Yohkoh (“Sunshine”) was launched in August 30, 1991, from the Kagoshima Space Center (Uchinoura) in Japan, and was a project of the Japanese Institute of Space and Astronautical Science (ISAS). The scientific objective was to observe the energetic phenomena taking place on the Sun, specifically solar flares in x-ray and gamma-ray emissions.

Yohkoh carried four instruments to detect energetic emissions from the Sun: the Soft X-Ray Telescope (SXT), the Hard X-Ray Telescope (HXT), the Bragg Crystal Spectrometer (BCS) and the Wide Band Spectrometer (WBS). A team from the United States collaborated on SXT, and teams from the United States and the United Kingdom collaborated on BCS.

SXT imaged X-rays in the 0.25 – 4.0 keV range. SXT used thin metallic filters to acquire images in restricted portions of the energy range. We are making images from the thin aluminium filter (thin-Al), and the aluminium-magnesium-manganese filter (AlMgMn) available. White-light images are also available up until November 1992. An example thin-aluminium image is shown below.

SXT could resolve features down to 2.5 arc seconds in size. Information about the temperature and density of the plasma emitting the observed x-rays was obtained by comparing images acquired with the different filters. Flare images could be obtained every 2 seconds. Smaller images with a single filter could be obtained as frequently as once every 0.5 seconds.

Yohkoh ceased operations on December 14, 2001. The SXT images we are making available cover portions of Solar Cycles 22 and 23 (we are currently somewhere close to the maximum of Solar Cyce 24). This historical data allows us to compare current solar behavior to previous solar behavior. Such studies allow us to better understand how the Sun operates on timescales of decades and longer.

Yohkoh SXT images are the first images of soft X-ray data available on helioviewer.org. We hope you enjoy examining this different view of the Sun on helioviewer.org.

JHelioviewer, in collaboration with the start-up company Luxunda, and SunPy have been selected as mentoring organizations, and students are encouraged to apply until 27 July 2012 (11 am UTC).

The new movie export menu makes it easier to set the exact scaling of the area you are interested in, and the processing itself is now performed on the graphics card using OpenGL:

The SDO Cutout Service plug-in allows you to request science-quality image data from the SDO/AIA and HMI instruments for the region of interest and time range selected in JHelioviewer:

Support has been added for embedding Helioviewer.org into third-party websites, and JSONP support makes it easier for new versions of the front-end to be created which interact with the main Helioviewer.org back-end. Similarly, the front-end has been rewritten to allow for easier creation of custom front-end clients without having to re-implement a tiling system, etc.

The back-end movie queuing system has been ported from Ruby to PHP to allow for better integration with the rest of the back-end, and the movies table structure has been modified for improved time estimation and similarity searching. Additional options (frame-rate and movie length) are offered to allow users further control over the movies they create and the duration option has been moved to a more obvious location.

Let us know what you think, or if you have any suggestions. Feedback is always welcome.

RELEASE NOTES:

Helioviewer.2.3.0 includes several new features to give users more control over how the site behaves. Let us know what you think, or if you have any suggestions. Feedback is always welcome.

New features:

* JSONP support
* Added option display date from last visit when returning to Helioviewer.org
* Added setting to automatically update images every 5 minutes
* Added support for embedding Helioviewer.org in other websites
* Added support for specifying frame-rate or duration during movie creation
* Added support for PROBA-2 SWAP data
* Created an installer diagnostic script
* Added support for tracking custom events in Google Analytics
* Movie and screenshot selection rectangle preserved during visit
* Data availability information included in getDateSources response

Bug fixes:

* Fixed bug #691356 JPX Summary file does not exist
* Fixed bug #783497 Port Helioqueuer to PHP
* Fixed bug #903360 Error occurs for certain layer orders when attempting to create AIA/LASCO
* Fixed bug #925542 The minimum width of the display window is too big
* Fixed bug #624857 After clicking “clear history” unfinished requests are still processed, and download links displayed
* Fixed bug #885795 Add image attribution to about dialog
* Fixed bug #888269 Attempt to normalize movie frame-rate instead of duration when possible
* Fixed bug #909795 Normalize date strings for API requests
* Fixed bug #909897 Mark movies that have not finished in less than x hours as Error
* Fixed bug #930628 Improve movie creation time estimation
* Fixed bug #942547 Validate value for dsun before attempting to process in front-side
* Fixed bug #609219 API should return an error message when an invalid parameter is specified in a request
* Fixed bug #783481 Report mouse coordinates immediately upon activation
* Fixed bug #787744 Add a checkSettings method to the UserSettings class to verify user settings integrity
* Fixed bug #876707 Included creation_time in FFmpeg metadata for mp4/webm movies
* Fixed bug #789515 Reduce filesize of WebM movies

Library updates:

* Flowplayer (3.2.7 => 3.2.8)
* jQuery (1.7.0 => 1.7.2)
* jQuery UI (1.8.16 => 1.8.18)
* jQuery.JSON (2.2 => 2.3)
* jQuery imgAreaSelect (0.9.5 => 0.9.8)

In the future we will try and take measures to keep this from happening again. The last couple of days have made us look at the services we provide in a whole new way, thanks to the huge interest from you, our users, and we are grateful for that. We are constrained by our resources, so we may not be able to process many more movies each minute any time soon, but what we can do is make it easier for users to find other movies that are out there that have already been made. Thousands of movies have been made by users on Helioviewer.org, but right now there is no simple way to search through those movies and find the ones you are interested in. Further, we will also take some measures to make the users more aware of what the current wait time is before they submit a movie request, and also provide them with an option to cancel the request if they decide they do not want to wait for the movie. All of this will make it easier for you to get to the movies you want.

