This page describes how to use the HSTonline Science Search form and describes the individual fields in that form. Please note that at the time of release the following links may lead to or link to other services that have the old or DADS versions of the data.
In addition, some of the examples below may contain references to other HST instruments. However, you should be able to use them as a guideline.
Use the HSTonline Science Search form to search the HSTonline Catalog by object name, position, observation date, proposal ID, wavelength, and data type. You can also mark data for retrieval using this interface. The HSTonline catalog contains meta-data for GHRS, FOC and FOS data.
If you mark data to download, the requested data will be gathered into a tar file and downloaded directly to your computer.
The search script will perform a database search for each extracted Data ID, target, or set of coordinates, contained in the uploaded list. Target names will be resolved to coordinates. If a resolver error occurs, the search will abort and the compiled results displayed. Coordinates may be given in several formats including sexigesimal and decimal degrees. If the output is requested in CSV or Excel spreadsheet format, a blank line will be used to distinguish the results of one target search from another. VOTable format incorporates separate RESOURCE tags for each database query.
Use the other form entries to specify field delimiters,
RA, DEC, or Target column numbers (when the file contains a table
of values), and file contents (target names or coordinates).
The browse button allows users to seach local directories to
locate files.
Warning: Since uploading long lists can take a while to run,
uploaded files are limited to 5,000 entries.
Note that each target, set of coordinates, or Data ID (when > 200 Data IDs are entered) specified in the uploaded file, is treated as a separate query. The results are displayed as each query is run. If less than 200 Data ID's are entered, it is processed as a single query (e.g., select * where data_id = did1 or data_id = did2 or data_id = did3 ...). Larger lists can cause memory problems which is why entries are treated as separate queries.
To avoid displaying column names after each query, consider usinig the comma-separated values output format.
The Target Name is used in combination with the Resolver Field. If the SIMBAD, CFA (SIMBAD at CfA), NED (default) or HLA name resolver options are chosen, then coordinates returned from these services are used to perform a cone search with the specified search radius.
You do NOT have to use the resolver. Choose the "Don't resolve" option to perform string searches on the object name in the database.
When you search on the object name in the database (i.e. without using the name resolver), case will be ignored. The object name will not be wildcarded at the front and back automatically (that's so if you innocently enter IO, you don't match things like ORION). You can however wildcard the object name using * (for example, *IO*). You can also enter a comma-separated list; for example, *JUP*,*SAT* would match object names containing either JUP or SAT. Note that most, if not all, missions store target names in a format that is not always compatible with the NED or SIMBAD name resolvers.
The two main name resolver services are SIMBAD and NED. 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 (SIMBAD at CDS). A mirror site at the Center for Astrophysics in Boston is also now available and is denoted as "SIMBAD at CFA". NED is an extragalactic database, and generally won't resolve object names within the Milky Way galaxy.
Because we occasionally have problems with network connections and web servers, we now store previously resolved target names and coordinates in our own local database and search this database before trying to access the other name resolvers using various web services. By default, If no entry is found in the local cache, the entered object names will first be sent to the NED service, and, if still not found, then CFA, CDS, and HLA in that order. You may also go directly to CFA, CDS, or HLA by changing the selected name resolver, although the local cache is always checked first.
If any error occurs, the search form will be redrawn with an error message at the top. Otherwise, the returned 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 stationary targets. 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).
The SIMBAD and NED name resolvers can resolve only fixed objects; they cannot compute the positions of moving objects (planets, comets, etc.). To find moving objects, try selecting the appropriate category option available on most MAST search forms, or as mentioned above, enter an object name that could match what you're looking for, and select "Don't resolve" for the name resolver. Note wild cards are allowed, so for Jupiter you might enter "*JUP*".
Note the examples listed below (and elsewhere) are only intended to show the format of the form entries. There is no guarantee that entering these specific values will return any search results.
You may also enter ranges of right ascension or declination, using the ".." operator. For example, you can enter 21h 51m .. 21h 52m for the right ascension, and 28 51 .. 29 51 for the declination. Comparators can also be used, i.e. ">", ">=", "<", "<=". For example, "> 85" as a declination value will return all observations with declination larger than 85 degrees. (Note when ranges of coordinates are specified the search radius will be ignored. Also, searches on ranges can be quite time consuming.)
