		User's Guide
NCSA Astronomy Digital Image Libary Help: Query Page

About the Query Page

The Query Page allows users to search the Library's image collection based on a variety of selected fields. After entering search criteria into the form, the user clicks on the button labeled "Submit Query" to initiate the search. When the search is complete, the user will receive a list of matched items (either images or projects). Each matched item will have a score that indicates how well it meets your search criteria, and the list of items is ordered accordingly with the best matches (high scores) first. Each item also provides links for browsing and/or downloading the associated images.

Return Types and Numbers

At top of the query form, you can specify the type of items--images or projects--to return as well as the number of items. The default type is "images", in which case, each item in the results list will correspond to a single FITS image found in the library. If you choose "projects" from the menu, then each item in the results list will correspond to an ADIL project (a collection of images making up a scientific study).

In this portion of the form, you can also specify how many items to return (which defaults to fifty items). Your query may generate a large number of matches with only a fraction meeting most of your search criteria. The best matches (given by their scores) appear first. By setting the number of matches returned, you can filter out poorly matched items. You can look at items that do not match as well by increasing the number in the second text field which indicates which item to start the results list with. For example, to see the second 20 best matching images, the Return selection line should read "Return 20 matching images starting with #21".

Search Fields

Position

The Right Ascension and Declination fields allow users to enter a region of sky as a search parameter. Positions by default should be given in J2000.0 coordinates; however, Epoch 1950 coordinates may be given by selecting "1950.0" from the Epoch pull-down menu below the Right Ascension input field.

Note that the Library contains survey images covering all portions of the sky. Thus, if you do a strict sky position search with no other parameters, you might consider excluding survey images by selecting "Exclude" from the Survey Filter menu in the Object section of the Query Form.

Right Ascension: The R.A. is given in time format, e.g. HH:MM:SS.SS (for hours, minutes, and seconds), and should have values between 0 and 24 hours. Two values seperated by a comma indicate a search range; all items that overlap with the range are returned. The following examples are all legal input values: Single values are converted to a range centered on that value. The extent of the range depends on the precision given for the input value. For example, a single value of 12:30 is turned into a range of 12:29:30, 12:30:30, while a single value of 12:30:00 is turned into a range of 12:29:59.5, 12:30:00.5.
Declination: Declination is given in degrees format, e.g. DD:MM:SS.SS (for degrees, minutes, and seconds), and should have values between -90 and 90 degrees. Two values seperated by a comma indicate a search range; all images located within the range are returned. The example inputs shown above for the Right Ascension field also apply to Declination. Default ranges for single value inputs are also handle in the same way as for Right Ascension.

Frequency

These fields allow the user to search for images in a specific waveband. A general frequency search criteria can be set in one of three way by selecting the appropriate radio (diamond) button:

Any Frequency: returns items at any frequency.
Search by Waveband: this method lists several wavebands by catagory, from Radio to Gamma. Choose one or more desired wavebands by clicking the appropriate button by the catagory name.
Search by Frequency Range: this method a allows you to enter a single frequency range to restrict the search to. The range can be specified in units of frequency (Hz, kHz, GHz), wavelength (m, cm, mm, microns, Angstroms), or energy (keV, MeV) by choosing the desired unit from the menu to the right of the text field. Two values in the text field seperated by a comma indicate the lower and upper bound of the search range. Single values are converted to a range centered on the value. The extent of the range depends on the precision given for the input value; for example, 115.2 would be converted to 115.15,115.25, while 115.27 would be converted to 115.265,115.275.

The search can be further limited to spectral line images by specifying a Rest Frequency range and/or a species. The format for the Rest Frequency range is the same as the general frequency described above. The species field can take a list (space- or comma-delimited) of inputs, each being a chemical formula or portion of a chemical formula. For example,

H C Si: select species containing hydrogen, carbon, or silicon
HNO CO: select species containing an HNO chain or a CO chain

Object

The Object Name and Object Type fields allow the search to be limited to specific astronomical objects. Object names should be listed one per line in the Object Name text box. Object names can be automatically converted to sky positions clicking one of the checkboxes for name resolvers (currently NED and SIMBAD) located just below the Object Name box; this allows you to effectively get back images of an object using any of its catalog names. Because the names are resolved to positions, it is recommended that you also select "Exclude" from the Survey Filter menu.

