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\begin{document}

\begin{titlepage}
\hspace*{\fill} {\huge Isaac Newton Group, La Palma} \hspace*{\fill}
\vfill
\hspace*{\fill} {\huge\bf The St Andrews RBS  User Manual} \hspace*{\fill} \newline
\newline
\hspace*{\fill} {\large R.~Edwin} \hspace*{\fill} \newline
\normalsize
\newline
\hspace*{\fill} {\bf Version 2.0, September 1988} \hspace*{\fill} \newline

\vspace{0.7cm}
\hspace*{\fill}
\parbox{12.2cm}{Scanned, OCR'ed \& Latex'ified, February 1997.  Sections labelled ``Obsolete, uncorrected'' are
seriously out of date, and have not been checked after scanning.}
\hspace*{\fill}

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\WHTlogo{4}
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\vfill
\footnotesize
\hspace*{\fill}
\parbox{82mm}{The Isaac Newton Group of Telescopes at the Observatorio del
Roque de los Muchachos del Instituto de Astrofisica de Canarias is operated by
the Royal Greenwich Observatory on behalf of the Science and Engineering
Research Council (UK) and the Nederlandse organisatie voor wetenschappelijk
onderzoek (NL).}
\hspace*{\fill}
\vspace{28mm}
\normalsize
\end{titlepage}
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\tableofcontents \listoffigures \listoftables 
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\part{}
\section{Introduction}

The Spectrograph is available at the f/15 Cassegrain focus of the 1.0m
Kapteyn Telescope.  The instrument was built at the University
Observatory, St Andrews and is based on the original design by
Richardson and Brealey (J.R.A.S. Canada 67, 165 (1973)).  Both the
camera and collimator optical systems are off-axis designs which
produce high quality spectral images in a flat focal plane.  The
aluminium instrument casing has low flexure, is compact and is light
in weight (18 kg).  At the time of writing the Spectrograph is
manually operated and uses photographic detection, although electronic
detection may become available.  The present instrument performance
makes it suitable for medium and low dispersion spectroscopy of
relatively bright objects.  Two sets of optics are available to
optimise efficiency in ``red'' or ``blue'' spectral regions and three
gratings provide different dispersions.  

\begin{figure}
\psfig{file=jktrbs.eps,width=15cm}
\caption{Schematic diagram of main optical components}
\end{figure}

The general construction, layout and facilities of the Spectrograph
are described initially, followed by details of operational procedures
and precautions.  Figure 1 is a schematic diagram of the main
optical components and their relative locations.

\section{ Acquisition and Guidance unit (A \& G UNIT)}

A separate manual is available for this unit and the associated TV
system so that only a brief description will be given. The
Unit contains systems to provide slit viewing and illumination of the
slit by  a comparison arc source.  The movements of optics within
the unit are remotely operated from the Control Console area and as
far as spectrograph operation is concerned, it is used in two
configurations.

\subsection {Object acquisition mode}

In this mode the Westinghouse SEC TV camera views the Cassegrain 
image  directly after a 90\degree reflection by a plane mirror.
Simultaneously, the spectrograph slit can be illuminated by the
comparison arc source.  In principle, an object can be acquired
whilst the arc is exposed.  However, arc exposures should be made
with the telescope and spectrograph oriented close to the celestial
exposure as is usual practice.  Arc exposures are of the order of
seconds.  Cu-Ar and Cu-Ne hollow cathode lamps are available.

\subsection {Slit viewing mode}

In this mode the acquisition/comparison arc mirror system is withdrawn
and the
Cassegrain image formed directly on the spectrograph slit.  The polished
slit jaws are inclined with their normal 7.5\degree from the telescope axis
so that the reflected beam has an axis inclined at 15\degree to the telescope
axis.  The slit viewing mirror enables the TV camera to view the
reflected image.  The slit can also be viewed via an eyepiece 
substituted for the TV camera.  In practice the TV system is used
because of its efficiency and
convenience.


\section{Filter spacer}

Between the A\&G unit and the Spectrograph is a mounting spacer,
which locates the slit at the correct f/15 focal plane.  The spacer is
normally mated with the Spectrograph and it houses a simple filter unit.
Details of the filters available are given in Appendix 5.  Any one of the
filters can be inserted in the convergent beam path to the
slit. The  image viewed by the the TV camera is necessarily
filtered also, but a double pass is avoided.  

The initial suite of
three gratings are designed for first order operation.  Thus, when
working in first order blue, there may be a need to filter out second order
ultra-violet radiation from the comparison arc.  When working in first order
red, filters will be required to remove second order blue for all spectra.
The photographic emulsion will provide the red cut-off.

The neutral density filters should not be required in photographic
mode.  
However, some neutral filters (Kodak ``Wratten'' gelatin)
can be inserted in front of the very sensitive TV camera.  The filters
should be used if objects brighter than m$_{v} = $6 are in the field.


\section{Spectrograph components}


\subsection{Slit and dekker assembly}


The slit and dekker slide are mounted from inside the main casing 
as a single unit.  A shutter mechanism is adjacent to the slit.

The dekker has four positions defined at follows:
\begin{enumerate}
\item  Slide fully ``in'': whole slit covered.
\item Inner detented position: star slot uncovered in which the central
2\,mm of slit is exposed.

\item Outer detented position: arc slots uncovered in which two 2mm
portions of the slit each side of the central 2\,mm are exposed.

\item Fully ``out'': the full length of the slit is exposed being some
20\,mm.
This position would normally only be used for acquisition purposes.
\end{enumerate}

The dimensions and location of star and arc slots are arranged so that
their respective spectra do not overlap.  20\,mm slit lengths project to
 approximately 0.5\,mm wide spectra at the camera focus.


The slit width is fixed but the whole unit can be replaced for a unit
having a different width.  Initially two units have been provided
widths of 70\,$\mu$m and 100\,$\mu$m corresponding, to I and 1.5
arc seconds projected onto-the sky.  During the commissioning period
it was determined that slits of equivalent width less than 1 arcsecond
would find less use than a 1.5 arc second slit.  Additional slit units
may be available in future, depending on demand.

The slit to detector reduction factor of 0.28 means that a slit width
of 1 arc second projects to 20\,$\mu$m at the detector (neglecting
foreshortening effects).  Geometrically the optics should produce
images of width less than 10\,$\mu$m for a zero width slit object.


\subsection{Shutter -- obsolete, uncorrected}

The shutter consists of an aluminium blade which slides under solenoid
control behind the slit.  A foam rubber light seal is made between
the, blade and slit unit.  A d.c.~power supply of 20 to 30Y is
required ideally on the @ telescope but during commissioning the power
supply  was located on the dome floor.

\subsection{Exposure meter -- obsolete, uncorrected}

Soon, after, leaving the slit, the divergent beam encounters the fuse
silica beam splitter of the exposure meter.  The beam splitter
consists, of a thin (1mm) window inclined at 450 which is
anti-reflection coated on one surface.  Consequently a few percent of
the radiation transmitted by the slit is fed to an exposure meter
photomultiplier (EMI type 9 This tube has a bialkali photocathode and
fused silica window. lent in the same system is also of fused silica
which makes the exposure meter UV sensitive.  A darkslide is provided
in front of t


The abode current from the photomultiplier is integrated by the
exposure meter control electronics located in the console Area and the
n is displayed as four digits.  The control electronics box also
houses the EHT supply which should normally be set at 1100V.

