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Search by redshift (open tool in new window)

Instead of, or in addition to, searching by position, you can also tell the Spectroscopic Query Form to search by redshift. To do this, use the Spectroscopy Constraints section. The default is no constraints (that is, to return quasars at all redshifts).

1. First, select the Redshift. Enter the minimum and maximum redshift to search.

2. Enter the Confidence of the redshift measurement. Confidence is a number from 0 to 1, with higher numbers meaning more confidence that the redshift is correct. Generally it is a good idea to restrict your sample to objects with a redshift confidence of greater than 0.35.

3. Select the spectral Classification. For quasars, be sure to select both QSO and HIZ_QSO.

4. You can also search for the presence or absence of specific target flags.

5. 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.

6. You will see your results in a new window.

7. If you would rather search by magnitudes with an SQL Search (new window), be sure to search in the specObj or specPhoto tables, and remember that the SDSS object IDs are referred to as bestObjID in these tables.

Next: Search by magnitudes

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