Finding Chart

Launch the Finding Chart tool

The Finding Chart lets you create and print "finding charts" - maps of the sky that can help you locate objects through your telescope. To create a finding chart, enter the right ascension and declination of the object you want to find in the "ra" and "dec" boxes at the top left. Enter the width and height of the chart in "width" and "height" (the chart doesn't have to be square). 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. You can also zoom by changing the image scale with the "Scale" box. Enter the scale in arcseconds per pixel.

Use the Finding Chart tool when you want to use your telescope to observe an object that the SDSS has already observed, or when you want to 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 chart. 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 chart. When you're ready to observe, point your telescope at the appropriate RA/Dec, and the Finding Chart can guide you to find your object.

In addition, the Finding Chart 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 chart center, along with the chart'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

  • Targets puts a white X on all objects targeted for spectral observations by the SDSS (whether or not spectra were successfully measured)

  • Outline marks the outlines of all photometrically identified objects in the chart

  • BoundingBox puts a box around the outline for each object in the chart

  • Fields marks the boundaries of SDSS fields in the chart

  • 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 chart (plates are 3 degrees across)

  • InvertImage inverts the colors for the onscreen display of the Finding Chart (images are automatically inverted by the printing utility)

    • See the Finding Chart help page

    Done