Wednesday, May 11, 2022

HMI as a Hi-Speed Coronagraph (updated)

The time in the header of the HMI movie turns out to be off by 3 hours (the movie runs from 1320-1342 UTC). Once I heard that, it was back to Helioviewer (, which now redirects to a GSFC website) to produce an AIA 221 Å movie. I selected the area around the flare and made a movie that covers between 1300 and 1400 UTC. Now there is good agreement in the presence and shape of the filament, even the change from upright oval to a more horizontal appearance. You can compare the movies yourself to see how well the HMI filament tracks the AIA 221 Å filament. The post-flare arcade is much easier to see in this movie.

I also looked at the AIA 1600 Å passband and see a beautiful filament at 13:23:50 UTC. The filament is bright because it reflects light from the Sun towards SDO and emits its own light. Use Helioviewer to create your own movie of this passband to see the rest of the flare and filament liftoff.

Solar Cycle 25 is getting interesting!

A magnetic complex, destined to become Active Region 3006, was rotating into view on May 3, 2022, when it was the site of an X1.1 flare at 1309 UTC. Three hours later HMI observed a filament liftoff.

Junwei Zhao used all of the HMI frames to produce this movie of a filament liftoff and other evolution of the solar atmopshere above the nascent AR 3006.

This movie was made by using all of HMI’s 6 line-position intensities — not just the continuum images. Thus, this movie has an amazing 7.5-sec cadence, showing many more details than a 45-sec cadence movie. Because the data is from above the limb, Fe I 6173 is no longer an absorption line, we mostly see how it scatters light from the solar surface towards SDO. (The same is true when you look at filaments in Hα. The filaments are dark against the disk but are seen as bright prominences above the limb.) In this movie the on-disk signal is completely saturated so that the off-limb signal is more easily seen. This movie is also showing a reverse image of the off-limb pixels. The dark material would be bright in the original images. The images are 150" squares. The Sun is 1904" across on May 3, so the area seen in the movie is only 0.6% of the Sun's area.

The movie clearly shows material being ejected from the Sun. Some material falls back towards the surface, but then stopped falling and was held there for a few minutes before the light faded away.

Another interesting thing is that a post-flare arcade formed right beside the limb. Although it is small and remains close to the limb, it was undoubtedly there for a few minutes.

This is the fourth off-limb flare captured by the HMI. The first three resulted in quite a few publications in studying the polarization of the off-limb flare loops, the emission mechanisms of the off-limb white flares, and studies coupling the white-light and UV/EUV/X-ray observations. This high-cadence movie shows that we still haven't figured out all of the ways SDO data can be used to study the Sun.

You are right if you are thinking HMI was lucky. Here is an AIA 304 image of the same region from 1619 UTC of May 3, 2022. The large number of coronal loops makes it very difficult to track the filament seen in the HMI movie.The AIA 304 Å images at the corrected times are saturated and need more analysis to see the filament.

Thanks to Todd Hoeksema, Sushant Mahajan, and Junwei Zhao, all members of the HMI Team at Stanford, for discovering and providing the movies of this limb flare and filament liftoff.

I hope you enjoy this movie.

Thursday, April 7, 2022

April Calibration Maneuvers

SDO will execute several calibration maneuvers during April.
  • April 13, 2022: EVE Field of View (1415-1700 UTC, 10:15 am - 1:00 pm ET) and HMI/AIA Flatfield maneuvers (1730-2010 UTC, 1:30-4:10 pm ET)
  • April 20, 2022: HMI Roll Maneuver (1400-2040 UTC, 10:00 am - 4:40 pm ET)
  • April 27, 2022: EVE Cruciform (1300-1755 UTC, 9:00 am - 1:55 pm ET)
Science data may be blurry or missing during each calibration maneuver.

Wednesday, April 6, 2022

Momentum Management Maneuver (Delta-H) #43 Today

SDO will execute Momentum Management Maneuver (Delta-H) #43 today. Between 1830 UTC (2:30 pm ET) and 1915 UTC (3:15 pm) SDO science data may be missing or blurred.

Thursday, March 31, 2022

An X1.3 Flare and a Cool View of Plasma Leaving the Sun

On March 30, 2022, active region 12975 was the site of an X1.3 flare. Here is the daily movie in AIA 171 from that day. AR 12975 is in the upper right quadrant to the right of the far more impressive looking coronal loops above AR 12976.

During the day we adjusted the fine guidance telescope, which causes the images to bounce a little bit. The flare starts at 17:26 UTC and ends at 17:46 UTC. What I found cool about this flare was the lass of plasma just south of the flare site. Here are two stills from the movie.

On the left the arrow points at some haze in the AIA 171 image. In the right image the arrow points at about the same place (there is a bright streak just to the right to get you oriented), but the image is less hazy where plasma has left the Sun.

