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Tutorials: Getting spectra of galaxies within a range of redshift and r magnitude.

  1. At the top of the Spectro Query Server (SQS) form, select the maximum number of objects to output. Then select the desired spectroscopy and imaging parameters ("minimal" is what you need to retrieve data from the Data Archive Server later, it outputs run, rerun, camcol, filter, field for imaging and plate,mjd,fiberID for spectroscopy; "typical" is more useful if you want to assess your results first, e.g., it includes redshift for spectra).
  2. Specify whether to retrieve and select on target or best imaging parameters.
  3. Select whether you want to see your results in an html table in the browser, or save them to disk in a csv file.
  4. Specify position constraints (or no constraint). For a proximity search, you can either type in coordinates or upload a csv file.
  5. Enter the Redshift min and max and the desired confidence in the redshifts (zconf > 0.35 is the bare minimum to avoid objects with uncertain classification and hence redshift; zconf > 0.65 already results in a very clean sample and should be good for most applications).
  6. Select "Galaxy" within Spectral Classification.
  7. Enter the photometric constraints (in this case, min and max for R-band model magnitude).
  8. De-select point sources if you wish to exclude objects identified by the imaging survey to be point sources. If you leave this selected, your results will include such objects later identified spectrally to be galaxies.
  9. Select the flags that you want or do not want turned on for your objects (see photometric processing flags; some flag checking is already applied by the targeting pipelines.
  10. Hit "Submit Request". The desired parameters for objects matching your query will then be displayed in a table if you selected html above, or you will be prompted to save the results in a csv table.
  11. Select the option to use a DAS web form with this query to get data.
  12. On the DAS retrieval form, select "spSpec" under "Step 1". Steps 2 and 3 should be filled in. Under "Step 4", select the file format. If you have more than 10 objects, you will always get the results via "rsync". Click "Submit Request".
  13. If you selected "rsync", you will now be asked to save a link as sdss-rsync.lis on your local computer. Further down on the page is a command that you should type on your computer to execute the rsync procedure. If you did not select "rsync", and your query produced 10 or fewer result files, you should be prompted to select where you would like the data to be saved on your computer.


An SQS query with the following specifications:

  • Minimal Imaging and Typical Spectroscopy Parameters
  • Best Imaging
  • No position constraint
  • Redshift Range: 0-0.03
  • Redshift confidence > 0.35
  • Spectral Classification: Galaxy
  • "Point Sources" De-selected
  • "Child" Flag Off

produced 1790 results.

Last modified: Thu Jun 14 16:22:45 CEST 2007