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%\section {Closing down the INT} \label{ch6:INT-close}
\section {CLOSING DOWN THE INT} \label{ch6:INT-close}
At the end of an observing night, the Telescope Operator will shut down the
Dome, the Telescope Control Computer, and the Telescope itself, after moving
it to a park position, {\it i.e.} the Zenith when in Cassegrain Mode
or the Access Park position when in Prime Focus Mode, with the telescope 
in a nearly horizontal position leaning towards the North. The Instrument
Control Software should be closed down, but may be left running if a dump
from Disk to Tape or a Flatfield exposure is in progress.

The process of closing down the INT is broadly the reverse of the
starting up described in the previous section \ref{ch5:INT-start}.
\subsection {Closing down Telescope and Dome}

\begin{enumerate}
\item Before moving the telescope to the park position, switch off the 
Cassegrain (if in use) and Finder TV cameras, and switch off the Autoguider. It
 is important
that this is done before slewing the telescope, in order to avoid accidental
damage to the cameras by a possible bright object appearing in the camera
field. The TV cameras are controlled from small racks near the top of
right-most panel of the Control Desk, to the left of the Autoguider Control.
Switch the cameras off by turning the gain controls 
anti-clockwise until they click, followed by pressing the small red
OFF button.  The autoguider is switched off by pressing the 
\doublebutton{ON}{OFF} button on the rack to the right.

\item Move the telescope to zenith by pressing \button{ZP} on the Control Desk
(Bay 2, Rack 3). This also disables the dome tracking.

\item Close the PRIMARY and SECONDARY mirror covers IN THAT ORDER by operating
the MIRROR COVER \button{CLOSE} on the Engineering Rack. This must be done
before closing the dome shutters for safety reasons.

\item Switch to Engineering mode by pressing the \doublebutton{ENG}{COMP} on
the Telescope Control Desk.

\item Close the dome shutter(s) by pressing \doublebutton{LOWER}{MICRO}
button on the Engineering Rack until the MAIN OVER TRAVEL light is out,
followed by pressing the \doublebutton{LOWER}{MAIN} button until that light 
comes
on again, and then finishing with pressing anew \doublebutton{LOWER}{MICRO}
for about 10 seconds. This procedure has to be done for BOTH shutters,
starting with the Lower Shutter (buttons on the right), but only if that 
shutter happens to be raised, which will not often be the case. The control 
buttons for the Upper Shutter are found on the left-hand side of the Rack.

The main (upper) shutter should be at a zenith distance of 71.9 degrees
when fully closed. This value is listed on the Information Display (section
\ref{ch8:display}) as `Upper Shutter ZD'\,. Take care: if only ``$*$''s are
displayed, this normally means that the Dome is fully open.
 Thus, a visual inspection is the best way to ensure that the Dome
is properly closed. Note, that the MAIN OVER TRAVEL indicator light for the
Upper Shutter will be on when the dome is closed; 
this is a necessary condition, but {\bf not} a sufficient one.

\item Switch off the dome fans and (if necessary, it is rarely done)
replace fan covers.

\item Switch off the EXTRACTOR and INPUT ventilators, on the second
and the ground floor, respectively, by pressing the red stop button on the
control panel near the telescope base, which can be reached via the small
Coude room opposite the CLIP Centre (beware oil on the floor!).

\item Close the Finder Cover.

\item When working at Cassegrain, the Primary Mirror Plug will have to be
replaced; when in Prime Focus Mode, the telescope has to be parked in the
Access Park position. In both cases, move the telescope to the park
position (manually; the PARK ACCESS button does not work!)
by following the procedure described in
item 12 of the previous section \ref {ch5:pmplug}:

\begin{enumerate}
\item
Move the telescope to the North Horizon Limit; use an Hour Angle of exactly
24.00 hours, so that the telescope needs to be moved in Declination only.  
If the Hour Angle is not exactly 24 hours, the telescope will hit the platform.
\item
Press the Declination \button{QM} (Quick Motion) button on the Engineering Rack
until the green light
comes on to signal that the mode is engaged. The corresponding light of the
\button{SM} (Slow Motion) button must be off.
\item
Press the Declination \button{$+$} button, which actually moves the telescope,
until the alarm sounds as sign that the telescope has run into a limit. Now
press the \button{Accept} button on the Control Desk to switch the alarm off.
\item
Turn the key-operated LIMIT switch on the Engineering Rack to the O/R position
(limit override).
\item
Repeat steps b) and c). This time there will be no alarm, but the telescope
will halt in Park Access position when it runs into a second limit switch.

