Clusters - Controls Explained Clusters Home


Select Button:
Use this button to enter the galaxy selection mode.
Cluster Selection Dropdown:
Use this menu to select which galaxy cluster you wish to analyze.
Cluster View Pane:
An image of the selected cluster will appear in this pane. If the image is too large to be viewed in the pane, you can use the scroll bars to view the hidden portions of the image.

When you move your mouse over a galaxy in the image, information regarding that galaxy will appear in the small window to the right.

When you click on a galaxy, a circle will be drawn around it, indicating that it has been added to the data set for analysis. Clicking the galaxy again will toggle its selection off. Holding down CONTROL while clicking will deselect all of the galaxies.
Analyze Button:
Clicking this button will bring you to the analysis screen, where you can analyze the cluster based upon the galaxies you have chosen.
Lower and Upper bounds of dispersion calculation:
In these fields you can alter the upper and lower bounds of the standard deviation calculation for the velocity histogram. This will allow you to get more accurate results by eliminating poor data points from the calculation.
Hubble Constant:
Enter a value for the Hubble Constant. It will be used in calculating the distance to the galaxy cluster, which in turn will be used to calculate other properties of the cluster.
Velocity Histogram:
Displays the number of galaxies that fall into each range of velocity. It also displays the mean velocity and velocity dispersion (standard deviation) of the current data set.
Fractional Luminosity Graph:
Displays the fractional luminosity of the cluster, based upon the selected galaxies, as a function of the radius from the center of the cluster. The half-light radius (in arcseconds) of the cluster is indicated by the dotted line.
Calculate Button:
After changing the bounds of the dispersion calculation or entering a new Hubble Constant, press this button to recalculate the various properties of the cluster with the updated values.