% change over to local paragraph setting because of many examples of input
% for the user interface programme
\newcommand{\uiprompt}{ {\bf UI--$>$} }
\newcommand{\newitem}[1]{{\vskip 0.25cm} {\bf #1}}
\newcommand{\smallparskip}{\parskip 0pt}
\newcommand{\largeparskip}{\parskip 0.25cm}
\smallparskip
\parindent 0pt

%\section {The Telescope User Interface} \label{ch8:INT-UI}
\section {THE TELESCOPE USER INTERFACE} \label{ch8:INT-UI}
\subsection { Introduction}
On the INT the User Interface is operated by the Telescope Operator so most
observers will not require a detailed knowledge of it.
The telescope user interface, of which many features are common to the JKT 
and INT, is used for two main purposes: 

\begin{itemize}
\item
the {\bf ENTRY OF DATA} which are then transferred to the on-line part of the 
control system by the action of pressing a button on the system control panel 
and 
\item {\bf the CHANGING OF OPERATING MODES}\@.
\end{itemize}

At present, the philosophy is that no action
occurs until a button is pressed, except for the two most commonly used
commands (GO and STOP) which can be issued either from the user interface
or from the control panel.   It is likely that all of the button functions
will eventually be duplicated within the user interface, but a clear
distinction between data input and action will remain.   For example, the
operations of entering the RA and Dec of an object and slewing to it are
separate.   An operating mode determines the way in which the control
system responds to a command, for instance whether the telescope or guide
probe is moved during autoguider acquisition or whether an object is to be
observed with the JKT, East or West of its pier.
 
\subsubsection {Starting the program}

Section~\ref{ch7:PE3220} describes the commands needed to start the telescope 
control software.  A successful start-up results in the User Interface 
displaying the name of the telescope (check that it is the correct one!)
and a short set of instructions on the usage of the LIST and GO commands:
The user interface program is ready to accept input when the terminal
prompts with:
\largeparskip

\uiprompt

In what follows, prompts issued by the computer will be in boldface and words 
in capital letters represent commands. In the text, commands are given in
full, but the permissible abbreviations are listed in section~\ref{ch8:UIC}.
\smallparskip

\subsubsection {How the program deals with input}

Character strings separated by spaces are entered at the User Console and
sent to the program USER by pressing \key{Return}\,.  USER's command processor
first attempts to identify the first string as a command name by comparing
it with its internal dictionary of such names.    If it is successful in
making a match, one of two things may happen: (1) a command which does not
take any arguments ({\it e.g.\/} GO) is executed immediately, or (2), if the
command takes arguments ({\it e.g.\/} RA), the command interpreter will go on 
processing the
input line until the requisite number of acceptable arguments have been
analysed, after which the command is executed.  If the input line is not
exhausted the next character string is interpreted as a new command and
processed in the same manner.  Thus, commands can be staggered; delimiters
are `space' and semicolon `;'. When the command processor is not able 
to match a character
string with a command name, the program outputs a message 
and ignores the rest of the input line. 
Commands may have up to 7 qualifiers and 5 parameters.   Most require a
button on the Control Desk to be pushed for any action to occur, {\it i.e.\/}
to  `activate' the command.   The full
specification of an action can therefore be of the form: \largeparskip

\UI{COMMAND/QUALIFIER1/QUALIFIER2/... PARAMETER1 PARAMETER2 ...}

possibly followed by pressing a control panel button. Note that occasionally
parameters are associated with only one qualifier. Section~\ref{ch8:UICD}
gives a complete
list of commands, their qualifiers, parameters and any required control
panel interaction. The {\em default\/} qualifier for all commands which take
qualifiers is the first one given. If the user interface requires a parameter 
which has not been specified it will request it with the prompt:

{\bf UI--Parm$>$}

If you have changed your mind and don't want to give a value,
just press \key{Return} and the command is ignored, {\it i.e.\/} the old 
value is retained. \smallparskip

\subsubsection {Catalogue entries}

There is an internal catalogue containing the names, positions and guide 
star references for up to 500 objects.   ADV/CAT will give the source names 
of all targets in the current catalogue, while LIST/CAT will give the
full details. Stored system cataloges are listed in 
section~\ref{ch8:catalogues}. There are 3 special entries:

\begin{itemize} 
\item the `EDIT source' is the catalogue entry whose parameters (RA, Dec,
equinox, proper motions, guide object) are presently being modified; 
\item the `CURRENT source' is the object being observed, and 
\item the `NEXT source' is the object that will be observed when the 
GO command is typed, or the `Telescope-Dome Source' button  \button{SRCE} 
on the Control Desk is pressed,
at which point the object also becomes the CURRENT source. The said button
is found under the label T/S\,DOME at the top centre of the `System Control' 
panel, which occupies the lower section of bay 2 (from left).
\end{itemize}

Modifications to the CURRENT source's parameters do not
affect the operation of the telescope directly.   This is only altered when
a button is pressed or GO is typed, in which case the parameters of the
NEXT source are always picked up.   When a new catalogue entry is defined
using the SOURCE command, it automatically becomes the EDIT source, except
if SOURCE/MARK is used. 
The edit pointer is also changed if an existing source name
is input.  Thus any data input will always be associated with the edit
source until the pointer is changed by a SOURCE or an already defined
source name.  Any source parameters which are not
specifically entered will be picked up from the first entry in the
catalogue .D(EFAULT)\@.
At STARTUP all three pointers point to .D(EFAULT)\@.  It is therefore,
possible to observe by merely entering R and D commands (each new entry
going into .D) and pressing GO at the end of the observation.  By this 
means the pointers are never reset and no source entries are accumulated in
the catalogue. \medskip

When the same objects are to be observed on different nights SA(VE) will
store the current internally held catalogue and this can then be recalled
from disc with I(NPUT)
on any subsequent occasion.  The contents of the catalogue are stored as
commands so that restoring the catalogue allows objects in it to be
acquired immediately without resort to any other commands apart from GO.

\subsection {HELP}

The on-line help facility displays information on User Interface commands 
and is usually quicker than looking in the manual itself. It is invoked by 
typing: \largeparskip

\UI{HELP command-name}

There are four single-character commands which can be entered in 
response to a prompt from the HELP system:

\begin{tabular}{ll}
   `?'   & list all topics below the current level\\
   ` '   & move one level up the hierarchy - terminates HELP at level 0\\
   `!'   & terminate the HELP command immediately\\
\end{tabular}
\vfill
\eject

