Tutorial: Position and Magnitude Limited Catalog Query

1. Access the SDSS Imaging Query Server (IQS)
    
2. Set "Limit number of output rows" parameter by estimating the number that you expect (or leave it blank).
    
3. Select the parameters to be returned:
   a.  minimal - full id info
   b.  radec - position info
   c.  magnitudes - SDSS filter magnitudes
   d.  iso_a_g, iso_a_r, iso_a_i, iso_a_z, iso_a_u – semi-major axis measurements
    
4. No spectroscopy parameters are necessary for this search.
    
5. Select the u, g, r, i, and z radio buttons.
    
6. Select "Cone Search" under "Position Constraints"
    
7. Enter the raCenter (decimal degrees), decCenter (decimal degrees) and then the radius of your search area in arcminutes (max = 30 arcmin).
    
8. In "Imaging Constraints" click the Target or Best radio button
    
9. Enter the r magnitude range (min and max) to which you wish to limit the search
    
10. Ensure that only the "extended Sources (Galaxies)" radio button is pressed in "Object Type"
     

11. Use defaults under objc_flags and objc_flags2
     

12. Click on the "Submit Query" button.
     

Sample Query Response Time

For a query using ra = 120, dec = 40, radius = 30 arcminutes, r magnitude range 17 - 17.1, 7, and number of rows set at 500:

• 7 rows returned
• 50 seconds of real time elapsed