  We present 10 and 20 micron images of IRAS 19500-1709 taken with the
mid-infrared camera, OSCIR, mounted on the Gemini North Telescope. An extended
circumstellar envelope is detected, with the N band image indicating an
elongation in a NE-SW direction. We use a dust radiation transport code to fit
the spectral energy distribution from UV to sub-mm wavelengths, with a detached
dust shell model. A good fit is achieved using dust composed of amorphous
carbon, silicon carbide and magnesium sulphide. We derive estimates for the
inner and outer radius, density and mass of the dust in the shell. The inner
radius is not resolved in our OSCIR imaging, giving an upper limit of 0.4
arcsec. With this constraint, we conclude that IRAS 19500-1709 must be at least
4 kpc away in order to have the minimum luminosity consistent with a post-AGB
status.