\smallparskip
\subsection {Summary of User Interface commands} \label{ch8:UIC}
\renewcommand{\arraystretch}{1.1}
\newcommand{\hlineskip}{\vspace{0.8mm} \\ \hline}
\vspace{2mm}
\begin{tabular}{lllc}
\multicolumn{1}{l}{COMMAND}             & \multicolumn{1}{l}{QUALIFIERS}
 &  \multicolumn{1}{l}{PARAMETER}  & \multicolumn{1}{l}{CONSOLE BUTTON} \\
\\
\hline
\\
$*$                 &                   &                    & None        % \\
\hlineskip
                    &                   &                    &               \\
AC(QUIRE)           & /PR(OBE)          &  None              & AUTOGUIDER    \\
                    & /TE(LESCOPE)      &                    & \button{ACQ}% \\
\hlineskip
                    &                   &                    &               \\
AD(VISE)            & /S(OURCE)         &  Source name       & None          \\
                    & /E(DIT)           &  None              & None          \\
                    & /N(EXT)           &  None              & None          \\
                    & /CU(RRENT)        &                    & None          \\
                    & /T(EL)            &  None              & None          \\
                    & /CAT              &  None              & None          \\
                    & /UI               &  None              & None        % \\
\hlineskip
                    &                   &                    &               \\
AP(ERTURE)          & /A                &  x y offsets for A & BEAMSWITCH    \\
                    & /B                &  x y offsets for B & 
                                      \button{A}\, \button{NOM}\, \button{B}%\\
\hlineskip
                    &                   &                    &               \\
AU(TOFFSET)         & /B(OTH)           & RA \& Dec Offsets  & None          \\
                    & /R(A)             & RA\  Offset        &               \\
                    & /D(EC)            & Dec Offset         &             % \\
\hlineskip
                    &                   &                    &               \\
B(EAMSWITCH)        & /A                & x y offsets for A  & BEAMSWITCH    \\
                    & /B                & x y offsets for B  & 
                                     \button{A}\, \button{NOM}\, \button{B}% \\
\hlineskip
                    &                   &                    &               \\
D(EC)               & None              & +/$-$ dd mm ss.s   & None        % \\
\hlineskip
                    &                   &                    &               \\
DEL(ETE)            & /F(ROM)           & source1 source2    & None \\
                    &                   &                    &               \\
                    & /A(LL)            &                    &               \\
                    & /S(EQ)            & seq.no 1 seq.no 2  &             % \\
\hlineskip
                    &                   &                    &               \\
DIF(F\?RATES)       & /B(OTH)           & RA \& Dec Rates    &
                                                    \doublebutton{DIFF}{RATE}\\
                    & /R(A) ........... & RA tracking rate   &               \\ 
                    & /D(EC)........... & Dec tracking rate  &             % \\
\hlineskip
                    &                   &                    &               \\
E(DIT)              &                   & source name        & None        % \\
\hlineskip
                    &                   &                    &               \\
EQ(UINOX)           & None              & B/J date in years  & None          \\
                    &                   & or A(pparent)      &             % \\
\hlineskip
\end{tabular}
%\vfill
%\eject
\clearpage
\vspace{9mm}
\begin{tabular}{ll}
\multicolumn{2}{c}{EXPLANATIONS OF}\\ 
\\
COMMANDS & PARAMETERS AND QUALIFIERS  \\
\\
\hline
 &  \\
\multicolumn{2}{l}{Marks comment line in catalogue or at terminal}     % \\
\hlineskip
\\
Acquire star by              &  moving guide probe                       \\
(Beware change from historical use) &  moving telescope                % \\
\hlineskip
                             &                                           \\
Give parameters at a given time of the       &  named source             \\
                             &  edit source                              \\
                             &  next source to be observed               \\
                             &  source currently being observed          \\
                             &  telescope                                \\
Lists                        &  names in catalogue                       \\
Gives summary of the         &  User Interface parameters              % \\
\hlineskip
\\
Set up collimation offsets   & offsets for aperture A ({\secs})           \\
                             & offsets for aperture B ({\secs})         % \\
\hlineskip
\\
Moves telescope by required  &                                            \\
offset and guide probes in   &  RA\  offset ({\secs})                     \\
reverse                      &  Dec  offset ({\secs})                   % \\
\hlineskip
\\
Set up collimation offsets   & offsets for aperture A ({\secs})           \\
(Synonym for APERTURE)       & offsets for aperture B ({\secs})         % \\
\hlineskip
                             &                                            \\
Declination of edit source is&                                          % \\
\hlineskip
                             &                                            \\
Delete Catalogue entries     &  - from source1 to source2 \\
                             &  \ \ (if source2 omitted, then only source1)  \\
                             &  - whole catalogue (except  .DEF .GUIDE .LINK)\\
                           &  - from sequence number 1 to sequence number 2 %\\
\hlineskip
                               &                                          \\
Non-sidereal tracking rate     &                                          \\
(Switched off on source change)&  RA\  rate in seconds/sec                \\
                               &  Dec  rate in {\secs}/sec              % \\
\hlineskip
\\
Selects given source as the  &  Edit source                             % \\
\hlineskip
                             &                                            \\
The equinox for coordinates is  & Byear or Jyear (Mean) or A=(apparent)   \\
                                & (B, J, or A {\em must\/} be defined)  % \\
\hlineskip
\end{tabular}
%\vfill
%\eject
\clearpage
\begin{tabular}{lllc}
\\ \\
\multicolumn{1}{l}{COMMAND}   & \multicolumn{1}{l}{QUALIFIERS}
 &  \multicolumn{1}{l}{PARAMETER}  & \multicolumn{1}{l}{CONSOLE BUTTON} \\
\\
\hline
                    &                   &                    &               \\
F(OCUS)             & None              &  focus position    & FOCUS\\
                    &                   &                    & \button{NOM}
                                                              \button{STOP}% \\
\hlineskip
                    &                   &                    &               \\
GO(TO)              & /N(EXT)           &  none              &  T/S~DOME     \\
                    &                   &                    & \button{SRCE}
                                                               \button{STOP} \\
                    & /SO(URCE)         &  source name       & none        % \\
\hlineskip
\\
GU(IDE\?OBJECT)     & None              &  object name       & GUIDE~PROBE  \\
                    &                   &                    &
                                                 \doublebutton{GUIDE}{STAR}% \\
\hlineskip
\\
HA(NDSET)           & /A(LL)            &set rate, guide rate,&Handset and   \\
                    &                   & increment step     & 
                                                             \key{$\uparrow$} \\
                    & /S(ET)   .......  & set rate           &
                          \key{$\leftarrow$}\hspace{1.0cm} \key{$\rightarrow$}\\
                    & /G(UIDE) .......  & guide rate         &
                                                           \key{$\downarrow$} \\
                    & /I(NCREMENT) ...  & increment step     & XY~AXES      \\
                    &                   &                    & 
                                  \button{SET} \button{GUIDE} \button{INC}% \\
\hlineskip
\\
H(ELP)              & None              &  command name      & None          \\
                    &                   &  /qualifier        &             % \\
\hlineskip
\\
I(NPUT)             & /N(ORMAL)         &  file name         & None          \\
                    & /P(ROMPT)         &  device name       &             % \\
\hlineskip
\\
L(IST)              & /A(LL)            &                    & None          \\
                    & /F(ROM) ......... & source1 source2    &               \\
                    & /PR(INTER)        &                    &             % \\
\hlineskip
\\
N(EXT)              & /NA(ME) ........  &  source name       & T/S DOME      \\
                    &                   &                    & \button{SRCE} \\
                    & /SEQ(UENCE) ....  &  sequence number   &             % \\
\hlineskip
\\
O(FFSET)            & /B(OTH)           & RA Dec Offsets     & OFFSET        \\
                    & /R(A)             & RA\   offset       &
                                                \button{NOM} \button{OFFSET} \\
                    & /D(EC)            & Dec offset         &             % \\
\hlineskip
\\
P(ROPER\?MOTION)    & /B(OTH)           &  proper motion RA \& Dec& None      \\
                    & /R(A)             &  proper motion in RA &             \\
                    & /D(EC)            &  proper motion in Dec &          % \\
\hlineskip
\end{tabular}
%\vfill
%\eject
\clearpage
\begin{tabular}{ll}
\multicolumn{2}{c}{EXPLANATIONS OF}\\ 
\\
COMMANDS & PARAMETERS AND QUALIFIERS \\
\\
\hline
 & \\
Define requested focus setting  & Focus Position in {\tt mm} of motion\\
Goto requested position with \button{NOM} & of secundary  % \\ 
\hlineskip
\\
Slew telescope and dome to the NEXT object &
             {\it Either} type `GO' {\it or} press \button{SRCE}    \\
           & Abort a slew by pressing \button{STOP}\\
GO to source name             &  !! Beware: {\em not yet debugged}% \\
\hlineskip
\\
Define guide-star name as 'edit source'.&Object Name must be a name \\
&in an existing Catalogue % \\
\hlineskip
&\\
Handset buttons are equivalent & all values can be defined in one instruction\\
to `arrowed' XY~AXES  buttons.&   setting rate in  ({\secs}/sec)         \\
`set' mode for continuous motion; &   guiding rate in  ({\secs}/sec)     \\
`increment' mode for steps.&   increment in  ({\secs})                   \\
                            &                                             \\
                            &                                           % \\
\hlineskip
                            &                                             \\
Provide information about a command  &         \\
or qualifier                &                                           % \\
\hlineskip
                            &                                             \\
Input from file or device   &   without \uiprompt prompt                  \\
                            &   with\ \ \ \ \   \uiprompt prompt        % \\
\hlineskip
                            &                                             \\
List catalogue entries      &   for whole catalogue                       \\
                            &   from source1 to source2 on screen         \\
                            &   to the line printer                     % \\
\hlineskip
                            &                                             \\
Define Next Source          &   Source Name must be catalogue name        \\
                            &Don't press \button{SRCE} until ready to go  \\
                            &   Sequence Number in current catalogue    % \\
\hlineskip
                            &                                             \\
Define Offsets in RA and/or Dec; & both can be defined in one instruction \\
Pushing \button{NOM} cancels offsets. &   offset in RA\  ({\secs})        \\
                            &   offset in Dec  ({\secs})                % \\
\hlineskip
\\
Proper motion               & both can be defined in one instruction      \\
                            & proper motion in RA\  (seconds/yr)          \\
                            & proper motion in Dec ({\secs}/yr)         % \\
\hlineskip
\end{tabular}
%\vfill
%\eject
\clearpage
\begin{tabular}{lllc}
\\ \\
\multicolumn{1}{l}{COMMAND}             & \multicolumn{1}{l}{QUALIFIERS}
 &  \multicolumn{1}{l}{PARAMETER}  & \multicolumn{1}{l}{CONSOLE BUTTON}\\
\\
\hline
                    &                   &                    &               \\
R(A)                & None              &  hh mm ss.s        & None        % \\
\hlineskip
                    &                   &                    &               \\
ROTATOR             & see TURNTABLE     &                    &             % \\
\hlineskip
                    &                   &                    &               \\
SA(VE)              & None              &  file name         & None        % \\
\hlineskip
                    &                   &                    &               \\
SE(T)               & /LST              &  hh mm ss          &               \\
                    & /UT               &  hh mm ss          &               \\
                    & /NOW              &                    &             % \\
\hlineskip
                    &                   &                    &               \\
SN(AFU)             & /N(OMINAL)        &  None              & Handset buttons\\
                    & /A                &                    & GUIDER buttons\\
                    & /B                &                    & \button{ACK}% \\
\hlineskip
                    &                   &                    &               \\
SO(URCE)            & /I(NPUT)          &  source name       & None          \\
                    & /MA(RK)           &  source name       & None        % \\
\hlineskip
                    &                   &                    &               \\
STOP                & None              &  None              & T/S~DOME      \\
                    &                   &                    &\button{STOP}% \\
\hlineskip
                    &                   &                    &               \\
T(ELESCOPE)         & /O(VER-POLE)      &  None              & None          \\
                    & /U(NDER-POLE)     &                    &               \\
                    & [/E(AST)]         &                    &               \\
                    & [/W(EST)]         &                    &             % \\
\hlineskip
\\
TI(TLE)             & None              & text                             % \\
\hlineskip
                    &                   &                    &               \\
TR(AIL)             & /ALL              &                    & SCAN/TRAIL    \\
                    & /D(URATION) ..... &  duration of trail & 
                                                 \doublebutton{START}{CONT}  \\
                    & /L(ENGTH)   ..... &  length of trail   &\button{HOLD}  \\
                    & /A(NGLE)    ..... &  position angle    &\button{BACK}  \\
                    &                   &                    &\button{ABORT}%\\
\hlineskip
                    &                   &                    &               \\
TU(RNTABLE)         &                   &  position angle    & TURNTABLE     \\
                    &                   &       &\button{NOM} \button{STOP}% \\
\hlineskip
                    &                   &                    &               \\
Z(EROSET)           & /A(UTO)           &                    &               \\
                    & /M(ANUAL)         &                    &             % \\
\hlineskip
\hline
\end{tabular}
%\vfill
%\eject
\clearpage
\begin{tabular}{ll}
\multicolumn{2}{c}{EXPLANATIONS OF}\\ \\
COMMANDS & PARAMETERS AND QUALIFIERS\\
\\
\hline
\\
Right ascension of edit source is  & % \\
\hlineskip
\\
See TURNTABLE   % \\
\hlineskip
\\
Save current catalogue to disc&                                         % \\
\hlineskip
\\
Sets which system and time to be &   set up sidereal time used by  ADVISE \\
used by ADVISE          &   set up UT for ADVISE                      \\
                            &   ADVISE will use current time            % \\
\hlineskip
                            &                                             \\
Sets pointing corrections   &   collimation errors in HA and Dec          \\
                            &   aperture offset for aperture A            \\
                            &   aperture offset for aperture B          % \\
\hlineskip
\\
Define a new catalogue entry & makes new entry in catalogue from terminal \\
                              & takes RA and Dec from telescope position% \\
\hlineskip
\\
Stop the telescope and dome & {\it Either} type `STOP' at the User Interface \\
                       & {\it or} press \button{STOP} on the Control Desk %\\
\hlineskip
                            &                                             \\
Sets mode of Telescope operation &   above the  Pole (INT - default)      \\
                            &   below the Pole (INT - not enabled)        \\
                            &   East of the pier (JKT - default)          \\
                            &  West of the pier (JKT)                   % \\
\hlineskip
&\\
Types initial USER Interface message to screen&                         % \\
\hlineskip
                            &                                             \\
Define a Trail on the sky.  & All values can be defined in one instruction\\
                            & Trail duration in seconds                   \\
                            & length of trail on sky in {\secs}.          \\
                            & position angle in degrees                   \\
                            &                                           % \\
\hlineskip
\\
Define required rotator setting. & Position Angle in degrees \\
Execute rotation with \button{NOM} & % \\
\hlineskip
\\
Zeroset encoders under computer control& See section \ref{ch11:zeroset}    \\

