Thursday, June 21, 2018

Happy Summer Solstice 2018!

Today, June 21, 2018, at 1007 UTC (6:07 am ET) the Sun reached its northernmost point in our sky. In the northern hemisphere we have the longest day of the year while people in the southern hemisphere have their longest night. Six months from now we will reverse places for the Winter Solstice. It's all due to the tilt of the Earth's rotation axis that tilts us toward the Sun in northern summer. Our ancestors often celebrated the Solstices with parties. I'll celebrate with some pictures of the Sun.

For those who thought Solar Cycle 24 had faded into history, please look at today's Sun. There are three active regions visible on the Sun and a sunspot number of 52. This blended image overlays an HMI magnetogram with an HMI continuum image. Helioviewer.org has provided pointers to the active regions. (The little β describes the complexity of the active region.) All three regions are at low latitudes in the northern hemisphere of the Sun and have the black magnetic field leading the white, so they are Solar Cycle 24 sunspots. Another region of Solar Cycle 24 field is visible on the left and will soon rotate into view.
Even as Solar Cycle 24 fades, we see the signs of the next cycle. Here is an AIA 171 Å image, also with the active regions pointed out. I added two arrows to the dark patches at the poles of the Sun. Those polar coronal holes contain the seeds of Solar Cycle 25. The strength of the polar magnetic field says that Solar Cycle 25 will be a little more active than Solar Cycle 24. We only have to wait until 2025 to find out.

Thanks to Helioviewer.org for the labels.

Enjoy the Solstice!

Monday, June 18, 2018

Congratulations to the EVE on a Successful Launch

The EVE team from LASP launched their calibration instrument over White Sands today at 1 pm MT (3 pm ET). They got about 10 minutes of data and the payload was parachuting to the ground.

Congratulations!

Tuesday, May 1, 2018

High-Gain Antenna Test is Complete

SDO completed the Failed High-Gain Antenna Simulation and rolled back to its normal orientation at 1900 UTC (3:00 p.m. ET) last Wednesday. Here is a short video using the Where's SDO? images showing that day in the life of SDO. Watch the Z-axis for the flip.
Many thanks to the FOT and instrument team member who planned and executed this test. We learned a lot!

Saturday, April 14, 2018

SDO Instrument Calibration Maneuvers

This past Wednesday starting at 1415 UTC (10:15 am ET) SDO performed the EVE FOV and HMI/AIA Flatfield instrument calibration maneuvers. The spacecraft rolled back to its normal orientation before the test. Once the maneuvers were complete, SDO rolled 180° to continue our simulation test. As always during a calibration maneuver, the AIA images may be streaky or cutoff at the edges of the CCDs. The movie shows how that day looked in the AIA 211 Å channel. The interference caused by the edges of the CCD are easily visible around 2000 UTC.

Next week SDO will perform the EVE cruciform maneuver on Wednesday, April 18, starting at 1430 UTC (10:30 am ET). Once again, SDO will roll to normal pointing before the test and roll 180° after the test.

Friday, April 13, 2018

The First Signs of Solar Cycle 25

On 20-Dec-2016 a USET observer saw a small patch of magnetic field in the southern hemisphere of the Sun. The outward magnetic field (white in the magnetograms) was behind the inward field (black patches). This patch is circled in blue in the HMI magnetogram. This high-latitude region (23°S) did not follow the pattern of magnetic field seen in Solar Cycle 24. George Hale noticed that sunspots tended to have a definite pattern of their magnetic field. One hemisphere has the patch of inward field leading the outward. The other hemisphere has the opposite pattern. During the next sunspot cycle the hemispheres reverse patterns.

The arrows in the magnetogram point to magnetic fields that follow Hale’s law for Solar Cycle 24. The blue arrows point to areas that show the pattern for the northern hemisphere and the single red arrow the southern. Even the broad areas of magnetic field in the northern hemisphere follow this pattern.

The magnetic field in the patch of magnetic field in the blue circle has the black leading the white — a sign that it is related to Solar Cycle 25, especially because it is at higher latitudes than most of the sunspots seen around this time. This is another pattern in sunspots. They tend to appear at higher latitudes early in a cycle and appear at ever-lower latitudes as the cycle progresses.

So, this little patch of magnetic field has two reasons to be the “First Sunspot of Solar Cycle 25.” It only needs to be seen as a sunspot and assigned an Active Region number.

The first observer notified other members of USET and one of them went and looked at the Sun. There was a small sunspot where the patch of magnetic field was seen. It was assigned the number AR 12620. It is the small black dot above the label in the orange HMI continuum image. Only one of the four other patches of magnetic field in the magnetogram was also visible as a sunspot (AR 12619). Looks like we have a winner!

Why mention this now? Because Sam Freeland saw another high-latitude (31°S), reversed-polarity patch of magnetic field in the southern hemisphere on 8-Apr-2018 (top panel of picture, the brightest area is the corona above the magnetic patch in an AIA 193 Å collage). This time the patch appeared and faded without forming a sunspot and did not receive an active region number. But Freeland saw a small flare at 12:57 UTC on 9-Apr-2018. This A2.5 flare may also be visible as a small blip in the GOES 14 X-ray flux (bottom panel, arrow points at blip).

