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NOAO Survey Data Search Help

This page provides helpful information not only on how to use the NOAO survey data search form, but also describes the individual search parameters both in words and with examples where appropriate. This page also provides documentation regarding the information on output results page.

You can use the NOAO survey data search form to search the current holdings of data from NOAO surveys by setting the available parameters according to your specific needs. At this time, the available search parameters are: equatorial coordinates (RA and Dec), object name, observation date, photometric depth, survey name, and filter. If you do not recall the coordinates of a particular field, then the Object Name entry can be used in conjunction with a name resolver (SIMBAD or NED) to determine equatorial coordinates which can then be used for your query.

Particular topics of note will be represented in a highlighted manner.

Parameter Help

Object Name
Object name you wish to use for the search. This entry acts in conjunction with the Resolver radio buttons. This entry can be used either to enter the object name explicitly to search the archive database, or the object name can be used with a name resolver (SIMBAD or NED) to determine coordinates (RA and Dec) in order to use the coordinates for the search.

If you wish to search the database explicitly for a specified object name, you should fill in the Object Name entry, and you must also set the Resolver to Do Not Resolve. When you are ready to perform the search, just press the Search button located at the top and the bottom of the form. When using the Object Name explicitly to search the archive database, the characters "*" (asterisk) and "?" (question mark) may be used as wild cards. The "*" can be used for matching a series of characters while the "?" can be used for matching a single character. The matches are done in a case-insensitive manner. For example,

    Object Name
       WL*   ==> returns objects named in the database beginning
                 with the letters ``WL'' and followed by some 
                 number of characters.

       ?L*   ==> returns objects named in the database which have 
                 an ``L'' as the second character in the name, 
                 preceded by a single character, and followed by 
                 some number of characters.

       ??WL  ==> returns objects named in the database which end 
                 in the characters ``WL'' and are preceded by 
                 two characters.

       grid 1* ==> returns objects which begin with the characters 
                   ``grid'', followed by a single space, the 
                   number ``1'', and finally some number of 
                   characters.
    

In general, unless you are knowledgeable about the details of the particular survey data, it is better to search the archive using coordinates or other parameters. The object names provided with the survey data have not been normalized.

If you wish to use the Object Name in order to determine coordinates (RA and Dec) for an object via a name resolver, you should fill in the Object Name entry, set the Resolver to SIMBAD or NED to perform the name resolution, and press the Find Coordinates button. When used with a name resolver, wild cards are not allowed for the object name. No quotes (single or double) should surround the text.

    Object names to use with the name resolver to obtain 
    coordinates can be in the following format:
       WLM
       ngc5548
    

In order to use the object name resolver, type an object name in the Object Name text field, select a name resolver (SIMBAD or NED), and press the Find Coordinates button. The search form will be redisplayed with the right ascension and declination of the specified object in the RA and Dec fields of the search form.

You do not need to press the Find Coordinates button in order to activate the name resolver. If you have entered an object name in the Object Name entry and you have chosen either SIMBAD or NED, when you press Search, the object name will be resolved to coordinates before a search of the archive database is performed.

However, if you intend to do repeated searches using the same coordinates obtained from SIMBAD or NED, it is recommended that you resolve the coordinates first using the Find Coordinates button, and then do your successive searches.

Resolver
The Resolver setting determines whether or not the text entered in the Object Name entry (if any) is used "as is" to search the archive database (via the Do Not Resolve setting), or whether the text is used in conjunction with the SIMBAD or NED databases to resolve (determine) the RA and Dec coordinates of the named object. If the coordinates are determined, the coordinates will be used to search the archive database.

RA, Dec
The right ascension (RA) and declination (Dec) about which you wish the search to be done. The acceptable formats for RA and Dec are sexigesimal, decimal hours for RA and decimal degrees for Dec in J2000. For example, the acceptable formats for M31 are:
    Decimal hours (RA) and Decimal Degrees (Dec)
       0.712311 (RA) and 41.269039 (Dec)
       0.712311 (RA) and +41.269039 (Dec)

    Sexigesimal 
    RA in hours, minutes, seconds
    Dec in degrees, arcminutes, arcseconds
       00 42 44.32 (RA) and +41 16 08.5 (Dec)
       00:42:44.32 (RA) and  41:16:08.5 (Dec)
    
For the sexigesimal format, you can only delimit the numerical values with a space or a colon.

If you enter coordinates in the RA and Dec entries, but you also enter text in the Object Name entry and choose the to resolve the coordinates, the values entered manually in RA and Dec will be ignored.

Please see the help for Width to understand how the RA, Dec and Width are used in combination to acquire images from the archive.