Manual ZEROSET          & !! Beware: {\em not yet debugged}             % \\
\hlineskip
\hline
\end{tabular}
%\vfill
%\eject
\renewcommand{\arraystretch}{1.0}
\clearpage
\subsection {Details of individual commands in alphabetical order}
\label{ch8:UICD}
\largeparskip

\newitem{$*$ (text)} 

In a line of input to the user interface, all characters
following an asterisk are ignored by the command processor.
In prepared or SAVEd files it is often useful to indicate
the purpose or significance of the commands that follow,
to flag and date amendments or to indicate the source of the
data values appearing as arguments of commands.   Comments may
be in blocks of lines, each with an asterisk in column 1, or
as in-line comments following a command and its argument.

At the console the text is ignored and the user is prompted
for further input;  in a file the command processor ignores
the text and moves on to interpret the next line.
There are no qualifiers.

\newitem{AC(QUIRE)} 

defines the autoguider acquisition mode and is used to tell the system
whether to move the guide-probes or the telescope when acquiring a guide
star. Veteran observers should beware the reversal of definitions compared
with the historical case. 

AC(QUIRE)/PR(OBE) moves the guide probes until the guide-star is
centred while the telescope remains fixed (tracking).   It is used when the
object of interest is already positioned in the TV or on the CCD chip and
should stay where it has been put.   The position of the guide star will 
probably not be known very accurately and moving the telescope rather
than the probe would cause the target to move. 

AC(QUIRE)/TE(LESCOPE) moves the telescope to acquire the star while
the guide-probe remains fixed in the focal plane of the telescope.   It
is used when the guide star position is known precisely {\em a priori} ; either
because it has been observed before and the probe position is known or
because the offset between it and the target has been measured in advance.

\newitem{ADVISE}

gives details of a source, telescope or UI parameters, or
lists the source-names in the resident catalogue. 

AD(VISE)/S(OURCE) source-name 

gives details of source-name and times to rise and set from
a given time.   The output is in LST and an example is given in 
Figure~\ref{ch8:fig1}. The desired time is input using SET/LST or SET/UT.
If no time has been set, the current time is used. 

AD(VISE)/E(DIT) 

gives details of the edit source and times to rise and set from a 
given time.   This time is input using SET/LST or SET/UT.   If no
time has been set, the current time is used. 

