Solar Activity Report: April 20 -26, 2026

Solar activity ranged from very low to high levels during the reporting period. Activity was very low at the start of the week, with X‑ray flux in the mid‑B-class range, before increasing to the upper B‑class level accompanied by frequent low‑ to mid‑C‑class flares. By early April 23, activity rose sharply, producing four M‑class flares that day. Activity intensified further on April 24 with two X‑class flares (X2.5 and X2.4) and two additional M‑class flares. Finally, the solar activity subsided on April 25 and continued with the similar conditions on April 26, although the X‑ray flux remained in the C‑class range with a few M‑class events. These flares were associated with CMEs, however, none of which had Earth‑directed components.

GONG UD is back on-line

 GONG station in Udaipur, India is back to operations.  NISP team worked with the site support group in India to run series of tests, which identified a failed electronic board. The board was replaced by a spare, and the system's operability was restored. The images error was cleared, and the PM (preventive maintenance) flag is turned off.  H-alpha image of the Sun taken after the repairs is shown below.

 

Solar Activity Report: April 13 - 19, 2026

Solar activity remained at low levels during the reporting period. X‑ray flux was predominantly within the B‑class range, with only occasional short‑lived increases into the C‑class. Active region 14419 was the dominant contributor, responsible for five of the seven C‑class flares recorded, including the strongest event of the week, a C4.1 flare on April 17. Additional low‑level C‑class flares were observed on April 13, 16, 17, and 18, while the remainder of the week stayed within the B‑class range. A few CMEs were detected, none with Earth‑directed components.

GONG network status

As of 18 April: 

• The Learmonth instrument is operational, and the sky is clear. 
• The Udaipur instrument is operational, and the sky is clear. On April 19, the Camera Rotator stopped rotating. Local support team was requested to check if the Camera Rotator amplifier may have a blown fuse. The observations are taken, but the image orientation is not correct (see images below taken on 18 and 19 April). UPDATE: on 20 April, GONG/UD was put into PM mode (no observations are taken) while the team is resolving the issues with oscillations in the camera rotator and the turret. 
• In early April, the internet connectivity at Udaipur experienced some instability. This was traced to a piece of cable chewed by the panther. This piece of cable was now replaced.
• The El Teide instrument is operational, and the sky is mostly cloudy.
• The Cerro Tololo instrument is operational, and the sky is clear.
• The Big Bear instrument is operational, and the sky is partly cloudy.
• The Mauna Loa instrument is down.
• Two engineering sites in Boulder, Colorado (TC and TE) are down for testing.
  
  
   

Solar Activity Report: April 6 - 12, 2026

 Solar activity fluctuated from low to moderate and back to low levels during the week. Most flares were in the C‑class X‑ray range. The week began with only low‑level C‑class activity, followed by an increase to a C5.7 flare on April 7, a C8.9 flare on April 8, and an M1.0 flare on April 9. Activity then dropped sharply on April 10, with only B‑class X‑ray levels observed, and a single C1.9 flare on April 11. Conditions rose slightly on the final day of the week, producing several low C‑class flares, the strongest of which was C2.4. Overall, active region 14409 was the most productive region, generating 11 C‑class flares and one impulsive M‑class flare. No earth-directed CMEs were detected during this period.

Yuri's Night and the International Day of Human Space Flight

Today is the 65th anniversary of first human space flight. On April 12, 1961, Soviet cosmonaut Yuri Gagarin orbited the Earth in the Vostok-1 spacecraft. Coincidentally, the first Space Shuttle mission was also launched on April 12, but in 1981, 20 years after the Gagarin's flight.

Space weather posed issues from the beginning of human space exploration resulting in failure of communication satellites due to radiation damage and electric discharges and loss of satellites due to enhanced atmospheric drag  (DOI: 10.1080/29979676.2024.2391688). GONG network provides critical observations for the operational space weather forecast issued by the NOAA's Space Weather Prediction Center (SWPC) and the prediction centers in other countries. 

Image shows a series of postage stamps issued in 2011 by the United Nations to commemorate 50 years of manned spaceflight. From left to right are the stamp depicting Yuri Gagarin's launch, an American astronaut on a ladder descending to the Moon's surface, the International Space Station, the Space Shuttle, and Soviet Soyuz spacecraft on its way to docking in orbit with the American Apollo spacecraft.

