code

df = gaia_v2 #change to desired dataframe
twomass_matches = []
for i in range(0, len(df)):
    result = Vizier(columns=["**"], catalog="II/246").query_region(SkyCoord(ra=df['ra'][i], dec=df['dec'][i],
                                                                                unit=(u.deg, u.deg)), radius='20s')
    if len(result) == 0:
        values = [np.nan for i in range(0, 62)]
        twomass_matches.append(values)
    else:
        result = result[0]

        if len(result) == 1:
            values = [result[colname][0] for colname in result.columns]
            twomass_matches.append(values)
        else:
            diffs = [(((df['ra'][1]-result['RAJ2000'][j])**2)+(df['dec'][i]-result['DEJ2000'][j])**2) for j in range(0, len(result))]
            index = diffs.index(min(diffs))
            values = [result[colname][index] for colname in result.columns]
            twomass_matches.append(values)

colnames = result.columns
for i in range(0, len(colnames)):
        values = [twomass_matches[j][i] for j in range(0, len(twomass_matches))]
        df[colnames[i]] = values
gaia_2mass = df

gaia_2mass.to_csv("2MASS_data") #insert desired filename to download as csv


print (gaia_2mass)



#full error is
AttributeError                            Traceback (most recent call last)
Cell In[53], line 21
     18             values = [result[colname][index] for colname in result.columns]
     19             twomass_matches.append(values)
---> 21 colnames = result.columns
     22 for i in range(0, len(colnames)):
     23         values = [twomass_matches[j][i] for j in range(0, len(twomass_matches))]