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