Residual bulk image

For a short time period (about a day), I thought I was famous.  Then reality set in.  I was taking images of the Owl nebula (M97) in narrowband, on the new 24" Planewave telescope located in California.  Below is a 15 minute stack with hydrogen alpha filter.  The dot which is marked is not present on any images on the web showing the nebula.  A new supernova?!  No.  After emailing the imaging specialist for iTelescope (very helpful btw), it turns out this is "residual bulk image".  Essentially a ghost of the star used to focus the scope just before this image was taken.  A CCD imaging artifact. Ouch.