In 2011, the United Nations General Assembly designated April 12 as the International Day of Human flight. Yuri's Night is celebrated internationally since 2001.

GONG/LE is back on-line

Internet connection to GONG station at Learmonth, Australia was restored, and the observations taken on previous days are now flowing to NISP data center. Attached images show example of magnetograms taken on 7-10 April 2026. Status of GONG network can be checked at the Network Monitor site and the data could be accessed via the main NISP data website.

 

Three Decades of Global Oscillation Network Group (GONG): From Helioseismology to Magnetic Field and Space Weather (Invited Review)

A review article on GONG has been published in Solar Physics. It offers a rich historical perspective on the network’s three‑decade evolution, tracing its origins as a three‑year program focused on full‑disk helioseismic Doppler measurements to its current role as a major data source for space‑weather prediction. The article also outlines a forward‑looking discussion on the next major chapter: highlighting plans for the next‑generation network, ngGONG.  

This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits free access while restricting commercial use and modifications.

DOI: 10.1007/s11207-026-02639-9

GONG/ML Status

The temporary Mauna Loa Access Road was officially completed on March 26th. 

While the road is officially open, the official status of the Mauna Loa Observatory remains closed to the general public. Since the site will be an active construction zone for the next two years, NOAA staff will tightly schedule site access for mission-critical activities only to ensure personnel safety. All visitors require explicit authorization to access the site.

Regarding utilities, NOAA does not have a date for commercial power restoration, but is actively engaging with the local utility provider.

Contractors are now on site at MLO installing off-grid solar electric systems for NOAA and MLSO.

Photo: Ben Berkey, HAO/MLSO

 

GONG/LE Status

 Power has been restored to the GONG shelter, and observations are being taken. The GONG engineering & operations staff have been in contact with LSO staff, and are getting regular updates.

GONG Tool screenshot via WhatsApp (Detrick Branston & Brian Newcomb, 4/8/26).

 

 One of the two air conditioning units was damaged beyond repair. All of the control electronics soaked in water, fan cover and fan blades missing. A quote has been received for that work, and the replacement unit has been ordered.

A quote for the replacement of the shelter power disconnect enclosure and surge arrestor is pending. 

Email update 4/9/26: "Electricians have been at the observatory all this afternoon and most days this week testing and replacing water-affected electrical infrastructure in the RSTN (radio telescope) building through which all our comms passes. Once they clear that building for electrical power restoration, we can then turn our attention to the comms side. In addition to this issue (water through the RSTN building), we still have no fibre connection to the outside world. We are working with the BOM IT Support and the internet provider to try to diagnose and resolve this. It is possible that the fibre was damaged at the main road end, as a deep ditch was scoured out by the sea water and rain inundation (we couldn't even drive into the site). "

GONG data are stored on site. The workstation can retain up to 61 days of data. 

Solar Activity Report: March 30 - April 5, 2026

 Solar activity fluctuated sharply over the past week. The period opened at high levels on March 30 with a long‑duration X1.4 flare from active region 14405, located in the southeastern quadrant of the visible disk. Activity then dropped markedly on March 31, with the strongest event reaching only C1.5 before declining into the B‑class range. Conditions rose again on April 1 as multiple high‑intensity C‑class flares were recorded, the largest being a C8.1 event. From April 2 through April 4, activity remained at moderate to high levels, driven by several M‑class and numerous strong C‑class flares. The largest daily events were M3.5, M1.3, and M7.5 on April 2, 3, and 4, respectively. Activity decreased once more on April 5, with a C3.8 flare as the day’s peak.

In summary, April 4 stood out as the most active day of the week. Active region 14409 dominated the activity, producing six M‑class flares and roughly 50 C‑class flares. Several CMEs were detected by coronagraphs throughout the week, but none were assessed to have significant Earth‑directed impacts.

Helioseismic maps of the far side show several active regions currently present. One of them—an active region from the previous rotation—appears to have a high likelihood of returning to the visible hemisphere around April 11.