\subsection{Collimator}

The collimator is an off-axis parabola of focal length 750\,mm
(nominal) aperture of 50\,mm.  The collimator can be removed from
outside of the casing after removing the protective screw cap. As with
other optics in the main optical train, two collimators are available,
identical except for the coatings optimised for ``red'' or ``blue''
spectral regions.   Information on the relative efficiencies of the two sets of
optics is given in a later section.  The ``red'' collimator is identified
by a red painted disc on the collimator cell with a similar blue
marking on the other unit.



\subsection{Gratings}

Four gratings of line spacings 300, 600, 1200 and 2400 L/mm provide
nominal dispersions of 160, 80, 40 and 20 A/mm.  The 600 and 1200
L/mm gratings are conventional replicas of ruled gratings and are
blazed for 4400\,A.  The 2400 L/mm grating is a replica of a
holographic grating and, although not blazed shows higher efficiency
in the blue.

Each grating is mounted in a prealigned cell so that grating
interchange is straightforward.  The grating is accessed by removing
the main casing lid.

Grating rotation is accomplished by a worm gear system with scales calibrated
in 0.25 degree divisions.

\subsection{Camera}

The camera system is an f/4.1 off-axis Maksutov design comprising a
two-element corrector, a spherical mirror and a field flattening element
adjacent to  the focal plane.  A 45\degree flat mirror before the field
flattener directs the convergent radiation to a focus outside of the
spectrograph.  Each element is interchangeable and ':identified as
before by red or blue painted discs on the cells.  The red and blue
flatteners are of different optical design.  Both the, camera casing and field
flattener unit are accessed from outside of the casing.

Focusing of the spectrograph is achieved by movement of the camera
mirror.  The collimator position is not adjustable except by a small
distance during alignment operations which are not the concern of the
normal user. The camera mirror position is determined by a micrometer
which is read from outside of the instrument.  The mirror slide is additionally
clamped by a nut which must be released before adjusting the
micrometer.  A Hartmann mask, located close to the slit dekker and
thermometer allow Hartmann focus tests to be conducted.
The camera position  for best focus can be defined to within \approx
50\,$\mu$m routinely.


In normal operations the Hartmann mask is withdrawn from the optical
path and held
by a nylon clamp.  In use the two operational positions of the mask are
determined by being fully ``in'' or at a detented position.
Adjacent halves of the collimator aperture are irradiated in the two
positions.


\subsection{Plate holder assembly -- Obsolete, uncorrected}


The Spectrograph is designed to use plates of size 76

5.@ x 255~ (3" The plate ate is held in the plateholder under leaf
spring pressure., The plateholder is kinematically located into a
recess on the plate slide.  Slide movement is controlled by a nut and
screw defeats corresponding to O.5mm slide movement.  The motion can
be monitored on a pointer and mm scale.

Sets of spectra (comparison arc and astronomical exposures) occupy a

2mm strips of plate and it is recommended that the plate is racked

5 or five detents between exposures.,

Up to five sets can be accommodated: on: one plate.  I A portion of
the plate can not be user

c@16-Se geometry of the field flatterer to the plate

c Mechanical fouling

 unless the 'plate movement Is tea



\section{Spectrograph operation}


\subsection{Optical Configuration}

Before the Spectrograph is used a choice should be made of optics, grating
and slit. Although either set of optics can be used throughout the
wavelength range 350 to 1000\,nm, there is an efficiency penalty.  The
performance data should be consulted, but as a general guide, red optics
should be used for wavelengths above 500\,nm.

The choice of slit will depend on the seeing but it is anticipated
1that the 1\,arcsec slit will be the normal choice.

The choice of grating will be governed by the observations and the dispersion
and wavelength data should be consulted.


{\begin{center}\Large\bf The ``mounting'' of the optics should only be attempted by
someone familiar with the spectrograph.\end{center}}

New users can quickly learn the necessary procedures which, with
everything to hand, takes about 20 minutes for a complete optics
changeover.  Many of the mounting screws mate with threads tapped into
aluminium and care should be taken not to overstress the threads,
i.e., a light hand is required.  The grating should not be removed
without having a protective cover in place.  It is wise to cover the grating
during most operations within the casing with the lid removed.  

{\large{OBSOLETE:}}In such operations
the EHT to the exposure 'C@: met stitched off and as an additional
precaution the me or e c is now described



\subsection{Slit replacement}

For this procedure the grating has to be removed first.  The 3\,mm AF
hex ball
driver kept with the gratings should be used to loosen
the three
captive screws holding the grating base in place on the turntable.
The grating may have to be rotated to gain access to the screws.
Before rotating the grating, release the clamp nut (anti-clockwise
rotation) by half a turn.   This brass knurled nut is located on the
rotation axis outside of the instrument.  Each grating assembly should
be held by the handle or base and not by the grating cell.  

The
shutter mechanism can be pulled away from the slit by holding onto
the body of the mechanism NOT the shutter blade.  The mechanism hinges
about the end remote from the slit.  

The dekker should be pulled to
the fully out position.  The two toggle clamps located at the edges of
the slit assembly should be loosened (anti-clockwise rotation) whilst
holding the assembly.  The assembly can then be removed by rotating
about 30\degree which releases the dekker control from the slide bar.

Mounting is the same procedure in reverse and the whole operation
should become more obvious when the hardware is inspected.  Before
tightening (lightly) the toggle clamps ensure that the new slit is
rotated anticlockwise against the rotation stop and that the dekker
slide and control rod are correctly engaged.  Check dekker and shutter
operation.

\subsection{Grating assembly mounting}

Once a grating is removed as described in the previous section a
different one can be mounted by reversing the procedure.  As with the
slit, before tightening the three holding screws ensure that the base
is rotated anti-clockwise to contact the tangent screw against its
stop.  The grating angle can be set according to the observational
requirements by reading the main scale (divided into whole degrees)
and the control knob scale (which produces 2\degree grating rotation per one
revolution and can be set to a precision of a quarter degree).



\subsection{Removal and replacement of optics}


\subsubsection{Collimator}

This component is accessed by removal of the protective screw cap as
previously mentioned.  Two toggle clamps hold the cell in place and
rotation of the cell is defined by a tangent screw and stop.
Removal and replacement procedures should be self evident.

\subsubsection{Corrector Unit}

Access is gained with the main casing lid removed.  This unit is an
expensive item and is held in place by two metal fingers which are
spring loaded.  Precise location of the cell is ensured by two cone
sockets in the cell base which locate onto matching cones on the
cell slide.

To remove the cell, hold the body of the cell (not the
optical surfaces) and lift each finger away from the cell and to the
side of the cell and not to the rear where  the fingers might
contact the optical surface.  Mounting is the reverse of removal.
Ensure that the cell base is correctly located on the cones.

\subsubsection{Camera Mirror}

From outside of the instrument identify the four Allen screws which
hold the mirror cell adaptor plate on to the casing.  Ensure that the
three pairs of tilt screws are not disturbed.  Mirrors can be
interchanged by simple removal and replacement of the four screws
after swapping the mirror assemblies.

\subsubsection{Field Flattener Unit -- Obsolete, uncorrected}

The field flattener is accessed via the plateholder recess.  The
plateholder or dummy should be removed to expose the two M6 Allen
screws located close to the outer surface of the field flattener
element.  Remove the screws whilst keeping a careful hold of the
flattener cell.  Movement of the plateholder slide may enable better
hold of the cell to be established.  When withdrawing the unit be
careful to avoid fouling of the 45 degree mirror surface on the
surrounding case plate.  Replacement should be obvious.









