Keyerror: 0 while using astropy SkyCoord

Question

I am facing a problem while using SkyCoord from astropy library. The scenario is as below,

• I have read the data from a fits file into a pandas dataframe.
• I have applied several quality cuts to the data
• I am trying to get the SkyCoord object for the remaining objects (about 250k objects)
• Python raises a KeyError: 0 while getting the SkyCoord object

Quite surprisingly when I run the same code without the quality cuts, the SkyCoord object is successfully initiated. It fails when I try to obtain the SkyCoord object after the quality cuts. Not sure why this is the case.

Below is the code snippet for your reference.

ra = data_ADR["RA_x"]
dec = data_ADR["DEC_x"]
dist = data_ADR["dist"]
pmra = data_ADR["GAIAEDR3_PMRA"]
pmdec = data_ADR["GAIAEDR3_PMDEC"]
rv = data_ADR["GAIAEDR3_DR2_RADIAL_VELOCITY"]
c = coord.SkyCoord(ra = u.Quantity(ra * u.deg),
                   dec = u.Quantity(dec * u.deg),
                   distance = u.Quantity(dist * u.pc),
                   pm_ra_cosdec = u.Quantity(pmra * u.mas/u.year),
                   pm_dec = u.Quantity(pmdec * u.mas/u.year),
                   radial_velocity = u.Quantity(rv * u.km/u.s))
c_galcen = c.transform_to(coord.Galactocentric(z_sun = z_sun, galcen_distance = galcen_distance))

Any idea on how to fix this would be appreciated.

Thank you in advance!

Below is the complete stack trace of the error message,

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
/usr/local/lib/python3.7/dist-packages/pandas/core/indexes/base.py in get_loc(self, key, method, tolerance)
   3360             try:
-> 3361                 return self._engine.get_loc(casted_key)
   3362             except KeyError as err:

6 frames
/usr/local/lib/python3.7/dist-packages/pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_loc()

/usr/local/lib/python3.7/dist-packages/pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_loc()

pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.Int64HashTable.get_item()

pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.Int64HashTable.get_item()

KeyError: 0

The above exception was the direct cause of the following exception:

KeyError                                  Traceback (most recent call last)
<ipython-input-271-8b519c152eeb> in <module>
----> 1 c = coord.SkyCoord(ra = u.Quantity(ra * u.deg),
      2                    dec = u.Quantity(dec * u.deg),
      3                    distance = u.Quantity(dist * u.pc),
      4                    pm_ra_cosdec = u.Quantity(pmra * u.mas/u.year),
      5                    pm_dec = u.Quantity(pmdec * u.mas/u.year),

/usr/local/lib/python3.7/dist-packages/astropy/units/quantity.py in __new__(cls, value, unit, dtype, copy, order, subok, ndmin)
    348                 # Convert all quantities to the same unit.
    349                 if unit is None:
--> 350                     unit = value[0].unit
    351                 value = [q.to_value(unit) for q in value]
    352                 value_unit = unit  # signal below that conversion has been done

/usr/local/lib/python3.7/dist-packages/pandas/core/series.py in __getitem__(self, key)
    940 
    941         elif key_is_scalar:
--> 942             return self._get_value(key)
    943 
    944         if is_hashable(key):

/usr/local/lib/python3.7/dist-packages/pandas/core/series.py in _get_value(self, label, takeable)
   1049 
   1050         # Similar to Index.get_value, but we do not fall back to positional
-> 1051         loc = self.index.get_loc(label)
   1052         return self.index._get_values_for_loc(self, loc, label)
   1053 

/usr/local/lib/python3.7/dist-packages/pandas/core/indexes/base.py in get_loc(self, key, method, tolerance)
   3361                 return self._engine.get_loc(casted_key)
   3362             except KeyError as err:
-> 3363                 raise KeyError(key) from err
   3364 
   3365         if is_scalar(key) and isna(key) and not self.hasnans:

KeyError: 0