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{\bf 2.11\_V2.2 CCD ORBITAL BACKGROUND MEASUREMENT }
{\bf WITH THE ACIS DOOR OPEN }
\ec
\vspace{0.25in}

\normalsize
\noindent{\it Last Revised: August 8, 1999}\\
\noindent{\bf Filename: bkg\_doorop} \\

\noindent {\bf BRIEF FUNCTIONAL DESCRIPTION:} \\
\normalsize
This procedure is executed after the ACIS door has been opened, but
while the HRMA sunshade and aft contamination cover are still closed.
It is designed to acquire the necessary data to characterize the ACIS
particle-induced background as a function of orbital position.
Consequently, {\em Chandra} must be in nearly its final orbit (apogee
$>120,000$~km) before this procedure is run.  This procedure consists
of 6 science runs of 28.8~ks each, 3 with the ACIS-I array and 3 with
the ACIS-S array.  Steps 2--5 of the procedure execute two science
runs, one with the ACIS-I array and the other with the ACIS-S array.
Step 6 merely states to repeat steps 2--5 two times.  This procedure
should span the 54 hours that {\em Chandra} is above 60,000~km, with
about 6 hours to spare.  During this time spacecraft telemetry will be
switched between format 2 and format 1 every hour.  Each ACIS science
run must start in format 2 and remain there for at least $\sim$35 min
to permit the bias maps to be telemetered down.  In addition, the
telemetry must be in format 2 when the stop science run command is
issued so the telemetry buffers can be emptied before the instrument
is configured for the next science run.  ACIS should be placed in the
canonical thermal standby mode at the end of this procedure.

\vspace{0.25in}
\noindent The sequence of actions will be: 
\be
\item warm boot and start DEA HKP if necessary
\vspace{-0.10in}
\item configure the instrument to collect imaging array data
\vspace{-0.10in}
\item execute the science run with the ACIS-I array, including a dump
of the complete configuration information
\vspace{-0.10in}
\item configure the instrument to collect spectroscopy array data
\vspace{-0.10in}
\item execute the science run with the ACIS-S array, including a dump
of the complete configuration information
\vspace{-0.10in}
\item repeat steps 2--5 two times
\vspace{-0.10in}
\item return to thermal standby mode
\ee


\vspace{0.15in}
\normalsize
\noindent {\bf ASSUMED INSTRUMENT STATE:} \\
\normalsize
Assumes the ACIS door is open. \\
Assumes the standard patches are loaded. \\
Assumes ACIS is in the canonical thermal standby mode. \\


%\vspace{0.25in}
\normalsize
\noindent {\bf SPECIAL INITIAL CONDITIONS:} \\
\normalsize
Assumes the HRMA sunshade and aft contamination cover are closed. \\
Assumes {\em Chandra} is in nearly its final orbit (apogee $>120,000$~km). \\

%\newpage 

%\vspace{0.25in}
\normalsize
\noindent {\bf OPERATIONAL CONSTRAINTS/CAUTIONS:} \\
\normalsize


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

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

{\bf V1.2}
\begin{itemize}
\item changed filenames from ``ccd\_orbbkg2'' to ``bkg\_doorop''
\end{itemize}

{\bf V1.3}
\begin{itemize}
\item changed the phrase ``Door Open'' to ``ACIS Door Open'' in the procedure title
\item updated description
\item split the old step 1 into two steps: the new step 1 performs a warm boot and start DEA HKP run, while the new step 2 configures the instrument for the imaging array
\item moved dump configuration and dump patches commands into steps 3 and 5
\item changed command mnemonics and echo values in steps 3.1, 3.2, 5.1, and 5.2
\item changed time required parameter in steps 3.14, 3.15, 5.14, and 5.15 so each science run takes a total of 8 hours
\item changed telemetry format requirement in steps 3.14 and 5.14 from format 2 to formats 1 or 2
\item added note to wait until in telemetry format 2 to stop science runs in steps 3.15 and 5.15
\item swapped sequence of steps 6 and 7
\item changed all SW verifier criteria from A to B
\item changed all HW verifier criteria from 1 to 2
\item added more items to Assumed Instrument State
\item added more items to Special Initial Conditions
\end{itemize}

{\bf V1.4}
\begin{itemize}
\item changed expected values of DPA and DEA input voltages and
currents in steps 2.1 and 7.4
\item expanded step 6 to include more text description
\end{itemize}

{\bf V2.0}
\begin{itemize}
\item ACIS Team signed-off version
\item changed expected version number of flight SW to either 26 or 27
since either would be acceptable
\item changed expected value of ``1STAT7ST'' in step 1.6
\item changed title of step 7 to ``Return to Thermal Standby''
\item replaced steps 7.1 and 7.2 with a new step 7.1 containing the
command ``WSPOW00000''
\item added last sentence in ``Brief Functional Description'' and
changed last step in sequence of actions
\end{itemize}

{\bf V2.1}
\begin{itemize}
\item Added comment ``Only if necessary'' to the title field in step 1.
\item Changed the command mnemonic from ``WT000BE014'' to ``????'' and the
command Id from ``729'' to ``????'' in step 3.1.  
\item Changed the command mnemonic from ``WT000C0014'' to ``????'' and the
command Id from ``732'' to ``????'' in step 5.1.
\end{itemize}

{\bf V2.2}
\begin{itemize}
\item Changed the command mnemonic from ``WT000BE014'' to
``WT0016A014'' and the command Id from ``729'' to ``1352'' in step 3.1.  
\item Changed the command mnemonic from ``WT000C0014'' to
``WT0016C014'' and the command Id from ``732'' to ``1357'' in step 5.1.
\end{itemize}


\newcommand{\tablecaptiontext}{CCD Orbital Background Measurement
With the ACIS Door Open}
\input{bkg_doorop.tab}

\end{document}