\section[Preparation for observations]{Preparation for observations --
Warning, needs to be updated}

It is assumed that the Spectrograph is optically complete and that
the instrument is mounted via the filter spacer onto the A and G
Unit.  The orientation of the Spectrograph relative to the A \& G
Unit must be such that the slit reflection is towards the TV camera.
Check that the TV camera, the dekker knob, Hartmann mask control and
thermometer are all on the same side of the telescope axis.


{\LARGE{NEEDS TO BE UPDATED}} There are several electrical connections
which must be made.  The A \& G Unit must be connected to its control
unit and in turn the comparison arc connected to the power unit on the
side of the A \& G Unit.  The exposure meter photomultiplier has two
coaxial leads for EHT (HNC connector) and anode signal (BNC
connector).  These leads are routed to the Console Area for connection
to the exposure meter control box.  The shutter, controlled  at
present from the dome floor, has an electronic box mounted on the
instrument casing and hand control paddle on a flying lead. A
d.c.~supply of 20 to 3O\,V is required to power the shutter
mechanism. At the time of writing all cabling to the telescope
instrumentation was in a temporary configuration.


{\LARGE{NEEDS TO BE UPDATED}} Operation of the A\&G Unit is simple.
Buttons are pressed to bring either the slit viewing mirror or the
comparison arc/direct view mirrors into position.  Panel lights
indicate the current status and interlocks prevent mechanical
fouling of the mirrors and operation of the comparison arc when in the
slit viewing mode.  A separate push button controls the comparison
arc.


{\LARGE\bf{OBSOLETE, uncorrected}} The exposure meter has very few
controls.  With the mains power 'on' -check the EHT voltage on the
panel meter (normally 11OOV).  Adjustment is achieved by turning the
multi-turn potentiometer with a screwdriver through the hole in the
front panel.  The digital display can be zeroed or reset at any time
by pressing the button under tile display.

{\LARGE\bf{OBSOLETE, uncorrected}}  A useful daytime cheek that the
exposure meter is functioning can be performed as follows.  Illuminate
the slit with the comparison arc by operation of the A\&G Unit
controls.  Switch the exposure meter on and open the darkslide in
front of the photomultiplier.  With the dekker in. either the star or
arc position and the slit shutter open, the digital display should
count rapidly.  With the darkslide or shutter closed, the count should
stop (an insignificant count rate corresponding to the dark current
will be registered).

Separate
instructions are available for operating the TV system and the
associated image integration system.  It is necessary before
observations are started to check that the slit is correctly focused
by the TV camera optics.  With the A\&G Unit in the slit viewing mode
and the dome lights extinguished view the slit image on the console
display. An assistant will be required to provide some field
illumination of the slit area eg., the telescope secondary can be
illuminated by a flashlight cautiously.  A 1 arc second slit occupies
about 2 raster lines of the display.  The dull dekker mask should be
seen readily against the bright background of the slit jaws.
Adjustment of the TV focus must be performed at the telescope by
moving the camera body relative to the A\&G Unit.  A screw system is
provided.  Careful adjustment at this stage will reduce frustration
during observations.


\section{Focusing the spectrograph}

{\LARGE\bf{OBSOLETE, uncorrected}}  With a plate loaded mount the plateholder on the Spectrograph noting
that there is only one correct orientation for this unit defined by
the three kinematic mounting locations and anti-fouling pins.  The
Plateholder slide should be moved to one end of its travel (with the I
scale reading 22mm or 12mm). --exposures are normally conducted with
@:t slide in positions 22, 19. 5, 17, 14. 5 and 12 mm.  The '22mm'
exposure., occurs near the middle of the plate and the 12-.mm exposure
at the edge the plate.  

{\LARGE{NEEDS TO BE UPDATED}} Ensure the slit shutter is closed, the
dekker is in the star position, the Hartmann mask is ``in'' and the
plateholder darkslide ``out''.  The focus micrometer should read
0.2\,mm greater than the anticipated focus (5.0\,mm for blue optics,
4.5\,mm for red optics).  With the slit illuminated by the arc source,
the slit shutter should be opened for about 10 seconds thus exposing
the plate.  Without moving the plateholder a second, exposure should
be made with the Hartmann mask in its detented location and the dekker
in arc (double aperture) position.  The plateholder can then be moved
to the next location and the micrometer focus screw decremented by
0.1\,mm.  The exposure cycle is repeated keeping the mask and dekker
in the same relative locations throughout i.e., mask ``in'' , dekker
``in'' and mask ``out'', dekker ``out''.  The plate should show a
total of five focus tests conducted at settings of e.g., 5.2, 5.1, 5.0
, 4.9 and 4.8\,mm.  The darkslide must be closed before removing the
plateholder!

The resultant spectra should show a shift in the relative positions
of the ``arc'' and ``star'' exposures as in the classical Hartmann test.
The best focus should be determined and the micrometer set to the
nearest 
0.05\,mm and the Spectrograph temperature noted.  A change of more
than 5\degree\,C will
require a new focus to be set or determined depending on the calibration data
available.  Based on experience with a similar spectrograph in St Andrews the
temperature coefficient of focus change will be about
0.025\,mm/\degree\,C.

The Spectrograph should now be ready for astronomical observations.
Any pre-slit filters should be prepared for use.

\section{Photographic plates -- Obsolete, uncorrected}

The size of the plate required is no longer available from Kodak a I
ad plates must be cut by the observer or arrangements made with the
Photographic: technician.  Special emulsions ,nay have to be supplied
by the observer.

Hypersensitizing of plates is also possible provided adequate notice
is given. Baking in forming; gas was used C> C> for the commissioning
observations.

Plate processing with bubble burst agitation is performed in the build
for the Kapteyn Telescope but plate cutting, hypering and storage T 7
facilities are located in the @@T building..

metric,).;:. calibration of plates requires the use of the calibration
spectrograph also located in the INT building.  There is insufficient
room on the small plates for the calibration spectra.  Calibration and
astronomical spectra have to be exposed on their respective
spectrographs, using.-- plates from the same batch.  The plates should
then be cam simultaneously but the system is not ideal.


\section[Astronomical exposures]{Astronomical exposures -- Warning, needs to be updated}

Astronomical exposures are straightforward compared with the
setting operations.'

{\LARGE{NEEDS TO BE UPDATED}} The loaded plateholder should be mounted
onto the instrument and positioned ready to receive the first
exposure.  The good pointing of the telescope in combination with the
versatile TV system enables objects within the magnitude range of the
Spectrograph to be easily acquired, Although the comparison arc/direct
view configuration of the A\&G unit enables a larger field of sky to be
viewed, the pointing is such that
slit viewing imaging system is adequate for acquisition.  The
2\,mm apertures of the dekker correspond to 27 arc seconds at f/15 focus.

{\LARGE{NEEDS TO BE UPDATED}} During stellar exposures, image trailing will be required.  At this
time the details of the trailing facility have not been finalised.
Telescope focus and guiding are performed from the Console.

{\LARGE\bf{OBSOLETE, uncorrected}} The duration of comparison arc exposures can either be timed or
'counted' on. the exposure meter.  At commissioning the hollow cathode
source was unstable (old tube) a-,id the exposure meter method was
preferred.'

