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Images of the Sun taken by the
Transition Region and Coronal Explorer

The TRACE images may be used without restrictions in publications of any kind. We appreciate an acknowledgement indicating that the Transition Region and Coronal Explorer, TRACE, is a mission of the Stanford-Lockheed Institute for Space Research, and part of the NASA Small Explorer program. More information on TRACE and other TRACE images can be found here.
Pre eclipse: 2006/03/29 1600Å
eclipse: 2006/03/29 1600Å> eclipse: 2006/03/29 1600Å

Eclipse: 29 March 2006

These images were taken by TRACE in its ultraviolet 1600Å passband around 08:04 UT on 29 March 2006 with 30s between exposures. It shows the Moon moving onto the solar disk, coming from the North and moving South. Seen on Earth, the Moon moves mostly from West to East, but because TRACE was moving from pole to pole in its orbit around Earth - compare this image showing the position of the Moon seen from TRACE in five minute intervals. (TRACE images courtesy of Dawn Myers, GSFC; the path of the Moon seen from TRACE, courtesy of Bart De Pontieu, LMSAL).
For another space view of the eclipse,including a view of the shadow on the Earth, have a look at images taken from the NASA Space Station.
3EUV full-disk mosaic 1999/07/30

The big picture I

TRACE's field of view covers only a fraction of the entire Sun, but by repeatedly repointing, it can create an image of the entire solar corona. This image shows the solar corona on 1999/07/30 in a false-color, 3-layer composite: the blue, green, and red channels show the 171Å, 195Å, and 284Å, respectively (most sensitive to emission from 1, 1.5, and 2 million degree gases).

The image (rescaled to 1500 by 1500 pixels to a side) shows the corona for a moderately active Sun, with some (red) hot active regions in both hemispheres, surrounded by the (blue/green) cooler plasma of the quiet-Sun corona. Notice also the north polar-crown filament, the trans-equatorial loops, and the coronal hole in the south-east (lower-right) corner of the image and the smaller one over the north pole.

P.S. There is also a 6.9MB 4500x4500 pixel version of this image. For those interested in an annotated list of all 3EUV mosaics made by TRACE prior to 2006, click here.

Astronomy Picture of the Day for 10 July 2006.