AD(VISE)/N(EXT) 

gives details of the next source and times to rise and set from a 
given time.   This time is input using SET/LST or SET/UT.   If no
time has been set, the current time is used. 

AD(VISE)/CU(RRENT) 

gives details of the current source and times to rise and set from a 
given time.   This time is input using SET/LST or SET/UT.   If no
time has been set, the current time is used. 

\vfill
\newpage
AD(VISE)/T(EL) 

gives all telescope parameters such as SET/GUIDE/INCREMENT rates, offsets, 
focus position and the like. Sample output Figure~\ref{ch8:fig1}. 

AD(VISE)/CAT 

gives a list of only the source-names and sequence-numbers in the resident
catalogue. This is a useful command to inspect object names in a large
catalogue. Its output, however, is formatted to fill the line accross the
VDU screen.

AD(VISE)/UI 

gives coordinates of the edit, current and next sources, acquisition
and telescope modes and the time set by SET.

\newitem{AP(ERTURE)} 

AP(ERTURE)/A x y (arcsecs) \hspace{1.0cm}   sets aperture A\\
AP(ERTURE)/B x y (arcsecs) \hspace{1.0cm}   sets aperture B 

sets up aperture offsets defined in an X-Y coordinate system fixed in the
instrument rotator.   These can be used, for example, to locate an object
within a particular aperture or detector pixel.  An aperture offset is
executed by pushing one of the beamswitch buttons on the control desk.

If it is required to beam-switch (for example on a two channel photometer),
then the apertures can be set up using the qualifiers /A and /B with
X-Y offsets in arcsecs as input parameters.   The control panel BEAMSWITCH
buttons \button{A}\,, \button{NOM} and \button{B} (near the centre of the
`System Control' Panel)
are then used to select between either aperture or the nominal
position.   If the required aperture offsets are not known {\em a priori\/}
then the /A and /B qualifiers for SNAFU may be used
to set them up interactively.

APERTURE is applied as a pointing correction, so it is not reflected in the
displayed telescope position: conceptually, applying an aperture offset
causes the SAME object to be observed using a DIFFERENT area of the
instrument whereas an RA/Dec offset causes a DIFFERENT object to be
observed on the SAME part of the detector and therefore causes the
displayed position to change. The RA \& DEC displacements corresponding to a
particular aperture offset will vary with the turntable rotator position
angle (unlike that for an RA/Dec offset, of course), but the displacement
on anything attached to the rotator (TV, CCD, IPCS) will remain constant.
All of the aperture offsets are calculated relative to a nominal aperture
position which is specified in the system startup (.STD) file and
corresponds to an easily visible reference position (the Grinnell
crosswires or the centre pixel of an imaging CCD).  This is because the
reference position does not usually coincide with the rotator axis (which
defines the origin of coordinates).   The displacement between the
reference position and the rotator axis (the base aperture offset) must be
calibrated from time to time. For the INT at prime focus, the reference
point is in the centre of the CCD chip (10 arcmin off-axis), but for the
Cassegrain systems on both telescopes, SNAFU is usually done on the
Grinnell cross wires so the reference aperture offset is set up to be the
(small) difference between the turntable centre of rotation and the
Grinnell cross-wires with the TV in the centre/acquisition position. 

\newitem{AUTOFFSET} 

is a method of doing precise blind offsets which gets round errors in the
declination encoder. The telescope and guide probe are offset by equal
and opposite amounts whilst autoguiding, and the guide star is kept at the
centre of the autoguider field. This exploits the fact that the probe
encoding is more accurate than that of the telescope. It is recommended
for blind ofsetting and for 2D spectroscopy when the slit is moved by
small increments to cover the field. 
\smallparskip
\vfill
\newpage
\begin{tabbing}
AU(TOFFSET)/B(OTH) \hspace{1.0cm} \=  RA \& Dec\\
AU(TOFFSET)/R(A)   \> RA\   \secs \\
AU(TOFFSET)/D(EC)  \> Dec \secs
\end{tabbing}

sets up the telescope offsets in arcsecs in RA, Dec or both according to the
qualifier.  These are defined in a tangent plane projection centred on the
current position of the telescope.  The telescope begins to move as soon as
\key{Return} key is pressed. As the telescope moves to the OFFSET the
autoguider automatically follows the reverse vector so that it does not
lose the guide star. Be careful: there is always the danger that the autoguider
probe may move to a position where it cannot see the guide star. Further, if
you press the OFFSET \button{NOM} button after an AUTOFFSET then the
telescope returns to its previous position but {\bf not} the autoguider probe.
\largeparskip

\newitem{BEAMSWITCH}

is synonymous with APERTURE

\newitem{D(EC)} 

D(EC) dd mm ss.s 

enters the declination for the current edit source.   The format
is: degrees minutes seconds.   The seconds and minutes may be omitted
but then the command must be terminated explicitly either by a 
carriage return or by a semicolon `;'.
There are no qualifiers.

\newitem{DELETE} 

deletes sources from the catalogue according to the qualifier.

DEL(ETE)/F(ROM) source-name source-name 

deletes the sources in the resident catalogue between and including
the given source-names.   If only one source name is given,
only that source will be deleted.

DEL(ETE)/A(LL) 

deletes all sources in the resident catalogue except the first three, since
 .DEFAULT, .GUIDE and .LINK are protected sources (for {\it e.g.\/} input
from the autoguider or via the interprocessor link). 

DEL(ETE)/S(EQ) sequence-number sequence-number 

deletes sources in the resident catalogue between and including the
given sequence numbers.   If only one sequence number is given, only
that source will be deleted.

\newitem{DIFF\?RATES}
\smallparskip
\begin{tabbing}
DIF(F\?RATES)/B(OTH) \hspace{1.0cm}\= RA-rate (secnds/sec) Dec-rate 
                                           ({\secs}/sec)\\
DIF(F\?RATES)/R(A) \>rate(sec/sec)\\
DIF(F\?RATES)D(EC) \>rate({\secs}/sec)
\end{tabbing}

sets up differential tracking rates in RA,Dec or both (according to
the qualifier).   This will be actioned by pressing the `differential track' 
button \doublebutton{DIFF}{RATE} in the right-hand lower corner of the System
Control Panel. Note that this mode is switched off upon source change.
\largeparskip
\vfill
\newpage

\newitem{EDIT}

E(DIT) Source-name

selects the given source as the edit source.
There are no qualifiers. If you define a new source name with the SO command,
it will become the current 'EDIT source'.

\newitem{EQUINOX}

EQ(UINOX) Byear\\
EQ(UINOX) Jyear\\
EQ(UINOX) A(pparent)

sets up the mean coordinate system (B for Besselian or J for Julian)
and the equinox (year) for the edit source.   The equinox for 
apparent coordinates is assumed to correspond to the current date.
FK4(B1950.0) and FK5(J2000.0) will eventually be supported, but at
the moment only FK4 is implemented. Note that B, J or A {\em must\/} be 
specified.

\newitem{FOCUS}

F(OCUS) position (mm)

Sets the required focus position.   The telescope focus will be
driven to this value when the FOCUS \button{NOM} button on the control
desk (right-hand side of System Control Panel) is pressed.   
Pressing the FOCUS \button{STOP} button halts a focus drive.
Once the focus drive has been set it will track to follow any
change in tube temperature. There are no qualifiers. The position value is
{\tt mm} of motion of either the secondary mirror (Gassegrain mode) or the
instrument at Prime. Increasing values mean that the secondary or primary
instrument is moving further from the main mirror.


\newitem{GOTO}

GO(TO)

slews the telescope to the NEXT or given source and initiates
tracking.

GO(TO)/N(EXT)

is equivalent to pushing the T/S~DOME \button{SRCE} button on the control
panel.   It will move the telescope to the NEXT source and initiates
tracking. If the source is within the 
software limits, then the green {\bf go} lamp will light up and the telescope
will commence slewing. If the object is beyond any (soft) limit, then the 
{\bf go} lamp will only flash briefly and the red {\bf stop} lamp will be lit. 
Appropriate messages will also be output to the Information Display (see
section \ref{ch8:display}).

