NED Queries (astroquery.ipac.ned)¶
Getting Started¶
This module can be used to query the Ned web service. All queries other than
image and spectra queries return results in a Table. Image
and spectra queries on the other hand return the results as a list of
HDUList objects. Below are some working examples that
illustrate common use cases.
Query an object¶
This may be used to query the object by name from the NED service. For instance if you want to query NGC 224
>>> from astroquery.ipac.ned import Ned
>>> result_table = Ned.query_object("NGC 224")
>>> print(result_table) # an astropy.table.Table
No. Object Name RA ... Redshift Points Diameter Points Associations
degrees ...
--- ----------- ---------- ... --------------- --------------- ------------
1 MESSIER 031 10.68479 ... 37 13 2
Query a region¶
These queries may be used for querying a region around a named object or
coordinates (i.e near name and near position queries). The radius of
the region should be specified in degrees or equivalent units. An easy way to do this is to use an
Quantity object to specify the radius and units. The radius may also
be specified as a string in which case it will be parsed using
Angle. If no radius is specified, it defaults to 1
arcmin. Another optional parameter is the equinox if coordinates are
specified. By default this is J2000.0 but can also be set to B1950.0.
>>> from astroquery.ipac.ned import Ned
>>> import astropy.units as u
>>> result_table = Ned.query_region("3c 273", radius=0.05 * u.deg)
>>> print(result_table)
No. Object Name RA ... Diameter Points Associations
degrees ...
--- -------------------------- ---------- ... --------------- ------------
1 WISEA J122855.03+020309.1 187.22917 ... 0 0
2 SSTSL2 J122855.02+020313.7 187.22925 ... 0 0
3 SSTSL2 J122855.23+020341.5 187.23013 ... 0 0
4 SSTSL2 J122855.36+020346.9 187.23068 ... 0 0
... ... ... ... ... ...
863 SSTSL2 J122918.24+020330.7 187.326 ... 0 0
864 SDSS J122918.38+020323.4 187.3266 ... 4 0
865 SSTSL2 J122918.52+020338.9 187.32718 ... 0 0
866 SSTSL2 J122918.64+020326.7 187.32767 ... 0 0
Length = 866 rows
Instead of using the name, the target may also be specified via
coordinates. Any of the coordinate systems available in astropy.coordinates
may be used (ICRS, Galactic, FK4, FK5). Note also the use of the equinox keyword argument:
>>> from astroquery.ipac.ned import Ned
>>> import astropy.units as u
>>> from astropy import coordinates
>>> co = coordinates.SkyCoord(ra=56.38, dec=38.43,
... unit=(u.deg, u.deg), frame='fk4')
>>> result_table = Ned.query_region(co, radius=0.1 * u.deg, equinox='B1950.0')
>>> print(result_table)
No. Object Name RA ... Diameter Points Associations
degrees ...
--- ------------------------- ---------- ... --------------- ------------
1 WISEA J035137.90+384313.7 57.90793 ... 0 0
2 WISEA J035138.59+384305.6 57.91062 ... 0 0
3 WISEA J035139.28+384324.4 57.91371 ... 0 0
4 WISEA J035139.77+384507.4 57.91572 ... 0 0
... ... ... ... ... ...
631 WISEA J035237.78+384519.3 58.15743 ... 0 0
632 WISEA J035238.62+384431.9 58.16083 ... 0 0
633 WISEA J035238.74+384352.1 58.16145 ... 0 0
634 WISEA J035238.84+384437.0 58.16177 ... 0 0
Length = 634 rows
Query in the IAU format¶
The IAU format for coordinates may also be used for querying
purposes. Additional parameters that can be specified for these queries is the
reference frame of the coordinates. The reference frame defaults to
Equatorial. But it can also take the values Ecliptic, Galactic and
SuperGalactic. The equinox can also be explicitly chosen (same as in region
queries). It defaults to B1950 but again it may be set to J2000.0. Note
that Ned report results by searching in a 15 arcmin radius around the specified
target.
