Mergers Zoo - Header Image

Data collection for Galaxy Zoo Mergers is closed.

Data Collection Closed

Thank you again to all of our volunteers. Galaxy Zoo Mergers is now in an archive status. To see the final data release visit the data page here.

Q. What makes a good match?

A. That's up to you to decide. Consider focusing on certain distorted features in an image such as any "tails" from either galaxy. Also be sure to match the rotation direction of the galaxies. We have some example simulations in our Gallery. For more information, see the Tutorial.

Q. The applet page won't load correctly or I see a blank section on the left-hand side of the screen. Why is this?

A. This probably indicates that your Java Plug-in is not installed/enabled/running properly, or there is an error with our software. First try to verify that your plug-in is working properly. You can follow this link Plug-in Test for our local plug-in test.

For more help verifying the configuration of your plug-in, go to this site to test your browser here. Our software is meant to be backwards compatible with Java versions all the way back to 1.4.2, and we've tested with 1.5 (5.0) and 1.6 (6.0) as well. So it's possible that your plug-in will fail the test site just mentioned but still work with the software. One place to test older plug-ins is here.

Q. Why doesn't the applet recognize when I've clicked the mouse?

A. Sometimes you'll click on a simulation in the Explore or Evaluate tabs, but no border is drawn around it. Some instances of the Java plug-in are very sensitive to the motion of the mouse while clicking. For a full "click" event to be sent to our software the mouse must be motionless when the button is pressed and released.

Q. Other people are discussing updated features in the applet, but I can't see them. Why not?

A. If you're looking for a new feature in the applet, one way to try to find new menu items is to right-click (or shift, left-click) on various items to see what comes up. It's also possible your browser is using an old version of the applet. You can try clearing your browser's cache to see if it will reload the applet.

If that doesn't seem to change anything, and you believe you still don't have the latest applet, you can try exiting the browser after clearing the cache. Next, restart your browser. Then you can try logging into the Zoo again.

Be aware, that clearing your browser's cache will delete cookies and other files for more websites than just the Zoo. So if you visit any websites that use persistent cookies to store preferences, you will probably have to set them up again the next you visit those sites.

Q. Why does the applet sometimes look very strange, like two screens on top of one another or only part of a menu shows up?

A. The simulations require frequent refreshes of the graphical components on screen. If your browser window is partially off the screen, or you have another application on top of it, you may see these strange errors quite often. To reduce their occurence, try running the applet only with the browser maximized. Also, you can use the pop-out feature to work with the applet in its own window.

Q. When I go to My Mergers, the Merger count is 0, but I know I looked at a large number of simulations. Why doesn't this number show that? Is my data getting lost?

A. The Merger count value is a bit obscure. It refers to the number of bundles of data saved while you used the Mergers applet. This number is increased whenever your results are sent back to the server. The value you see in the My Mergers page is based upon a database query. This query is not 100% accurate. But don't worry, even if this number doesn't show an increase while you're working, you're data is not lost. Your results are saved on the server two ways before the database is contacted.

The My Mergers page is still under development and we welcome feedback. The features there are of an experimental nature, and we would like to hear back from you on what aspects you like and definitely the ones you don't like. A good place to provide feedback and see what other have to think is on the main forum or the board set up for the Merger Zoo

Q. Why can't I save the galaxy when it is rotated at a different angle?

A. When we set up the simulations for a collision, we measure the locations of the centers of the two galaxies directly from the original image. We align our simulations to these points in order to ensure that the final positions of the simulations are exactly aligned to the real positions of the galaxies. When you rotated the simulation to a different angle, you are misaligning the location of the simulation relative to the image. Although the outer tidal features might look better, the locations of the galaxies has been altered making the match you found less valid. The rotation features were included to let you get a three dimensional sense of the simulation. We don't allow you to save these rotations since they aren't really matches to the original system.

Q. Why don't the simulations in My Favourites match what I saw when I first saved them from the Merge Galaxies Applet?

A. There are several reasons why the simulations in My Favourites do not produce the same results. The first is the simulation scale. Each target merger in the main simulation is associated with a set of contraints that place the galaxies at specific points to attempt to recreate the target image. These constraints are not easily accessible from the favourites simulation. The second reason may be due to an error in our simulation software. We're working to fix this now. Another reason relates to the use of different force model calculations. Simulations run before March 1, 2010 used a slightly different force model than those run on or after that date. Other reasons why the version of the simulation run as a favourite may not appear the same relate to rotation angles, particle numbers and other parameters that may have changed.

Q. Why do I see a message flash on the screen telling me I need to login even though I just did?

A. Sometimes the first page you visit after logging in will think you still need to do so. You can try reloading the page or clicking on the menu option to get there again to see the page load without the incorrect warning.

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