Affiliated Package: Astroquery¶
Astroquery is an Astropy-affiliated package that contains a collection of tools to access online Astronomical data. To install it, do:
pip install astroquery
The following modules have been completed using a common API:
- SIMBAD Queries (
astroquery.simbad) - VizieR Queries (
astroquery.vizier) - IRSA Dust Extinction Service Queries (
astroquery.irsa_dust) - NED Queries (
astroquery.ned) - Splatalogue Queries (
astroquery.splatalogue) - IRSA Image Server program interface (IBE) Queries (
astroquery.ibe) - IRSA Queries (
astroquery.irsa) - UKIDSS Queries (
astroquery.ukidss) - MAGPIS Queries (
astroquery.magpis) - NRAO Queries (
astroquery.nrao) - Besancon Queries (
astroquery.besancon) - NIST Queries (
astroquery.nist) - NVAS Queries (
astroquery.nvas) - GAMA Queries (
astroquery.gama) - ESO Queries (
astroquery.eso) - xMatch Queries (
astroquery.xmatch) - Atomic Line List (
astroquery.atomic) - ALMA Queries (
astroquery.alma) - Skyview Queries (
astroquery.skyview) - NASA ADS Queries (
astroquery.nasa_ads) - HEASARC Queries (
astroquery.heasarc) - LCOGT Queries (
astroquery.lcogt)
These others are functional, but do not follow a common & consistent API:
- Fermi Queries (
astroquery.fermi) - SDSS Queries (
astroquery.sdss) - ALFALFA Queries (
astroquery.alfalfa) - Spitzer Heritage Archive (
astroquery.sha) - LAMDA Queries (
astroquery.lamda) - OGLE Queries (
astroquery.ogle) - Open Exoplanet Catalogue(
astroquery.open_exoplanet_catalogue) - CosmoSim Queries (
astroquery.cosmosim)
SIMBAD¶
As an example, let's run a SIMBAD query:
In [1]:
from astropy import units as u
from astroquery.simbad import Simbad
In [2]:
r = Simbad.query_region('m42', radius=3. * u.arcmin)
In [3]:
r.colnames
Out[3]:
In [4]:
r
Out[4]:
SDSS¶
In the following example we are looking for the SDSS photometry for a small subset of objects from the WTS survey and aim to have get a table that contains both the UKIRT JHK and SDSS griz values.
In [5]:
from astropy.table import Table, join
from astropy.coordinates import SkyCoord
from astroquery.sdss import SDSS
In [6]:
input_objects = Table.read('data/WTS_sources.txt', format='ascii')
input_objects
Out[6]:
In [7]:
coords = SkyCoord(input_objects['RA'], input_objects['DEC'],
unit=u.rad)
photoobj_fields = ['ra', 'dec',
'psfMag_g', 'psfMagErr_g',
'psfMag_r', 'psfMagErr_r',
'psfMag_i', 'psfMagErr_i',
'psfMag_z', 'psfMagErr_z']
In [8]:
sdss_match = SDSS.query_crossid(coords, photoobj_fields=photoobj_fields,
obj_names=input_objects['obj_id'])
sdss_match
Out[8]:
In [9]:
result = join(input_objects, sdss_match, keys='obj_id', join_type='left')
result
Out[9]:
In [10]:
import matplotlib.pylab as plt
%matplotlib inline
plt.rc('figure', figsize=(10, 5))
plt.ylabel('J')
plt.xlabel('g-z')
plt.plot(result['psfMag_g']-result['psfMag_z'], result['J'], 'x')
Out[10]:
Practical Exercise¶
Go to the documentation and try out a query interface for a service that might be relevant to you!