>>> from astroquery.ipac.ned import Ned
>>> result_table = Ned.query_region_iau('1234-423', frame='SuperGalactic', equinox='J2000.0')
>>> print(result_table)
No. Object Name RA ... Diameter Points Associations
degrees ...
--- ------------------------- ---------- ... --------------- ------------
1 WISEA J123639.37-423822.9 189.16406 ... 0 0
2 WISEA J123639.47-423656.3 189.16458 ... 0 0
3 WISEA J123639.61-423637.9 189.16506 ... 0 0
4 WISEA J123639.91-423709.9 189.1663 ... 0 0
... ... ... ... ... ...
760 2MASS J12374631-4236174 189.44299 ... 0 0
761 WISEA J123746.44-423727.9 189.44359 ... 0 0
762 WISEA J123746.48-423838.1 189.4437 ... 0 0
763 WISEA J123747.07-423742.9 189.44616 ... 0 0
Length = 763 rows
Query a reference code for objects¶
These queries can be used to retrieve all objects that appear in the specified
19 digit reference code. These are similar to the
query_bibobj() queries.
>>> from astroquery.ipac.ned import Ned
>>> result_table = Ned.query_refcode('1997A&A...323...31K')
>>> print(result_table)
No. Object Name RA ... Diameter Points Associations
degrees ...
--- ------------------------- ---------- ... --------------- ------------
1 NGC 0262 12.19642 ... 12 0
2 NGC 0449 19.0302 ... 7 0
3 NGC 0591 23.38028 ... 7 0
4 UGC 01214 25.99084 ... 12 0
... ... ... ... ... ...
33 WISEA J202325.39+113134.6 305.85577 ... 2 0
34 UGC 12149 340.28163 ... 8 0
35 MRK 0522 345.07954 ... 4 0
36 NGC 7674 351.98635 ... 8 0
Length = 36 rows
Image and Spectra Queries¶
The image queries return a list of HDUList objects for the
specified name. For instance:
>>> from astroquery.ipac.ned import Ned
>>> images = Ned.get_images("m1")
Downloading http://ned.ipac.caltech.edu/dss1B2/Bb/MESSIER_001:I:103aE:dss1.fits.gz
|===========================================| 32k/ 32k (100.00%) 00s
Downloading http://ned.ipac.caltech.edu/img5/1995RXCD3.T...0000C/p083n22a:I:0.1-2.4keV:cop1995.fits.gz
|===========================================| 52k/ 52k (100.00%) 01s
Downloading http://ned.ipac.caltech.edu/img5/1996RXCD6.T...0000C/p083n22a:I:0.1-2.4keV:cps1996.fits.gz
|===========================================| 96k/ 96k (100.00%) 03s
Downloading http://ned.ipac.caltech.edu/img5/1995RXCD3.T...0000C/p084n22a:I:0.1-2.4keV:cop1995.fits.gz
|===========================================| 52k/ 52k (100.00%) 01s
Downloading http://ned.ipac.caltech.edu/img5/1998RXCD8.T...0000C/h083n22a:I:0.1-2.4keV:cps1998.fits.gz
|===========================================| 35k/ 35k (100.00%) 00s
>>> images
[[<astropy.io.fits.hdu.image.PrimaryHDU at 0x4311890>],
[<astropy.io.fits.hdu.image.PrimaryHDU at 0x432b350>],
[<astropy.io.fits.hdu.image.PrimaryHDU at 0x3e9c5d0>],
[<astropy.io.fits.hdu.image.PrimaryHDU at 0x4339790>],
[<astropy.io.fits.hdu.image.PrimaryHDU at 0x433dd90>]]
To get the URLs of the downloadable FITS images:
>>> from astroquery.ipac.ned import Ned
>>> image_list = Ned.get_image_list("m1")
>>> image_list
['http://ned.ipac.caltech.edu/dss1B2/Bb/MESSIER_001:I:103aE:dss1.fits.gz',
'http://ned.ipac.caltech.edu/img/1995RXCD3.T...0000C/p084n22a:I:0.1-2.4keV:cop1995.fits.gz',
'http://ned.ipac.caltech.edu/img/1996RXCD6.T...0000C/p083n22a:I:0.1-2.4keV:cps1996.fits.gz',
