Among the million objects analyzed in the GalaxyZoo.org morphological 
census, perhaps the strangest is SDSS J094103.80+344334.2 (first noted 
by a Dutch schoolteacher). It appears as an irregular cloud 20 kpc from the
disk galaxy IC 2497. A WHT spectrum shows very strong emission, with 
high-ionization lines (He II, [Ne V]) suggesting AGN photoionization, 
coextensive with the continuum. Images and further data are at
http://www.astr.ua.edu/keel/research/voorwerp.html.

Several interesting possibilities are allowed by these data, which
rule out ionization only by hot stars or shocks. We see a truly enormous 
narrow-line region, but where is the AGN? The ionizing luminosity must be 
3e43-4e44 erg/s (for source in the cloud or in IC 2497). It is difficult to 
hide such an AGN. The galaxy's far-IR luminosity is barely compatible with 
this if it is dominated by an obscured AGN. If we see no evidence of an 
obscured AGN, this may be a "ghost AGN" which has recently turned off. 

The UVW2 filter traces starlight or scattered AGN light at z=0.05. For a flat 
continuum shortward of SDSS u the UVOT UVW2 count rate is 0.03 count/second, 
about twice the dark level. This gives S/N=4 within 1000 seconds, reaching
10 after 5 ksec. A bluer slope (higher S/N) is likely in view of the low 
spectroscopic metallicity and extended nature of the object. At S/N=10, we 
can easily distinguish a young stellar population from scattered AGN light 
(too blue for any mix of stars).

The XRT can detect even a strongly obscured AGN, and distinguish whether it 
lies in the cloud or IC 2497. Even for a heavily absorbed AGN, a few ksec 
would give a clear measurement, since the 0.5-5 keV intensity
would be comparable to the ionizing luminosity estimated above (that is, 
of order 1e-11 erg/cm^2 s).