Gaia Catalog#
The European space mission Gaia aims to measure the positions, distances, motions, and brightnesses of over 1 billion stars within the Milky Way galaxy, as well as provide data for a significant number of extragalactic and Solar system objects. This information, along with data on multiplicity, variability, and other astrophysical parameters, is stored in the Gaia Archive.
astroquery provides a query interface to Gaia, using gaia module. But, as we do with another sources, GaiaDR3SourcesCatalog can directly query the Gaia Archive and return a SourcesCatalog object. This can be done using the gaiadr3 or GaiaDR3SourcesCatalog.
In [1]: from astropop.catalogs import gaia
In [2]: gaia_sources = gaia.gaiadr3('Sirius', radius='20 arcsec')
INFO: Query finished. [astroquery.utils.tap.core]
In [3]: gaia_sources.table()
Out[3]:
<Table length=1>
id ra ... RP RP_error
deg ...
str28 float64 ... float64 float32
---------------------------- ------------------ ... ----------------- ----------
Gaia DR3 2947050466531873024 101.28662552099249 ... 8.398789405822754 0.03957837
In [4]: from astropop.catalogs.gaia import GaiaDR3SourcesCatalog
In [5]: gaia_sources = GaiaDR3SourcesCatalog('Sirius', radius='20 arcsec')
INFO: Query finished. [astroquery.utils.tap.core]
In [6]: gaia_sources.table()
Out[6]:
<Table length=1>
id ra ... RP RP_error
deg ...
str28 float64 ... float64 float32
---------------------------- ------------------ ... ----------------- ----------
Gaia DR3 2947050466531873024 101.28662552099249 ... 8.398789405822754 0.03957837
Currently, only the Data Release 3 (DR3) is supported. The GaiaDR3SourcesCatalog class is a subclass of SourcesCatalog, so all the methods of SourcesCatalog are available.
All the 3 Gaia filters are available for photometry: G, BP and RP. As Gaia catalog do not provide a direct magnitude error, we compute it from phot_*_mean_flux_over_error columns, using the approximation:
Limiting Magnitude and Number of Sources#
Gaia catalogs can be huge. So, additionally, the initialization of the GaiaDR3SourcesCatalog class accepts a parameter to perform maximum G magnitude for the query called max_g_mag. This parameter is useful to limit the number of sources returned by the query. For example, if we want to query the Gaia DR3 catalog for the Sirius star, but only for sources with G magnitude less than 10, we can do:
In [7]: gaia_sources = gaia.gaiadr3('HD 5020', radius='60 arcsec', max_g_mag=10)
INFO: Query finished. [astroquery.utils.tap.core]
In [8]: gaia_sources.table()
Out[8]:
<Table length=1>
id ra ... RP_error
deg ...
str28 float64 ... float32
---------------------------- ------------------ ... -------------
Gaia DR3 2524633801529229440 13.048142264281589 ... 0.00026115746
Additional Catalog Properties#
The GaiaDR3SourcesCatalog class has some additional properties. You can get parallax and radial velocities from the catalog using the parallax and radial_velocity properties.
- GaiaDR3SourcesCatalog.parallax()#
Return the parallax for the sources.
In [9]: gaia_sources.parallax()
Out[9]:
<QFloat at 0x7f6265594e50>
[11.57+-0.02] unit=mas
- GaiaDR3SourcesCatalog.radial_velocity()#
Return the radial velocity for the sources.
In [10]: gaia_sources.radial_velocity()
Out[10]:
<QFloat at 0x7f62653da390>
[6.0+-0.2] unit=km / s
Also, important variability and non-punctual flags are available as properties:
- GaiaDR3SourcesCatalog.phot_variable_flag()#
Return the photometric variable flag for the sources.
In [11]: gaia_sources.phot_variable_flag()
Out[11]: array([ True])
- GaiaDR3SourcesCatalog.non_single_star()#
Return if each source is the non single star table.
In [12]: gaia_sources.non_single_star()
Out[12]: array([0], dtype=int16)
- GaiaDR3SourcesCatalog.in_galaxy_candidates()#
Return if the source is in galaxy candidates table.
In [13]: gaia_sources.in_galaxy_candidates()
Out[13]: array([False])
astropop.catalogs.gaia Module#
Query and match objects in catalogs using TAP services.
Classes#
|
Sources catalog from Gaia-DR3 catalog. |
alias of |