Archive for category EIT
SDO AIA and HMI images are currently lagging behing real time by about 18 – 22 hours. This is due to some necessary hardware upgrades in the processing pipeline that have interrupted the flow of images. The availability of LASCO, EIT, COR1, COR2, EUVI and SWAP images is unaffected by these hardware upgrades. We expect that the lag in SDO AIA and HMI images compared to real time will be caught up in the next few hours. We apologize for the interruption in availability of near real time AIA and HMI images.
Recent images from the LASCO, EIT, COR1/2 instruments are now available again. We will be filling in the missing images over the coming days. We apologize for the interruption in providing these images.
The most recent LASCO, EIT, COR1/2 and EUVI images are currently unavailable to Helioviewer Project browse clients. This is because the computer that converts the science data to JPEG 2000 images experienced a mechanical failure on Friday January 13th. We will replace the failed machine, and make an announcement via the blog concerning the resumption of the availability of images from LASCO, EIT, COR1/2 and EUVI. We are apologize for any inconvenience this may cause. Finally, images from AIA and HMI should be unaffected.
These videos show some of the larger scale effects of flares on the Sun. In the video, you can see two big eruptions approximately 10 and 17 seconds into the video, from the active region in the lower left.
But look more closely – can you see a wave of coming out of each of these explosions? They are faint, and can be difficult to see, but they are there. These are examples of EIT waves, so called because they were first seen in the SOHO-EIT instrument. These waves are thought to be examples of magnetohydrodynamic waves that propagate in the corona. They are truly large waves; for comparison, the radius of the Earth is about 1/100th that of the Sun. By studying these waves we can learn more about the structure and properties of the solar corona. There is also some evidence that these waves have ‘knock-on’ effects on other parts of the Sun, perhaps causing other events at parts distant from the original explosion. Look at the video – what do you think?
Around 2010/10/29-30 the SOHO spacecraft changed flight operations so it is no longer constantly aligned with the rotation axis of the Sun. SOHO now points to ecliptic north, which makes an approximate seven degree angle with the equator of the Sun. SOHO will still flip 180 degrees in order to maintain optimal communication with the Earth, but the rotation will now flip the spacecraft relative to ecliptic north. The raw image data that SOHO takes therefore shows the new orientation. At the Helioviewer Project, we rotate the data so that solar north is towards the top of your screen and the rotation axis of the Sun is vertical (i.e., parallel to the left and right hand side of a rectangular screen). Our science data processing software – JP2Gen – now takes account of the new rotation of SOHO and rotates SOHO science data appropriately. This is done to maintain homogeneity with the existing images we already provide, and makes it easy to compare images from multiple telescopes.