BSM develops blocked column

The Bright Star Monitor ST-8XME looks like it has developed a partially blocked column around column 772 (that is, nearly the center of the 1530-pixel-wide CCD.  This became visible on images taken on 2011-02-11; all earlier images are ok.  We are studying the problem, but be aware that blocked columns will affect photometry for any aperture that includes the blocked column.  This was probably due to a cosmic ray hit damaging a CCD pixel around (772,244).  This is more likely to occur at Tom Krajci's 9400ft elevation than at sea level, and is a major problem for space-based missions.

Arne