The duration of the astronomical exposure can be estimated from the
data in Appendix 4, but observers will have to modify their exposures to
match their measurement goals.

{\LARGE\bf{OBSOLETE, uncorrected}}  After use, the dummy plateholder should be mounted to protect the vulnerable field flattener.  Unlike the plateholder, the dummy can he mounted in two orientations.





\clearpage
\part{Appendices}
\setcounter{section}{0}
\section {Special Precautions Summary}
\begin{enumerate}
\item
Screws must not be overtightened,
especially where aluminium thread, are involved.

\item
Optical surfaces, particularly grating surfaces, must not be
touched or contacted.
\item
{\LARGE\bf{OBSOLETE, uncorrected}}  The exposure ,meter darkslide must be closed before removing the
case lid.  As an added precaution the EHT should be switched off.
\item
{\LARGE\bf{OBSOLETE, uncorrected}}  The shutter should be swung away from the slit by holding the
body of the mechanism not the shutter blade.
\item
 When adjusting the camera mirror focus with the micrometer, ensure
that the clamp nut is released.  For highest stability this nut should
be tightened once best focus has been determined.
\item
 The grating rotation clamp must be released before the rotation
knob is adjusted.
\item
 There is a possible fouling of the telescope pier by the collimator
tube at 
declinations greater than +70 degrees when operating below
the pole.
\item
 The grating should be protected by a cover during all operations
within the casing.  
\item
 Grating angles outside the range +60\degree to -30\degree
should not be set to avoid mechanical fouling between casing and
grating.
\item
{\LARGE{NEEDS TO BE UPDATED}}  When not in use, the field flattener should be protected by either
the plateholder or the dummy cover.
\item
 When removing a corrector unit lift each clamp finger and swing to
the side of the cell and not to the rear where there is a danger of
contact with the rear optical surface.
\end{enumerate}

\section{Wavelength Ranges and Dispersion Data}


{\LARGE{NEEDS TO BE UPDATED}} The two conventional gratings (600 and
1200 L/mm) are blazed for 4400\, A.  The gratings are mounted with the
``blaze to collimator'' i.e., angle of incidence greater than angle of
diffraction.  The 2400\,L/mmm grating is used in a similar
configuration but this type of grating is not specifically blazed.

The rotation angle given in the tables can be determined or set using
the circular scale and control knob subdivisions.  0\degree on the scale
corresponds to the grating being normal to the collimated
beam. Because the angle between the collimated beam and camera axis is
23\degree, a setting of +11.5\degree puts zero order centrally in the camera
field.  

There are mechanical limits to the maximum grating rotation.  The
limits correspond to scale readings of +60\degree and -30\degree.  At
high angles of incidence (larger than 30\degree) the projected width
of the 58\,mm wide gratings is less than the collimated bean and so
some light loss occurs.

The following three tables give for each grating the dispersions
and wavelengths for the centre and edges of the camera field for a
range of
angle settings.



{\LARGE\bf{OBSOLETE}} February 1997: The tables are obsolete, and not reproduced in
the Latex version.


\section{Optical specifications}

\begin{tabular}{ll}
Collimator focal length & 749.25\,mm (f/15)\\
Camera effective focal length & 208\,mm (f/4.1)\\
grating apertures & 58\,mm x 58\,mm \\
Slit width (1 second of arc) & 70\,$\mu$m\\
Slit width (1.5 second of arc) & 100\,$\mu$m\\
Slit height (star mode) & 2\,mm\\
Slit height (comparison ard mode) & 2 x 2\,mm\\
Angular field of camera (unvignetted) & 13.7 \degree (\approx
6.85\degree)\\
Angle between collimated beam axis and camera axis & 23\degree\\
{\LARGE\bf{OBSOLETE}}Photographic plate size & 3'' x 1''\\
& = 765\,mm x 255\,mm\\
{\LARGE\bf{OBSOLETE}}Plate thickness & 0.04'' nominal\\
& = 1\,mm\\
{\LARGE{Needs to be updated}} Focus setting at 20\degree\,C (blue
optics) & 5.0\,mm\\
{\LARGE{Needs to be updated}} Focus setting at 20\degree\,C (red
optics) & 4.5\,mm\\
Temperature coefficient of focus setting & 0.025\,mm/\degree\,C
\end {tabular}

\section{Performance data}
The following data are preliminary results obtained at the time of
commissioning.  Modifications may be required with experience.

\subsection{Exposure times}

Since it is expected that the dispersion of 40A/mm (1200 L/mm
grating) will be used the most, this dispersion is taken as the
standard.  It was found that to a good approximation exposure times  
are inversely proportional to dispersion.  The exposure times for the
comparison arc are independent of dispersion.

Exposure times are quoted which produce a density of 0.8 above fog in
the middle of the spectral range (unless otherwise specified).  Seeing
conditions of 1 to 2 arc seconds are assumed using the 1 arcsec slit.
{\LARGE{Needs to be updated}}  Image trailing uses the full 2\,mm of
slit exposed by the star aperture in the dekker.  It is estimated that
at the time of commissioning that there was 0.4 magnitudes of
extinction at the zenith by dust.

The exposure times are quoted for stars of zeroth magnitude.


\subsection{Radial velocity measurements}
Laboratory tests on the spectrograph before commissioning and
subsequent tests on the telescope yielded a flexure of 1\,$\mu$m per
hour for spectra (hour here refers to telescope/spectrograph RA motion
during the course of an exposure).

{\center\LARGE{Needs to be updated}}
\subsubsection [Blue optics]{IIaO -- 3200 to 5000 A -- Blue optics -- 40 A/mm}

\begin {tabular}{ll}
a) Arc exposure & 350 counts x 2 (15 seconds x 2 approx.)\\
b) Star exposure & 1400 counts for all spectral types\\
& (1.9 seconds for a B = 0 mag star)\\
&(for H and K in a K type star, increase x 2)\\
&(for H and K in a M type star, increase x 5)\\
c) Red optics & Penalty -- increase exposure x 2\\
d) Sensitization & Little improvement -- decrease exposure by30\%\\

\end{tabular}

\subsubsection [Blue optics]{IIIaJ -- 3200 to 5000 A -- Blue optics -- 40 A/mm}

\begin {tabular}{ll}
a) Arc exposure & 1000 counts x 2 (45 seconds x 2 approx.)\\
b) Star exposure & 9000 counts for all spectral types\\
& (12 seconds for a B = 0 mag star)\\
&(for H and K in a K type star, increase x 2)\\
&(for H and K in a M type star, increase x 5)\\
c) Red optics & Penalty -- increase exposure x 2 below 4500 A\\
&Same exposure for 4500 to 5500 A\\
d) Sensitization & Decrease exposure x 5\\

\end{tabular}

\subsubsection [Red optics]{IIIaJ -- 3500 to 6900 A -- Red optics -- 40 A/mm}

\begin {tabular}{ll}
a) Arc exposure & 1000 counts x 2 (45 seconds x 2 approx.)\\
b) Star exposure & Spectral type ~~~~~~~~~~~Counts\\
&M~~~~~~~~~~~~~~3000\\
&K~~~~~~~~~~~~~~4000\\
&G~~~~~~~~~~~~~~8000\\
&A,F~~~~~~~~~~~12000\\
&O,B~~~~~~~~~~~16000\\
&(for 6600 to 5500 A: 30 seconds for a V =) star)\\
c) Blue optics & Penalty -- increase exposure x 2 for 6600 to 5500 A\\
d) Sensitization & Decrease exposure x 2\\
\end{tabular}

