NRAO Queries (astroquery.nrao)

Getting started

This module supports fetching the table of observation summaries from the NRAO data archive. The results are returned in a Table. The service can be queried using the query_region(). The only required argument to this is the target around which to query. This may be specified either by using the identifier name directly - this is resolved via astropy functions using online services. The coordinates may also be specified directly using the appropriate coordinate system from astropy.coordinates. Here is a basic example:

>>> from astroquery.nrao import Nrao
>>> import astropy.coordinates as coord
>>> result_table = Nrao.query_region("04h33m11.1s 05d21m15.5s")
>>> print(result_table)

  Source     Project    Start Time Stop Time ...  RA DEC ARCH_FILE_ID
---------- ------------ ---------- --------- ... --- --- ------------
  0430+052  SRAM-public         --        -- ...  --  --    181927539
  0430+052  SRAM-public         --        -- ...  --  --    181927647
  0430+052  SRAM-public         --        -- ...  --  --    181927705
     3C120  BALI-public         --        -- ...  --  --    181927008
     3C120  BALI-public         --        -- ...  --  --    181927008
     3C120  BALI-public         --        -- ...  --  --    181927010
     3C120  BALI-public         --        -- ...  --  --    181927016
     3C120  BALI-public         --        -- ...  --  --    181927024
       ...          ...        ...       ... ... ... ...          ...
J0433+0521 13A-281-lock         --        -- ...  --  --    424632771
J0433+0521 13A-281-lock         --        -- ...  --  --    424632771
J0433+0521 13A-281-lock         --        -- ...  --  --    424632771
J0433+0521 13A-281-lock         --        -- ...  --  --    424632771
J0433+0521 13A-281-lock         --        -- ...  --  --    424632771
J0433+0521 13A-281-lock         --        -- ...  --  --    424632771
J0433+0521 13A-281-lock         --        -- ...  --  --    424632771

More detailed parameters

There are several other optional parameters that may also be specified. For instance the radius may be specified via Quantity object or a string acceptable be Angle. By default this is set to 1 degree. equinox may be set to ‘J2000’ or ‘B1950’ for equatorial systems, the default being ‘J2000’. You can also specify the telescope from which to fetch the observations. This can be one of the following.

'gbt' 'all' 'historical_vla' 'vlba' 'jansky_vla'

Another parameter is the telescope_config. Valid values are

'all' 'A' 'AB' 'BnA' 'B' 'BC' 'CnB' 'C' 'CD' 'DnC' 'D'  'DA'

You may also specify the range of frequencies for the observation by specifying the freq_low and freq_up in appropriate units of frequency via astropy.units. The other optional parameters are the sub_array which may be set to ‘all’ or any value from 1 to 5. Finally you may also set the frequency bands for observation

'all' '4' 'P' 'L' 'S'  'C' 'X' 'U' 'K' 'Ka' 'Q' 'W'

Here’s an example with all these optional parameters.

>>> from astroquery.nrao import Nrao
>>> import astropy.units as u
>>> import astropy.coordinates as coord
>>> result_table = Nrao.query_region(coord.SkyCoord(68.29625,
... 5.35431,  unit=(u.deg, u.deg), frame='icrs'), radius=2*u.arcmin,
... telescope='historical_vla', start_date='1985-06-30 18:16:49',
... end_date='1985-06-30 18:20:19', freq_low=1600*u.MHz, freq_up=1700*u.MHz,
... telescope_config='BC', sub_array=1)
>>> print(result_table)

Source     Project    Start Time Stop Time ...  RA DEC ARCH_FILE_ID
 -------- ------------- ---------- --------- ... --- --- ------------
 0430+052 AR0122-public         --        -- ...  --  --    181888822
 0430+052 AR0122-public         --        -- ...  --  --    181888822

Reference/API

astroquery.nrao Package

Module to query the NRAO Data Archive for observation summaries.

Classes

NraoClass()
Conf Configuration parameters for astroquery.nrao.