Filament eruption in AR10856 in 171Å
This QuickTime movie (20MB) shows a filament activation and B2 flare, at roughly 1-min. cadence, from 2006/03/07 14:24 UT through 21:50 UT, observed by TRACE in its 171Å channel. The region starts out looking very quiescent, although its non-potentiality (pointed out in this earlier entry) is clearly discernable in the arc of loops from the leading to following polarity that is nearly perpendicular to the high-arching loops emanating from the region's central domain. Then a filament-like field configuration is activated, running to the bottom-left from the active region, and seems to roll and unwrap in the process. As the arc of nonpotential loops begins to move upward, weak flare ribbons form under the activated filament-like field, followed by the formation of post-flare loop arcades. Towards the end of the movie, the region looks to be largely potential, so we expect no further substantial activity from it. Note the dimming of much of the corona towards the lower left of the active region as the eruption progresses. The field of view is 960x720 pixels (scaled down by a factor of 1.5 to a 640x480 movie).
AR10856 in 171Å
With the Sun in its cycle minimum, there was only one substantial active region on the disk on 2006 March 6. This image shows AR10856, a region of average size, already breaking up, and ready to disperse its magnetic field across the solar surface. Yet, this tired old region remains interesting. The TRACE 171Å images show pronounced loop systems emanating from the main field concentrations in the leading and following polarities ... but without any sign of sunspots or pores in the SOHO/MDI visible-light image. The region also appears to carry strong electrical currents, or at least so we think because of the nearly perpendicular loops systems that we see just below the center of the 768x768 pixel (375km each) field of view. And a movie of this active region over several days reveals pronounced ongoing waves propagating up into the corona along the strong-field loop systems over the leading and following polarities. Where do all these loops go that leave the small field of view? See the TRACE 171Å full-disk mosaic.
More to come
TRACE can observe the corona in three separate coronal pass bands: the 171Å (1MK; shown in yellow), 195Å (1.5MK; green), and 284Å (2MK; red). This composite image shows three such sets, each composed of relatively long exposures (ranging from 20 to 260 seconds, longest for the 284Å channel). At the top (images 1,2,3) we see the solar south polar region, with a filament running diagonally through the image and with an active region just at the upper edge of the field of view. The central row (4,5,6) sows a region near the center of the disk, again with a filament and a compact active region, surrounded by quiet Sun. The bottom row (7,8,9) shows a very quiet region with strands of filaments, long loops, and compact ephemeral regions. The intensities in each have been scaled logarithmically to cover the large dynamic range in these exposures. The original images are all 1024 by 1024 pixels of 375 km to a side; these can be accessed here: 1, 2, 3, 4, 5, 6, 7, 8, 9 (note that the exposure dates and times are contained in the names of the files). Comparing these images shows many differences reflecting both the field geometry and the thermal structure of the quiescent corona.
Spot/pore group evolution, in WL, 2006/01/16 12:58UT
This 5-day QuickTime movie (0.5MB), taken in the visible-light (WL) channel (2006/01/15 04:56UT - 2006/01/20 19:32UT), shows the evolution of a small spot group from emergence to decay. The movie starts as TRACE observed the first signs of magnetic-field emergence and pore formation. As time proceeds, pores form groups and migrate and regroup, eventually forming a small leading sunspot (with penumbra) early on January 17. But shortly after it forms, it begins to disintegrate, and fades into the faculae (increasingly visible as the region approaches the solar limb) by the middle of January 19. The trailing pore cluster never forms a real sunspot, and fades into the facular field about a day later.
AR10826 in 171Å
This TRACE 171Å image, taken on 2005/12/07 at 02:37 UT, shows Active Region 10826 ahead of a much smaller neighbor as it approaches the western solar limb. Among the many loops that arch over AR10826, some on the righthand, leading side of the region stand out because they are dark rather than bright. These structures persist for days, although they do evolve so that it is hard to say if from one hour to the next we are looking at the same magnetic structures or whether new adjacent fields have taken on their properties. As we see no indications of material flowing along the loops, we take them to be dark because they are virtually empty, not because cool absorbing material flows along them. What makes the especially interesting, is that we can trace them from near the solar surface to their apex and perhaps beyond, and we can see them expand with height. This is an interesting contrast with the bright loops that have been measured to have nearly constant cross sections along their lengths. These dark loops may help us understand why the bright loops do not expand with height even though we would expect them to.
AR at limb in 171Å
This image, taken by TRACE on 21 September 2005, at 03:27 UT, shows bright, high active region loops above the solar limb. With the active region rotated off the visible hemispere of the Sun, only the high-arching coronal loops remain visible.Seen in projection against that, is a filament that trails the active region. In this image, several thin, dark strands are seen; these are filled with relatively cool material that absorbs the extreme ultraviolet emission from the bright loops behind the filament. The material can be seen to be in continual motion. The entire filament destabilizes in a flare-like eruption just over an hour after this picture was taken, but things settle back again and the filament lives on.
TRACE movies:
Large files:
QT files

DVD img files

Short (POD) movies: PODs
POD listing

200+ GigaBytes of TRACE movies in QuickTime or DVD format

Since its launch in 1998, the Transition-Region and Coronal Explorer, TRACE, has taken over 17 million images of the Sun (as of October 2005). A selection of these images has found its way into a widely diverse set of publications, ranging from scientific studies to the printed newsmedia (and over 200 have been discussed on the TRACE home pages at http://trace.lmsal.com). Images sequences have an even greater power to surprise and enchant, as illustrated in the selection of movies on the TRACE web site. These movies were necessarily short and small, however, to allow easy downloads onto a variety of platforms.