\subsubsection [Red optics]{IIIaJ -- 3200 to 5000 A -- Red optics -- 40 A/mm}

\begin {tabular}{ll}
a) Arc exposure & 50 counts x 2 (2seconds x 2 approx.)\\
b) Star exposure & Spectral type ~~~~~~~~~~~Counts\\
&M~~~~~~~~~~~~~~2500\\
&K~~~~~~~~~~~~~~8000\\
&A~~~~~~~~~~~~~30000\\
&(18 minutes for star with 0 mag at 8000 A)\\
c) Blue optics & Increase exposure x 4\\
d) Sensitization & Not investigated\\
\end{tabular}

\subsection{IAU radial velocity standards}
Measurements have also been conducted on spectra of IAU radial
velocity standards.  Most observations were conducted at dispersions
of 40 and 80 A/mm.  Arcturus was observed repeatedly but some hotter
stars with sharp lines were also studied.  The plates were scanned on
the RGO PDS machine and the results show that the radial velocities
measured are consistent with the IAU scale.  In each case the standard
deviation is quoted for the uncertainty.

\begin{enumerate}
\item At 40 A/mm for 18 observations of 5 IAU standards, the mean
difference spectrograph - IAU = +0.2 +- 1.9\,km/s

\item At 40 A/mm for 11 observations of Arcturus, the difference 
(standard deviation from IAU value) was 1.1\,km/s

\item At 40 A/mm for 13 observations of 9 other stars, the mean
difference spectrograph - IAU = -0.8 +- 3.9\,km/s

\item At 40 A/mm for 5 observations of 5 stars (1 IAU standard), the mean
difference spectrograph - IAU = -2.2 +-  7.6\,km/s

\item At 40 A/mm for 6 observations of 4 stars (1 IAU standard), the mean
difference spectrograph - IAU = -0.8 +-  4.8\,km/s
\end{enumerate}

The commissioning data were obtained by D.J.~Stickland and R.P.~Edwin.

\section{Pre-slit filter data}

Filters available:


\begin{tabular}{llrl}
Schott&  RG& 830~~&\\
Schott&  RG& 695~~&\\
Schott&  RG& 630~~&\\
Schott&  GG& 495~~&\\
Schott&  GG& 395~~&\\
Schott&  GG& 385~~&\\
Schott&  BG&  38~~&\\
Schott&  BG&  28~~&\\
Schott&  UG&   1~~&\\
&&~~~~1.4&(neutal density, metal film)\\
&&~~~~3.0&(neutal density, metal film)\\
\end{tabular}

\begin{figure}
\psfig{file=rbstr1.eps,width=15cm}
\caption{Transmission curves}
\end{figure}

\begin{figure}
\psfig{file=rbstr2.eps,width=15cm}
\caption{Transmission curves, continued}
\end{figure}


\clearpage

\section[Supplement:  Operation with a CCD camera]{Supplement To The
Technical And User Manuals For The St Andrews Richardson Brealey
Spectrograph - Operation With A CCD Camera\\\begin{center}R.P.~Edwin\\ May 1988\end{center}}




\subsection{Introduction}


During 1987 components were manufactured and purchased by the
University Observatory, St Andrews under SERC contract SO/792/86 to
enable the Richardson Brealey Spectrograph to be used with a CCD
camera.  In photographic mode the instrument had proven inefficient
when 
compared with other spectrographs equipped with electronic detectors.
The modifications allow CCD cameras of the standard RGO design (with kinematic mounting
interface) to be mounted onto the spectrograph.

In February 1988 the system was commissioned during a one week
allocation of time on the JKT.  The changes in the operation of the
spectrograph in this mode are described in thisa supplement.  Also
some data on instrument stability and sensitivity are presented.


\subsection{Optical modifications}


The optical system has required minor changes to match the spectrum
imaging plane to the CCD elements within the cryostat.  In the original
design, the focal plane was located 12.5\,mm from outer surface of the main
instrument casing.  The CCD surface is located some 15.5\,mm (RCA)
or 14.5\,mm (GEC) from the cryostat faceplate.  In addition, the window on the
cryostats is 4\,mm thick which must be included in the optical design.

A new field flattener has been provided which images over a 30\,mm
field at the CCD plane.  One surface of the field flattener is within
a mm or so of the cryostat window, although fouling is mechanically
impossible if everything is installed correctly.  Relative to the 56\,mm
x 90\,mm aperture in  the main casing plate (through which the field flattener
protrudes),  the optical centre, for both the spectrograph and
cryostat is located 20\,mm from the edge nearest the camera and is in
the 90\,mm dimension.  (The 20\,mm dimension represents a 2\,mm shift of the
optical centre).

The field flattener has been coated with single layer MgF$_{2}$
anti-reflection coatings optimised for the CCD red response.  The coatings
were conducted by David Jackson at the RGO.

A new low dispersion grating has been added to the existing suite of
three.  The new grating has 300 l/mm and provides a dispersion of
approximately 160 A/mm. (Grating is Milton Roy (ex Bausch and Lomb)
type 35-53-06-180 with blaze of 6.5\degree for 7500 A).  Details
of wavelength ranges and dispersions for all gratings are given in
Section 5.  These tables assume that the detector format covers 15\,mm of
spectrum.


\subsection{Mechanical modifications}


The major mechanical modification has been the removal of the
plateholder and replacement by an adapter ring to which the cryostat
can be clamped.  The ring incorporates the standard clamping and
location arrangements common to RGO cameras.  The ring is held onto
the casing via 7 x M6 studs with nuts and washers.  The ring is
precisely located on the surface of the  casing by three metal pads
permanently bolted to the casing.  No
attempt should be made to disturb the pad locations.

The cryostat can be rotated about the optical centre in order to align
the CCD pixels relative to the dispersion direction.  The 7 x M6 nuts,
securing the ring, should be loosened and fine control of rotation is
achieved using a micrometer tangent screw included in the
modification.  The radius on which the tangent screw operates is 14l\,mm.

The shutter mounted within the casing adjacent the slit has been
removed because it was not compatible with the CCD control system.
Also the shutter limited grating rotation.  A different shutter
(Compur model 141) has been mounted within the filter spacer ``above''
the slit.  This location is not ideal because, when the shutter is
``shut'', the slit can not be viewed, but the physical size of the
unit restricted mounting at any other location.  The shutter is
interfaced for control by the CCD software and operates from fully
open to closed within 4 msecs.  The shutter is not permanently
allocated to the spectrograph but it is now necessary for normal
operations.


\subsection{ Routine operational procedures}


The CCD detector system has simplified spectrograph operation and
observations require less physical contact with the instrument.  Once
the CCD cryostat is mounted on the telescope, there some alignment and
focusing procedures to be conducted.  The grating mounting rotation
and choice of optics are as per the original manuals.

Since the spectrograph should be in approximate focus after previous
use, the CCD rotational alignment is probably the first task.  As
mentioned previously the cryostat can be rotated by first releasing
the 7 x M6 nuts holding the adapter ring.  It is advised that this
operation should be performed with the telescope pointing so that the
cryostat is held in intimate contact with the casing by gravity.
Integrations on arc spectra and resultant image displays will quickly
reveal the pixel alignment relative to the spectrum axis and rotation
adjustments should quickly converge to satisfactory alignment.

