Does the Shutdown of a Single Site Affect the GONG Network Duty Cycle?

The duty cycle measures how many observations are available over a given period. For GONG, it generally represents the fraction of observations obtained during a single day. The six GONG sites distributed across the northern and southern hemispheres were selected to ensure that at least two sites observe at any given time, with no interruption to the observations during the non-observing period of one site. Their locations were carefully chosen based on long‑term weather patterns and year‑round sunlight availability. A detailed study of the duty cycle for individual GONG sites and for the full network clearly demonstrates that the network duty cycle is adversely affected by the shutdown of a particular site only when adjacent sites also lack observations.

For example, the Udaipur (UD) site was turned off on July 8 due to the Indian monsoon. The gap in the network observations on this day (marked in the left figure) is not caused solely by the shutdown of UD - it occurred because the adjacent El Teide (TD) site during the overlapping periods with LE and UD on the same day was down due to a technical issue. Once that issue was resolved the following day, the network duty cycle returned to its usual high value and has remained stable. 

The figure below reinforces this point: on July 7 and 9, both TD (green oval) and Learmonth (LE marked by the red oval) provided observations, and no comparable gap appeared in the window function despite UD being offline. The absence of UD observations is indicated by the brown ovals for July 7 - 9, while the brief overlap between LE and TD on July 7 and 9 (shown by the gray shaded bars) ensued continuity to the observations. Provided TD and LE remain operational, no major duty‑cycle impact is expected during the UD monsoon shutdown.

It is important to note, as mentioned previously, that the Mauna Loa (ML) site in Hawaii has been offline since late November 2022 due to a volcanic eruption, and efforts are ongoing to restore operations. There have been periods when the network duty cycle has dipped for the reasons described above, including weather‑related or technical issues. Even when high duty cycle values can be achieved with fewer observing sites, full operation of all six sites remains essential for the precise determination of the p‑angle (the angle that defines the true solar north in the images) which is critical for measuring subsurface flows using helioseismic methods.  Moreover, a network with a reduced number of operational sites is inherently more vulnerable to lower duty cycle performance over the course of the year.

GONG/Udaipur is down for monsoon

The monsoon has arrived in Udaipur, India for the 2026 season. Consequent;y, GONG station in Udaipur  (GONG/UD) has initiated its seasonal monsoon shutdown. On July 8, at 14:05 UT, the GONG/UD preventive maintenance (PM) flag was officially set to reflect that the station is in its monsoon season shutdown.

Solar Activity Report: June 29 - July 5, 2026

 Solar activity ranged from moderate to high throughout the reporting period. Multiple C‑ and M‑class flares occurred each day, along with two X‑class flares on separate days. In total, 42 M‑class flares were recorded, majority of them originating from active regions 14475, 14478, 14479, and 14480, which produced 3, 5, 30, and 4 M‑class flares, respectively.

An M1.4 flare from active region 14479 was the strongest event on June 29. Activity reached high levels on June 30 with an X1.1 flare from the same region and an M5.8 flare from active region 14475. A sustained sequence of M‑class flares kept activity high on July 1, most of them from region 14479; its largest event was an M3.5 flare, accompanied by several high‑intensity C‑class flares. Region 14478 also produced an M8.5 flare following C‑class activity.

Activity remained moderate on July 2, with several M‑class flares from regions 14479 and 14480; the strongest was an M4.2 flare from region 14479. Moderate activity continued on July 3 due to flaring from regions 14478 and 14479. Region 14479 produced an M6.7 flare from the northern hemisphere, followed shortly by an M6.3 flare from region 14478 in the southern hemisphere.

Solar activity rose to high levels again on July 4, with more than ten M‑class flares and one X‑class flare. The X1.3 event originated near the southeast limb from active region 14482 as it rotated toward the Earth‑facing side. High activity persisted on July 5, with nine M‑class flares; the largest was an M5.3 flare from region 14479.

Region 14478 was the largest active region during this period. All major flare‑producing regions are now approaching or crossing the west limb, leaving the Earth‑facing side less active. Several CMEs were observed, some producing glancing impacts on Earth.

The latest helioseismic map of the far hemisphere shows several active regions, some of which remain roughly two weeks away from rotating into Earth view, provided their magnetic signatures persist. A moderate‑sized region near the equator in the southern hemisphere is expected to reach the east limb around July 12. Collectively, these regions may contribute to elevated activity on the far side that will be hidden from direct observations.

The IEEE BigData Cup 2026

Segmentation of solar filaments using GONG H-alpha observations was selected by the Institute of Electrical and Electronics Engineers (IEEE) for their (IEEE) Big Data Cup 2026 as one of seven Data Challenges at the Frontier of AI, Science & Society. The challenge is to produce pixel-precise segmentations of solar filaments in full-disk H-Alpha images — capturing fine structures (barbs), separating faint material from ground-based noise, and detecting each filament as one coherent object. Any method is welcome, from classical image processing to deep neural networks.

 

For more information and to enter, see Azim Ahmadzadeh, Dustin J. Kempton, Qin Li, and Alexei A. Pevtsov. Solar Filament Segmentation Challenge 2026. https://kaggle.com/competitions/filament-segmentation-2026, 2026. Kaggle. 

Solar Activity Report: June 22 - 28, 2026

 Solar activity remained at low levels during the past week. The X‑ray flux stayed mostly in the B range from June 22 through midday on June 23, after which it rose to the C level and remained there for the rest of the week. Numerous C‑class flares were produced by multiple active regions throughout the period. The strongest events observed from Monday through Sunday were C1.5, C8.7, C3.8, C6.6, C5.7, a long‑duration double‑peak C7.4, and C9.5, respectively.  The largest active region on the disk was AR 14478 in the southern hemisphere, which, along with AR 14475, also located in the southern hemisphere, was responsible for most of the week’s flaring activity. Multiple CMEs were also observed in coronagraph imagery during this period, a couple of them likely contained Earth‑directed components. The first CME is expected to arrive at Earth between 29 - 30 June, with a second CME around 1 July. No additional Earth‑directed CMEs were identified. 

  Helioseismic maps of the far side show no significant active regions likely to rotate into Earth view in the next few days.  

 

GONG data processing update

Processing of the network-merged daily velocity and magnetogram images,  p-mode-coefficient time series, and ring-diagram analysis products for GONG month 314,  and  the  p-mode frequency data products for central GONG month 313 is completed and the data products are now available.

The largest sunspot group of 2026

Sunspot group 14478 observed today (June 28, 2026) East of solar central meridian has a total area of 1190 Millionth of Solar Hemisphere (MSH). This makes it the largest sunspot group of this year. Attached image from GONG Learmonth station in Western Australia shows this group with two large sunspots on the left side of the solar disk. While this is a large sunspot group, it is not a record-breaking one. The largest sunspot group was observed in April 1947. The sunspot drawing from the Mount Wilson Observatory in California provides example of that monstrous sunspot group on 7 April 1947. The drawing is scaled to match the size of GONG image (circle corresponds to the same disk size as GONG). The area of that group was 7400 MSH, or about 6.2 times of AR14478. Sunspot group areas approximately scale as the total magnetic flux of an active region. Groups with larger areas have more potential for producing solar flares and coronal mass ejections. In comparison, in March 1989, an active region with the total area of 2400 MSH produced a very powerful flare and CME. The eruption caused one of the strongest geomagnetic storms, which resulted in a nine-hour outage of Hydro-Québec's electric transmission system in Canada. The Carrington event (1-2 September 1859) was associated with an active region of 2300 MSH in size. However, not all large sunspot groups produce strong eruptions. So far, AR14478 showed only a few moderate C-class flares.