AlfalfaClass¶
- class astroquery.alfalfa.AlfalfaClass[source]¶
Bases:
BaseQuery
Attributes Summary
Methods Summary
Download catalog of ALFALFA source properties.
query_region
(coordinates, *[, radius, ...])Perform object cross-ID in ALFALFA.
Attributes Documentation
- CATALOG_PREFIX = 'http://egg.astro.cornell.edu/alfalfa/data/a40files/a40.datafile1.csv'¶
- PLACEHOLDER = -999999¶
Methods Documentation
- get_catalog()[source]¶
Download catalog of ALFALFA source properties.
- Returns:
- resultDictionary of results, each element is a masked array.
Notes
This catalog has ~15,000 entries, so after it’s downloaded, it is made global to save some time later.
- query_region(coordinates, *, radius=<Quantity 3. arcmin>, optical_counterpart=False)[source]¶
Perform object cross-ID in ALFALFA.
Search for objects near position (ra, dec) within some radius.
- Parameters:
- coordinatesstr or
astropy.coordinates
object The target around which to search. It may be specified as a string in which case it is resolved using online services or as the appropriate
astropy.coordinates
object. ICRS coordinates may also be entered as strings as specified in theastropy.coordinates
module.- radiusstr or
Quantity
object, optional The string must be parsable by
astropy.coordinates.Angle
. The appropriateQuantity
object fromastropy.units
may also be used. Defaults to 3 arcmin.- optical_counterpartbool
Search for position match using radio positions or position of any optical counterpart identified by ALFALFA team? Keep in mind that the ALFA beam size is about 3x3 arcminutes.
- See documentation for astropy.coordinates.angles for more information
- about (‘ra’, ‘dec’, ‘unit’) parameters.
- coordinatesstr or
- Returns:
- resultAGC number for object nearest supplied position.
Examples
>>> from astroquery.alfalfa import Alfalfa >>> from astropy import coordinates as coords >>> C = coords.SkyCoord('0h8m05.63s +14d50m23.3s') >>> agc = Alfalfa.query_region(C,'3 arcmin')