Friday, November 14, 2014
Wednesday, November 12, 2014
Tuesday, November 11, 2014
Active Region 12192, which was the location of 6 X-class and several M-class flares in late October, is coming back for an encore. Here is a movie of the Sun showing the magnetic field on the side facing the Earth and the farside image from HMI data. It shows the part of the Sun containing AR 12192 rotating back into view, with a large magnetic feature still there.
These composite maps of the Sun’s farside (in yellow) and the line-of-sight magnetic field (blue) show NOAA AR12192 as a bight-dark magnetic feature rotating out of view over the west limb at the beginning, passing the far-side meridian in the middle as a dark area, and approaching the east limb at the end. The farside information is shown as the travel time change in the echo produced by a strong magnetic region.
This farside images allow us to track magnetic features where SDO cannot see. They have been compared with the full-Sun images we make by combining SDO and STEREO images. When AR 12192 returns it will have a new number but we hope it will be just as active.
Many thanks to the HMI team for producing these images and movies. They are available at JSOC.
Friday, November 7, 2014
Wednesday, November 5, 2014
Update 11/6/2014 1447 UTC (9:47 am ET): The fiber optics provider has found the break, dug it up, and should be splicing the fiber links soon. I do not know how long each fiber takes to splice or how many fibers are in this bundle, so there is no estimate at this time when we will return to service.
Friday, October 31, 2014
Monday, October 27, 2014
I downloaded the active region dataset produced by David Hathaway at Marshall SFC and looked at the largest active regions since 1874. This area data comes from the photographs taken at the Royal Greenwich Observatory until 1976 and various sources after that. I checked the list against the tables in Sunspot and Geomagnetic-Storm Data by Sir H. Spencer Jones just to make sure. I also added two regions from 2014 (AR 12192, of course, and AR 11967). Areas of active regions are measured in micro-hems (millionths of a solar hemisphere, where 1 micro-hem is about 1.54 million sq km.)
The yearly Sunspot Number is drawn as a red line. This allows you compare how the maximum area of active regions changes with the number of active regions. It was surprising that the largest active regions are not in Solar Cycle 19, which has the largest amplitude in Sunspot Number, but in Solar Cycle 18. The top 5 active regions appeared between 1946 and 1951. Solar Cycle 19 started in 1954. The next set of large active regions have areas of 3000-4000 micro-hems and are spread across many sunspot cycles.
How big was the active region that was the site of the Carrington Flare? It was 2300 micro-hems, not even in the top 50! You can look it up on p. 102 of the table by Jones. The flare on 1-Sep-1859 has been estimated at X35, showing that large flares can come from medium-sized active regions.
So long for now to AR 12192 but perhaps we will see you next rotation!