If you changed your mind while the telescope is moving push the \button{STOP} 
button to halt the slew.

GO(TO)/SO(URCE) source-name

slews the telescope to the named source and initiates tracking.
Beware, {\it this option has not yet been tested\/}!

\newitem{GUIDE\?OBJECT}

GU(IDE\?OBJECT) guide-name

defines a guide object for the edit source by linkage to an
existing entry in the catalogue containing the coordinates of
the object which you want to be the guide star. After the telescope is 
pointed to a new source
and the GUIDE PROBE button \doublebutton{GUIDE}{STAR} is pressed on 
the Acquisition and Guidance panel (A\&G, the right-hand panel in bay 3,
 {\it NOT\/} to be confused with the Autoguider Panel), the probes
will drive to the position of the guide object, but only if it is at a legal
position, {\it i.e.\/} within its physical limits.
 This procedure can be used when the coordinates of a 
guide star are known in advance.  
There are no qualifiers.

\newitem{HANDSET}
\smallparskip
\begin{tabbing}
HA(NDSET)/A(LL) \hspace{2.0cm} \= set-rate guide-rate increment \= \\
HA(NDSET)/S(ET)                \> set-rate \> [0 - 75] {\secs}/sec  \\
HA(NDSET)/G(UIDE)              \> guide-rate \> [0 - 75] {\secs}/sec\\
HA(NDSET)/I(NCREMENT)          \> increment \> [0 - 6000] \secs
\end{tabbing}

\largeparskip
This command inputs the set and guide rates and the increment step to be 
actioned by the handset and/or the `arrow' buttons on the System Control
panel, and the XY~AXES buttons \button{SET}, \button{GUIDE} and \button{INC},
which are found in the lower-left corner of the System
Control panel. When in SET or GUIDE mode, the motion is continuous; 
when in INCREMENT mode, the motion is stepped everytime the button is pressed.
If you change a HANDSET parameter the control software will not adopt the new
value {\bf until} the appropriate button has been pressed.


\newitem{H(ELP)}
 
H(ELP) Command

provides on-line help information about a specific command.
There are no qualifiers.
 
\newitem{INPUT}

I(NPUT)

inputs a catalogue from a specified disc file. 

I(NPUT)/N(ORMAL) file-name

If no extension of the file-name is given then .CAT is assumed.
A maximum of 500 entries in the catalogue is allowed.

I(NPUT)/PROMPT device name:

This is used on startup of the user-interface to select input from
this terminal interactively, and is rarely needed.

\newitem{LIST}

L(IST)
 
will list the source names and coordinates from the resident catalogue.

L(IST)/A(LL)

will list the whole resident catalogue to the screen, pausing after
     each page to ask whether more output is wanted.

L(IST)/F(ROM) source1 source2

will list from source1 to source2 on the screen.

L(IST)/PR(INTER)

will list the whole resident catalogue to the line printer.
 
\newitem{NEXT}

N(EXT)/NA(ME) source-name\\
N(EXT)/SEQ(UENCE) sequence-number
 
defines the next source to be observed, selected by name or sequence
number according to the qualifier used. .DEFAULT is number 1,
.GUIDE is number 2 and so on through the catalogue.

\newitem{OFFSET}
\smallparskip
\begin{tabbing}
O(FFSET)/B(OTH) \= RA-Offset \= Dec-Offset \= \\
O(FFSET)/R(A)   \> RA-Offset \>            \> ({\secs})\\
O(FFSET)/D(EC)  \>           \> Dec-Offset \> ({\secs})
\end{tabbing}

\largeparskip
Sets up the telescope offsets in arcsec in RA, Dec or both
(according to the qualifier).   These are defined in a
tangent-plane projection centred on the
current position of the telescope.   They are actioned by the control panel
OFFSET buttons. Pressing \button{OFFSET} will action the offset; pushing the
\button{NOM} button will return the telescope to the
original position. The current offset values are displayed on the information
display. Beware: If you use the FOCUS or MULTEXP commands from the ADAM terminal
then you will find that any values you have previously entered for OFFSET have
been overwritten.

\newitem{PROPER\?MOTION}
\smallparskip
\begin{tabbing}
P(ROPER\?MOTION)/B(OTH) RA Dec \= \\
P(ROPER\?MOTION)/R(A)   RA     \> (secs/year)\\ 
P(ROPER\?MOTION)/D(EC)     Dec \> ({\secs}/year)
\end{tabbing}

\largeparskip
sets the proper motion of the edit source in RA,Dec or both.
The corresponding epoch is assumed to be the same as the equinox. Note
the {\em different units\/}!

\newitem{RA}

R(A) hh mm ss.s
 
sets up the Right Ascension for the edit source.  This format is hours
minutes seconds.  As with D(EC) the last two are optional but the
command must be terminated with a semi-colon if they are omitted.
There are no qualifiers.

\newitem{ROTATOR}

RO(TATOR) position (deg)

synonym for TURNTABLE (q.v) 
 
\newitem{SAVE}

SA(VE) Filename
 
saves the catalogue in memory to a user-specified disk file, which will
have a .CAT extension, whatever extension was defined at the User Interface;
if you were to specify another extension, a warning would appear: `File type
is forced to .CAT'\@. There are no qualifiers.

\newitem{SET}
 
Sets up various UI parameters for the ADVISE (\qv) command according to 
the qualifier:

SET/LST hh mm ss

sets up the Local Sidereal Time for use by the ADVISE command.

SET/UT  hh mm ss

sets up the UT for use by the ADVISE command

SET/NOW

ADVISE will use the current time (this is the default on startup)

\newitem{SNAFU}
 
sets up the telescope collimation and index errors or the aperture offsets.

SNAFU/NOMINAL

 sets the collimation and index errors.   

      The sequence of events for a ONE-STAR SNAFU is as follows:

\smallparskip
\begin{enumerate}
     \item  slew the telescope to an accurately-known source position;
     \item  Type SN(AFU) and follow the instructions on the terminal 
         {\it i.e.\/} press \key{Return} and ....
\item  use the set/guide/increment functions to position the object on 
the defined reference mark (either the Grinnell cross-wires or the  centre of
         a CCD chip) -- see APERTURE
     \item  press the `acknowledge button' \button{ACK} in the right-hand lower
corner of the System Control panel.
\end{enumerate}
\largeparskip

SNAFU/A  and SNAFU/B

The qualifiers /A and /B enable the different aperture positions to be
recorded by the system for use by the BEAMSWITCH buttons \button{A} and
\button{B}\,. The procedure is:

\smallparskip
\begin{enumerate}
     \item  set an object on the reference mark (see above) using the guide
         buttons or the handset;
     \item  type SNAFU/A on the user interface console;
     \item  move the object to the desired aperture position, again using the
      handset or desk buttons;
     \item  press the \button{ACK} button and then BEAMSWITCH \button{NOM} to
      restore the object to the reference position.
\end{enumerate}
\largeparskip

\newitem{SOURCE}

SO(URCE)

defines a new entry in the source catalogue. 
Note that the first three entries,
.DEFAULT, .GUIDE and .LINK, cannot be deleted nor redefined, because they
have a dedicated function in data transfer via the CAMAC interfaces. For 
instance,
.LINK is used to transfer source data from the PE~3210 instrument computer
over the interprocessor link, and enables the sending of a pointing command to
the telescope control software from the ADAM environment.

A newly defined entry automatically becomes the current 'edit' source, so
its parameters (RA, Dec {\it etc.\/}) can be entered immediately. Note that,
until a new SOURCE command is issued, all commands which specify source 
parameters ({\it e.g.\/} RA, Dec, P, {\it etc.\/})
will update the values associated with the 'source-name' last entered.

