Using SDSS Navigator


Let's look at the properties of Abell 2065.  The cluster's sky position is

(RA,Dec) = (230.62156, +27.70763)

where both coordinates are given in decimal degrees.

Go to SDSS Skyserver: http://skyserver.sdss.org/ and click on the Navigate tool.

Go to the coordinate box (top of image, RA/dec coords in degrees shown in purple), erase what's in there, then type in the cluster coordinates and hit return.  Hopefully you'll see a cluster.

At the bottom of the image, you'll see the field of view of the image. And if you click on the globe symbol icon, you'll get a a coordinate grid as well.

You can zoom in and out using the "+/-" buttons (or a scroll wheel).
You can pan by right-click-dragging.
You can change brightness and contrast by left-click-dragging.

If you get lost, go back to the coordinate box and type "Abell 2065", then hit return. It recognizes names as well as coordinates!

In the side menu, under "Select Objects", click "Photo". This will mark all objects which have available photometry (the number of objects marked depends on how zoomed in you are). If you click "Optical Spectra DR19" it will show you all objects which have spectroscopy.


Click on a galaxy (you may need to zoom in to find its center). The "quick look" side panel will show a little zoomed-in image, the ugriz magnitudes, and (if it was observed spectroscopically), a thumbnail spectrum. Clicking on the spectrum will blow it up, or if you click the "Explore" button underneath the zoom window, a new webpage will open up with more detailed properties of the galaxy, and more tools.

VERY IMPORTANT: When Navigate says an object has type = STAR, that does not mean it is actually a star. It only means that it is an unresolved point source. It might be a star, but it could also be a small, unresolved galaxy.
 
Play around. Scroll, zoom, click on galaxies and hit "Explore", etc. Look at a few spectra of galaxies in the field. Work out the following: