Object CrossID

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Catalog Upload


Crossmatch SQL Query


CrossID Help

This page is for dynamic cross identifications of SDSS objects with a user defined list of object positions, 5-part SDSS object ID (consisting of run,rerun,camcol,field,obj) for photometric objects, or 3-part SDSS spectroscopic object ID (consisting of plate, MJD and fiber. You can even join a photometric object list with matching spectra (SpecObj) if you want spectroscopic information, or join a spectroscopic object list with matching photometric objects. Just check the appropriate "JOIN with" box to return the matching objects. You will see the default query in the query window changing accordingly.

For this browser-based synchronous cross-ID service, the upload file is limited to 1000 rows and the output is limited to 500,000 rows to ensure that the results are returned in a timely manner. For larger uploads, please use the asynchronous CasJobs service (see the Help page for Advanced Queries under Nearest Neighbor Searches (Cross-ID)).

Upload list format:

You have the following choices:

  1. List of (ra,dec) pairs or list of objIDs (run,rerun,camcol,field,obj)
    Always ra comes first, followed by dec. Both ra and dec must be in degrees. The separator can be any white space or a comma. The objIDs must be the 5-part SDSS identifiers, i.e. run, rerun, camcol, field and obj numbers, not the long 64-bit objIDs.
  2. List of preceding non-data fields followed by (ra,dec) or (run,rerun,camcol,field,obj) data fields
    The fields must always be in this order. The preceding columns can be any fields that you want repeated in the output. The number of preceding columns must be specified in the second parameter above. The default example shows one preceding column ("name"). Both ra and dec must be in degrees. The separator can be any white space or a comma.
  3. Same as above, with a single header line
    The formats (1) and (2) can also contain a single header line, containing the column names. The header must use the same separator as the data. The names ra and dec or run,rerun,camcol,field and obj are mandatory.
  4. Lists in the IRSA Gator format
    For details see the IRSA website.

You need to either cut/paste the list into the textbox, or upload a text file. Various extensions (.txt, .dat, .csv, .tbl) are allowed, as long as the MIME type does not get confused. Binary files are not accepted.
If both the paste buffer and file upload are specified, the file upload takes precedence.

Setting up query in the query window:

Add or remove fields that you want returned from the SELECT list, and add more constraints to the WHERE clause if you desire (preceded with a boolean operator). If your query does not include a p.objID field in the SELECT for a photometric object list, it will be added for you, because the matching with the upload list is done based on objID. You may also replace PhotoTag with Galaxy, Star, or any other photo view or table. if you want to restrict the kind of object that is matched. Remember that PhotoTag will be the fastest usually because it is a thin table (more rows fit in the cache), so unless you need the fields from larger tables, use PhotoTag (with a mode or type constraint if necessary). Make sure the photo table/view is aliased as 'p'. Similarly you can replace SpecObjAll with SpecObj as applicable.
Do not modify the #x and #upload parts of the FROM clause otherwise your upload will not work .

If you have a header row with the column names, the #upload temp table created for you on the server will have the corresponding column names with a "up_" prefix, e.g., up_name, up_ra, etc. You can then refer to these columns as "u." in your modified query.

Getting FITS files from the SAS

If run, rerun, camcol and field columns are included in the imaging columns list, a button will be included on the query results page to upload the list of fields to the SAS for FITS file retrieval. If spectra are included and the SELECT list includes the columns plate, mjd and fiber, a button will also be included on the results page to upload the spectra list to the SAS to retrieve FITS spectra. The default queries include these columns for your convenience.