Guide users are the most savy group I know when it comes to
asteroids. Anyone here who knows what's going on with 7 Iris? I've
been viewing asteroids for a couple of years now, and I've never
experienced a bright "major asteroid" dimming as far as Iris appears
to have done.

I'd chosen 9th mag Iris as a star party object back in November, and
I couldn't find it thru my 12" LX200GPS.

The other night (Feb 6, 21:00 hrs. EST) I'd chosen Iris as our last
viewing object for a class in backyard astronomy. This time I
couldn't find it during the class - using my permanently mounted 14"
LX200GPS. Some high haze had moved in, and I was having considerable
trouble seeing to only 13th magnitude. After class I did locate
Iris - right where Guide 8 and a very current ephemeris download said
it would be. But it was down to about 12.5 magnitude (compared to
very nearby stars known to have magnitudes ranging from 8.2 to
invisible) A DSS download confirmed that it wasn't a star.

How could such a relatively bright asteroid repeatedly appear to be
so diminshed in brightness? According to web info, "UBV photometry
yields a model for (7) Iris as an ellipsoid with axial ratios 3:4:5"
This certainly doesn't explain it.

Any thoughts?

Pete Peterson