Gemini Queries (astroquery.gemini)

Getting Started

This module can be used to query the Gemini Archive. Below are examples of querying the data with various parameters.

Positional Queries

Positional queries can be based on a sky position. Radius is an optional parameter and the default is 0.3 degrees.

>>> from astroquery.gemini import Observations
>>> from astropy import coordinates, units

>>> coord = coordinates.SkyCoord(210.80242917, 54.34875, unit="deg")
>>> data = Observations.query_region(coordinates=coord, radius=0.3*units.deg)
>>> print(data[0:5])

exposure_time detector_roi_setting detector_welldepth_setting  telescope   ...
------------- -------------------- -------------------------- ------------ ...
     119.9986           Full Frame                         -- Gemini-North ...
     119.9983           Full Frame                         -- Gemini-North ...
     119.9986           Full Frame                         -- Gemini-North ...
     119.9983           Full Frame                         -- Gemini-North ...
      99.9983           Full Frame                         -- Gemini-North ...

Observation Name Queries

You may also do a query by the name of the object you are interested in.

>>> from astroquery.gemini import Observations

>>> data = Observations.query_object(objectname='m101')
>>> print(data[0:5])

exposure_time detector_roi_setting detector_welldepth_setting  telescope   ...
------------- -------------------- -------------------------- ------------ ...
     119.9986           Full Frame                         -- Gemini-North ...
     119.9983           Full Frame                         -- Gemini-North ...
     119.9986           Full Frame                         -- Gemini-North ...
     119.9983           Full Frame                         -- Gemini-North ...
      99.9983           Full Frame                         -- Gemini-North ...

Observation Criteria Queries

Additional search terms are available as optional arguments to the query_criteria call. These all have default values of None, in which case they will not be considered during the search.

Some examples of available search fields are the instrument used, such as GMOS-N, the observation_type, such as BIAS, and the program ID. For a complete list of available search fields, see query_criteria

>>> from astroquery.gemini import Observations

>>> data = Observations.query_criteria(instrument='GMOS-N',
...                                    program_id='GN-CAL20191122',
...                                    observation_type='BIAS')
>>> print(data[0:5])

exposure_time detector_roi_setting detector_welldepth_setting  telescope   mdready ...
------------- -------------------- -------------------------- ------------ ------- ...
          0.0        Central Stamp                         -- Gemini-North    True ...
          0.0           Full Frame                         -- Gemini-North    True ...
          0.0           Full Frame                         -- Gemini-North    True ...
          0.0           Full Frame                         -- Gemini-North    True ...
          0.0           Full Frame                         -- Gemini-North    True ...

In addition, the criteria query can accept additional parameters via the *rawqueryargs and **rawquerykwargs optional parameters.

The orderby parameter can be used to pass the desired sort order.

>>> from astroquery.gemini import Observations

>>> data = Observations.query_criteria('centralspectrum',
...                                    instrument='GMOS-N',
...                                    program_id='GN-CAL20191122',
...                                    observation_type='BIAS',
...                                    filter='r',
...                                    orderby='data_label_desc')

Observation Raw Queries

Finally, for ultimate flexibility, a method is provided for driving the “raw” query that is sent to the webserver. For this option, no validation is done on the inputs. That also means this method may allow for values or even new fields that were not present at the time this module was last updated.

Regular args search terms are sent down as part of the URL path. Any kwargs are then sent down with key=value also in the URL path. You can infer what to pass the function by inspecting the URL after a search in the Gemini website. This call also supports the orderby kwarg for requesting the sort order.

This example is equivalent to doing a web search with this example search . Note that NotFail, notengineering, RAW, and cols are all sent automatically. Only the additional terms need be passed into the method.

>>> from astroquery.gemini import Observations

>>> data = Observations.query_raw('GMOS-N', 'BIAS', progid='GN-CAL20191122')
>>> print(data[0:5])

exposure_time detector_roi_setting detector_welldepth_setting  telescope   mdready ...
------------- -------------------- -------------------------- ------------ ------- ...
          0.0        Central Stamp                         -- Gemini-North    True ...
          0.0           Full Frame                         -- Gemini-North    True ...
          0.0           Full Frame                         -- Gemini-North    True ...
          0.0           Full Frame                         -- Gemini-North    True ...
          0.0           Full Frame                         -- Gemini-North    True ...

Authenticated Sessions

The Gemini module allows for authenticated sessions using your GOA account. This is the same account you login with on the GOA homepage at https://archive.gemini.edu/. The astroquery.gemini.ObservationsClass.login method returns True if successful.

>>> from astroquery.gemini import Observations

>>> Observations.login(username, password)
>>> # do something with your elevated access

File Downloading

As a convenience, you can request file downloads directly from the Gemini module. This constructs the appropriate URL and fetches the file. It will use any authenticated session you may have, so it will retrieve any proprietary data you may be permissioned for.

>>> from astroquery.gemini import Observations

>>> Observations.get_file("GS2020AQ319-10.fits", download_dir="/tmp")

Reference/API

astroquery.gemini Package

Classes

ObservationsClass(*args)

Query class for observations in the Gemini archive.