Fine focus is achieved using the Hartmann mask.  The focus adjustment
is still by means of a micrometer which defines the location of the
camera mirror.  The clamp mentioned in relation to photographic use
has been removed because it fouled the adapter ring.  The focus
setting used during commissioning was close to 5\,mm.  Shift between
Hartmann exposures was detected graphically on the ARGS display, there
being no software routines available.

The slit dekker is normally used so that only the central portion of
the slit is exposed (2\,mm or 27'' sky equivalent).  For arc spectra
and 22\,$\mu$m pixels, the width of spectra were found to be
correspondingly about 20 pixels wide (1 pixel = 1.1" geometrically).
On the other hand, flat field exposures were made with a long slit.
Because of fringing effects with the coated GEC chip it was found
necessary to obtain flat fields at each grating/dispersion setting of
the instrument.  A temporary arrangement for a flat field source was
used in which a tungsten halogen source was used to illuminate the
slit through the A and G comparison arc unit.  An out-of-focus
diffusing screen was directly illuminated at this location.  If the
screen is in sharp focus at the slit then non-uniform illumination
along the slit is possible from the ``grain'' of the screen.  This
results in a spectrum with streaks, as if the slit jaws are dirty.

The possibility of the spectrograph fouling the telescope at
declination settings of greater than +75\degree still exists.  An
algorithm has been incorporated into the telescope control software
certain telescope motions.  The installation and successful operation
of this software should be checked and particular care taken whenever
declination settings greater than +75\degree are used.

The filters for photographic mode remain available for use with CCDS.
Glass Schott filters with a blue cut-off are efficient for blocking
blue orders in red spectra.  However, a copper sulphate filter is the
most efficient filter for blocking red scattered light in blue
spectra.  The red sensitive CCD could detect a relatively high
background of red radiation without the filter.  A suitable filter was
borrowed from the People's Photometer.  

{\LARGE\bf{OBSOLETE}}The exposure meter was a useful indicator of
integration progress and can be used as in photographic mode.




\subsection{Wavelength and Dispersion Tables}



The following tables summarise the possible wavelength ranges and
dispersion with each of the four gratings, 300, 600, 1200 and 2400
l/mm.  Data assumes first order operation and a CCD format of 15\,mm
along the dispersion direction.




\begin{table}
\caption{Wavelength ranges and dispersion 300 L/mm}
\begin{tabular}{rrrrrrr}

ANGLE   &\multicolumn{2}{c}{EDGE}& \multicolumn{2}{c}{CENTRE}& \multicolumn{2}{c}{ EDGE}\\
SETTING & \multicolumn{1}{c}{A}& \multicolumn{1}{c}{A/MM} & \multicolumn{1}{c}{A}  &    \multicolumn{1}{c}{A/MM} & \multicolumn{1}{c}{A}  &   \multicolumn{1}{c}{A/MM}\\
15.0  & 2839.0 & 157.8 &  3988.2&  158.7 &  5143.0&  159.4\\
15.5  & 3406.4 & 158.1 &  4557.1&  158.9 &  5713.1&  159.5\\
16.0  & 3973.4 & 158.3 &  5125.6&  159.1 &  6282.7&  159.6\\
16.5  & 4540.2 & 158.5 &  5693.7&  159.2 &  6851.9&  159.8\\
17.0  & 5106.6 & 158.7 &  6261.4&  159.4 &  7420.5&  159.9\\
17.5  & 5672.7 & 158.9 &  6828.7&  159.5 &  7988.6&  160.0\\
18.0  & 6238.3 & 159.1 &  7395.4&  159.6 &  8556.0&  160.0\\
18.5  & 6803.4 & 159.2 &  7961.5&  159.8 &  9122.8&  160.1\\
19.0  & 7368.0 & 159.4 &  8527.1&  159.9 &  9689.0&  160.2\\
19.5  & 7932.0 & 159.5 &  9091.9&  160.0 & 10254.3&  160.2\\
20.0  & 8495.5 & 159.6 &  9658.1&  160.0 & 10818.9&  160.2\\

\end{tabular}
\end{table}











\begin{table}
\caption{Wavelength ranges and dispersion 600 L/mm}
\begin{tabular}{rrrrrrr}

ANGLE   &\multicolumn{2}{c}{EDGE}& \multicolumn{2}{c}{CENTRE}& \multicolumn{2}{c}{ EDGE}\\
SETTING & \multicolumn{1}{c}{A}& \multicolumn{1}{c}{A/MM} & \multicolumn{1}{c}{A}  &    \multicolumn{1}{c}{A/MM} & \multicolumn{1}{c}{A}  &   \multicolumn{1}{c}{A/MM}\\

15.0  &  1419.5 & 78.9  &  1994.1&  79.3  &  2571.5&  79.7 \\
15.5  &  1703.2 & 79.0  &  2278.5&  79.4  &  2856.5&  79.8 \\
16.0  &  1986.7 & 79.1  &  2562.8&  79.5  &  3141.4&  79.8 \\
16.5  &  2270.1 & 79.2  &  2846.9&  79.6  &  3425.9&  79.9 \\
17.0  &  2553.3 & 79.3  &  3130.7&  79.7  &  3710.3&  79.9 \\
17.5  &  2836.3 & 79.4  &  3414.3&  79.8  &  3994.3&  80.0 \\
18.0  &  3119.1 & 79.5  &  3697.7&  79.8  &  4278.0&  80.0 \\
l8.5  &  3401.7 & 79.6  &  3980.8&  79.9  &  4561.4&  80.1 \\
19.0  &  3884.0 & 79.7  &  4263.5&  79.9  &  4844.5&  80.1 \\
19.5  &  3966.0 & 79.8  &  4546.0&  80.0  &  5127.2&  80.1 \\
20.0  &  4247.7 & 79.8  &  4828.1&  80.0  &  5409.5&  80.1 \\
20.5  &  4529.1 & 79.9  &  5109.8&  80.1  &  5691.3&  80.1 \\
21.0  &  4810.2 & 79.9  &  5391.1&  80.1  &  5972.8&  80.1 \\
21.5  &  5090.9 & 80.0  &  5672.1&  80.1  &  6253.3&  80.1 \\
22.0  &  5371.2 & 80.0  &  5952.6&  80.1  &  6534.3&  80.1 \\
22.5  &  5651.1 & 80.1  &  6232.6&  80.1  &  6814.3&  80.1 \\
23.0  &  5930.5 & 80.1  &  6512.2&  80.1  &  7093.8&  80.1 \\
23.5  &  6209.5 & 80.1  &  6791.3&  80.1  &  7372.8&  80.1 \\
24.0  &  6488.1 & 80.1  &  7069.8&  80.1  &  7651.2&  80.O \\
24.5  &  6766.1 & 80.1  &  7347.8&  60.1  &  7929.0&  80.0 \\
25,0  &  7043.6 & 80.1  &  7625.3&  80.1  &  8206.2&  79.9 \\
25.5  &  7320.6 & 80.1  &  7902.2&  80.1  &  8482.8&  79.9 \\
26.0  &  7597.1 & 80.1  &  8178.5&  80.0  &  8758.8&  79.8 \\
26.5  &  7872.9 & 80.1  &  8454.1&  80.0  &  9034.1&  79.8 \\
27.0  &  8148.2 & 80.1  &  8729.1&  79.9  &  9308.1&  79.7 \\
27.5  &  8422.8 & 80.1  &  9003.5&  79.9  &  9582.5&  79.6 \\
28.0  &  8698.8 & 80.0  &  9277.1&  79.8  &  9855.7&  79.5 \\
28.5  &  8970.1 & 80.0  &  9550.1&  79.8  & 10128.1&  79.4 \\
29.0  &  9242.8 & 79.9  &  9822.3&  79.7  & 10399.7&  79.3 \\
29.5  &  9514.7 & 79.9  & 10093.8&  79.6  & 10870.5&  79.2 \\
30.0  &  9785.9 & 79.8  & 10364.5&  79.5  & 10940.6&  79.1\\