We apologize to all of the users who have queued movies during the last couple days that did not get processed. If you are still interested in making a movies please go ahead and queue it up again. Hopefully we will not have to take such extreme measures again. Thanks to you all for your patience.

Try it out! If you have any comments or suggestions, or run into any problems, report a bug or feature request.

RELEASE NOTES:

Helioviewer.org 2.2.0 is a major release including a number of stability and performance improvements, as well as a large amount of bug fixes. The main focus of this release is the recently added movie and screenshot creation capabilities. A large amount of work has been done to improve the reliability of those features, and also to pave the way for new functionality which will be added in upcoming releases and will be directed at giving users more fine-tuned control over the movie creation process.

We hope to have a stream of the very latest STEREO images very soon. Watch this space!

While Helioviewer.org has offered High-definition H.264 movies for several months now (encoded using the excellent x264 library), the amount of compression used was fairly high. The result of this was very small file sizes (around 1-5MB), but some noticeable compression artifacts; the effect of which was especially noticeable for larger movies.

For example, the below movie was generated on Helioviewer.org several days ago:

Example 1: In-browser movie before update (download video)

A number of changes were made to the H.264 encoding parameters in order to improve the quality, for example, whereas movies were previously generated using a constant variable bit-rate (-b 2048K), the newer movies use a different rate-control method called “Constant Ratefactor (CRF)” in order to achieve a desired level of quality.

Here is an example of a movie created for viewing in the browser using the new code:

Example 2: In-browser movie after update (download video)

What’s more, the “high-quality” download option is now much higher quality than ever before. Previously, when users clicked on the link below in the in-browser movie that says “Click here to download a high-quality version“, what they got was actually the same movie that was already playing in their browser, but packed in a container format compatible with the user’s operating system. With the update this morning, however, the high-quality download link now points to a separate and visibly higher-quality movie from what is shown in the browser. The high-quality option available now is actually a lossless movie, with respect to the underlying JPEG 2000 data archive used by Helioviewer.org.

Example 3: High quality movie after update (download video)

(Note: If you are having trouble viewing the above video, you can download an MP4 version directly from here.)

Of course, nothing comes for free, and that is true in the case of these improvements as well. The improvements made to quality come at the cost of increased movie filesize. For the standard-quality movie that is shown directly in the browser, the filesize has increased from by a factor of around 1.5-10x with the largest files around 50MB each. The real behemoths, however, are the high-quality (lossless) movies which range from around 50-300MB. It’s a lot, but try watching a few of high-quality AIA movies and you won’t ever want to go back again.

Update 2010/12/31: Thanks to Dark_Shikari on #x264 for some help making sense of some of the many rate control options available when encoding using x264.

Try it out! If you have any comments or suggestions, or run into any problems, report a bug or feature request.

Stayed tuned for some exciting new features next week

RELEASE NOTES:

Helioviewer.org 2.1.0 is a major release which includes many new features and a large number of bug fixes. Major features added include: full support for AIA images, on the fly movie and screenshot creation and a custom resource management and queuing system. Other changes include:

New features:

* Overhauled error back-end error handling
* Support for HEK FRM/Event querying
* PHP IMagick used in place of convert when available for better performance (See: http://valokuva.org/?p=40 for more information)
* Custom FFmpeg wrapper used in place of PHPVideoToolkit
* FirePHP support
* Documentation for each back-end module now handled at the module level rather than globally
* IE8 local storage support
* Conversion from tile coordinates to spatial coordinates now handled on front-end
* Removed dependencies on image archive directory structure
* Added a JHelioviewer JNLP generation method so that users can easily jump from Helioviewer.org to JHelioviewer
* Color of image layer timestamps now ranges on a scale from green (near requested time) to red (far from requested time). Absolute difference is used so that it does not matter whether actual image is ahead or behind requested one

Bug fixes:

* Fixed bug #544338 Edge effects for tiles viewed at higher magnification
* Fixed bug #605412 Helioviewer-generated Flash movies degrade in quality as the movie progresses
* Fixed bug #614558 Use of IMagick#extentImage results in images with incorrect dimensions
* Fixed bug #619944 Movie history panel occasionally stays in viewport
* Fixed bug #312205 Sandbox dimensions are too large for C2 and C3 Images
* Fixed bug #383939 Disable tiling when layer is hidden
* Fixed bug #508723 Check to see if data exists for each source, or provide option to disable a data source
* Fixed bug #605398 Improve JPX request cadence optimization for non-evenly distributed data
* Fixed bug #605411 Fullscreen, etc. button tooltips are hidden by movie/screenshot creation dialogs
* Fixed bug #608265 Chrome appends .html on movies
* Fixed bug #610456 FITS header dialog not updated when image is changed
* Fixed bug #645836 shortcuts for time steps “<” or “>” not working
* Fixed bug #535645 Add link to uncompressed JavaScript and CSS for better “view source” function
* Fixed bug #544352 backfill JP2s from SOHO mission up to most recent
* Fixed bug #322857 Sandbox dimensions do not update right away when layers are removed
* Fixed bug #415455 helioviewer logo issues/request

Library updates:

* jQuery imgAreaSelect (0.8 => 0.9.2)
* jQuery jGrowl (1.2.0 => 1.2.4)
* jQuery qTip (1.0 r34 => 1.0 r54)