Major M1.0 X-class flare on April 4, 2026

 On April 4, 2026, a major X-class solar flare of M1.0 magnitude was observed at about 22:54 UT in active region NOAA 14409. The flare was recorded by GONG/Big Bear station using its Hydrogen H-alpha instrument. GONG/BB restarted its observations on the day of flare after been down for a preventive maintenance. Image shows the location of flaring region before (22:39 UT) and during the flare (23:02 UT, marked by thick black arrow). The active region continues exhibiting a complex magnetic configuration and new flux emergence, and thus, may produce additional flares. The observations can be access via GONG website.

 

GONG low duty cycle (updated on 4/4/2026)

GONG network is operating at a very low duty cycle (see plot attached) due to three adjacent stations  down: GONG/Mauna Loa - in aftermath of volcanic eruption, GONG/Big Bear - preventive maintenance trip, and GONG/Learmonth - damages in aftermath of the tropical cyclone (TC) Narelle.

The LE GONG station was shut down on March 25th in anticipation of the arrival of Tropical Cyclone Narelle. TC Narelle caused significant damage to Exmouth and Learmonth, but there is no damage to GONG/Learmonth station itself, except for one air-conditioning units, and some external access power panels. After the electrician inspection, the power to GONG was restored, and the instrument may have resumed observations. However, there is no internet access and thus, data are stored on the site. 

NISP engineering team are performing preventive maintenance work at GONG/Big Bear. It is expected that GONG/BB will be back to operations on 4/4/2026. UPDATED on 4/4/2026: The preventive maintenance was completed. GONG/Big Bear is back to full operations.

Primitive access road to Mauna Loa is completed, but access is still limited. NISP team plans visiting the site for the evaluation of restart activities after the commercial power to the site is restored.

GONG/LE Status

 The LE GONG station was shut down on March 25th in anticipation of the arrival of Tropical Cyclone Narelle. TC Narelle made landfall near Exmouth at approximately 8am on March 27th at a Category 4 level with wind speeds between 160–199 km/h. An electrician was able to visit the site, and power was restored to the shelter on April 2nd. We are awaiting word as to when the internet connection to the LSO will be restored.

 One of the first reports from the LSO staff reads:

"Unfortunately, the damage to Exmouth and Learmonth is significant. The road was closed for days due to flooding and the airport across the road is closed for the foreseeable future due to extensive damage to the terminal.

We were able to access the site for the first time yesterday (March 31st) and inspected the GONG shelter. The shelter and turret appear to be unscathed (no obvious wind damage or impacts) but one of the air-conditioner compressor units has been damaged.

The inside of the shelter was dry (hooray) so we attempted to repower, however the main circuit breaker tripped on both attempts. The metal box surrounding the main circuit board outside was blown open and bent at the hinge, and we suspect water may have gotten in behind it. It's also possible there is water in the light fixtures that may be tripping the circuit breakers.

We are also experiencing a site-wide internet outage, so no data flow is possible currently anyway. We are investigating with the network provider to find out what kind of infrastructure damage has occurred and ETA for return to service. We will keep you posted on this front too."

 

Does the Solar Tachocline Change with Solar Cycle

 A thin transition layer where the Sun’s rotation changes abruptly — the outer convection zone rotates differentially, while the inner radiative zone rotates almost like a solid body- is termed as the tachocline similar to the thermocline in oceanic dynamics.  This sharp shear is believed to generate the Sun’s strongest toroidal magnetic fields, which later rise to the surface as sunspots. The tachocline’s  sub-adiabatic stratification allows strong magnetic fields to be stored without immediately rising due to buoyancy. If the solar dynamo exists in the tachocline and generates the magnetic field of the Sun, one would expect solar-cycle related changes in the properties of the tachocline. 

A recent study using three decades of GONG observations reports a secular shift in the tachocline’s position at low latitudes. The analysis also indicates that the tachocline  has been gradually moving closer to the base of the convection zone, indicating that it may be related to the complexity of the solar magnetic field.  

This work is published in Astrophysical journal, 1000, 272 (1000) 2026 April 1. 

Latitude-dependent Time Variations of the Solar Tachocline - IOPscience