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STORM SIGNALS

From Satellites: RHESSI Images

Live Data

RHESSI Images

A complete list of real-time data links is located in the Space Weather Resources section.

RHESSI images are particularly useful because this resource only contains images of flares! By browsing for images from a particular day you can determine when a flare occurred and where on the Sun the flare was.
Caution: flares can occur when RHESSI is out of position to capture images. See RHESSI Light Curves for a discussion of these special times.

Knowing where a flare was serves two purposes. You can check your prediction that a particular sunspot region would be the location of a solar storm. You can also use the location of a flare to help you predict whether the storm might affect Earth.

The Wrath of Ra is a great interactive game at the Space Weather Center that will show you how the location of a flare or coronal mass ejection makes a difference in the effect on Earth.

When you connect to RHESSI Images you will see a page like the one below.

Screen Shot of RHESSI Quick Look images

Navigation

Click on the year and month you want to examine.
Click on the day of the month in the column numbered 1 - 30 or 31.
The outside arrows at the top allow you to choose previous day (back arrow) or the next day (forward arrow).
The inner arrows allow you to choose the next flare (forward arrow) or the previous flare (back arrow).
Click on the arrows until you get the flare you want.
Just above the image is a pull-down menu. Set the menu to "Full Sun (6 - 25 keV)"

Interpreting the Image

The colored bar across the top indicates what the colors in the image represent, which is essentially the intensity of the x-ray emission: yellow colors indicate more x-ray intensity than orange, etc.
The coordinate system on the axes is angle on the sky in units of arcseconds (1 arcsecond is 1/3600 of a degree). The center of the Sun is the origin of the coordinate system. (If you check some of the other image options available in the pull-down menu, you will see a curved white line running through it. That represents the edge of the Sun, or its limb as scientists call it.)
The first line of text inside the plot gives the date and time (Universal Time) of the observation.
The second line tells which detectors aboard the spacecraft were used, but you don't need to know that.
The third line gives the energy range of light represented in the image. The units of energy given are in kilo-electronvolts (keV). The other information are technical details that are not likely to be useful for your research.
The image above shows a bright spot just left of center of the Sun. That is the flare. The rings of red and blue or purple around the bright spot are due to the way the x-rays from the flare interact with the detector and should be ignored. You will often see these as complete rings or arches. What you are looking for is the location of the brightest spot on the image.

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