'http://ned.ipac.caltech.edu/img/1998RXCD8.T...0000C/h083n22a:I:0.1-2.4keV:cps1998.fits.gz',
'http://ned.ipac.caltech.edu/img/1995RXCD3.T...0000C/p083n22a:I:0.1-2.4keV:cop1995.fits.gz']
Spectra can also be fetched in the same way:
>>> from astroquery.ipac.ned import Ned
>>> spectra = Ned.get_spectra('3c 273')
Downloading http://ned.ipac.caltech.edu/spc1/2009A+A...495.1033B/3C_273:S:B:bcc2009.fits.gz
|===========================================| 7.8k/7.8k (100.00%) 00s
Downloading http://ned.ipac.caltech.edu/spc1/1992ApJS...80..109B/PG_1226+023:S:B_V:bg1992.fits.gz
|===========================================| 5.0k/5.0k (100.00%) 00s
Downloading http://ned.ipac.caltech.edu/spc1/2009A+A...495.1033B/3C_273:S:RI:bcc2009.fits.gz
|===========================================| 9.4k/9.4k (100.00%) 00s
>>> spectra
[[<astropy.io.fits.hdu.image.PrimaryHDU at 0x41b4190>],
[<astropy.io.fits.hdu.image.PrimaryHDU at 0x41b0990>],
[<astropy.io.fits.hdu.image.PrimaryHDU at 0x430a450>]]
Similarly the list of URLs for spectra of a particular object may be fetched:
>>> from astroquery.ipac.ned import Ned
>>> spectra_list = Ned.get_image_list("3c 273", item='spectra')
>>> spectra_list
['http://ned.ipac.caltech.edu/spc1/1992/1992ApJS...80..109B/PG_1226+023:S:B_V:bg1992.fits.gz',
'http://ned.ipac.caltech.edu/spc1/2009/2009A+A...495.1033B/3C_273:S:B:bcc2009.fits.gz',
'http://ned.ipac.caltech.edu/spc1/2009/2009A+A...495.1033B/3C_273:S:RI:bcc2009.fits.gz']
Fetching other data tables for an object¶
Several other data tables for an object may be fetched via the get_table()
queries. These take a keyword argument table, which may be set to one of
photometry, diameters, redshifts, references or object_notes. For
instance the table=photometry will fetch all the relevant photometric data
for the specified object. We look at a simple example:
>>> from astroquery.ipac.ned import Ned
>>> result_table = Ned.get_table("3C 273", table='positions')
>>> print(result_table)
No. RA ... Published Frequence Mode Qualifiers
...
--- -------------- ... ------------------------ -------------------------
0 12h29m06.6997s ...
1 12h29m06.7000s ... Uncertain origin
2 12h29m06.7000s ... Uncertain origin
3 12h29m06.7000s ... Uncertain origin
... ... ... ... ...
114 12h29m07.9s ... Uncertain origin
115 12h29m04s ... Uncertain origin
116 12h29m06s ... Uncertain origin
117 12h29m08s ... Uncertain origin
Length = 118 rows
Reference/API¶
astroquery.ipac.ned Package¶
NED Query Tool¶
Module containing a series of functions that execute queries to the NASA Extragalactic Database (NED):
Revision History
Refactored using common API as a part of Google Summer of Code 2013.
- Originally contributed by
Willett, Jun 2011
- Acknowledgements
- Based off Adam Ginsburg’s Splatalogue search routine:
https://github.com/keflavich/agpy/blob/master/agpy/query_splatalogue.py
Service URLs to acquire the VO Tables are taken from Mazzarella et al. (2007) The National Virtual Observatory: Tools and Techniques for Astronomical Research, ASP Conference Series, Vol. 382., p.165
Classes¶
|
Class for querying the NED (NASA/IPAC Extragalactic Database) system |
|
Configuration parameters for |