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Hints for Searching for Data in MAST
- Searching for Planets, Comets and Asteroids
- Searching by object class in the HST archive
- Search HST catalog by Region in the Sky
- Searching with ranges of coordinates
- Searching with ranges in time
- Searching Across Multiple Missions
- Comparing observations from two different missions
- Abstract Searches
- VizieR / MAST Cross Correlation Search
- High-Level Science Product Searches
- Performing Large HST Searches
- How to Locate and Retrieve the HST Ephemeris
- Return to the Tutorial Index
Using coordinates to search MAST for moving targets such as planets and comets
is not usually the most efficient way of locating such observations.
The most straightforward way to search for observations of such a target is to search
on the object name using the "Don't Resolve" option in the Resolver form element.
For some of the MAST missions, such as HST, the object name is designated by the
original observer.
For example, an observation of Jupiter might have the object name "CP1-JUP-NORTH-LIMB-A".
To find all the items of interest you may want to use a wild card search using the minimum
number of characters. To do this enter *JUP* in the target element of the search form.
You must remember to choose the "Don't Resolve" option in the resolver form element.
You can narrow the search using such items as the time of observation, instrument, filter etc.
This type of search may take a little longer than a search by coordinates.
For some MAST missions, targets have been assigned a target class or category.
You can utilize this to find all solar system objects. For shorter duration missions, such as
HUT or UIT this might be the most efficient way of searching for planets or comets.
For longer term missions such as IUE, this type of search will find many rows unless
you are able to narrow the search using other criteria such as time or exposure length.
HST observations are not assigned an object class, but are given a short descriptions of the target.
Every morning we generate a list of all the target descriptions
currently in use. This list is linked back to the HST Science Search page,
so you can read through this list (or search it with your browser's find capability)
and find datasets matching the description. (see the next section
for hints on searching by object class in the HST Archive).
Another way to locate observations of solar system objects is to search the
abstracts of missions with a Guest Investigator program
(HST, FUSE,
IUE, EUVE).
Entering the target of interest into these search forms will find programs that planned to observe the target.
A list of the programs contains the abstract as well as
links to listings of the observations associated with that program.
There are two object category fields in the HST Archive:
the "broad category" and the "target description" fields.
The target description field is one of the fields explicitly
on the HST search form.
This is the longer description and probably the more useful search field.
You may also search on the broad category utilizing the
User-specified field options on the search form.
The format is NOT uniform and so you will need to utilize wild cards
to search on a keyword or phrase.
The words might be separated by semi-colons, spaces, or dashes so you will need to place a wild card
between each word or phrase in the search criteria.
For example: *GALAXY*SPIRAL*. This search will find most of the observations of interest.
However, word order is important so you might need to try *SPIRAL*GALAXY* as well.
Searches on object category fields are likely to return many rows.
You may wish to further qualify your search by instrument, filters etc.
Every morning we generate
a list of all the target descriptions
currently in use. This list is linked back to the HST Science Search page,
so you can read through this list (or search it with your browser's find capability)
and find datasets matching the description.
Another way to locate observations of possible interest by category is to utilize the
(HST abstract search.
Entering the target of interest into this search form will find programs
that proposed to observe the target. A list of the programs contains the abstract
as well as links to listings of the observations associated with that program.
Using the VizieR/MAST or the NED/MAST Cross-correlation tools are two addtional ways of finding classes of
targets within the MAST archive. See the tutorial section
VizieR/MAST Cross Correlation Search or the section MAST/NED Cross Correlation Searchfor more information.
There was a tutorial published in the January 2007 Archive Newsletter (also available as a powerpoint presentation, and in the .
The MAST "pointings" interface allows a user to search for ACS, WFPC2, STIS, FOC and NICMOS images in a powerful way.
For each of these instruments we have assembled a searchable data table that allows users to look for sky regions (or pointings) which have been observed N times or more, observed with 2 or more filters, or have been observed more than twice with a time separation of more than (or less than) N days. An exposure is defined to be the file created after the shutter closes. The total number of exposures for each of the defined bands within a defined pointing were tallied.
The definition of a pointing is different for each instrument.
See the Search Help page for a more complete description of the methodology used to define a pointing.
This page also includes descriptions of the search fields and the input and output columns.
You may search on 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,
Searching on ranges of time is important if you wish to search on any time field. If you enter the
date July 19, 2002, then midnight (00:00:00) is assumed. If you enter July 2002, then the date
July 1, 2002 at midnight is assumed. If you don't know the exact time of an observation then you will need to search
using a range.
To search for observations before a given date, use <, and for observations after a given date, use >.
For example,
You can use the .. operator to search on a range of dates. To find all observations in July 2002 enter:
Finally, you can search on a list of dates or date ranges. For example,
The MAST Cross Correlation Search
permits searches across all the HST instruments and most MAST missions.
This interface is similar to the mission search forms.
For more detailed information about search options see the
help page.
