When you select a date range and click Filter the map will populate with dots, and the calendar will fill with observation schedules. Each dot is an object in our universe and the color coding indicates which telescope is looking at it. Click the dots to find out more about the object.
These telescopes are mounted on satellites orbiting the Earth. When you plot the objects that they are looking at you'll notice they look like a wave in the sky - this follows the orbital path of the satellite across our sky.
Each telescope has different design specifications and is sensitive to different wavelengths. For example Fermi measures gamma rays - electromagnetic radiation with a frequency above 1019Hz. XMM-Newton looks at X-rays, with frequencies around 10 times lower. Objects in space look different at different frequencies - just as you can't see a person in a dark room with he naked eye, but they glow like a lightbulb to infra-red. So XMM-Newton is looking at the universe through X-ray specs.
Scientists around the world can reserve time on telescopes to look at objects they are interested in. This can range from a particular star, or a distant galaxy. Satellites can be re-targeted automatically to respond to a sudden event like a supernova. Click a target on the map above - if it's been observed before you'll see a picture. Click through to see more images of the same object.
Astronomers use a range of different coordinate systems to identify objects in the sky. In the map at the top of the page the points are plotted using l and b, the galactic longitude and latitude. As with longitude and latitude on earth, l and b define the x and y location on a map, and like earth there is a galactic equator. This is the plane of the galaxy - visible as the bright line of stars, and corresponds to b=0. All astronomical coordinates increase to the left.
RA and Dec refer to Right Ascension and Declination. Unlike l and b, these coordinates are defined with respect to earth - so Dec=0 corresponds to the projection of the earth's equator onto the sky, and Dec=90 is the direction of the earth's north pole.