In {\bf Prime Focus} mode, leave the telescope in this position. \vspace{4mm}

In {\bf Cassegrain} mode, replace the mirror plug, and 
move the telescope via the pole position back to zenith, as follows:
\item
Press the Declination \button{$-$} button to move the Telescope back to the
the pole position at declination 90\degs.
\item
Turn the LIMIT switch to the NULL position.
\item
Press the \button{SM} button on the Engineering Rack.
\item
Switch to computer mode by turning the key on the Control Desk.
\item
Press the  \button{ZP} button on the Control Desk to move 
the telescope to the `zenith park' position.
\end{enumerate}

\item Press the \doublebutton{EMERGENCY}{STOP} button in order to disable
any subsequent motion of the telescope. This is not essential, but good
practice. One has to remember, however, to press the \button{RESET} button
before starting up in the following afternoon.

\item Switch off the oil pump, by pressing the OIL PUMP switch on the
Engineering Rack.

\item But DO NOT SWITCH OFF POWER to either Dome or Telescope.

\item Top up the Cryostats with Liquid Nitrogen.

\item Check that the access doors to the dome are closed.
\end{enumerate}

\subsection {Control Software and Instrument shut down}
\begin{enumerate}

\item The PE\,3220 Telescope Computer will be shut down. However, before
stopping the Telescope Control Software, save, if so wanted, the observer's
object catalogue on a disk file (see section \ref{ch8:UICD}) with the SAVE
command.

Terminate the Telescope Control Program
by typing on the PE\,3220 System Console (on the desk to the left of the
Engineering Rack):

\PE{FINISH}

and shut down the Telescope Computer with:

\PE{MA MSMD:,OFF}

This command shuts down the Telescope Computer to a known state, and leaves
the disk protected.

\item The PE\,3210 Instrument Computer is normally left running. 
Nevertheless, it is good practice to shut down the ADAM control software,
unless
the observer is going to take flatfield exposures or do a tape dump of his
data. The PE\,3210 is frequently used during daytime for development work.

If the observer leaves a flatfield or other calibration 
exposure running at the end of the night,
it is very important that special warning signs are placed on BOTH 
doors leading into the dome as well as on the console in the Control Room. 
It is the responsibility of the Telescope Operator to
put up these signs, who therefore has to be properly informed by the 
observer(s). 
 Further, the observer should make sure that, when using a 
CCD detector, the TO has filled the cryostats 
with Liquid Nitrogen before starting calibration exposures.
The interval between dawn and 09:15 Local Time is reserved for the taking of
flat field exposures.

\item 
When observing or other data taking has finished, ensure that the spectrograph's
camera shutters are closed (on both 235 and 500 cameras; use IDS CLOSE),
and, if the IPCS was used,
that, most importantly, the EHT switch on the IPCS rack below the telescope
mirror cell is switched to STANDBY. After a long morning flatfield, 
the day crew will safely shut down the IPCS after an exposure
has finished, and shut down the Instrument Control Software.

\item
If it is necessary to completely close down the PE\,3210 Instrument Computer,
for instance because a power cut is expected, proceed as follows:
\begin{enumerate}
\item \ADAM{SHUTDOWN}
\item Sign Off at the User Terminal(s) with:

\PE{SO}
\item Type at the System Terminal in the Computer Room:

\PE{STOPALL}

\PE{OFF}

\PE{MA EGLE:,OFF}
\item On the EGLE disc drive switch WRITE PROTECT to ON, and POWER to OFF.
\end{enumerate}
\end {enumerate}

\subsection{Logbooks and Magnetic Tapes}
The following logbooks and forms should be completed:-
\begin{enumerate}
\item
Telescope Operators Log and Telescope Log.
\item 
Nightly Report Sheet, to be completed by the Telescope Operator and left
in the tray on top of the book shelves in the Control Room.
\item
Fault Sheets and SER forms, to be left in the same tray.
\item
The Telescope Operator will complete the printing of the Observing Log and
place the sheets in the ring-backed binder. A second copy should be given
to the observer. The printer, the PC and its VDU should be switched off.
\item
Magnetic Tape Copying Requests. Leave both the D-Tape and the completed Request 
form in the grey tray in the Control room. If a tape dump is done at the end
of the night, complete the form and ask the day crew to remove the tape after
the dump has completed correctly.
\end{enumerate}

Observers should keep their tape copying up to date as far as possible.
Otherwise there may be not sufficient time at the end of an observing run
to copy all the D-tapes (1600\,BPI) to C-tapes (6250\,BPI) before the
observer leaves. It is {\bf strictly forbidden} to take D-tapes from the
mountain, and it can take ages for a C-tape to reach your home institution
by post.

Normally, the C-tape(s) will be left in the pigeon-hole marked ``Copied Tapes''
in the East-West Corridor on the first floor of the INT building. If they
aren't there, inquire in the software office at the East end of
the same corridor; if no-one who knows can be found, try the WHT 
computer room. Observers having little time before leaving after the end of
their run are well-advised to inform the person doing the copying by a note
to that effect on the Tape Copy Request Form. If you are blessed with a
Support Astronomer of an especially big-hearted and generous nature he/she might
copy your tapes in an emergency.
\vfill
\eject