The TRACE team is pleased to announce the completion of three TRACE DVDs that together contain almost 400 movies of a variety of phenomena. They are arranged into three themes: active regions, flares, and filaments (with a few quiet-Sun bonus movies on-line only). The individual movie files are available on-line as QuickTime movies. Altogether, the movies claim over 200 GB of disk space, with individual file sizes ranging from a few MB up to 4 GB. The DVD img files (1.5-3.6 GB) are also available on-line; these may be downloaded and played, or burned onto DVD, using machines that are capable of DVD playing and writing (a fourth DVD img file contains SOHO/MDI magnetograms from launch until 2005); the DVDs show all TRACE movies in the collection, sorted by topic and date, with all materials rescaled to the available screen size of 640x480 pixels; the QT movies often show a substantial field of view with more pixels.

The movies on the DVD set were compiled and produced by Alan Title, the Principal Investigator of TRACE.

Filament forming
Late on 13 April 2000, TRACE observed a curious event, which we interpret as a filament formation (the magnetic environment is shown in the MDI magnetogram cutout above). The QuickTime (JPEG compressed) movie (3.8MB) shows a 10 hour time interval with TRACE images at about 5 min. spacing (there are many more, but the movie file would have been very large had they all been included here). Notice how a dark intrusion forms at the bottom center of the field of view. We had a hard time differentiating between two possible interpretations of the darkening: it could be an absence of emission possibly as a result of a field reconfiguration (perhaps the formation of the footprint of a newly formed coronal hole), or it could be the formation of an absorbing structure known as a filament. We decided a filament formed because of the appearance in TRACE 171Å, because the YOHKOH/SXT image gave no hint of a coronal hole forming, and because of the dynamics of the event. In case you want to compare images from these various instruments, read on:

How to compare TRACE images with MDI, SXT, or a field model:

Comparisons with other instruments and with field models for all of the TRACE pointings are available in two different sets of web pages. First, there are summary pages for every day of TRACE observing with images of each of the observed regions in 171Å or 195&ARing;, if available. These can be accessed by typing a day into the top-left search field on this web page, or by clicking on 'TRACEview' on the lefthand side of this web page.
Alternatively, you can look at the 'Active Region web pages' at http://www.lmsal.com/ar/. These enable a quick-look comparison of EUV, UV, and WL images taken by TRACE (171Å, 1600Å, and the 'white light' channel), coronal images taken by Yohkoh/SXT, and magnetograms by SOHO/MDI of all NOAA active regions observed by TRACE since its launch in April 1998. A user interface allows searching for an active region by NOAA number or by date.
Each active region has one or more web-pages associated with it. In case observations are available, there usually is a page with TRACE 171Å, SXT, MDI, TRACE WL and TRACE 1600Å images centered as close as possible on the active region for the day closest to disk center passage. If more observations are available, there are also pages for other days before and after disk center passage of the AR.
On each of these pages, you can "blink" images of various wavelengths and days. For example, you can study how the TRACE 171Å appearance of an active region changes as it passes from the east limb to the west limb. Or you can study how the TRACE 171Å and Yohkoh/SXT images compare on one given day (or multiple days). This is done by clicking "blink", and then selecting which wavelengths and/or days you would like to blink. You can change how fast things blink by changing the "Time Interval (in sec)".
Another feature is that you can overlay coronal potential field extrapolations (based on Schrijver & DeRosa's pfss) on top of all images, and once again blink them. This is done by clicking on the "with fields" button on the upper left (below the search bar) of the page.
For example, for AR8948, data are available around midnight (UT) on 14-Apr-2000 that show the images by themselves (TRACE/171, SXT, MDI, TRACE/WL, TRACE/1600) or with the potential-field overlays (TRACE/171, SXT, TRACE/WL, TRACE/WL, TRACE/1600). These can be accessed from the active region page of that day: http://www.lmsal.com/ar/ARpages/8948_14-APR-00.html.
An easy way to compare these images is to "blink" them. Try, for example, http://www.lmsal.com/ar/blink/dayblink/8948.html. The link on that sends you to a page with all the data that is available for that active region. Whether it will show images with the field or without the field extrapolations will depend on the "cookie" that is set when you click on the "blink button" at the active-region home page.

Other TRACE images in this collection:
Set 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26.

See also a collection of images related to the Sun, other cool stars, and solar-terrestrial effects


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