AlfalfaClass¶
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class
astroquery.alfalfa.
AlfalfaClass
[source]¶ Bases:
astroquery.query.BaseQuery
Attributes Summary
CATALOG_PREFIX
FITS_PREFIX
PLACEHOLDER
Methods Summary
get_catalog
()Download catalog of ALFALFA source properties. get_spectrum
(agc[, show_progress])Download spectrum from ALFALFA catalogue. get_spectrum_async
(agc[, show_progress])Download spectrum from ALFALFA catalogue. query_region
(coordinates[, radius, …])Perform object cross-ID in ALFALFA. Attributes Documentation
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CATALOG_PREFIX
= 'http://egg.astro.cornell.edu/alfalfa/data/a40files/a40.datafile1.csv'¶
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FITS_PREFIX
= 'http://arecibo.tc.cornell.edu/hiarchive/alfalfa/spectraFITS'¶
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PLACEHOLDER
= -999999¶
Methods Documentation
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get_catalog
()[source]¶ Download catalog of ALFALFA source properties.
Returns: result : Dictionary 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.
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get_spectrum
(agc, show_progress=True)[source]¶ Download spectrum from ALFALFA catalogue.
Parameters: agc : int
Identification number for object in ALFALFA catalog.
ascii : bool
Download spectrum from remote server in ASCII or FITS format?
Returns: spectrum :
HDUList
Spectrum is in
hdulist[0].data[0][2]
See also
get_catalog
- method that downloads ALFALFA catalog
query_region
- find object in catalog closest to supplied position (use this to determine AGC number first)
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get_spectrum_async
(agc, show_progress=True)[source]¶ Download spectrum from ALFALFA catalogue.
Parameters: agc : int
Identification number for object in ALFALFA catalog.
ascii : bool
Download spectrum from remote server in ASCII or FITS format?
Returns: result : A file context manager
See also
get_catalog
- method that downloads ALFALFA catalog
query_region
- find object in catalog closest to supplied position (use this to determine AGC number first)
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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: coordinates : str or
astropy.coordinates
objectThe 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.radius : str or
Quantity
object, optionalThe string must be parsable by
astropy.coordinates.Angle
. The appropriateQuantity
object fromastropy.units
may also be used. Defaults to 3 arcmin.optical_counterpart : bool
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.
Returns: result : AGC 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')
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