Observations - Header Information

Only a small subset of the keywords present in the data products can be obtained with the query_instrument(), query_main(), query_surveys(), or query_tap() methods.

There is, however, a way to get the full primary header of the FITS data products using get_headers().

>>> from astroquery.eso import Eso
>>> eso = Eso()

>>> table = eso.query_instrument("midi",
...                     column_filters={
...                         "date_obs": "between '2008-01-01' and '2008-01-02'"
...                     },
...                     columns=["object", "date_obs", "dp_id"]
...                          )

While the archive query interfaces expose the most commonly used metadata fields, they do not return the complete FITS headers associated with each data product. For applications that require access to instrument- or pipeline-specific keywords, the full primary FITS header can be retrieved directly from the archive using a dedicated helper method.

>>> table_headers = eso.get_headers(table["dp_id"][:5])
>>> table_headers
<Table length=5>
        DP.ID             SIMPLE BITPIX ...   HIERARCH ESO OCS EXPO8 FNAME1     HIERARCH ESO OCS EXPO9 FNAME1
        str28              bool  int64  ...               str33                             str33
---------------------------- ------ ------ ... --------------------------------- ---------------------------------
MIDI.2008-01-01T08:29:16.388   True     16 ...
MIDI.2008-01-01T08:39:38.000   True     16 ...
MIDI.2008-01-01T08:47:35.000   True     16 ...
MIDI.2008-01-01T08:52:00.623   True      8 ... MIDI.2008-01-01T08:51:42.000.fits MIDI.2008-01-01T08:52:00.623.fits
MIDI.2008-01-01T09:00:10.000   True     16 ... MIDI.2008-01-01T09:00:10.000.fits

As shown above, for each data product ID (DP.ID; note that this is equivalent to dp_id in table), the full primary header (336 columns in our case) of the archive FITS file is collected. In the above table table_headers, there are as many rows as there are entries in the table['dp_id'] column.

Note

At present, astroquery returns only the primary header; the rest of the FITS header is not accessible through astroquery yet. Support for returning the entire header is planned for a future version.