Width
The Width pertains to the length of a side of a square region (in arcminutes) that is centered on the specified RA and Dec values. Any survey image which contains any portion of this circumscribed region will be acquired from the archive. The default value for Width in the search form is 10; the maximum allowed value is 5400. If no value is provided for this entry, Width will have the value of 0. Floating point values are allowed.

Please see the accompanying graphic for a visual description of how the RA, Dec and Width are used in combination. The object corresponding to the provided RA and Dec values is contained within the light red-shaded box and identified by the black circle at the center of of the box. The length of a side of the red-shaded box (square) is set by the Width value. The red-shaded box is totally encompassed by image 4 (white); the red-shaded box is partially contained within images 2 (green) and 3 (purple). Note only a portion of the red-shaded box need be within an image (2, green) for it to be considered a match to the input criteria; it is not necessary for the input RA and Dec to be within the matching image. Images labelled 2, 3, and 4 will be acquired from the database as matches to the input criteria.

Observation Date
This is the date of the observation. Many of the NOAO Survey Data products are composite images (e.g., coadded from many individual exposures), and the observation date stored in the database is obtained from the composite image. Therefore, the observation date may actually represent the date of the start of the observations (e.g., the observation date of the youngest constituent image in the composite). The acceptable formats for the observation date are:
     Month DD YYYY or Month-DD-YYYY
       Jan 01 1999
       september-27-2000
       Octo 8 1997

     MM/DD/YYYY or MM-DD-YYYY  <== Note American ordering of values.
        01/01/1999
        9-27-2000
        10/1/1997

     DD Month YYYY or DD-Month-YYYY
        01 jan 1999
        27-sep-2000
        1 oct 1997

     YYYY Month DD or YYYY-Month-DD
        1999 JAN 1
        2000-sep-27
        1997 oct 01
     
The text representing the month as a string must have at least three characters, and case does not matter. Single digit numerical values can be represented by "01" or "1". The year must be represented by four digits and only years between 1000-2999 are currently acceptable.

The less than ("<") and greater than (">") symbols can be used with the date in order to search for data before a specified date ("<") or after a specified date (">"). For example,

     Before a date:
        < apr 10 1999
        < 2000 sep 27
        <10/1/1998

     After a date:
        > apr-10-1999
        >2000-sept-27
        > 10/01/1998
     

Photometric Depth
The Photometric Depth has been computed for the case of a Gaussian Point-Spread-Function dominated sky. It is expressed as an N sigma detection above the background sky in units of magnitude, where N is defined by the particular survey. Appropriate input formats are:
       <23.9
       > 20.22
       21.4   <== This format requires an exact match, so it is 
                  limiting and not necessarily useful.
    

Survey
This is a list of the NOAO Survey data currently available in the archive. The default is to search for data from any of the survey datasets; no selection within the listbox is required by the user for the default value of any to be used. Alternatively, you can perform a search based on only selected surveys. Please note multiple surveys may be chosen.

A listing and description of the Survey Programs is available.

Please be aware the listbox which is used to allow the you to choose multiple entries for Survey (as well as other search parameters) is implemented differently for various browsers. The you should ensure that only the desired selections are highlighted in black.

Filter
This is a list of the filters used by the various surveys during the acquisition of the data. The default is to search for data acquired using any of the available filters; no selection within the listbox is required by the user for the default value of any to be used. Alternatively, you can perform a search based on only selected filters. Please note multiple filters may be chosen.

Listings and descriptions of the filters at KPNO and filters at CTIO are available.

Please see Survey help above for more information on the issues related to the listbox widget.

Action Buttons

Search
The Search button is used to begin a search of the database of NOAO Survey Data. Upon successful completion of a search, you will be presented with a new page containing all entries in the database which match the specified search parameters. If there were an error, the main search page will be redisplayed with the error message in red at the top of the page.

Reset to Defaults
The Reset to Defaults button is used to set certain specified parameters to their default values; all the remaining parameters will be cleared.

View Cart
The View Cart button is used to show the contents of your image selection cart. If no cart exists, the selection cart page displays a red message. If the cart exists, a tabular view of the selection is displayed.

Information on the Results Output Page (User Record Viewer)

The output results page provides the user with a tabular listing of results from the database which matches the user's input criteria. In the instance that no matches in the database were found, a message highlighted in red will be displayed at the top of the output results page.

In the instance of successful matches, the number of matches will be indicated at the top of the output results page. This message will be followed by the tabular output information.

If results exceed a specific limit, they are separated into several pages, and links to each page of results are preceeded by "Results Page". The current page is indicated by the page number in bold, and is not a link.