SO(URCE)/I(INPUT) source-name

This command provides the source with default values for RA, DEC,
EQUINOX, coordinate type (MEAN or APPARENT) and PROPER\?MOTION in both
coordinates.   The default values for all these quantities are copied 
from the source which is called .DEFAULT .   This is the first entry
in the catalogue and has its parameters set on start up. 

SO(URCE)/M(ARK) Source-Name

This command reads values for RA,DEC, EQUINOX and coordinate type
from the current position of the telescope: proper motions are set to
zero.   Thus, it provides a means to record the positions of objects with
poor or unknown coordinates, as measured at the telescope. Again, the
new entry in the catalogue becomes the 'edit' source.

Error checks are made to see if the source-name is already in the catalogue;
whether the maximum number of catalogue entries has been exceeded;
whether the storage allocated to the dictionary of source-names has been
filled;  or whether the name of the source is too long. If the source name
does already exist the entry is simply overwritten without error message.
Otherwise, appropriate
messages are displayed in each case and no catalogue entry is made.
 
\newitem{STOP}

STOP
 
is the equivalent of the T/S~Dome \button{STOP} button on the control panel.
It stops both the telescope and the dome. There are no qualifiers. 

\newitem{TELESCOPE}
\smallparskip
\begin{tabbing}
T(ELESCOPE)/O(VER\?POLE) \hspace{1.0cm} \= {\sl(INT default)}\\
T(ELESCOPE)/U(NDER\?POLE) \> {\sl(INT not enabled)}\\
T(ELESCOPE)/E(AST)       \> {\sl(JKT)}\\
T(ELESCOPE)/W(EST)       \> {\sl(JKT)}
\end{tabbing}

\largeparskip
is used to set the mode of telescope operation according to the qualifier;
{\it i.e.\/} working either East or West of the pier on JKT with E(AST) as 
default.
On the INT, OVER is the default and UNDER\?POLE is {\em NOT\/} enabled. 
 
\newitem{TITLE}

TI(TLE)
 
is only used for input from files.  The text following the command is
printed on the terminal.  It is used for instance to output the initial
messages for the user interface. There are no qualifiers. 
 
\newitem{TRAIL}
\smallparskip
\begin{tabbing}
TR(AIL)/ALL   \hspace{2.5cm} \= duration length angle\\
TR(AIL)/D(URATION) \>  duration (secs)\\
TR(AIL)/L(ENGTH)   \>  length (arcsecs)\\
TR(AIL)/A(NGLE)    \>  position-angle (degrees)
\end{tabbing}

\largeparskip
sets up the parameters for a trail on the sky to be followed by the telescope.
The trailing is activated by pushing the associated buttons under SCAN/TRAIL
near the centre of the System Control panel (see below).
The starting position is where the telescope happens to be at the time the 
TRAIL begins; thus, its definition is relative to the starting point; there 
is no offset to a central position.  

Note that the default mode is TRAIL, with the \doublebutton{SCAN}{TRAIL}
button {\it un\/}lit. (SCAN is a command very similar to TRAIL;
if the SCAN mode is selected this button lights up. 
In SCAN mode you are supposed to be able to make a series of parallel trails, 
in order to scan an area of sky; this command has, however, not yet been 
commissioned.) 

A TRAIL is performed as follows:-
\smallparskip

\begin{tabular}{ll}
To start a trail & press: \doublebutton{START}{CONT}\\
To pause a trail & press: \button{HOLD}\\
To reverse a trail direction & press: \button{BACK} \\
To stop a trail and return to the start position & press:  \button{ABORT}
\end{tabular}

\largeparskip
\newitem{TURNTABLE}

TU(RNTABLE)   position angle (degrees)

sets the required rotator position at Cassegrain. The turntable will be 
driven to this position when the TURNTABLE \button{NOM} button on the control 
desk is pressed. There are no qualifiers. 
Note that it has a synonym, ROTATOR.

\newitem{ZEROSET}
 
is used to zeroset the incremental encoders.  

Z(EROSET)/A(UTO)

sets the incremental encoder readings to zero when the telescope slews 
past a hardware marker.   The sequence of operations is: 

\smallparskip
\begin{enumerate}
     \item  
Move telescope to within a few degrees of the zero set  position;
     \item  
Press \key{Return} when ready to continue
the green handset lamps on the control panel will light up
     \item 
 Use the engineering-mode telescope control buttons to move the
         telescope through the zeroset position at the speed marked on
the control potentiometers (about \Degs{1}/sec) in each of the
         coordinates successively.  As each axis is zero-set the
         appropriate console light will go out indicating successful
         completion for that axis. 
\end{enumerate}
To get out of this procedure at any time, press \button{ACK} on
the control desk. \largeparskip

Z(EROSET)/M(ANUAL)

Warning: this command is not yet fully debugged. It can be used when the
hardware zeroset is broken.   In this case, move the telescope to the
zeroset position at the zenith (HA = 0; Dec = latitude) as indicated by
the synchros (INT) (or setting circles at the JKT) and enter Z(EROSET)/M(ANUAL).
This effectively does a SNAFU operation assuming that the telescope is
at the zeroset position. The result will be significantly less accurate 
than the standard hardware zeroset. See section \ref{ch11:refpt} for more
information.

\smallparskip
\vfill
\newpage
\subsection {Examples of working with Catalogues} \label{ch8:catalogs}
Suppose it is desired to observe three objects, as follows:

\begin{enumerate}
\item   A star called HD~1234 at RA~$07^{h}~08^{m}~09.32^{s}$, 
        Dec~\Degs{+17}~\Mins{14}~\Secs{44.1} at
          equinox B\,1950.0 (Besselian).
          This has annual proper motions of +0.034 secs of
          time in RA and \Secs{-0.127} in Dec.

\item   A galaxy called NGC~3456 at RA~$10^{h}~11^{m}~12.3^{s}$, 
   Dec~\Degs{-3}~\Mins{7}~\Secs{14} at
          equinox B\,1900.0.

\item   A nearby star, to be used as a standard, HD~2345 at 
          RA~$10^{h}~13^{m}~15.7^{s}$  Dec~\Degs{-4}~\Mins{5}~\Secs{6} at 
          equinox J2000.0 (Julian).
\end{enumerate}

HD\,1234 is to be observed first and then the main object will be
NGC\,3456 with HD\,2345 as the standard.

\subsubsection{Adding sources to a Catalogue}
The UI commands may be used to enter an object name and details in the
following way (minimum abbreviations are used): 

\medskip
\begin{tabular}{ll}
\multicolumn{1}{c}{Command}  &\ \ Comment \\
                               &                     \\
     \UI{SO HD1234}           &      $*$ Object name \\
     \UI{R 07 08 09.34}       &      $*$ RA \\
     \UI{D 17 14 44.1}        &      $*$ Dec \\
     \UI{EQ B1950}            &      $*$ Equinox (Besselian) \\
     \UI{P/R +0.034}          &  $*$ RA Proper Motion (sec/year) \\
     \UI{P/D $-$0.0127}       &  $*$ Dec Proper Motion ({\secs}/year)\\
\end{tabular}

\largeparskip
Source names may be defined with any letters inside brackets used as
optional descriptors, {\it e.g.\/} AL(VIN) may be recalled as ALVI, ALV or AL. 

An alternative way of entering commands is to put all of them on a single
line leaving spaces between each trailing field and the next command word.
NGC\,3456 may be input, using minimum abbreviations, as follows: 
 
\UI{SO NGC3456 R 10 11 12.3 D -03 07 14 EQ B1950}

The semicolon may be used as an alternative to \key{Return} as a
command terminator.   For example, each of the commands RA and DEC expect one
sexagesimal argument with 3 fields (hrs mins secs or degs mins secs), but
right ascension $1^{h}$, declination \Degs{+30}\, and equinox 1950 is 
abbreviable to: 

\UI{R 1; D 30; E B1950}

The command processor ceases looking for further arguments for R and D on
detecting the semicolon and begins processing afresh at the next
character.

