lower left corner
is that a lens?
by Budgieye moderator
A nebula in the foreground in our galaxy?
An internal reflection in the telescope?
Or an exciting floating lens?
I must ask gumbosea
I believe you have an image artifact. Floating rings are very rare, and the only confirmed one I know of is associated with a very large galaxy cluster, Abell 1703. Download the following paper, "An Atlas of Predicted Exotic Gravitational Lenses", by Gilles Orban de Xivry and Phil Marshall, then refer to Figures 27 and 28, which show a Hubble image and computer simulation. Keep looking, though, as I'm betting more of them exist.