VO Simple Cone Search (deprecated)

Warning

Cone Search has been moved to Astroquery 0.3.5 and will be removed from Astropy in a future version. The API here will be preserved as “classic” API in Astroquery, however some configuration behavior might change; See Astroquery documentation for new usage details.

Astropy offers Simple Cone Search Version 1.03 as defined in IVOA Recommendation (February 22, 2008). Cone Search queries an area encompassed by a given radius centered on a given RA and DEC and returns all the objects found within the area in the given catalog.

Default Cone Search Services

Currently, the default Cone Search services used are a subset of those found in the STScI VAO Registry. They were hand-picked to represent commonly used catalogs below:

  • 2MASS All-Sky
  • HST Guide Star Catalog
  • SDSS Data Release 7
  • SDSS-III Data Release 8
  • USNO A1
  • USNO A2
  • USNO B1

This subset undergoes daily validations hosted by STScI using Validation for Simple Cone Search. Those that pass without critical warnings or exceptions are used by Simple Cone Search by default. They are controlled by astropy.vo.Conf.conesearch_dbname:

  1. 'conesearch_good' Default. Passed validation without critical warnings and exceptions.
  2. 'conesearch_warn' Has critical warnings but no exceptions. Use at your own risk.
  3. 'conesearch_exception' Has some exceptions. Never use this.
  4. 'conesearch_error' Has network connection error. Never use this.

If you are a Cone Search service provider and would like to include your service in the list above, please open a GitHub issue on Astropy.

Caching

Caching of downloaded contents is controlled by astropy.utils.data. To use cached data, some functions in this package have a cache keyword that can be set to True.

Getting Started

This section only contains minimal examples showing how to perform basic Cone Search.

>>> from astropy.vo.client import conesearch

List the available Cone Search catalogs:

>>> conesearch.list_catalogs()
[u'2MASS All-Sky Point Source Catalog 1',
 u'Guide Star Catalog v2 1',
 u'SDSS DR7 - Sloan Digital Sky Survey Data Release 7 1',
 u'SDSS DR7 - Sloan Digital Sky Survey Data Release 7 2',
 u'SDSS DR7 - Sloan Digital Sky Survey Data Release 7 3',
 u'SDSS DR7 - Sloan Digital Sky Survey Data Release 7 4',
 u'SDSS DR8 - Sloan Digital Sky Survey Data Release 8 1',
 u'SDSS DR8 - Sloan Digital Sky Survey Data Release 8 2',
 u'The HST Guide Star Catalog, Version 1.1 (Lasker+ 1992) 1',
 u'The HST Guide Star Catalog, Version 1.2 (Lasker+ 1996) 1',
 u'The HST Guide Star Catalog, Version GSC-ACT (Lasker+ 1996-99) 1',
 u'The PMM USNO-A1.0 Catalogue (Monet 1997) 1',
 u'The USNO-A2.0 Catalogue (Monet+ 1998) 1',
 u'Two Micron All Sky Survey (2MASS) 1',
 u'Two Micron All Sky Survey (2MASS) 2',
 u'USNO-A2 Catalogue 1']

Select a 2MASS catalog from the list above that is to be searched:

>>> my_catname = 'Two Micron All Sky Survey (2MASS) 1'

Query the selected 2MASS catalog around M31 with a 0.1-degree search radius:

>>> from astropy.coordinates import SkyCoord
>>> from astropy import units as u
>>> c = SkyCoord.from_name('M31')  
>>> c.ra, c.dec
(<Longitude 10.6847083 deg>, <Latitude 41.26875 deg>)
>>> result = conesearch.conesearch(c, 0.1 * u.degree, catalog_db=my_catname)
Trying http://wfaudata.roe.ac.uk/twomass-dsa/DirectCone?DSACAT=TWOMASS&...
Downloading ...
WARNING: W06: ... UCD has invalid character '?' in '??' [...]
WARNING: W50: ... Invalid unit string 'yyyy-mm-dd' [...]
WARNING: W50: ... Invalid unit string 'Julian days' [...]
>>> result
<Table masked=True length=2008>
         cx                  cy                  cz         ... coadd_key coadd
                                                            ...
      float64             float64             float64       ...   int32   int16
------------------- ------------------- ------------------- ... --------- -----
0.73822176804799999 0.14085682400300001 0.65968778699599995 ...   1590632   244
0.73829073865999995      0.140689543019 0.65964629741500003 ...   1590632   244
                ...                 ...                 ... ...       ...   ...
>>> result.url
u'http://wfaudata.roe.ac.uk/twomass-dsa/DirectCone?DSACAT=TWOMASS&DSATAB=twomass_psc&'