\subsubsection{To inspect catalogue contents}

To check that the coordinates have been typed in correctly, we
can LIST the target objects and their positions on the screen:

\UI{LIST}

which results in:

\begin{tabular}{lcccccl}
\multicolumn{1}{c}{Name}   & \multicolumn{1}{c}{ RA} &\multicolumn{1}{c}
{Declination} &\multicolumn{1}{c}{Equinox}& 
\multicolumn{1}{c}{PM-RA} &\multicolumn{1}{c}{PM-Dec}&
\multicolumn{1}{c}{Guide-Object}\\
       &               &                &        &        &       &\\
NGC3456&  10:11:12.300 &   $-$03:07:14.000& B1950.0&  0.000 & \ 0.000 & .GUIDE\\
HD2345 &  10:13:15.700 &   $-$04:05:06.000& J2000.0&  0.000 & \ 0.000 & Not
specified\\
HD1234 &  07:08:09.340 &\ \ 17:44:44.100& B1950.0&  0.034 &$-$0.127 & .GUIDE\\
\end{tabular}

The catalogue information for individual sources may be displayed by: 

\begin{tabular}{ll}
     \UI{AD/E}           &  for the entry now being edited     \\
     \UI{AD/N}           &  for the next source to be observed\\
     \UI{AD/CU}          &  for the source currently being observed\\
\end{tabular}

The command AD/CAT lists just the source names in the resident catalogue.   
\smallparskip
\subsubsection{To enter a parameter for several catalogue entries}
\label{ch8:enter}
Parameters which are not entered specifically for a new source are taken from
the previously entered source (or from .DEFAULT). This allows one to
specify parameters which are then valid for all subsequently entered sources.
For instance, in order to enter a list of stars with J1900.0 coordinates,
one would only have to type: \largeparskip

\UI{EQ J1900}\\
\UI{SO STAR R 12 34 56 D 12 34 56}
 
and the equinox of all following entries will be J1900 until changed.
 
\subsubsection{To save the catalogue in a Disc File}

\UI{SA(VE) STAR}

Will save the current catalogue in file STAR.CAT\@.
All SAVE files are given the extension `.CAT'\@.
 
\subsubsection{To restore a catalogue from disc file}
\label{ch8:input}
Use the INPUT command to load a catalogue from disk:

\UI{I(NPUT) STAR.CAT}

The catalogue could have been typed in during a previous session and SAVE,
or the catalogue may have been created outside the User Interface software
by using the Perkin Elmer EDITOR (see section \ref{editor} for details).

\subsubsection{To LIST the resident catalogue on line printer}

The line printer is found in the Instrument Computer room, beside the PE~3210
System Console. There is a black box with a switch, most likely resting on the
floor beside the printer. Ensure that this selector switch is switched to 
{\em Telescope\/} Computer, {\it i.e.\/}  not to Instrument Computer.
(It is intended to replace it by a device without switch.) Go back to
the control room and type at the UI console:
 
\UI{L(IST)/PRI(NTER)}

Wait for a few seconds.
If nothing happens, type (on the PE~3220 Telescope System Console):

$*${D(isplay) M(emory)}

in order to check that the Spooler task, `.SPL', is not Paused.
(See section \ref{PEOS} for more details about the Perkin Elmer 
operating system.) If the Spooler task is paused, type on System Console:

$*${T(ask) .SPL}   \\
$*${CO(ntinue)}

and try again LI/PRI at the User Interface. If .SPL was not loaded, then
type on System Console:

$*${STARTSPL} 

and try {\tt LI/PRI} again.

\subsubsection {To remove objects from a Catalogue }
Use the DEL command, but do it carefully:

\UI{DEL/F HD1234 HD2345}

This removes {\it all\/} the objects in the catalogue with entry numbers between
those of HD\,1234 and HD\,2345.

\subsubsection{To move the telescope}
 
Indicate which source is to be observed by using the NEXT command, followed
by pressing \button{SRCE}\,or typing GO:

\begin{tabular}{ll}
\UI{NEXT NGC3456}       & : Select NGC3456 as your `next' object\\
\UI{GO}                 & : Move telescope to this object\\
\end{tabular}
 
If you change your mind, or whatever, the telescope is halted by pressing 
T/S~DOME \button{STOP} on the System Control panel.

\subsubsection{To use a catalogue entry as guide star}

The standard HD 2345 can be set up as the guide star for
target HD1234 by using the GUIDE command:
 
\UI{SO HD2345 R 10 13 15.7 D -04 05 06 EQ J2000}\\
\UI{GU HD2345}\\
\UI{NE HD1234}\\
\UI{GO/NEXT}

This sequence moves the telescope to HD\,1234 and specifies the object
HD\,2345 as guide star. Now, push the \doublebutton{GUIDE}{STAR} button in
right-hand upper corner of the Acquisition~\&~Guidance panel (bay 3).
This causes the guide probe to be driven to the correct offset to pick up 
HD\,2345, if within range.
It will assume that the guide star and target source coordinates
have the same equinox and makes no allowance for proper motions.

\subsection {Standard catalogues on disc} 
\subsubsection {Catalogue format}
A catalogue for the telescope computer is a set of user interface commands
and as such can be in free format.   For legibility and neatness, however,
it is worth adhering to a more rigid tabular format with one object per
line of the file.   The guidelines for generating catalogues may be divided
into essential rules (disregard of which will cause the interface to be
unable to read in the file) and conventions (which are guidelines for
producing catalogues which may be read in as quickly as possible and are
easy to maintain). 

{\bf Essential rules}

The following rules MUST be followed.
\begin{enumerate}
\smallparskip
     \item  The file should consist of 80-byte records.   Consequently, no
            more than 80 characters per line are allowed.

     \item  There should be no non-alphanumeric characters (carriage returns,
            line feeds, {\it etc.\/}) anywhere in the file.

     \item  The filename must consist of 8 alphanumeric characters
            or less, starting with a letter, and must have the extension `.CAT'.

     \item  There should be no more than 500 objects in the file, as this is
            the maximum number that can be held in memory at once.
\largeparskip
\end{enumerate} 

{\bf Conventions}

\begin{enumerate}
\smallparskip
     \item  Every standard catalogue should start with a comment line
            giving its contents and giving the name of the originator. 

     \item  If all of the objects in the catalogue have the same equinox,
            and coordinate type (ie J B or A(pparent))
            then this should be given at the beginning of the file, not
            repeated for every object.

     \item  The format should be as given in the examples below, {\it i.e.\/}:

 {\tt SO OBJECT R hh mm ss.ss D +dd mm ss.s P/R +s.ssss P/D +s.sss EQ Jyyyy.y}

          with the equinox omitted if it does not change from line to line.

     \item  It is expected that each catalogue file will have an associated
            documentation file with the same name but with the extension
            `.DOC'.

     \item  Catalogues should be split by Right Ascension in order to
            minimise the number of records to be read in - there is no point
            storing objects if they are unobservable..
\largeparskip
\end{enumerate} 

{\bf Coordinate Systems}

The restrictions on coordinate types are as follows:
\begin{enumerate}
\smallparskip
\item  Coordinates may be either mean or geocentric apparent. B1950 (FK4)
       and J2000 coordinates are supported at present.

\item  Geocentric Apparent coordinates refer to the current date and time.

