Query Gaia by star name

Question

I am attempting to query Gaia programmatically in python to get certain properties for specific stars. I can write a query which obtains some properties, but only for all stars, not a set of stars or one specific star. Ideally I would just be able to pass the query function a star name but I can't figure out from the documentation how to do this (or even how to make the star name, rather than just the Gaia source_id, a column in the returned table). My current script is as follows:

query = """SELECT source_id, ra, dec, parallax FROM gaiadr2.gaia_source """
job = Gaia.launch_job(query)
results = job.get_results()

Any pointers are much appreciated!

Answer 1

Hello Random_Astro_Student,

If you have not already, refer to this document. Section 14.1.1 provides the schema for gaiasource. You will note that there is no field with a name (eg: 'Alpha Centauri A').

I had queried Gaia data using the function below. GaiaDR2SourceIDs is a comma separated string (ID1,ID2,ID3,.....,IDn) for ID's to retrieve. FolderForLocalStorage is a destination folder to store the retrieved data rows in CSV. I had done this to avoid any possible issues where I would not be able to access the Gaia servers.

# ---------------------------------------------------------------------------
def GetGAIAData(GaiaDR2SourceIDs, FolderForLocalStorage):
    # gets the GAIA data for the provided GaiaDR2SourceIDs's
    # and writes to a local CSV
        
    dfGaia = pd.DataFrame()
    
    #job = Gaia.launch_job_async( "select top 100 * from gaiadr2.gaia_source where parallax>0 and parallax_over_error>3. ") # Select `good' parallaxes
    qry = "SELECT * FROM gaiadr2.gaia_source gs WHERE gs.source_id in (" + GaiaDR2SourceIDs + ");"
    
    job = Gaia.launch_job_async( qry )
    tblGaia = job.get_results()       #Astropy table
    dfGaia = tblGaia.to_pandas()      #convert to Pandas dataframe
    
    npGAIARecords = dfGaia.to_numpy() #convert to numpy array    
    lstGAIARecords = [list(x) for x in npGAIARecords]   #convert to List[]
    
    FileForLocalStorage = FolderForLocalStorage + str(lstGAIARecords[0][2]) + '.csv'  # use SourceID from 1st record
    dfGaia.to_csv (FileForLocalStorage, index = False, header=True)    

If you only have a few stars you might get their Gaia Source_ID values by direct querying on SIMBAD or using AstroQuery as in sample below.

from astroquery.simbad import Simbad
result_table = Simbad.query_objectids("eta carinae")
        
for x in result_table:
    if 'gaia' in x['ID'].lower():
        print (x['ID'])

You may also do away with direct query to Gaia, instead using astroquery.gaia.