From: Jon Brinkmann
Date: Sat, 9 Mar 2002 23:51:24 -0700
Subject: Re: 2.5m obslog 20020308 (MJD 52342)
This is a well known, documented "feature" of all the cameras.  See
	http://sdsshost.apo.nmsu.edu/folklore/spectro/index.html
Jon
> VS+ on the Spectrograph CCDs:
> -----------------------------
> On fMJD 52342, around 0005Z, watcher reported a vs+ error on CCD04.  The
> real-time display showed vs+ on CCD01 as +0.04V, and CCD02/3/4 as +0.06V.
> After clearing the error, watcher reported "vs+ is within limits for all
> CCDs".  That's fine, but a _plot_ of vs+ for the spectro CCDs showed the
> nominal range as about 7+-0.5V, and the CCD04 value as about zero since at
> least 10am MST (1700Z), so we were disconcerted.
>
> We checked with Alan Uomoto, then Connie and learned that vs+ should
> indeed be registers are being read.  So, the problem seems to be that
> watcher is not smart enough to plot two nominal ranges for a voltage. A
> PR was filed.