MAST: Locate & Download FGS data?

Does the MAST API (and/or, the `Observations` interface) support access to & retrieval of JWST FGS data? I was surprised at this null result:

```python
regionCoords = coordinates.SkyCoord(0*u.deg, 0*u.deg, frame='galactic')

matched_obs = Observations.query_criteria(
coordinates=regionCoords,
radius=3*u.deg,
obs_collection = 'JWST',
instrument_name='FGS',
)
```
(`matched_obs` is empty)

because there are many observations executed in the Galactic Center region, and each includes several FGS images.

It may be that I specified the `instrument_name` incorrectly, but I couldn't piece together how to determine the correct instrument name.

FGS data are not associated with program IDs, even when they are taken under a specific program, e.g.:
```python
>>> obs_table = Observations.query_criteria(proposal_id=2221, )
>>> set(obs_table['instrument_name'])
{'MIRI/IMAGE', 'NIRCAM/IMAGE'}
```

but the FGS data can be found by `get_product_list`:
```python
Observations.get_product_list('90458115')
```

Is there a direct way to search for the JWST FGS data, or do I have to search first for all executed programs, then filter through the product lists?

Start by reproducing the empty result with Python's Observations.query_criteria for JWST and FGS, then compare it with the get_product_list call for product 90458115. The issue names no repository files or tests; done would be a documented determination of whether FGS data can be searched directly and, if not, what supported retrieval path is required.

Written by the indexing model from the issue text.