Subject: Re: DIS red chip bias

From: Jim Lauroesch

Submitted: Fri, 7 Feb 1997 13:34:10 -0600 (CST)

Message number: 28 (previous: 27, next: 29 up: Index)

Looking quickly at the biases I took last Sunday night (February 2nd) I
find that an imhistogram of the red chip bias frames does seem to be bimodal
with a separation between the peaks of ~20-25 pixels.  Looking at older 
data I find no such second peak (data taken November 11, 1996).

It is hard to say with a quick look like this whether the widths of
the two peaks are the "expected" 15 DN (they may be slightly narrower), but
the overall width of the distribution is of order 30 DN essentially doubling
the read noise.

I have not been able to detect any pattern either yet (I haven't really had time
to look that much).  I hadn't noticed this before as I was really looking
for something in my blue spectra, and hadn't really done more than glance at the
latest red data.

			Jim Lauroesch

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