This is how to use
The CADC's WWW interface


How to query the catalogues

  • Specifying your query constraints.
  • Specifying dates and range of dates.
  • Specifying the search box for coordinate.
  • Submitting Your Query
  • Setting up output modes

  • Tabular Output
  • Controlling Tabular Output
  • How to limit the number of retrieved records?
  • Want more info on each retrieved records?
  • You want to use a full screen mode output?
  • What about those preview modes?

  • What about the preview modes offered to the user?
  • Preview GIF.
  • Preview FITS.
  • Preview CADC.
  • What about the target name?

  • Using the target source field
  • What about those other links?

  • Anchor to other archives and services.
  • How to get data from CADC

  • Marking a dataset for retrieval.
  • What is the status of my requests?

  • How to query the catalogues


    Specifying Query Constraints.

    When you first enter a WDB query form you will see a lot of query fields like this :

    Exp.Time....... :

    These are the operands that are available for querying in the fields.
    <
    Less than.
    >
    Greater than.
    <=
    Less than or equal to.
    >=
    Greater than or equal to.
    !=
    Not equal to.
    =
    Equal to (=NGC will be translated to *NGC*, i.e. wild cards before and after )
    ~
    As = but ignoring case.
    ==
    Exact match (No wild-cards)
    *
    Wild-card in strings ( A*B will match AB, AxB, AxxxxB, etc. ).
    ..
    A range of values (ex.: 234.56 .. 678.9 ).
    |
    OR
    Will match any of the specified expressions (ex.: =123 OR > 5000 OR < 1 ).

    For example, to select all exposures with exposure times greater than 500 seconds you would enter:

    Exp.Time....... :

    The default (no operator) will be interpreted like '~*your-text*'

    Some fields has a fixed set of allowable values from which you can choose.
    Instrument...... :

    If no items are selected from the above menu, then there is no constraint on this field. More than one entry can be selected.


    Specifying dates and range of dates

    Dates are specified by DD/MM/YY. If a range is desired, two dates have to be specified separated by two single dots (..). To select all exposures that started between the first of January and the fifth of February you could enter :

    Exp.Start....... :


    Specifying the search box for coordinates

    In most catalogues, it is not feasible to search directly by target names since there is no standard for naming astronomical targets. We strongly suggest that users use the SIMBAD resolver instead. Then any known astronomical names can be use with SIMBAD providing the coordinates.

    To specify the search box around these coordinates, a box size (DD MM SS) is specified. The default box size is 10 arc minutes.


    Submitting Your Query

    To get the result of your query you have to submit it. At the top and at the bottom of the query form you will see a set of buttons like this :

    In order to to submit your request press the "Search" button. If you want to reset all the fields back to the way they where before you started entering qualifiers in them, press the "reset" button. (You could try to edit the "Exp.Start" field above and then press the "Reset" button).


    Setting up output modes


    Tabular Output

    Once your search is completed, you will see a table like this one.

    The data is presented in tabular format with special action fields.

    How to limit the number of retrieved records?

    Right now, there is a default limit of 100 in number of records one can retrieve from the database. If you are reaching this limit in your query result, there is more likely other entries which match your query. Or you will have to modify the limit, or specify your query. Please note that for internal reasons, there is a hardcoded limit setup to 500 records.

    Want more info on each retrieved records?

    For each records retrieved from the archive, there is a more link written as M. This allows the user to retrieve all known information concerning this particular entry independently of the field selected.

    You want to use a full screen mode output?.

    There is a selection box on each form wich allows the user to be able to retrieve the information from each archive in full screen mode instead of the default tabular format. This is quite usefull when only few records are expected since this mode could generates a tremendous amount of information.

    What about those preview modes


    What about the preview modes offered to the user

    The CADC WEB based system offer now 3 differents modes to receive images. They are described within the following table.

    Preview Mode Description .mailcap entry
    CADC The CADC preview mode is a very special one. It does allow transmission of a specially compressed image directly to a special CADC viewer which then, call the necessary display system. This make possible sequential display without having to start a new instance of the viewer. Unfortunately, it is available only on SUN platforms (SUSOS and Solaris). The package includes three executable.
    • mddisplay, which acts as an intelllligent viewer for the WEB browser
    • cadcimage, a special version of SAOimage
    • cadcgr, a special version of XMGR
    cadc/x-preview; mddisplay %s
    GIF The GIF preview mode is a simplle way to tranmit an image to a browser. Those images are usually highly compressed and are only 8 bit color, suitable for display to be display on a wide variety of systems. No image analysis is available through this mode. But it is the fastest. No action required since most browsers can display GIF files
    FITS The FITS preview mode is a simple fits transmission from the CADC WEB server. It is up to the user to specify the action upon complete recption of the file. The most likely action would be to display the file using popular FITS viewer such as SAOimage. Our FITS image header includes WCS conversion. We strongly recommend using the latest version of SAOimage 1.14 which is capable of displaying RA and DEC from standard FITS images which have the World Coordinate System keywords in their headers. application/x-fit; saoimage -fits %s
    application/x-fits; saoimage -fits %s

    A new button is now showing up when browsing the HST catalogue. It is used to be able to look at the PC preview of all WFPC2 observations when available. Please be warned that it is not always possible to generate a PC preview. Also, because of some limitations of our retrieval system, the button will show up even for non WFPC2 instrument.


    What about the target name


    Using the target source field

    For most archive search, we are providing to the user 2 different sources for the target name. The default one is using SIMBAD to resolve the name in coordinate and performs the search using precise standard coordinates instead of the original name supplied by the archive.

    The second mode is using the default archive target name for the search, without resolving it in cooordinates. The research based on this mode are useful only when non astronomical objects are wanted (i.e. observations for the medium depth sky survey)

    We do not offer directly object classes search. One have to pass through cross correlation catalogues for this.


    What about those other links


    Links to other archives and services.

    The CADC is now offering a standard tool to perform search on its archives. This tool is now used to display, for each successful retrieval, a range of search through other supported services. Here are the actual list.

    Link name Short description Exemple
    Universal Gateway to all other CADC links to other services and archives http://cadcwww.dao.nrc.ca/cadcbin/universal/
    IRAS Link to the IRAS HCON images server at CADC http://cadcwww.dao.nrc.ca/cadcbin/universal/1212+12/0010/iras
    SIMBAD Query Simbad around the coordinate of this retrieved observation http://cadcwww.dao.nrc.ca/cadcbin/universal/1212+12/0010/simbad
    HST archive Query the HST archive around the coordinate of this retrieved observation http://cadcwww.dao.nrc.ca/cadcbin/universal/1212+12/0010/hst
    CFHT archive Query the CFHT archive around the coordinate of this retrieved observation http://cadcwww.dao.nrc.ca/cadcbin/universal/1212+12/0010/cfht
    ESO archive Query the ESO archive (NTT) around the coordinate of this retrieved observation http://cadcwww.dao.nrc.ca/cadcbin/universal/1212+12/0010/eso
    NED access Query NED around the coordinate of this retrieved observation http://cadcwww.dao.nrc.ca/cadcbin/universal/1212+12/0010/ned
    Digitized Sky Survey access
    DSS
    Query the Digitized Sky Survey access survey around the coordinate of this retrieved observation. http://cadcwww.dao.nrc.ca/cadcbin/universal/1212+12/0010/dss


    How to get data from CADC?


    Marking a dataset for retrieval

    What is the status of my requests?