Download
This column contains the names of the data files which match the input criteria. Left-click on a file name to invoke a pop-up window which will allow you to save the file to your local disk.

RA(hms), Dec(dms)
On the output page the RA(hms) and Dec(dms) columns correspond to the RA and Dec coordinate values defined at the center of the output image. Since the algorithm for matching images in the archive based upon the input coordinates and Width parameter setting requires only a portion of the region specified need overlap an image to satisfy the input criteria, the RA and Dec of the matching images will not be the same as the input coordinates. Please see the help for the Width parameter and how it is used in conjunction with the input coordinates to define a search region.

If the database search were invoked using search coordinates, then these columns will also include the the X- and Y-pixel values at the center of the output image, corresponding to the output RA and Dec respectively.

Click on RA(hms) or Dec(dms) to sort the search results. This sorts the images by descending RA or Dec. Click them again to reverse the sort.

Offset in X, Offset in Y
These columns are only present if the archive search were done using input coordinate (RA and Dec) values. These columns represent the offsets or differences, in pixels, between the RA and Dec coordinates input for the archive search and the RA and Dec coordinates of the center of the output matched image.

The accompanying graphic best illustrates the meaning of these offset values. The light red-shaded box is centered on the input RA and Dec values and the length of the box side is set by the Width parameter. Image 1 is a "match" from the archive which contains a portion of the requested search region. The center of Image 1 in both pixels and sexigesimal coordinates is reported in the output columns RA(hms) and Dec(dms). The offset values are represented in a right-handed coordinate system; positive X is to the right, and positive Y is to the top.

Object
The Object column displays the string value of the Object keyword found in the header of the data file. Since this keyword is populated in real-time during the observation, the value may or may not be very descriptive.

Filter
The Filter column displays the string value of the Filter keyword found in the header of the data file. Listings and descriptions of the filters at KPNO and filters at CTIO are available.

Survey
This column contains the database designation for each survey. Currently, the name mappings are as follows:

Survey Name in Search Form Survey Name From the Database
NOAO Deep Wide Field ndwfs
Resolved Stellar Content of Local Group Local Group
Deeprange Deep Range

Select
The Select column is used in conjunction with the Add Selections to Cart button. Click on the checkbox to select the image for addition to the image selection cart.

Action
The Action column contains a mechanism which can be activated via a left-click. This will invoke a pop-up window which provides additional information regarding the data, access to the entire data file header (left-click on View FITS header), access to a block-averaged version of the image in the data file (left-click on Display Image), and access to the cutout viewer (left-click on Cutout Viewer).

For specific help on the Image Cutout viewer, click here.

Action Buttons

Home
Click Home to return to the NOAO Survey Data homepage.

Add Selections to Cart
Click the Add Selections to Cart button to add image selections to the Image Selection Cart. This button is used in conjunction with the Select column in the search results.

View Cart
Click the View Cart button to view your Image Selection Cart. Results are displayed in tabular form, with all columns from the search results except the Select buttons.

Information on the Selection Cart

The Selection Cart is a page to centralize selection of various images. Images can be downloaded from this page individually, or through the Bulk Download mechanism.

Click the link in the Download column to download the file. Click the Stage button to prepare the data for bulk download. This feature provides an anonymous FTP connection to the archive, with a directory containing all staged images.

To remove images from the Cart, click the corresponding checkbox in the Remove column, then click Update Cart.

Action Buttons

Click Stage to prepare the Cart for Bulk Download. Staging may take a while, as the data are prepared and staged into an anonymous FTP directory. Please be patient.

Click Update Cart to remove selections in the Cart. This is used in conjunction with the Remove column in the Cart listing.

Click Home to return to the homepage.

Click Back to go back one page in the browser.

Bulk Download

The Bulk Download utility is provided as a convenience to download many images with the least amount of intervention. The results may take a while to appear. Please be patient.

After the data is staged to the anonymous FTP site, information about which images were staged, and instructions on how to access them are presented.

Staged data have a limited lifetime before they are removed from the FTP site. Please be sure to download all data as soon as possible, if not immediately.

Action Buttons

Back
Click Back to return to the Selection Cart.

NOAO Survey Data Archive Limitations

This archive of NOAO Survey Data (R2) was developed to provide access to processed datasets from the NOAO Surveys Program, with an initial release in April 2002. The R2 code was frozen in the Fall of 2003, and we began developing the next generation archive on a new software foundation. Since then, only bug-fixes have been implemented for the R2 Archive. Requests for upgrades and improvements to the R2 web interface have been and will be considered for incorporation in the new NOAO Archive system. If you have requests or suggestions, please send them to vohelp@noao.edu so that we may make the new archive even better. Thank you for your patience!