Gemini Science Archive

Gemini is deploying a new archive system (see here for details). This page and other CADC GSA pages will be removed at the end of December 2015. However, the CADC will continue to provide access to public Gemini data through its Advanced Search interface and Virtual Observatory services.

Gemini Science Archive Form Help

Form Help


Most "fields" in the query form consist of three parts: a label, a check box, and a text box or selection box. First, enter any parameters in the appropriate text boxes or select desired options in the selection boxes. The more entries you make, the more restrictive is your search of the database. Make sure you do NOT select both an object and a coordinate - choose one or the other.

To include a field in the resulting tabular output from the submitted query, click on the check box beside that field. Several of these are selected by default. "Deselect" the check box if you do not want these items listed in the output.

After submitting your query, a table of returned records is produced (assuming the search was successful). If a preview is available, you can preview observations by click on the "P" in the "Pre" column. If a preview is not available "N/A" is displayed.

To retrieve particular data sets simply click on the "Mark" column of the desired observation(s) and click the "Request Marked Datasets" button. You can select every observation in the table by clicking the "MarkAll" button.

Click on a query parameter label for a description of each parameter.

Specifying Query Constraints.

The query forms contain many entries like this:

The following operators are available to constrain the content of the fields:
Less than.
Greater than.
Less than or equal to.
Greater than or equal to.
Not equal to.
Equal to (=NGC will be translated to *NGC*, i.e. wild cards before and after)
As = but ignoring case.
Exact match (No wild-cards). It is important to use this string operator when possible as it will greatly improve database query execution speed and possible server timeouts.
Only a trailing wild card; (e.g. {B600 is translated to B600*)
Wild-card in strings (A*B will match AB, AxB, AxxxxB, etc.).
A range of values (ex.: 234.56 .. 678.9 ).
Will match any of the specified expressions. e.g. "=123 | > 5000 | < 1" and "==partnerCal | ==progCal"

For example, to select all exposures with exposure times greater than 500 seconds you would enter:

The default (no operator) will be interpreted like '~*your-text*'

Some fields have a fixed set of possible values from which you can choose.

If no items are selected from the above menu, then there is no constraint on this field. More than one entry can be selected.

Specifying dates and range of dates

Dates can be specified in several formats. Examples include "MM/DD/YY" or "Day Month Year". If a range is desired, two dates can be separated by two single dots (..). For example, to select all exposures that started between the 1st of January and the 5th of February 2002 you could enter :

Specifying the search box for coordinates

In most catalogues, it is not feasible to search directly by target names since there is no standard for naming astronomical targets. We strongly suggest that users use the SIMBAD/NED resolver instead. Then any known astronomical name can be used with the name resolver providing the coordinates.

To specify the size of the search box around these coordinates a box size (DD MM SS) must be specified. The default box size is 10 arc minutes.

Submitting your query

To get the result of your query you have to submit it. At the top and at the bottom of the query form you will see a set of buttons like this :

In order to to submit your request press the "Search" button. If you want to reset all of the fields back to their original values simply press the "Reset" button.

Want more info on each retrieved records?

For each dataset retrieved from the GSA, clicking on the dataset name enables the user to retrieve additional information for this particular entry in the archive.