Troubleshooting#

Clearing Cache#

If you encounter repeated query failures or see outdated or inconsistent results, you may be dealing with a stale or corrupted local cache. You can clear the entire Astropy cache for ESO with the following command:

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

This will remove all cached ESO queries and downloaded metadata files. Data products already downloaded will remain unless manually deleted.

Using Correct column_filters#

Note

This section applies to eso.query_main (and, in practice, to eso.query_instrument when using similar column_filters patterns). It is not intended for catalogue queries (eso.query_catalog) or direct ObsCore/TAP queries (e.g. eso.query_tap against ivoa.ObsCore).

If your query fails or silently returns no results, it might be because you’re using column names that are accepted in the ESO web interface (WDB) but not supported by the TAP/ADQL interface that is now used within astroquery.eso. A common case involves using stime and etime, which are not valid TAP fields. Instead, use exp_start, the TAP-compliant column representing the observation start time. This field supports SQL-style date filtering.

Below are examples of invalid filter usage and their corrected TAP-compatible versions.

Filtering between two dates#

❌ Invalid (WDB-specific fields, not recognized by TAP)

>>> column_filters = {
...    "stime": "2024-01-01 12:00:00",
...    "etime": "2024-01-03 12:00:00"
...    }

✅ Correct (TAP-compliant syntax using ‘exp_start’)

>>> column_filters = {
...        "exp_start": "between '2024-01-01 12:00:00' and '2024-01-03 12:00:00'"
...    }

OR

>>> column_filters = {
...        "exp_start": "between '2024-01-01T12:00:00' and '2024-01-03T12:00:00'"
...    }

Filtering with only a start date#

# ❌ Invalid

>>> column_filters = {
...        "stime": "2024-01-01 12:00:00"
...    }

# ✅ Correct

>>> column_filters = {
...        "exp_start": "> '2024-01-01 12:00:00'"
...    }

Filtering with only an end date#

# ❌ Invalid

>>> column_filters = {
...        "etime": "2024-12-31 12:00:00"
...    }

# ✅ Correct

>>> column_filters = {
...        "exp_start": "< '2024-12-31 12:00:00'"
...    }