GALEX Science Search Help

This page describes how to use the GALEX Science Search form and describes the individual fields in that form.

Use the GALEX Science Search form to search the GALEX Archive Catalog by object name and position.

All object searches should include either a NED/Simbad-resolvable target name or coordinates, plus a search radius. This requirement differs from many of the other Search forms for other MAST missions.

RA Column Number

The column number containing either the Right Ascension or the target name (depending on how file_contents is set). The default is to assume the first column contains the RA value.

Dec Column Number

The column number containing the Declnation. The default is to assume the second column contains the DEC value.

Column Delimiter

The character used to delimit table entries in the uploaded file. Allowed values include tabs( ), commas(,), vertical bar (|), or semi-colons(;). The default is to assume tabs are the delimiters.

Object Name

The name of the astronomical object you want to search for. Examples of valid names include M101, NGC 1068, and Ark 123.  Avoid bright point-source objects (less than magnitude ~10) that cannot be observed by GALEX.

The Object Name is used in combination with the Resolver Field. If the SIMBAD or NED Resolver options are chosen, then coordinates returned from these services are used to perform the search.

Resolver

The name resolver you want to use, if you want to resolve an object into its coordinates. You can resolve an object name either before a search, or you can redraw the form with the resolved coordinates in place. You can also elect not to resolve the object name when doing the search, and search the database on the object name instead.

The resolver services that may be chosen are NED and SIMBAD. NED is the NASA Extragalactic Database at Caltech in Pasadena, California, and SIMBAD is the Set of Identifications, Measurements, and Bibliography for Astronomical Data at the Centre de Données astronomiques in Strasbourg, France. The object name will be sent to the chosen resolver, which will send back the coordinates. (If the object name is not recognized by the resolver, or there is some other problem with the SIMBAD or NED services, then the search form will be redrawn with an error message at the top.) These coordinates will then be used to search the database, along with whatever other query qualifications you have given.

We recommend that you use object name resolution to find observations of specific objects in the database. This is the most reliable way to look up observations, because the observer could have given any object name at all (for example, NGC1976 instead of M42, or PARALLEL-FIELD). However, if you do know the object name that the observer used, you can select Don't resolve, in which case the object name will not be resolved into coordinates, but will be used as a search qualification in the database. (This will happen only when you press the Search button.)

The SIMBAD and NED object name resolvers can resolve only fixed objects; they cannot compute the positions of moving objects (planets, comets, etc.). NED is an extragalactic database, and generally won't resolve object names within the Milky Way galaxy.

Right Ascension, Declination

The Right Ascension and Declination values. If single values are entered, a cone search is performed using the specified search radius (default = 3 arcminutes).

Coordinate values may be specified using a number of formats. Examples of accepted values include:

Decimal Degrees
185.63325 29.8959861111111

Hours, minutes and Seconds
12 22 31.98      29 53 45.55
12h22m31.98s     29d53m45.55s
12:22:31.98     +29:53:45.55
12h22'31.98"     29d53'45.55"
12h 22m 31.98s   29d 53m 45.55s
12h 22' 31.98"   29d 53' 45.55"
12h 22' 31.98"  -29d 53' 45.55"
12h22'31".98    -29d53'45".55
12h22m31s.98    -29o53m45s.55
12h 22' 31".98  -29d 53' 45".55

Hours/Degrees and Minutes (no seconds)
12 22     29 53
12h22m   +29d53m
12h22m    29d53m
12:22m    29:53m
12h22'    29d53'
12h 22m   29d 53m
12h 22'   29d 53'
12h 22'  -29d 53'

The RA may be given in decimal degrees by indicating
a D or d after the degrees:
12d 22m   29d 53m

Spacing is not important, as long as the value is unambiguous, and that you can delimit the hours/degrees, minutes, and (optional) seconds with letters, colons, spaces, or any character that's not a digit or a decimal point.

Radius

The radius of the search box around the RA and Dec, in floating-point arcminutes (e.g., 5.0). You should be careful about giving too restrictive a search radius since (for some missions) the coordinates of the object were given by the Guest Observer, and may not reflect the precise pointing of the instrument at the time of the observation.

The search routine computes the angular separation between each result dataset and the search center so this really is a circular radius. (Results are generally sorted on the angular separation by default.) Note a range may also be specified so, for example, to search for all observations between 2 and 8 arcminutes from the center of a galaxy, just enter 2 .. 8 for the radius.

