Gaia on TAP
Python utilities and examples for accessing ESA Gaia data using Table Access Protocol (TAP).
Authors
- Andrew R. Casey (Monash University)
Installation
Install using pip:
pip install gaia-on-tap
Getting Started
The gaia.tap package includes two main functions for accessing Gaia data: query and cone_search.
By default, both will return all retrieved sources as an astropy.table.Table object, so you can then
write the results to disk or do something useful with them.
Select stars around M67
# Get all sources within 1 degree of M67
import astropy.coordinates as coord
from gaia.tap import cone_search
cluster = coord.SkyCoord.from_name("M67")
cluster_candidates = cone_search(cluster.ra.deg, cluster.dec.deg, 1.0)Select hypervelocity star candidates in TGAS
This doesn't treat the errors correctly, but it's a useful example to show what you can do:
import gaia.tap
# Identify stars with tangential velocities exceeding 500 km/s, and reasonable parallaxes
hvs_candidates = gaia.tap.query(
""" SELECT *
FROM gaiadr1.tgas_source
WHERE parallax_error/parallax < 0.2
AND (4.74 * SQRT(POWER(pmra, 2) + POWER(pmdec, 2)))/parallax > 500 """)Authenticate using your ESA/Gaia Archive credentials
If you have an account with the ESA/Gaia archive, you can include your credentials so that
you can upload or query private tables. This is done by having a file (e.g., credentials.yaml)
like:
username: acasey
password: my-super-awesome-password
And then in the code:
import gaia
# Read in our credentials. You only have to do this once per Python session!
gaia.config.read("credentials.yaml")
# For any further queries use the authenticate flag, and the code will log you in automagically
sources = gaia.tap.query(" ... ", authenticate=True)Upload a table to your local space on the ESA/Gaia archive
If you want to upload a VOtable and use it for cross-matches through the ESA/Gaia archive:
import gaia
# Read in our credentials.
gaia.config.read("credentials.yaml")
# Upload our table, which we will ask ESA/Gaia to call 'my_table'
gaia.tap.upload("my_table", "/local/path/to/your/table.votable")
# Now use it!
# (Ensure that you use the authenticate=True flag so that you can access your private tables)
xmatched_sources = tap.query(
""" SELECT *
FROM gaiadr1.gaia_source as gaia,
<YOUR_USERNAME>.my_table as my_table
WHERE 1=CONTAINS(
POINT('ICRS', my_table.ra, my_table.dec),
CIRCLE('ICRS', gaia.ra, gaia.dec, 1.5/3600)
)
""", authenticate=True)Resources
-
ESA Gaia TAP documentation -> Help -> Command-line access
