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Solar Cycle 24

SOHO main page
SOHO latest update
Solar Terrestrial Activity Report
See also:
SARL interest items page
Solar Physics
( NASA )
N6RT Propagation Page
Ionogram Images from Rhodes University 

Information on the behaviour of the sun
is always of great interest to radio amateurs.  Here we provide some useful information regarding the sun, and some links to useful pages on the web.

Solar Cycle 24

The graph below illustrates the performance of Solar Cycle 24. For more information visit the Solar Physics page at NASA. 

Record of Solar Activity over time.

Click here for sunspot number graphs since 1750!

Solar picture on the Home Page

The small picture on the Home Page is taken live from the Current Solar Images page on the NASA website. ( ). This page is updated automatically every few hours, and shows mini-views of the sun obtained from various different sources.  The first few pictures on this page are obtained from the SOHO satellite, the SOlar and Heliospheric Observatory.  Refer to page for more information on this fascinating resource. Clicking on any of the small images on this page will download a larger version of the picture.

These images are provided by courtesy of The SOHO EIT Consortium; SOHO is a joint ESA-NASA program.

Occasionally there will be no image, but the word "Bakeout" will appear in its place. The following explanation is from Joe Gurman, Facility Scientist at SDAC, the Solar Data Analysis Center, who maintains the web site:

The CCD (backside-thinned, EUV-sensitive) detector on EIT requires baking out (raising operating temperature from its normal, ~ -67 C, to ~ +16 C) in order to "cure" throughput losses in the detector caused by the very EUV photons we want to image. Normally, we perform bakeouts ~ every 4 months. We perform an exhaustive series of tests and calibrations before and after each bakeout.

Interestingly,  the environment at L1 is much more benign than low earth orbit (LEO) or geosynchronous orbit (GO). In LEO, spacecraft pass in and out of the lowest parts of the Van Allen belts (the "South Atlantic Anomaly" is the largest) nearly every orbit, and if in polar or near-polar orbit, can get a concentrated dose of SEP's if a proton event occurs --- such events last at least as long in the earth's magnetosphere as they do at L1, and often longer, as the magnetosphere relaxes. GO's get two different whammies: the geotail when on the nightside, and, during major solar storms, the compression of the magnetosphere leaves the GO satellites open to the full proton fluence. GO satellites in particular run the risk of passing through magnetosheath current surfaces and can be seriously damaged by "charging up." Cf. the Telstar 401 satellite lost in 1997 January.

SEP's are also a danger for SOHO, both in single-event upsets to the electronics (most of which can be dealt with in software or hardware), as are micrometeorites, but both are relatively low probability events (though we've had both already). In general, the lack of day-night thermal cycling is much more important for the survivability of the spacecraft than any of the above.

Solar Terrestrial Activity Report

This extremely useful page ( ) is maintained by Jan Alvestad, webmaster of the Norway DX-Listeners' Club.  It contains a graph which is updated daily, showing the Sunspot Number, the Solar Flux, and the Planetary A-Index for the last two months.

Notes are also provided on Solar activity which may give rise to geo-effective conditions, and predictions of expected solar activity.

Live Solar report
Updated every 10 min

Solar X-rays:

Geomagnetic Field:

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This page last modified: 26/4/2018