Wiki Navigation
About
Contact
Get an account
Publication policy
Next workshop: GC5 in Paris (9-13 September 2019)
Test suites
Tutorial sessions
Gaia errors
Snapdragons
Limepy
Agama
Discussion Forum
Wiki Help!
LOC pages
Discussion Forum
Python code for simulating Gaia errors
The python package for simulating Gaia data (using the formula from the Gaia science performance web pages) can be obtained from:
https://pypi.python.org/pypi/PyGaia
This code allows you to transform your phase space data (x,y,z,vx,vy,vz) into astrometry and radial velocities. In addition you can calculate the predicted Gaia errors as a function of magnitude and colour of your simulated stars.
For question/comments/suggestions/corrections for this code contact:
Example code
Assuming you've installed everything successfully, here's an example of simulating Gaia catalogue data.
The code above calculates sky averaged parallaxes. If you want to account for the variations of the errors across the sky here's an examples of how to do that.
For errors on the sky positions, proper motions, and radial velocities you can write code along the same lines.
Note that in it's current state the code happily returns errors for stars beyond Gaia's magnitude range G=20 (Grvs=17 for radial velocities). It's you responsibility to make sure stars fainter than these limits are not included in the simulated data.
Comment on the reference systems used in the PyGaia example
The code example above assumes that the phase space coordinates are referred to the ICRS (i.e. equatorial coordinate system). The actual code doesn't know in which reference frame the phase space coordinates are and just returns a consistent set of astrometric observables.
Note that the error prediction code is for the ICRS reference system.
You can use the
class to rotate your phase space coordinates from the Galactic to the ICRS reference frame.