The top section is the same as the mission search forms and includes both the standard
and file upload options. The second section permits selection of the instruments of
interest. You may customize the search radius for any of the instruments.
The third section gives some options such as the output format, but the options
are not as extensive as the mission search pages.
The output from the search is grouped by instrument. Up to 10 rows are displayed for
each instrument, but the number of available rows is displayed. The output utilizes
the default output fields for each instrument/mission. The HTML version includes links
to the previews, the proposal search, the references and High-Level Science Products.
At the bottom of the output display is a summary listing each instrument and the number of
observations found per instrument. The summary is not listed in the CSV, Excel and VOTable formats.
Perhaps you are interested in seeing what targets (perhaps of a specific type of object)
have been observed by two different missions. If you have a list of specific target then the
easiest thing is to just use the Cross-correlation search described just above.
But perhaps you are just interested in finding out what BL Lacertae objects have observed
by both FUSE and STIS without a pre-determined list of objects.
First you would need to determine the unique target names or coordinates observed by
one of the instruments for that type of target. You might choose to obtain this initial
list from the FUSE search, as it is easier to search by object class.
Follow these steps:
The abstract search form can be used to find
HST,
FUSE,
IUE, and
EUVE proposal abstracts or titles
containing specific words or phrases.
You may also search on proposer name and proposal id.
Fairly complex searches may be performed using the search forms.
For more details see the search form help pages.
The results list the proposal id, the title, the PI and institution and the abstract.
Search criteria are highlighted in red in the search result display.
The proposal ID is a link to the proposal search.
For HST, the PI name is a link to a search that lists other HST proposals by authors
with that last name.
You can find the abstract search on the Searches page under the mission specific searches.
There is also a link under the Search & Retrieval left menu pullout for the appropriate missions.
The VizieR / MAST Cross Correlation Search permits users
to search for catalogs held by VizieR
and then to either search them internally or to
use them as input for a MAST cross-mission search. There is a
help page for these searches, but below is an overview of the process.
First search for a VizieR catalog.
When searching for a catalog name, you will often be more successful if you search using a wild card (e.g. *Abell*).
The results of the search list the catalogs found at VizieR with two options to the left of each found catalog (S and CC).
There are two kinds of High-Level Science Product (HLSP) searches.
One is a search by Project
and the other is a search by target.
Search by HLSP Project
Search HLSP by target
The output lists the project, filename and other associated information.
The project id is a link to a webpage giving more information about that project.
The filename is a link that permits you to download the data directly to your workstation or desktop.
Most HLSP are also stored in the anonymous ftp area on archive.stsci.edu.
See the page on download options for more information
Links to the HLSP searches may be found in the left navigation menu for the main MAST page
and for each mission with associated HLSP. The searches are also on the
searches web page linked from the top navigation bar which appears on
most MAST web pages.
You may need to perform searches and make requests for large amounts of data.
MAST web based search forms currently limit the number of rows returned
from a query to a maximum of 15,000 rows. Additionally, if you want to retrieve
a large number of data sets, requests should probably be kept to less than a few
thousand observations. Please see the
Submitting Large Requests
page for more information and options. i
Advice is also available on submitting
large HST requests.
This page also documents some HST operation limititations that you may
need to take into consideration.
Searching for Planets, Comets and Asteroids
Searching by Object Class in the HST Archive
Search HST catalog by Region in the Sky
Searching with Ranges of Coordinates
> 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.)
Searching with Ranges in Time
> Jul 15 2002
< Jul 15 2002
Jul 1 2002 .. Aug 1 2002
This operator is inclusive on the first date and exclusive on the second.
Jul 1 2002 .. Jul 3 2002, Dec 1 2002 .. Dec 6 2002
will search for observations done within either one of these date ranges.
Searching Across Multiple Missions
Comparing observations from two different missions
After editing the file to remove any header information, you may use this file as input for an
HST search.
Follow these steps:
Abstract Searches
VizieR / MAST Cross Correlation Searches
High-Level Science Product Searches
This is a simple form with three search criteria: Product Type, Wavelength, and Object Type.
The attributes were assigned by the MAST staff scientists.
To search select one or more of each criteria.
Hold down the shift key to select more than one option per category.
After you click on the Search button, a list of pertinent sets of HLSP is displayed.
The form includes a listing of all the HLSP sets grouped by Product type.
The search results use the same display format.
The title is a link to a web site giving more information about that set of data.
Most sets of HLSP have a "Search" button link to the left of the title. Click on that search button
to get a listing of all the HLSP products from that project.
A few sets of data have not yet been completed or are not actually hosted at MAST.
These do not have a search button.
This search looks like a mission search form with the usual three
page sections. As usual, the top section allows you to enter target names or coordinates.
The second section permits you to specify specific projects and
limit the search by instrument, product type and format.
The third section permits you to specifiy the output content and formats.
Performing Large Searches
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