\end{tabular}
\end{table}



\begin{table}
\caption{Wavelength ranges and dispersion 1200 L/mm}
\begin{tabular}{rrrrrrr}

ANGLE   &\multicolumn{2}{c}{EDGE}& \multicolumn{2}{c}{CENTRE}& \multicolumn{2}{c}{ EDGE}\\
SETTING & \multicolumn{1}{c}{A}& \multicolumn{1}{c}{A/MM} & \multicolumn{1}{c}{A}  &    \multicolumn{1}{c}{A/MM} & \multicolumn{1}{c}{A}  &   \multicolumn{1}{c}{A/MM}\\


15.0 &    709.8 & 39.5 &    997.0 & 39.7  &  1285.8 & 39.8\\
16.0 &    993.4 & 39.6 &   1281.4 & 39.8  &  1570.7 & 39.9\\
17.0 &   1276.7 & 39.7 &   1565.4 & 39.8  &  1855.1 & 40.0\\
18.0 &   1559.6 & 39.8 &   1848.8 & 39.9  &  2139.0 & 40.0\\
19.0 &   1842.0 & 39.8 &   2131.8 & 40.0  &  2422.2 & 40.0\\
20.0 &   2123.9 & 39.9 &   2414.0 & 40.0  &  2704.7 & 40.1\\
21.0 &   2405.1 & 40.0 &   2695.6 & 40.0  &  2986.4 & 40.1\\
22.0 &   2685.6 & 40.0 &   2976.3 & 40.1  &  3267.2 & 40.1\\
23.0 &   2965.3 & 40.0 &   3256.1 & 40.1  &  3546.9 & 40.0\\
24.0 &   3244.0 & 40.1 &   3534.9 & 40.1  &  3825.6 & 40.0\\
25.0 &   3521.8 & 40.1 &   3812.6 & 40.0  &  4103.1 & 40.0\\
26.0 &   3798.5 & 40.1 &   4089.2 & 40.0  &  4379.4 & 39.9\\
27.0 &   4074.1 & 40.0 &   4364.6 & 40.0  &  4654.3 & 39.8\\
28.0 &   4348.4 & 40.0 &   4638.6 & 39.9  &  4927.8 & 39.8\\
29.0 &   4621.4 & 40.0 &   4911.2 & 39.8  &  5199.9 & 39.7\\
30.0 &   4893.0 & 39.9 &   5182.2 & 39.8  &  5470.3 & 39.6\\
31.0 &   5163.1 & 39.8 &   5451.8 & 39.7  &  5739.1 & 39.5\\
32.0 &   5431.6 & 39.8 &   5719.6 & 39.6  &  6006.1 & 39.3\\
33.0 &   5698.4 & 39.7 &   5985.7 & 39.5  &  6271.3 & 39.2\\
34.0 &   5963.6 & 39.6 &   6250.0 & 39.3  &  6534.5 & 39.0\\
35.0 &   6226.9 & 39.5 &   6512.4 & 39.2  &  6795.8 & 38.9\\
36.0 &   6488.3 & 39.3 &   6772.8 & 39.0  &  7055.0 & 38.7\\
37.0 &   6747.7 & 39.2 &   7031.1 & 38.9  &  7312.1 & 38.5\\
38.0 &   7005.1 & 39.0 &   7287.3 & 38.7  &  7566.9 & 38.3\\
39.0 &   7260.4 & 38.9 &   7541.3 & 38.5  &  7819.5 & 38.1\\
40.0 &   7513.4 & 38.7 &   7793.0 & 38.3  &  8069.6 & 37.9\\
41.0 &   7764.1 & 38.5 &   8042.3 & 38.1  &  8317.3 & 37.6\\
42.0 &   8012.5 & 38.3 &   8289.2 & 37.9  &  8562.5 & 37.4\\
43.0 &   8258.5 & 38.1 &   8533.5 & 37.6  &  8805.0 & 37.1\\
44.0 &   8501.9 & 37.9 &   8775.2 & 37.4  &  9044.9 & 36.9\\
45.0 &   8742.7 & 37.6 &   9014.3 & 37.1  &  9282.0 & 36.6\\
46.0 &   8980.9 & 37.4 &   9250.6 & 36.9  &  9516.3 & 36.3\\
47.0 &   9216.3 & 37.1 &   9484.1 & 36.6  &  9747.7 & 36.0\\
48.0 &   9449.0 & 36.9 &   9714.7 & 36.3  &  9976.1 & 35.7\\
49.0 &   9678.7 & 36.6 &   9942.3 & 36.0  & 10201.5 & 35.4\\
50.0 &   9905.5 & 36.3 &  10167.0 & 35.7  & 10423.8 & 35.0\\

\end{tabular}
\end{table}








\begin{table}
\caption{Wavelength ranges and dispersion 2400 L/mm}
\begin{tabular}{rrrrrrr}

ANGLE   &\multicolumn{2}{c}{EDGE}& \multicolumn{2}{c}{CENTRE}& \multicolumn{2}{c}{ EDGE}\\
SETTING & \multicolumn{1}{c}{A}& \multicolumn{1}{c}{A/MM} & \multicolumn{1}{c}{A}  &    \multicolumn{1}{c}{A/MM} & \multicolumn{1}{c}{A}  &   \multicolumn{1}{c}{A/MM}\\



