  AIMS: The object W Aql is an asymptotic giant branch (AGB) star with a faint
companion. By determining more carefully the properties of the companion, we
hope to better constrain the properties of the AGB star. METHODS: We present
new spectral observations of the binary star W Aql at minimum and maximum
brightness and new photometric observations of W Aql at minimum brightness.
RESULTS: The composite spectrum near minimum light is predominantly from the
companion at wavelengths $\lambda$ < 6000 $\AA$. This spectrum can be
classified as F8 to G0, and the brightness of the companion is that of a dwarf
star. Therefore, it can be concluded that the companion is a main sequence
star. From this, we are able to constrain the mass of the AGB component to 1.04
- 3 $M_\odot$ and the mass of the W Aql system to 2.1 - 4.1 $M_\odot$ . Our
photometric results are broadly consistent with this classification and suggest
that the main sequence component suffers from approximately 2 mag of extinction
in the V band primarily due to the dust surrounding the AGB component.