Equinox

The equinox of the RA and Dec you have entered, either B1950 or J2000. (Note: currently only J2000 is allowed as input.) This only applies to the input coordinates. The coordinates displayed in the search results will depend on the mission database and the selected output columns. (Note: all MAST missions include J2000 coordinates as default output columns.)

If you enter n object name and use either the SIMBAD or NED name resolver, the equinox will be set to J2000.

User-defined Field / Field Contraint

Enter you own contraints on the most commonly used keywords. These type of contraints are used to further reduce the number of objects returned by a query. For additional syntax information see Coordinates

Output Columns

This form element allows one to choose the columns to be displayed and their order, for the search results. A set of columns that are commonly requested has been chosen as a default.

You remove output columns by highlighting the column to be removed and then clicking on the remove button to the right of the output columns list.

You may determine the order of columns by highlighting a column and then clicking on the up or down buttons to the right of the list of chosen output columns.

You may also add a column to the list. Select the desired column from the pull down menu beneath the list of chosen output columns, then click the add button. The column will be added to the bottom of the output column list.

Note the output column form element has its own reset button to restore the list of output columns to the values initially displayed when the page was drawn. The reset button at the top of the form is used to reset the other form elements. Clicking the "clear form" button however can be used to restore the original default values.

Sort output by:

Choose how you want the output rows sorted. You can select up to three fields to sort on. The rows will be sorted in the order of the first sort field; if two rows have the same sort field, they will be sorted in order of the second sort field, and so on.

For each field, you can select that the rows be sorted in reverse order on that field by selecting the reverse checkbox. For example, you can sort the rows with the most recent observations first by selecting Observation Date for the first sort field and selecting the reverse checkbox next to it.

Maximum number of records

Some queries will be capable of returning thousands of rows or more. such large search results tend to use up memory on both the client and server sides, and aren't usually useful. For the standard search form, the default number of rows displayed is set to 100, but you can increase (or decrease) this limit as needed. For the file upload form in which multiple targets or coordinates can be specified, the default is set to 10 rows per entry.

Show SQL Query

Select this checkbox if you want to see the SQL query that the IUE Search engine constructs from your query qualifications. The query will be shown at the end of the search results.

SQL (Standard Query Language, pronounced either "ess cue ell" or "sequel") is a language used used by most relational database systems for retrieving information from database tables. The sarch script takes your search specifications and converts them to an SQL query to run on our database. Viewing the generated query is often useful for debugging, and may also be useful for SQL-literate users who want to see what logic was used in the query. (In fact, this may be useful for most people, since SQL is pretty easy to understand.)

Make Rows Distinct

Select this checkbox if you want to have a set of distinct rows displayed. This is useful if you would like to see a distinct list of objects with certain criteria e.g. all the objects within an IUE or FUSE object class. In this case, one would limit all but the "Object Name" (or RA and Dec); this is done with the "Remove" button in the Output Columns window. This action permits a selection only on unique object names (or coordinates) that have been observed by the satellite for the object class given. (Hint: be sure to keep the "Maximum Records" number large enough for the length of your anticipated list!) Also note that columns such as RA, Dec and Magnitude were frequently defined by the observer and often have different values for the same object name. If columns such as these are chosen as output columns, there will often be more than one row listed per object name.

Output Format

You may choose one of following four formats for displaying/storing search results :

1. HTML_Table (default) - results stored as a standard HTML table including various links for displaying previews, literature references, plotting spectra, etc.
2. CSV (comma separated values) - a simple ASCII file containing column headings followed by comma-separated entries. In file upload mode, a blank line is inserted between database queries. (Note this option will execute more quickly then the others since it involves the least amount of processing),
3. Excel_Spreadsheet - results are stored as an Excel spreadsheet table (note: assumes users computer/browser provides support for Excel-format files),
4. VOTable - an XML file format being considered for the NVO project. For searches returning results from more than one mission and/or object, multiple "resource" tags are created. Searches with a radius of 0 will return a VOTable file listing the output fields for that particular mission/catalog. (See VOTable documentation.)

Note: If no entrees are found for an entry in file upload mode, a "no entries found" message is written in the selected format and the program continues. In the standard mode, "no entries found" results will be returned as an HTML page, showing the search form with the original search selections. The user can them modify the selection criteria and resubmit the form. For all VOTable output, all messages and results are returned in VOTable format. In all cases, error conditions will cause the database search to abort.