\item  The epoch for the proper motions must be equal to the equinox for 
       mean coordinates. (Conversions can be made using the COCO program
       on the VAX~8300, if necessary.)
\largeparskip
\end{enumerate} 

\subsubsection {List of standard catalogues} \label{ch8:catalogues}
{\bf Astrometric standards}

PTGRID (see listing in Appendix \ref{ptgrid}) 
contains a grid of stars with accurately-known positions for pointing 
tests. The following four catalogues are subsets of PTGRID and contain
stars which pass through the zenith.   They are to be used for
setting the encoder zeropoints of the telescope (SNAFU) (section 
\ref{ch11:1-snafu} and for measuring the seeing (section \ref{ch14:seeing}).

\begin{tabular}{ll}
{\bf PTGRID}       &  \ 0 hr $<$ RA $<$ 24 hr\\
{\bf SEE0006}      &  \ 0 hr $<$ RA $<$ \ 6 hr\\
{\bf SEE0612}      &  \ 6 hr $<$ RA $<$ 12 hr\\
{\bf SEE1218}      &  12 hr $<$ RA $<$ 18 hr\\
{\bf SEE1824}      &  18 hr $<$ RA $<$ 24 hr\\
\end{tabular}

{\bf Spectrophotometric Flux Standards}

{\bf SPECPHOT}  \hspace{2cm}  Spectrophotometric flux standards

A description of this data is given in La Palma Technical~Note~65. There is
a blue loose-leaf binder on the control-room shelf entitled: `Spectral Flux
Standards' which includes LPTN\,65, and further standards from Oke, J.B. 1990
(A. J., {\bf  99}, 1621) and Massey, P. et al. 1988 (Ap. J., {\bf 328}, 315).

{\bf Photometric standards}

The following six catalogues contain stars from Landolt's list of
equatorial standards for UBVRI photometry.   There are two
overlapping sets, one with photometry by D.H.P. Jones \& J.E.
Sinclair (from SAAO) and the other with photometry by Landolt
(from KPNO; see INT Prime Focus manual for details).   
Users should be warned that there are differences
between the two datasets in the U and B bands, as is discussed
further in the .DOC files.   All of the positions have, however,
been checked and/or remeasured.   There is a further division
between stars suitable for CCD's (V $>$ 10) and those which should
only be used with photoelectric photometers.

\begin{tabular}{ll}
{\bf UBVRIRG}      &  Jones \& Sinclair photometry; no magnitude restriction\\
{\bf UBVRIRGB}     &  Jones \& Sinclair photometry; V $<$ 10\\
{\bf UBVRIRGF}     &  Jones \& Sinclair photometry; V $>$ 10\\
{\bf UBVRIKP}      &  Landolt photometry; no magnitude restriction\\
{\bf UBVRIKPB}     &  Landolt photometry; V $<$ 10\\
{\bf UBVRIKPF}     &  Landolt photometry; V $>$ 10\\
\end{tabular}
\vfill
\eject
\newpage
\parindent 0pt
\parskip 0.3cm
\subsection{The Information Display} \label{ch8:display}
The Control System's TNHZ task regularly updates (roughly once a second)
the Beckmann Displays at the top of the Control Desk and the Information 
Display, which can be routed by the Telescope Operator to a selection of up to
three monitors in the Control Room; the monitor on the System Control Panel
(Control Desk, Bay 2) always carries the Information Display. A sample output
is shown in Figure \ref{ch8:fig1}; some additional comments are given here:
\begin{figure}
\vspace{20.0cm}
\caption{Sample Output on the Information Display}
\label{ch8:fig1}
\end{figure}

\begin{itemize}
\item
The top line gives the Date, the Universal Time and the 
geocentric Julian Date. 
\item
The block labelled INPUT echoes details of the current source 
as supplied to the User Interface:
\begin{enumerate}
\item
The RA and Dec will be either Mean coordinates, in which case the 
associated Equinox is also displayed, or Geocentric Apparent,
as defined when entering the position data. This display will not change
when the telescope is tracking or guiding.
\item
The proper motion values shown are as given to the User Interface.
\item
Offsets in RA and Dec are updated when one of the buttons \button{OFFSET} or
\button{NOM} on the Control Desk is pressed (and the offset increments used
by the Telescope Control Software are not equal zero).
On source change the offset values are reset.
\item
The differential tracking rate display reflects the values passed on
with the DIF command. The displayed values are updated
(and the telescope acts upon those values) whenever the differential
track button \doublebutton{DIFF}{RATE} on the console is pressed. 
Note that the value is reset to its normal value (usually zero) on change
of source.
\item
The aperture display shows which aperture position is being used. 
The RA and Dec position values are calculated
from the X,Y rotator coordinates to indicate where on the sky the 
current aperture is positioned. Note that the offset is executed by pushing
the BEAMSWITCH buttons on the System Control Panel. The NOMINAL position
usually has
non-zero X and Y because the reference point used for the SNAFU procedure is
not on the rotator axis.
\end{enumerate}
\item
The TELESCOPE block of the Information Display gives
details of the {\it current\/} telescope parameters:
\begin{enumerate}
\item
For the INT is indicated whether the telescope is OVER (above) or below the 
pole (or, equivalently, for the JKT, whether the telescope
is East or West of the mounting).
\item
The status of the telescope drive is indicated with the display of FAST SLEWING,
SLOW SLEWING, TRACKING or STOPPED, according to the velocity demand. 
Note that TRACKING only indicates that 
the slow-motion drive is turned on, {\it not} that it is tracking
within any particular error. If the Telescope is in fact tracking but the Dome
is still out of position, then the Information Display reads SLOW SLEWING.
\item
The two positions displayed are, firstly, on top, the telescope position
(mean or apparent) as entered via the User Interface, and secondly, below,
the Geocentric Apparent coordinates.

For the purists among the readers it
is noted that the latter position is strictly only accurate if the telescope 
is tracking with a negligible position error.
This is because the apparent position is calculated by adding
the demanded position to the known position error; the
position error, however, is determined in the encoder coordinate system,
which is skewed with respect to the 
telescope mean or geocentric apparent systems. Therefore, this calculation
is not accurate for large position errors. 
\item
The position error represents the telescope's (momentary) distance from the 
the correct tracking position. These values should be zero (or at most $\pm~$2
in the least significant digit) under normal operations.
\item
The Local Sidereal Time  and Hour Angle displays are accompanied 
by details of the current source's visibility:
\begin{enumerate}
\item
If the source is visible its Local Sidereal Time of Rising and remaining 
time above the horizon are
given. The number of hours left for observation is calculated as the time 
to lapse before the source goes below one of the telescope (software) limits.
This will be either the Hour Angle, Zenith Distance or, for the INT, the
Southern Declination limit.
\item
If the source has not yet risen the rise time and possible
observing time are given. 
\item
If the requested source either never rises or is circumpolar then 
appropriate messages are displayed. 
\end{enumerate}

\item
The three azimuth position angles displayed, refer to the telescope, the
demanded dome position, and the actual dome position. (The demanded dome 
position will be different from the telescope azimuth for an offset-mounted
mounted telescope, such as the JKT or the finder.) The actual dome azimuth
value is read directly from the encoder, and its alignment should 
be checked daily because the encoder gearing occasionally slips.
\item
The Zenith Distance (software) limit is set at 70\degs. The airmasses are
simply relative to zenith, but {\sl no\/} allowance is made for the
altitude above sea-level.
\item
For the INT the zenith distances of the edges of the wind
shields are also given. These are the actual zenith distances,
not when the telescope begins to be obscured! With the lower shutter 
{\it down\/} the telescope starts to vignette at a zenith distance of 58\degs;
with the lower shutter fully {\it up}, the telescope is vignetted at
a zenith distance of 49\degs and {\it lower}. Further, when the shutter is
fully open the lower edge of the shutter is beyond the zenith, its zenith
distance is without meaning and a row of asterisks (``$*$'') is displayed.
\item
The Parallactic Angle and Instrument Rotator positions are very useful 
information when doing spectroscopy at large zenith distances. The Telescope
Operator can rotate the A\&G box to align the spectrograph slit vertically
so that atmospheric dispersion spreads starlight
along the slit and not across it.
\item
The control software includes a model of the Telescope Focus as a function of
the ambient temperature. Once the focus has been determined at the beginning
of a night, the telescope will remain in focus, even when the temperature
changes. The displayed values allow on-line inspection of this little miracle.
\end{enumerate}

\item
The last line displays the selected NEXT object to observe. The telescope
will move to this object either by typing {\tt GO/NEXT} on the User Interface or
pressing the \button{SRCE} button on the Control Desk. Typing {\tt GO} is 
sufficient to go to the NEXT source.
\end{itemize}
\vfill
\eject
