Getting Started with Navigate

Launch Navigate

The Navigation tool is one of the most versatile tools on SkyServer. You can use it to look through millions of objects to find those you are interested in.

To use the Navigation tool, enter a right ascension and declination in the “ra” and “dec” boxes at the top left, then click “Get Image.” Use the Zoom bar (the magnifying glasses and rectangles under “Get Image”) to zoom in our out on the center of the chart. Use the NWSE buttons to pan through the sky, looking at neighboring areas.

When you click on any object in the main frame of the Navigation tool, a close-up of the object will appear in the right-hand frame. A summary of its data will appear above the close-up. This summary shows its position (ra and dec), its type (star or galaxy), and its magnitudes in the SDSS’s five filters (u,g,r,i,z). To learn more about this object (including spectral information), click “Explore” to open its Object Explorer entry. To add the object to your online notebook, click “Add to Notes.” To view your notes, click “Show Notes.”

Use the Navigation tool when you are looking for objects to study. You can search through hundreds of objects at a time, clicking them one after another. When you find an object you are interested in, you can save it in your notebook, or use the Object Explorer to look up all its photometric and spectroscopic data.

You can create a Finding Chart for any object you find in the Navigation tool by clicking the “Chart” link above ra and dec. You can also print out a picture of an object or region of sky. To print, click the Printer icon. A new window will pop up; click “Send to Printer” to print the image. In the print window and on the printout, colors will be inverted – black will become white and white will become black. The printing utility will automatically generate a grid and labels for the image.

In addition, the Navigation tool can add several optional features to your image and/or printout. To turn on an optional feature, click the checkbox next to its name. The optional features are:

  • Query to mark objects puts purple triangles on top of objects selected by a marking string
  • Grid overlays a grid and scale
  • Label overlays a label with the RA/Dec of the image center, along with the image’s scale and zoom factor
  • PhotoObjs puts blue circles around all the objects that the SDSS photo algorithms identified
  • SpecObjs puts red squares around all objects for which the SDSS has measured spectra
  • Outline marks the outlines of all photometrically identified objects in the image
  • BoundingBox puts a box around the outline for each object in the image
  • Fields marks the boundaries of SDSS fields in the image
  • Masks marks any regions masked out of the science data (masks are applied for a variety of reasons)
  • Plates shows the boundaries of SDSS spectroscopic plates on the image (plates are 3 degrees across)
  • InvertImage inverts the colors for the onscreen display (images are automatically inverted by the printing utility)