Conversion of table to HDU fails depending on how column was added

When I add a Column whose content is a Time to a Table writing the table to a FITS file fails if the data is put into a column before adding it to the table.

Code below reproduces the issue on current master (it is also present in 3.0.x):

from astropy.time import Time
from astropy.table import Table, Column
from astropy.coordinates import EarthLocation
t = Table()
t['a'] = Column(data=Time([100.0, 200.0], scale='tt', format='mjd',
              location=EarthLocation(-2446354, 4237210, 4077985, unit='m')), name=['a'])
t.write('my_table.fits', overwrite=True)
# Exception traceback

If one does not create a column first the write succeeds:

from astropy.time import Time
from astropy.table import Table, Column
from astropy.coordinates import EarthLocation
t = Table()
t['a'] = Time([100.0, 200.0], scale='tt', format='mjd',
               location=EarthLocation(-2446354, 4237210, 4077985, unit='m'))
t.write('my_table.fits', overwrite=True)
# Succeeds

Finally, the traceback when the exception occurs:

In [8]: from astropy.time import Time
   ...: from astropy.table import Table, Column
   ...: from astropy.coordinates import EarthLocation
   ...: t = Table()
   ...: t['a'] = Column(data=Time([100.0, 200.0], scale='tt', format='mjd',
   ...:               location=EarthLocation(-2446354, 4237210, 4077985, unit='m')), name=['a'])
   ...: t.write('my_table.fits', overwrite=True)
   ...:
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-8-23c31caf9f6c> in <module>()
      5 t['a'] = Column(data=Time([100.0, 200.0], scale='tt', format='mjd',
      6               location=EarthLocation(-2446354, 4237210, 4077985, unit='m')), name=['a'])
----> 7 t.write('my_table.fits', overwrite=True)
      8

~/Development/astronomy/astropy-org/astropy-bug-fixes/astropy/table/table.py in write(self, *args, **kwargs)
   2590         serialize_method = kwargs.pop('serialize_method', None)
   2591         with serialize_method_as(self, serialize_method):
-> 2592             io_registry.write(self, *args, **kwargs)
   2593
   2594     def copy(self, copy_data=True):

~/Development/astronomy/astropy-org/astropy-bug-fixes/astropy/io/registry.py in write(data, format, *args, **kwargs)
    558
    559     writer = get_writer(format, data.__class__)
--> 560     writer(data, *args, **kwargs)
    561
    562

~/Development/astronomy/astropy-org/astropy-bug-fixes/astropy/io/fits/connect.py in write_table_fits(input, output, overwrite)
    386     input = _encode_mixins(input)
    387
--> 388     table_hdu = table_to_hdu(input, character_as_bytes=True)
    389
    390     # Check if output file already exists

~/Development/astronomy/astropy-org/astropy-bug-fixes/astropy/io/fits/convenience.py in table_to_hdu(table, character_as_bytes)
    497             col.null = fill_value.astype(table[col.name].dtype)
    498     else:
--> 499         table_hdu = BinTableHDU.from_columns(np.array(table.filled()), header=hdr, character_as_bytes=character_as_bytes)
    500
    501     # Set units and format display for output HDU

~/Development/astronomy/astropy-org/astropy-bug-fixes/astropy/io/fits/hdu/table.py in from_columns(cls, columns, header, nrows, fill, character_as_bytes, **kwargs)
    123         """
    124
--> 125         coldefs = cls._columns_type(columns)
    126         data = FITS_rec.from_columns(coldefs, nrows=nrows, fill=fill,
    127                                      character_as_bytes=character_as_bytes)

~/Development/astronomy/astropy-org/astropy-bug-fixes/astropy/io/fits/column.py in __init__(self, input, ascii)
   1373         elif isinstance(input, np.ndarray) and input.dtype.fields is not None:
   1374             # Construct columns from the fields of a record array
-> 1375             self._init_from_array(input)
   1376         elif isiterable(input):
   1377             # if the input is a list of Columns

~/Development/astronomy/astropy-org/astropy-bug-fixes/astropy/io/fits/column.py in _init_from_array(self, array)
   1408             cname = array.dtype.names[idx]
   1409             ftype = array.dtype.fields[cname][0]
-> 1410             format = self._col_format_cls.from_recformat(ftype)
   1411
   1412             # Determine the appropriate dimensions for items in the column

~/Development/astronomy/astropy-org/astropy-bug-fixes/astropy/io/fits/column.py in from_recformat(cls, recformat)
    271         """Creates a column format from a Numpy record dtype format."""
    272
--> 273         return cls(_convert_format(recformat, reverse=True))
    274
    275     @lazyproperty

~/Development/astronomy/astropy-org/astropy-bug-fixes/astropy/io/fits/column.py in _convert_format(format, reverse)
   2398
   2399     if reverse:
-> 2400         return _convert_record2fits(format)
   2401     else:
   2402         return _convert_fits2record(format)

~/Development/astronomy/astropy-org/astropy-bug-fixes/astropy/io/fits/column.py in _convert_record2fits(format)
   2361         output_format = repeat + NUMPY2FITS[recformat]
   2362     else:
-> 2363         raise ValueError('Illegal format `{}`.'.format(format))
   2364
   2365     return output_format

ValueError: Illegal format `object`.

[pllim]

“I really should not touch FITS” – Wise person

[astropy-bot[bot]]

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