Since the name resolver services are located elsewhere on the network, using them can make a search take a little longer, or cause the search to fail if the services are not available. If you do not use one of the resolvers, you may find it useful to check the current list source names (via the List of names link below the box) to determine how to fill in the search field. (The list can be text-searched using the "Find" capabilities of your WWW browser, e.g. Cntl-S for NCSA Mosaic.)

Object types should also be listed one per line in the Object Type text box. A complete listing of object types currently in the Library may be examined by clicking on the List of types link below the input box; however, it is not necessary to give the type exactly as given in the list. The search will actually return all images whose types contains the words listed in the input field.

This section also contains the Survey Filter menu which determines whether images that are part of sky surveys should be returned in the results list.

Include: Search results will include both survey images and non-survey images (default).
Exclude: Survey images will be excluded from the search results; thus, only non-survey images will be listed.
Only: Search results will contain only survey images; non-survey images will be excluded.

For example, if you are searching for images of a particular object by specifying a sky position, you may want to choose "Exclude" to filter out large-field survey images.

Name Resolution

Clicking on one of the checkboxes just below the Object Name box will engage a name resolution service to help with your search. Currently supports name resolvers are the NASA/IPAC Extragalactic Database (NED) and SIMBAD. When you submit a query using one of the name resolvers, the ADIL server will first send an object name query to the requested name resolver(s) located elsewhere on the network, getting back a sky position for each object list in the Object Name box. Each position returned by the resolver is then added to your search criteria. Even if a name is not recognized by the resolver, it will still be included an object name to look for in your ADIL search.

Note that because the names are resolved to positions, it is recommended that you also select "Exclude" from the Survey Filter menu. Also, using a name resolver can sometimes add a little more time to your search, especially if network traffic is heavy. If the search fails for this reason, try "unclicking" the name resolver button and try the search again.

Acknowlegments
SIMBAD name resolution is provided in collaboration with the SIMBAD project, Centre de Donnees astronomiques de Strasbourg, France. For questions about SIMBAD content and for access to the full on-line interactive database, please contact: question@simbad.u-strasbg.fr.
NED name resolustion is provided courtesy of the NASA/IPAC Extragalactic Database which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
The ADIL would like to thank both institutions for their help and cooperation in the integration of Web services for astronomers.

Image Origin and Related Science

The Authors, Title, and Telescope fields allow the search to be limited according to the images' origins.

The Authors field is for requesting projects whose author list include one or more specified names. These names should be listed one per line in the Authors text box giving the last name first. One can optionally follow the last name with a comma and a first initial. For example, all of the following are correct:

   Smith
   Kepler, J
   Brahe,T

The Title words field is for requesting projects whose title contains one or more specified words. These words can be given in any order in the Title words text box and need not be restricted to a single or multiple lines.

The Telescopes field if for requesting images originating from one or more specified telescopes. These telescopes should be listed one per line. It is often useful to check the List of telescopes accessible from the link below the text box to see what telescopes are currently in the Library.

Result Scoring

When you submit a query to the Library, the Library search engine generates a list of items that at least partially matches your search criteria. Each item is given a score (0-1) indicating how well the item matches your criteria, with 1 meaning a perfect match. The list of items is then returned to you in descending order of the score, i.e., the best matches first.

Certain fields from the query page are considered filter fields; that is, when you provide an input for such a field, then items must satify the input criterion in order to be returned. (In database language, the filter criteria are AND-ed with the other criteria in the search.) Currently, the filter fields are set to sky position (RA and Dec.), Frequency, and the Survey Filter (although in the future, this will be user-controlable).

All non-filter fields (currently, species, object name and type, authors, title words, and telescopes) can produce partial matches. (In database language, these criteria are OR-ed together.) With these fields, one can give more than one value to search for (e.g. multiple authors, words in a title, etc.). The search engine will then return items that match at least one of the input values--the more input values matched, the higher the score it will be given. Currently, every input value in each non-filter field is weighted equally in the calculation of the score (although in the future, the weighting will be user-controllable).

User's Guide

The Astronomy Digital Image Library is a project of Radio Astronomy Imaging Team
at the National Center for Supercomputing Applications on the campus of the University of Illinois at Urbana-Champaign

Contact the ADIL: adil@ncsa.uiuc.edu