Get the number of matches and returned column names:

>>> result.array.size
2008
>>> result.array.dtype.names
('cx',
 'cy',
 'cz',
 'htmID',
 'ra',
 'dec', ...,
 'coadd_key',
 'coadd')

Extract RA and DEC of the matches:

>>> result.array['ra']
masked_array(data = [10.620983 10.672264 10.651166 ..., 10.805599],
             mask = [False False False ..., False],
       fill_value = 1e+20)
>>> result.array['dec']
masked_array(data = [41.192303 41.19426 41.19445 ..., 41.262123],
             mask = [False False False ..., False],
       fill_value = 1e+20)

Using astropy.vo

This package has four main components across two subpackages:

They are designed to be used in a work flow as illustrated below:

VO work flow

The one that a typical user needs is the Simple Cone Search component (see Cone Search Examples).

Reference/API

astropy.vo Package

The vo subpackage provides virtual observatory (VO) related functionality.

Classes

Conf Configuration parameters for astropy.vo.

astropy.vo.client.vos_catalog Module

Common utilities for accessing VO simple services.

Functions

get_remote_catalog_db(dbname[, cache, verbose])

Deprecated since version 2.0.
call_vo_service(service_type[, catalog_db, ...])

Deprecated since version 2.0.
list_catalogs(service_type[, cache, verbose])

Deprecated since version 2.0.

Classes

VOSBase(tree)

Deprecated since version 2.0.
VOSCatalog(tree)

Deprecated since version 2.0.
VOSDatabase(tree)

Deprecated since version 2.0.

astropy.vo.client.conesearch Module

Support VO Simple Cone Search capabilities.

Functions

conesearch(center, radius[, verb])

Deprecated since version 2.0.
search_all(*args, **kwargs)

Deprecated since version 2.0.
list_catalogs(**kwargs)

Deprecated since version 2.0.
predict_search(url, *args, **kwargs)

Deprecated since version 2.0.
conesearch_timer(*args, **kwargs)

Deprecated since version 2.0.

Classes

AsyncConeSearch(*args, **kwargs)

Deprecated since version 2.0.
AsyncSearchAll(*args, **kwargs)

Deprecated since version 2.0.

astropy.vo.client.async Module

Asynchronous VO service requests.

Classes

AsyncBase(func, *args, **kwargs)

Deprecated since version 2.0.

astropy.vo.client.exceptions Module

Exceptions related to Virtual Observatory (VO).

Classes

BaseVOError Base class for VO exceptions.
VOSError General VO service exception.
MissingCatalog VO catalog is missing.
DuplicateCatalogName VO catalog of the same title already exists.
DuplicateCatalogURL VO catalog of the same access URL already exists.
InvalidAccessURL Invalid access URL.
ConeSearchError General Cone Search exception.

Class Inheritance Diagram

Inheritance diagram of astropy.vo.client.exceptions.BaseVOError, astropy.vo.client.exceptions.VOSError, astropy.vo.client.exceptions.MissingCatalog, astropy.vo.client.exceptions.DuplicateCatalogName, astropy.vo.client.exceptions.DuplicateCatalogURL, astropy.vo.client.exceptions.InvalidAccessURL, astropy.vo.client.exceptions.ConeSearchError

astropy.vo.validator Package

Classes

Conf Configuration parameters for astropy.vo.validator.

Class Inheritance Diagram

Inheritance diagram of astropy.vo.validator.Conf

astropy.vo.validator.validate Module

Validate VO Services.

Functions

check_conesearch_sites([destdir, verbose, ...])

Deprecated since version 2.0.

astropy.vo.validator.inspect Module

Inspect results from astropy.vo.validator.validate.

Classes

ConeSearchResults([cache, verbose])

Deprecated since version 2.0.

astropy.vo.validator.exceptions Module

Exceptions related to Virtual Observatory (VO) validation.

Classes

BaseVOValidationError Base class for VO validation exceptions.
ValidationMultiprocessingError Validation using multiprocessing failed.

Class Inheritance Diagram

Inheritance diagram of astropy.vo.validator.exceptions.BaseVOValidationError, astropy.vo.validator.exceptions.ValidationMultiprocessingError