How TRACE Images the Sun

TRACE takes images using a digital camera. The area of the Sun which TRACE can take images of are circles with a radius of 256 arcseconds. These become images with a maximum size of 1024x1024 pixels. That means that TRACE can resolve structures with a size as small as 0.5 arcseconds.


A full disk mosaic of the Sun taken using the Fe XII filter on TRACE on 4th January 1999

But if the radius of the images is 256 arcseconds and the radius of the Sun is about 960 arcseconds,

When making a full disk mosaic, TRACE uses 22 images to cover the Sun completely. The pattern it uses is shown to the right, the small circles show where the TRACE images are taken, the large dashed circle represents the Sun and the even larger dotted circle shows the extra edge of the Sun that the scientists would like to get as well.

TRACE can look at the Sun in different wavelengths, in a similar way that we can see different colours. If we put a red filter (some transparent red plastic for example) in front of our eyes, we see only the red parts of what we are looking at. TRACE uses different filters to see different wave bands including normal light and ultraviolet light.

Each different wavelength band looks at different temperature ranges in the Sun. Using different bands we can see how hot different parts of the Sun are.

Find out about the different wavebands that TRACE uses by using the table below.

Wavelength: 5000 AngstromsWidth: Broad
Filter: White LightTemperature: 4,000-6,400 Kelvin
This filter images the photosphere of the Sun. It includes the wave bands that we can see in, ie normal light. The image shows a sunspot which occured on 18th June 1998.
Wavelength: 1700 AngstromsWidth: 200 Angstroms
Filter: BroadTemperature: 4,000-10,000 Kelvin
This filter images the chromosphere in ultraviolet light. This is region of the solar atmosphere which is the coolest, it is also the lowest level of the atmosphere.
Wavelength: 1600 AngstromsWidth: 275 Angstroms
Filter: CI, FeIITemperature: 4,000-10,000 Kelvin
This filter images the chromosphere in ultraviolet light. This is region of the solar atmosphere which is the coolest, it is also the lowest level of the atmosphere.
Wavelength: 1550 AngstromsWidth: 20 Angstroms
Filter: CIVTemperature: 60,000-250,000 Kelvin
This filter images the transition region. The image above was taken at the same time as the sunspot in the white light image, the activity around the sunspot can be seen.
Wavelength: 1216 AngstromsWidth: 84 Angstroms
Filter: HI Lyman AlphaTemperature: 10,000-30,000 Kelvin
This filter images the upper part of the chromosphere. The image was taken at the same time as the sunspot in the white light image, the activity around the sunspot can be seen.
Wavelength: 171 AngstromsWidth: 6.4 Angstroms
Filter: FeIXTemperature: 160,000-2,000,000 Kelvin
This filter is the first of the extreme ultraviolet light (EUV) bands. it images the corona, and low underlying plasma structures can be seen.
Wavelength: 195 AngstromsWidth: 6.5 Angstroms
Filter: FeXIITemperature: 500,000-2,000,400 Kelvin
This filter images the corona in an extreme ultraviolet light (EUV) band. This is one of the more commonly used filters and can see a good range of plasma structures in the corona.
Wavelength: 284 AngstromsWidth: 10.7 Angstroms
Filter: FeXVTemperature: 1,250,000-4,000,000 Kelvin
This filter images the corona in an extreme ultraviolet light (EUV) band. This band picks out the hottest coronal structures and can resolve features that the other EUV bands (171, 185 Angstroms) can only see as a hot blur.

What next? Well you can look in the TRACE gallery or at some TRACE movies, or if you have internet access you can visit the TRACE homepage where you will find more information, images and movies.

Look in the TRACE gallery
See some TRACE movies
Visit the TRACE homepage (external link)
Go back to Solar Explorers page