\documentclass[11pt]{article}

\usepackage{lscape}

\topmargin -0.75truein
\oddsidemargin -0.0truein
\textheight 9.5truein
\textwidth 6.7truein
\hbadness=10001
\hfuzz=200pt


\begin{document}
%\input dspace12.tex
%\input pstricks.tex
%\input psfig
\newcommand{\be}{\begin{enumerate}}
\newcommand{\ee}{\end{enumerate}}
\newcommand{\bc}{\begin{center}}
\newcommand{\ec}{\end{center}}
\newcommand{\bi}{\begin{itemize}}
\newcommand{\ei}{\end{itemize}}
\newcommand{\bd}{\begin{description}}
\newcommand{\ed}{\end{description}}
\newcommand{\bt}{\begin{tabbing}}
\newcommand{\et}{\end{tabbing}}
\newcommand{\eg}{{\it e.g.~}}
\newcommand{\ie}{{\it i.e.~}}
\newcommand{\ul}{\underline}
\newcommand{\axaf}{{\em AXAF}}
\def\la{\hbox{\rlap{$<$}\lower0.5ex\hbox{$\sim$}\ }}


\large
%\vspace*{-0.5in}
\centerline {\bf 1.16\_V2.0 DARK CURRENT MEASUREMENT } 
\vspace{0.25in}

\normalsize
\noindent{\it Last Revised: June 27,1999}\\
\noindent{\bf Filename: dark\_cur} \\


\noindent {\bf BRIEF FUNCTIONAL DESCRIPTION:} \\
\normalsize
It is useful to measure the dark current of the CCDs at a
slightly elevated temperature (T=-90~C) since the dark current of the
ACIS CCDs at the operational temperature (T=-120~C) is so low that it
is difficult to measure with the existing sensitivity.  In order to measure
the dark current, we will compute and telemeter bias maps with 9.9~s
and 3.3~s exposures.  By examining the difference between these maps,
one can derive the dark current.  If time allows, this measurement may
also be made with the CCD temperature at -110~C.



\vspace{0.25in}
\noindent The sequence of actions will be: 
\be
\item start a DEA HKP run if necessary
\vspace{-0.10in}
\item configure the instrument to collect imaging array data
\vspace{-0.10in}
\item execute the 9.9 and 3.3~s bias computations with the imaging
array include the full configuration dumps
\vspace{-0.10in}
\item configure the instrument to collect spectroscopy array data
\vspace{-0.10in}
\item execute the 9.9 and 3.3~s bias computations with the spectroscopy
array include the full configuration dumps
\vspace{-0.10in}
\item power down the video boards and FEPs and return to thermal
standby state if necessary
\vspace{-0.10in}
\ee

The sequence above will be repeated at the desired temperatures.


\vspace{0.15in}
\normalsize
\noindent {\bf ASSUMED INSTRUMENT STATE:} \\
\normalsize
Assumes the focal plane temperature is regulating at the desired temperature.\\
Assumes that both DPAs and side A of the DEA are on and the flight SW
is running. \\
Assumes that the standard patches are loaded.\\



%\vspace{0.25in}
\normalsize
\noindent {\bf SPECIAL INITIAL CONDITIONS:} \\
\normalsize


%\newpage 

%\vspace{0.25in}
\normalsize
\noindent {\bf OPERATIONAL CONSTRAINTS/CAUTIONS:} \\
\normalsize
This procedure does not include a warm boot at the beginning in order
to preserve the focal plane temperature setting.  If a warm boot is
needed, the atomic procedure should be executed, followed by the
appropriate procedure to set the focal plane temperature.



\vspace{0.15in}
\normalsize
\noindent {\bf REFERENCES:} \\
\normalsize

\normalsize
\noindent {\bf CHANGE HISTORY:} \\
\normalsize

{\bf V1.2}
\begin{itemize}
\item changed filenames from ``ccd\_dark'' to ``dark\_cur''
\end{itemize}

{\bf V1.3}
\begin{itemize}
\item changed step 1 to include a warm boot and start DEA HKP run if
necessary
\item edited step 2 to include the configuration for data acquisition
with imaging array
\item edited step 3 to include all the dumps
\item edited step 5 to include all the dumps
\item added step 6 to put the instrument back into the thermal standby
state
\item added value of commandEcho for all SW command packets
\end{itemize}

{\bf V1.4}
\begin{itemize}
\item removed the warm boot which was in the old step 1
\item changed the expected value of the DPA A \& B and DEA A input
voltage  and changed the expected values of the 
DPA A \& B and DEA A input currents in steps 2.1 and 6.3
\item changed the start science command to ``XTZ0000005'' in steps
3.2, 3.17, 5.2, and 5.17
\item changed the expected time duration of steps 3.29 and 5.29 to
30~m from 45~m
\item used command ``WSPOW00000'' in step 12.1 to power-down the video
boards and FEPs
\end{itemize}

{\bf V2.0}
\begin{itemize}
\item ACIS team signed-off version.
\item edited the ``Sequence of Actions''
\item added comment in step 6.2 to verify that FEPs and video boards
are off
\end{itemize}

\newcommand{\tablecaptiontext}{Dark Current Measurement}
\input{dark_cur.tab}

\end{document}