The material that left the Sun isn't all that close to the flare. But you can see in the movie that the haze goes away just after the flare. Look at the movie a few times and you will see the haze disappear.

There is also an excellent coronal cavity display at about 4 o'clock on the limb. These cavities are usually much slower in their evolution.

It is already a great Solar Cycle!

Wednesday, March 2, 2022

Computational Modeling for 3D Data Reconstruction of Solar Coronal Magnetic Fields

Nat Mathews / NASA GSFC
March 2, 2022, 3:30pm Eastern US Time

Abstract: The solar corona supports a variety of magnetic structures that constitute major drivers of space weather. Such a rope of magnetic field can twist and break to launch the plasma locked inside it in a Coronal Mass Ejection. The analysis and prediction of events of this nature is a major goal of the heliophysics community, and reconstructing the current state of the coronal magnetic field is a central component.

Determining the shape and structure of the magnetic fields arcing through the solar corona is a form of nonlinear inverse problem. The goal of this work is to provide a solid foundation for the construction of coronal inversion frameworks. First, a full working version of such an inverse framework is presented. For a variety of reasons, the parameterized forward model is deemed the component of this full inverse model most needing improvement. Subsequent work lays out a brand new methodology for computation of the forward model. The result is a construction that addresses many of the traditional issues around coronal field modeling. Future work extending the approach with Physics-Informed Neural Nets is discussed.</p>

Bio: Nat Mathews recently completed their PhD in applied mathematics with a focus on coronal physics at CU Boulder, advised by Natasha Flyer and Sarah Gibson. They are now a postdoctoral fellow at NASA Goddard.

Thursday, February 17, 2022

SDO 12 Years on Orbit, Large Active Region Approaching?

Last week, we celebrated the 12th anniversary of the launch of SDO. This amazing mission is still going strong, measuring the beginnings of Solar Cycle 25 with the same data stream as Solar Cycle 24. The science teams of AIA, HMI, and EVE are one part of the success of SDO. They keep the data flowing to their research, other solar scientists, and the public. Some 440 million images are now stored in the JSOC and EVE SOC!

The Flight Operations Team at Goddard Space Flight Center is another part of SDO’s success. The satellite and ground station are in great shape. FOT members help the science team by planning maneuvers to reduce the of time science data can’t be recorded. They have come to the MOC at odd hours to help resolve a problem and keep the data flowing.

But we shouldn’t forget the final team member, the Sun. And today we can see in the far-side images from February 13, 2022, that a large active region is sitting on the far side of the Sun. We should be seeing it rotate into view about 4 days from today (7 days from February 13). There are at least 4 numbered active regions on the Sun right now. How many will be there next week?

Here is a composite far-side image showing the magnetic field of the near-side (visble disk) of the Sun in greyscale and the time shifts of the far-side in color. A large active region (or sunspot) depresses the surface of the Sun and causes the wave to re-appear earlier than average. We can see a large region on the far-side with τ about -6 seconds.

Far-side images come from analyzing the helioseismic data of HMI and similar instruments. They are useful to watch for active regions developing on the far-side of the Sun where we have little or no other information. Twelve years of HMI data have improved the far-side images, now we will benefit from that work during Solar Cycle 25.

SDO is GO!

Friday, February 4, 2022

Snow Disrupts Data

Accummulated snow in the SDO-1 antenna caused an outage in the SDO Ka science data from approximately 1815 UTC to 2310 UTC (1:15 pm ET to 6:10 pm ET) on February 4, 2022. The weather is improving in Las Cruces and we anticipate no further outages.

Wednesday, February 2, 2022

SDO Station Keeping Maneuver #24 today

SDO will execute Station Keeping maneuver #24 today from 2310-2340 UTC (6:10-6:40 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.

Thursday, January 20, 2022

The Winter 2022 EVE Cruciform is Complete

Yesterday SDO performed an EVE Cruciform maneuver starting at 1400 UTC (9:00 am ET). During this maneuver the SDO spacecraft nods back and forth and up and down. The science images appear to move as well and can be blurry.

Over the next few days SDO will be supporting the validation of the PHI instrument on Solar Orbiter. PHI is similar to the HMI instrument on SDO. It uses the same spectral line of iron at 6173 Å to measure the line-of-sight Doppler velocity and the vector magnetic field on the solar surface. This weekend marks a time when the SO orbital position allows the scientists to do stereoscopic helioseismic observations, a first for us.

Next month, on 25 Feb 2022, SDO will support the 11th perihelion passage of the Parker Solar Probe.

Other dates of interest are: The Spring 2022 Eclipse Season starts 24 Jan 2022 and ends 17 Feb 2022. Stationkeeping Maneuver #24 is tentatively scheduled for 2326 UTC (6:26 pm ET), 02 Feb 2022.