The Very Large Array (VLA), a network of 27 radio telescopes in the New Mexico desert, is one of the most sophisticated radio telescope arrays in the world. Right now, the VLA is conducting a sky survey called FIRST (Faint Images of the Radio Sky at Twenty-one centimeters). The FIRST Survey covers almost exactly the same area of the sky as the SDSS – so we can use FIRST to find radio sources that correspond to our data.
Now, get SDSS’s visible-light image of the same object using the Navigation tool. Enter the RA and Dec (in degrees) in the appropriate boxes, then click “Get Image.” An image of the object will appear in the main frame of the tool, and the object’s data will appear in the right-hand frame.
Get a radio and a visible-light image (in separate windows) for each object, then answer questions 1 and 2.
|Ra (hours)||Ra (degrees)||Dec|
Photo does not have enough information from an image to classify all types of objects correctly. Sometimes, to tell the difference between a star or galaxy and a potentially more interesting object, you need to look at the object’s spectrum. In the next section, you will look at the spectrum of one of the objects you saw and compare it to a typical star spectrum and galaxy spectrum.