25.0 &   1760.9 & 20.0  &  1906.3&  20.0 &   2051.6 &  20.0\\
26.0 &   1899.3 & 20.0  &  2044.6&  20.0 &   2189.7 &  20.0\\
27.0 &   2037.0 & 20.0  &  2182.3&  20.0 &   2327.2 &  19.9\\
28.0 &   2174.2 & 20.0  &  2319.3&  20.0 &   2463.9 &  19.9\\
29.0 &   2310.7 & 20.0  &  2455.6&  19.9 &   2599.9 &  19.8\\
30.0 &   2446.5 & 20.0  &  2591.1&  19.9 &   2735.1 &  19.8\\
31.0 &   2581.5 & 19.9  &  2725.9&  19.8 &   2869.5 &  19.7\\
32.0 &   2715.8 & 19.9  &  2859.8&  19.8 &   3003.0 &  19.7\\
33.0 &   2849.2 & 19.8  &  2992.9&  19.7 &   3135.6 &  19.6\\
34.0 &   2981.8 & 19.8  &  3125.0&  19.7 &   3267.3 &  19.5\\
35.0 &   3113.4 & 19.7  &  3256.2&  19.6 &   3397.9 &  19.4\\
36.0 &   3244.1 & 19.7  &  3386.4&  19.5 &   3527.5 &  19.3\\
37.0 &   3373.9 & 19.6  &  3515.6&  19.4 &   3656.1 &  19.3\\
38.0 &   3502.6 & 19.5  &  3643.7&  19.3 &   3783.5 &  19.2\\
39.0 &   3830.2 & 19.4  &  3770.7&  19.3 &   3909.7 &  19.1\\
40.0 &   3756.7 & 19.3  &  3896.5&  19.2 &   4034.8 &  18.9\\
41.0 &   3882.1 & 19.3  &  4021.1&  19.1 &   4158.7 &  18.8\\
42.0 &   4006.3 & 19.2  &  4144.6&  18.9 &   4281.2 &  18.7\\
43.0 &   4129.2 & 19.1  &  4266.7&  18.8 &   4402.5 &  18.6\\
44.0 &   4250.9 & 18.9  &  4387.6&  18.7 &   4522.5 &  18.4\\
45.0 &   4371.4 & 18.8  &  4507.1&  18.6 &   4641.0 &  18.3\\
46.0 &   4490.4 & 18.7  &  4625.3&  18.4 &   4758.2 &  18.2\\
47.0 &   4608.2 & 18.6  &  4742.0&  18.3 &   4873.9 &  18.0\\
48.0 &   4724.5 & 18.4  &  4857.3&  18.2 &   4988.1 &  17.8\\
49.0 &   4839.4 & 18.3  &  4971.2&  18.0 &   5100.8 &  17.7\\
50.0 &   4952.8 & 18.2  &  5083.5&  17.8 &   5211.9 &  17.5\\
51.0 &   5064.7 & 18.0  &  5194.2&  17.7 &   5321.4 &  17.3\\
52.0 &   5175.0 & 17.8  &  5303.4&  17.5 &   5429.4 &  17.2\\
53.0 &   5283.8 & 17.7  &  5411.0&  17.3 &   5535.6 &  17.0\\
54.0 &   5390.9 & 17.5  &  5516.9&  17.2 &   5840.2 &  16.8\\
55.0 &   5496.5 & 17.3  &  5621.1&  17.0 &   5743.1 &  16.6\\
56.0 &   5600.3 & 17.2  &  5723.7&  16.8 &   5844.2 &  16.4\\
57.0 &   5702.5 & 17.0  &  5824.4&  16.6 &   5943.6 &  16.2\\
58.0 &   5802.9 & 16.8  &  5923.4&  16.4 &   6041.1 &  16.0\\
59.0 &   5901.5 & 16.6  &  6020.6&  16.2 &   6136.8 &  15.8\\
60.0 &   5998.3 & 16.4  &  6118.0&  18.0 &   6230.6 &  15.6\\
\end{tabular}
\end{table}

\clearpage

\subsection{Performance Data}

Image resolution with a 1.5" slit and 22$\mu$m pixels estimated from
arc spectra.

\nopagebreak

\begin{tabular}{ll}
FWHM arc lines     &     \approx 2 pixels\\
&\approx  40$\mu$m\\
22\,$\mu$m pixel  =   1.1" &\\
&\\
Camera focus settings  &      4.45\,mm red optics\\
  &      4.40\,mm blue optics\\
&\\
\multicolumn{2}{l}{Cryostat rotation adjustment for camera GEC3-B}\\
micrometer reading & 4.45 \\
&\\
\multicolumn{2}{l}{Cryostat tilt adjustment screws with above camera}\\
A& 3.87\\
B & 3.74\\
C&3.35\\
\end{tabular}

Adjustments A, B and C produce a clearance of 0.3\,mm between casing
and end face of cryostat.


Field flattening lens, bi-convex, fused silica with surface radii
249\,mm and thickness 1500\,mm. See separate drawing for more details.


\clearpage







\subsection{Signal vs Magnitudes}


The data have been normalised for a star with m$_{v}$ = 10 and for 100
sec integrations.  In each case the signal, averaged over 2\,mm of
spectrum, is in ADUs integrated across a 22\,$\mu$m (1 pixel) section
of the spectrum.  The conversion of ADUs for the camera in use was 1
ADU = 1 electron approximately.  The electronic readout noise was 6 to
7 electrons per pixel per readout.  The spectrum with normal seeing
and and manual guiding was typically 5 pixels wide.
\nopagebreak

\begin{table}[h]
\caption{Signal vs magnitudes}
\begin{tabular}{lcc}
Spectral Type	&Central Wavelength (A)&\multicolumn{1}{l}{Signal (ADUs per 22\,$\mu$m of spectrum}\\
\hline
\multicolumn{3}{l}{2400 l/mm grating}\\
&&\\
B & 3500  &~150\\
&&\\	   
B & 4000  &~400\\
K & 4000  &~160\\
&&\\  	   
B & 4200  &1500\\
F & 4200  &1200\\
G & 4200  &~100\\
K & 4200  &~~60\\
&&\\ 	   
K & 6500  &~380\\
&&\\	
\hline
\multicolumn{3}{l}{1200 l/mm grating}\\
B &  4100  &   520\\
G &  4100  &   160\\
M &  4100  &    50\\
&&\\ 	   
G & 5200   &  1200\\
&&\\	   
G & 6250   &  1400\\
&&\\ 	   
B & 6500   &   580\\
M & 6500   &  2000\\
&&\\ 	   
G &  6770  &  1900\\
&&\\
\hline
\multicolumn{3}{l}{300 l/mm grating}\\

G  & 4800   &   5700\\
G  & 7050   &  24000\\
G  & 9100   &   3600\\
&&\\
GD7l (White dwarf)    & 5125  & 6800\\
\end{tabular}
\end{table}

\clearpage

\subsection{Flexure Data }
Flexure was measured using cross correlation analysis of arc spectra.
Spectra were recorded at telescope positions separated in H.A. by 1
hour and at declinations +70\degree, +30\degree and -10\degree.
Spectral shifts are given in units of a pixel (22\,$\mu$m) in the
dispersion direction for the equivalent of 1 hour integrations.  The
shifts were found to be smooth and regular.

\begin{table}[h]
\caption{Flexure data}
\begin{tabular}{lrrr}
Declination & 	H.A. start &	H.A. end & Shift\\
+70\degree  &    -5   &   -4   &   -0.074\\
            &    -4   &   -3   &   -0.078\\
            &    -3   &   -2   &   -0.069\\
            &    -2   &   -1   &   -0.062\\
            &    -1   &   0    &   -0.043\\
            &    0    &   +1   &   -0.029\\
            &    +1   &   +2   &   -0.009\\
            &    +2   &   +3   &   0.010\\
            &    +3   &   +4   &   0.021\\
            &    +4   &   +5   &   0.066\\
&&&\\
+30\degree   &   -5   &   -4	&  -0.055\\
             &   -4   &   -3    &  -0.058\\
             &   -3   &   -2    &  -0.058\\
             &   -2   &   -1    &  -0.055\\
             &   -1   &   0     &  -0.037\\
             &   0    &   +1    &  -0.027\\
             &   +1   &   +2    &  -0.017\\
             &   +2   &   +3    &  0.002\\
             &   +3   &   +4    &  0.022\\
             &   +4   &   +5    &  0.039\\
&&&\\

-10\degree   &  -4  &   -3  &   -0.015\\
             &  -3  &   -2  &   -0.018\\
             &  -2  &   -1  &   -0.024\\
	     &	-1  &   0   &   -0.026\\
	     &	0   &	+1  &	-0.049\\
	     &	+1  &	+2  &	-0.019\\
	     &	+2  &	+3  &	-0.024\\
	     &	+3  &	+4  &	-0.019\\

\end{tabular}
\end{table}


\end{document}
