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Instead of, or in addition to, searching by position, you can also tell the Imaging Query Form to search by magnitude.
To do this, use the Imaging Constraints section. The default is no constraints (that is, to return objects with any magnitudes).
First, select the Type of magnitude on which you would like to search: Petrosian, Model (the better fit of
a DeVaucouleurs and exponential profile), or PSF. Next, enter the magnitudes you would like to search for in the Magnitudes textbox. You can enter constraints on any of the
SDSS's five filters (u, g, r, i, z), and you can enter minima and/or maxima for each value. You can search by color instead of or in addition to magnitude. Your choices for colors are u-g, g-r, r-i, and
i-z. You can enter minima and/or maxima for each value. You also search for specific types of object: extended sources, point sources, sky, or unknown. You can also search for the presence or absence of specific flags. See the guide How do I check quality of SDSS
photometry for an object (photo flags)? to see what flags mean and how to use them. When you have finished entering all your constraints, click Submit Request. The tool will return only the objects you asked for,
in the output format you specified. You now have the data you requested. See the next step to learn how to get the same data using SQL. If you would rather search by magnitudes with SQL, add the following line to the WHERE block of your query:
WHERE g < 17
Substitute any of the filters, the operator (=, <, >, <=, >=, !=), and the value. You can also use BETWEEN to specify a range of magnitudes.
For example, here is a query to find objects with r magnitudes between 15 and 19 (click Submit to run):
Next: Find by Absolute Magnitude
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