Each Solar Cycle overlaps with the ones before and after. We study this overlap in our quest to understand the solar magnetic field and the dynamo that creates it. Our modern data, especially the full-disk magnetograms, makes looking for these overlapping regions a little easier.

As solar minimum draws near, we will see fewer sunspots but more and more of them will have the properties that put them into Solar Cycle 25. Eventually, solar minimum will be reached and after that sunspots associated with Solar Cycle 25 will become the majority. That should happen in 2020.

It is good to see that solar activity will continue to fascinate us in Solar Cycle 25.

Tuesday, April 3, 2018

High-Gain Antenna Test Continues

The SDO Team continues running the high-gain antenna (HGA) test. We are pretending that the “bottom” HGA has stopped working and we are running the spacecraft upside down to stay in contact with the ground. There has been no problem with the HGAs, but we need to keep the SDO Team thinking how to handle these problems before they happen.

As you can see in the picture, the FOT is using Camilla as a reminder what roll angle SDO is at. Currently at 153.7°, tomorrow SDO will roll to 180°. The test will end on April 25 at 1900 UTC (3 pm ET).

As the test progresses, the software to correct the orientation of the near-realtime images continues to be improved. By the end of the test all of the images will be correct!

Monday, March 26, 2018

On-Orbit Testing of SDO, March 28–April 25, 2018

SDO uses two high-gain antennas (HGAs) on the spacecraft to maintain continuous contact with the SDO ground station in New Mexico. Should one of those antennas fail we would have to roll the spacecraft to a variety of position angles during the year to keep the remaining HGA in contact with the ground station. The SDO Team will be testing the procedures needed to run SDO on a single HGA from March 28, 2018, to April 25, 2018.

During the test the roll angle of SDO will vary from 0 to 180 degrees. Near-realtime images from SDO may appear with the incorrect position angle, similar to what happens during an instrument calibration. To ensure you have correctly aligned science data, please use the exported images from the JSOC or the SSW IDL routines aia_prep.pro and hmi_prep.pro. If you use other software for data analysis, make sure you properly account for the value of the CROT2 when preparing the data.

Remember: This is only a Test!"

Wednesday, March 14, 2018

Happy Pi Day!

Although there isn't a major geomagnetic storm happening today (and none expected tomorrow), here is a lovely picture of the Sun showing a coronal hole. The high-speed plasma streaming out of this coronal hole will probably hit the Earth and create some lovely aurora, but a geomagnetic storm is not expected.

Enjoy Π Day!

Wednesday, February 14, 2018

Station Keeping Maneuver #16 Today

SDO will perform station-keeping maneuver #16 today. The maneuver begins at 22:12 UTC (5:12 pm ET) and lasts until 22:56 UTC (5:56 pm ET). During the maneuver science data may be blurry or unavailable.

Station-keeping maneuvers are performed to keep SDO inside of its box in the geostationary belt. Even though SDO’s orbit is inclined 28° to the equator (where geostationary satellites orbit), we pass through the geostationary belt twice each day. We must stay inside our longitude box to avoid interfering with our neighbors. SK maneuvers happen about twice each year.

Sunday, February 11, 2018

Happy 8th Birthday, SDO!

It was a cold day at Cape Kennedy as SDO rose slowly into the sky. Eight years later, SDO has sent over 260 million images of the Sun to the ground. Over 3000 scientific papers have described how the Sun's magnetic field is created and destroyed. We have a large number of citizen scientists who study our images, especially using HelioViewer.

SDO still produces high quality data of the Sun every day. Even Solar Cycle 24 fades from view, we are watching the polar region magnetic fields grow. Large coronal holes can often be seen in the AIA coronal images. Solar Cycle 25 will soon be visible. SDO is ready!

Monday, January 29, 2018

2018 Maneuvers, Past and Future

SDO ran a number of maneuvers during January 2018. Science data may be unavailable or blurry on days when a maneuver is run. During eclipse season the Earth blocks the Sun for up to 72 minutes each day around 0700 UTC (2:00 am ET). This is also midnight Mountain Time, the timezone of the SDO ground station.
  • 01/03/18: RWA Jitter Test Successful: Instruments reported no blurring in images; ISS performance looked reasonable.
  • 01/17/18: EVE Cruciform Successfully Executed
  • 01/24/18: HMI roll, starting at 1500 UTC (10:00 am ET)
  • 02/10/18: Spring 2018 Eclipse Season Begins
  • 02/14/18: Stationkeeping Maneuver #16 (2234 UTC, 5:34 pm ET)
  • 03/05/18: Spring 2018 Eclipse Season Ends
Above is a movie in AIA 171 Å showing the effects of the EVE Cruciform on January 17, 2018. During the HMI Roll the Sun appears to rotate.

Thursday, January 11, 2018

Server maintenance, January 11, 2018

Today, January 11, 2018 at approx. 1:30 pm the SDO website will undergo server maintenance. The website will still be operational. However, images, movies, and data will not be available for some time.