic storm in over 20 years took place on 11 May 2024. It's nice to see some geomagnetic activity after the storm-poor Solar Cycle 24. Large solar and geomagnetic activity makes it more difficult to track satellites in low-Earth orbit to keep them from colliding but that’s why we study the Sun.

AR 13664 was a fascinating feature of Solar Cycle 25!

On April 8, 2024, people along a path from Mexico thru the USA and into Canada were treated to a total solar eclipse. SDO waited until much later in the day (actiually the next day in the UT timezone) and saw this glancing lunar transit.
The Moon covered about 5% of the solar disk at 09-Apr-2024, 03:36 UTC (08-Apr-2024, 11:36 ET). It is an interesting problem to understand why the motion of SDO in its geosynchronous orbit above the Mountain timezone against the lunar velocity later in the day allowed the transit many hours after the eclipse on the ground. Perhaps the next post will explore those details.

You should check out the spectacular photos of the total solar eclipse. There was at least one prominence visible to my eyes on the limb.

Today SDO will execute the EVE Field of View (at 1315 UTC, 9:15 am ET) and the HMI/AIA Flatfield (at 1630 UTC, 12:30 pm ET) calibration maneuvers. During these maneuvers SDO science data may be missing or blurred.
SDO will execute Momentum Management Maneuver (Delta-H) #49 today. Between 1830 UTC (2:30 pm ET) and 1910 UTC (3:10 pm ET) science data may be missing or blurred.
On April 8, 2024, a large swath of North America will enjoy a Total Solar Eclipse from Mazatlán up through Texas to Maine and the Maritime Provinces of Canada. Although those along the path of totality will enjoy a beautiful view of the solar corona, SDO will only see a short, almost glancing transit of the Moon across the Sun long after the TSE ends. The SDO transit starts at 03:29 UTC on 9 Apr 2024 (10:29 pm EDT on 8 Apr 2024), 7 hours after the TSE ends on the ground.

Here is a movie from the SDO Flight Dynamics Team showing the transit.

The transit will only cover 5% of the solar disk.

If you live in Mexico, USA, or Eastern Canada, please go watch the Total Solar Eclispe. They are a wonderful way to see the Sun in a different light.

SDO will execute Station Keeping maneuver #28 today from 2315-2400 UTC (6:15-7:00 pm ET). During a maneuver SDO science data may be missing or blurred. These maneuvers are needed to maintain SDO's assigned position as it passes through the geostationary orbit belt.
Between 0557--0612 UTC (01:57--02:12 ET) on 18 Jun 2023, SDO is experience a brief lunar transit. The Moon will cover about 3% of the Sun, but because it will pass over the top diode SDO will leave science mode during the transit.

Here is the Flight Ops Team movie of the transit

I hope everyone is enjoying SDO's view of the Sun as we near the maximum of Solar Cycle 25!

The 2023-094 FDS Quarterly (Long-Set) Predicts have been delivered. They include events through 05 Nov 2023. The highlights are:
  • 20 May 2023, 0222--0306 UTC (22:22--23:06 ET) - LunTran_2023140_3dc_82pshdw
  • 18 Jun 2023, 0557--0612 UTC (01:57--02:12 ET) - LunTran_2023169_1dc_3pshdw
  • 21 Jun 2023, TBD - Tentative date for Momentum Management Maneuver #47
  • 04 Jul 2023, 1148 UTC (07:48 ET) - Handover Season Starts with First Handover (-Z HGA Active Prior)
  • 20 Jul 2023, 0725 UTC (03:25 ET) - Eclipse Season Starts
  • 26 Jul 2023, TBD - Tentative Date for Station Keeping Maneuver #27
  • 04 Aug 2023, 1913--1919 UTC (15:13--1519 ET) - Solar RFI
  • 05 Aug 2023, 1910--1918 UTC (15:10--1518 ET) - Solar RFI
  • 06 Aug 2023, 1909--1916 UTC (15:09--15:19 ET) - Solar RFI
  • 15 Aug 2023, 0248 UTC (22:48 ET) - Handover Season Ends with Completion of Last Handover (+Z HGA Active After)
  • 16 Aug 2023, 0659 UTC (02:59 ET) - Eclipse Season Ends
  • 05 Nov 2023, 0200 ET - Daylight Saving Time Ends, GSFC Local Time now UTC-5:00
(All dates and times in parentheses are GSFC Local time.)

Here is a movie of the predicted 20 May 2023 lunar transit:

And here is what a daily movie shows for that date:
All is Go for the launch of the SDO EVE calibration rocket (NASA #36.389) on May 3. The EVE Team has approvals from NASA, WSMR (White Sands Missile Range, where the flight will occur), and the Navy (who run the launch pad) for a launch window of 18:10-18:40 UTC (2:30 PM - 2:40 PM ET). The weather forecast for White Sands, NM, is also looking good.

The EVE sounding rocket used to calibrate the SDO EVE instrument launches from the White Sands Missile Range in New Mexico in 2015. (Image courtesy LASP.)

NASA TV will stream the launch starting at 11:45 AM MDT (1:45 pm ET) at the link


The SDO Team will power cycle Inertial Reference Unit #2 (IRU-2) today. These cold starts are used to maintain the IRUs and ensure their longevity. The spacecraft will execute a series of off-point maneuvers after the power cycle. These will be done in all three axes, so images will appear to move left to right, nod up and down, and roll to and fro. Once the testing and calibrations are over SDO will return to routine science data collection.

During the calibration activity science data may be missing, blurred, or shifted.