Coordinate values may be specified using a number of formats. Examples of valid formats 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. 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.
Like target names, multiple coordinates can be entered if separated by commas.
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.
Note the precession is only applied 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 a target name and use either the SIMBAD or NED name resolver, the equinox will be set to J2000.
Jul 15 1994
Jul 1994 15
15 Jul 1994
1994 Jul 15
1994 15 Jul
7/15/1994
7-15-1994
7.15.1994
If the day is omitted, the first day of the month is assumed. This means that a specification
like "July 1994" will look for observations done on July 1 1994 00:00:00,
not for observations done during July 1994. Note also that when entering a date with the month in
numerical format, the American ordeing is used; i.e., the first number is the month.
If a time is omitted, then midnight (00:00:00) is assumed. Otherwise, you can specify a time in any of these formats:
14:30
14:30:20
14:30:20:999
14:30:20.9
4am
4 PM
04:30:20 AM
To search for observations before a given date, use <, and for observations
after a given date, use >. For example,
> Jul 15 1994
< Jul 15 1994
You can use the .. operator to search on a range of dates:
Jul 1 1994 .. Aug 1 1995
This operator is inclusive on the first date and exclusive on the second.
Finally, you can search on a list of dates or date ranges. For example,
Jul 1 1994 .. Jul 3 1994,
Dec 1 1995 .. Dec 6 1995
will search for observations done within either one of these date ranges.
< 100 > 1000.0 100 .. 1000You can exclude a range of exposures using a comma:
< 100, > 1000
Every morning, we generate a list of all the target descriptions currently in use. This list is linked back to the HSTonline Search page, so you can read through this list (or search it with your browser's find capability) and find datasets matching the description.
50CCD, 50CORON, WF2-FIX, WF3-FIX are a subset of the complete list.
F606W is a subset of the complete list.
You may want to enter a list of filters separated by a comma e.g. F110W, F160W .
For some instruments (e.g. ACS) you may need to use a wild card when specifying the filter/grating. *F658N*
If you enter a list of filters you will need to wild card each member of the list: *F658N*,*F775W*
About 75% of all science datasets are archived within 24 hours after the end of the observation (delays longer than this are usually due to problems in pipeline calibration, or if the data stream gets backed up. Delays like this are rare, however, and are more likely to apply to the newer instruments early in their careers.)
As an example, a Kepler user might select "E(B-V)" from the pulldown menu and enter "< 0.5" in the "Field Descriptions" box.
NOTE only fields which are not already included on the search form should be selected. Specifying search criteria for a field that is listed in BOTH the form and in the User Specified field, may cause either the query to fail or return unexpected results.
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 will restore the original defaults to all isections of the form.
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.
One word of caution: the selected sort field can change the search results when the query finds more rows than are displayed ( i.e, when the number of found rows exceeds the value of "maximum records"). For example, for a search on a particular coordinate that finds 5,000 entries, if the search is sorted on exposure time and 1,001 rows are to be displayed (the default), then the 1,001 shortest exposures from the 5,000 found entries will be displayed which may not include the entries closest to the desired position. (It is a good idea to always sort on "ang_sep" for target or coordinate searches).
Note when displayed as HTML, the latest search scripts will display 50 records per page. Links to the additional pages are shown on the results page. This paging feature however does require javascript to be turned on.
When queries are submitted as a web service, the default number of rows returned is 2,000, but any value is allowed when max_rows is specified as a query parameter. (See the MAST Web services page for more information.)
SQL (Standard Query Language, pronounced either "ess cue ell" or "sequel") is a language used by most relational database systems for retrieving information from database tables. The search 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.)
As an example, a IUE or FUSE user might want to create a list of unique target names for a specific object class/category. He or she would specify the desired object class, select only "object Class" and "target name" for the output columns, click the "Make Rows Distinct" button, then click "Search".
Note that for some missions, columns such as RA, Dec and Magnitude were frequently defined by the observer and often have different values for the same target. If columns such as these are chosen as output columns, there will often be more than one row listed per object name.
Note: If no entries are found for an entry a "no entries found" message is written in the selected format and the program continues. In all cases, error conditions will cause the database search to abort.