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General statement of research interests
My major interest in astronomy is
the evolution of stars. Although this interest has ranged from
hot blue supergiants, the youngest and brightest stars, to brown
dwarfs and white dwarfs, the common thread has been the use of
high to low resolution spectroscopy (40000 - 2000) and continuum
colours combined with theoretical model atmosphere computations
to obtain reliable temperatures, effective gravities and compositions
for particularly interesting stars. The success of this work has
involved several basic factors -
a) the obtaining of high quality spectroscopic data at the highest resolution possible,
b) the obtaining of continuum colours in spectral regions best suited for different stars,
c) the use of theoretical data within an empirical framework based on fundamental data for the nearby stars,
d) having stimulating colleagues,
students and support staff, in Australia and overseas, with complementary
expertise.
I take a keen interest in instrumentation
and am always seeking to push current instruments to their limits
to obtain answers to astrophysical questions. I have been quick
to expand observational programs to new spectral regions made
accessible by improvements in detector technology, and have encouraged
others to do like-wise. I am one of the few users of all the telescopes
and instruments at MSO and SSO. I have also used the Parkes Telescope
for OH source searches. I have recently become Associate Director,
Facilities with responsibility for the workshops, telescopes
and the CCD program at MSSSO. I also chair the Users' committee,
Faculty and co-chair the Instrument Committee.
The extremely important observational
side of my research has been possible through a combination of
access to the Anglo-Australian Telescope and the range of ANU
telescopes. Being an astronomer at MSSSO with access to a wide
range of our own telescopes and first-rate ancillary equipment
and to design staff and workshops, has, I believe, provided me
with a great advantage compared with most of my overseas competitors.
I have been able to design or modify equipment to provide the
specific measurements needed to explore particular problems and
to obtain sufficient data to tie down uncertainties.The equally
important theoretical side has been greatly assisted by being
able to seek out collaborators from overseas and arrange reciprocal
visits.
In the following pages my research
will be grouped into particular aspects and the highlights will
be briefly discussed. Papers of particular interest are asterisked.
As is evident from my list of publications, I have collaborated
with many people. I enjoy working with other astronomers, particularly
students, involving them in my interests and using my expertise
in photometry, spectroscopy and instrumentation to further their
research interests. It is invariably to our joint benefit. In
joint publications the order of authorship generally reflects
the relative input effort, the exceptions being alternating authors
in some series of papers; and in papers with M.Scholz the authorship
is alphabetical.
Resume of Research Activities
Variable F Stars
My PhD thesis (papers 2,3,4*,5*) involved
the investigation of some Delta Scuti and dwarf Cepheid stars
whose nature was not understood. Previous workers were deriving
cool temperatures and very low masses for these stars and the
pulsation theory appeared unable to explain their properties.
As a result of my work it was shown that their results could be
explained as being due to an incompatibility between the model
temperatures and gravities and the true parameters for some fundamental
stars. This could be overcome by adopting an empirical calibration
for the flux of Vega different from the accepted absolute flux
measurements. More recent and accurate absolute calibrations of
Vega since obtained are very similar to the empirical calibration
that I adopted in 1967. I also made spectroscopic observations
of newly discovered dwarf cepheids (papers 10, 22) and maintained
a continuing involvement with abundance analyses of other F stars
(papers 11, 25). I collaborated with Eggen (paper 15*) on an erratically
variable F star which we found to be a pre-main sequence star
surrounded by an accretion disk. The data and analysis of 1972
compares more than favorably with the extensive observations and
monitoring since carried out at ESO and published in 1989. An
innovative part of this investigation was the simultaneous polarization,
photometric and spectroscopic observations which I organised that
showed the photospheric temperature and gravity of the star remained
constant while the brightness and colour changed by up to 1 magnitude.
The ratio of the polarization and colour during these changes
resembled that of interstellar dust suggesting a dusty disk around
the star. (In my collaborations with Eggen I contributed mainly
through my spectroscopic and instrumental expertise.)
Young blue stars
In 1969 I began investigating the
evolution of the young stars in the Orion nebula and the Scorpius
OB association, topics in which I became interested whilst at
the Yerkes Observatory. Spectra and colours of many stars were
obtained, defining the main sequence and the evolutionary tracks
of the massive supergiants (paper 14 and unpublished). This data
was also compared with theoretical tracks especially computed
by John Robertson for his thesis. The high resolution spectroscopic
work on the Scorpius association proved invaluable in the investigation
of the bright X-ray binary stars in 1973 as I already knew the
properties of young blue supergiants and was able to identify
the bright X-ray binary primaries as such, whereas others groups
initially did not. In 1988 I returned to those young blue stars,
especially those stars in clusters in the Magellanic Clouds and
have obtained very high resolution spectra to derive abundances
and CCD images to derive much more accurate colour-magnitude diagrams
than possible with the photographic data of 1969. I gave three
talks in Europe in 1989 on the abundances of some of these stars
and am currently completing the analysis of the spectroscopic
data. In 1991 I commenced collaborations with Bernhard Wolf and
Bodo Baschek in Heidelberg on the blue supergiants in the Cloud
clusters and the Galaxy. The colour magnitude diagrams of these
young blue stars (M > 10M ) is not in good agreement with
current evolutionary theory and I am currently following up this
investigation observationally and theoretically with Peter Wood
and PhD students Alister Graham and Stefan Keller. Preliminary
work (125*) shows that much greater convective overshoot is required
to explain the temperature and luminosity of massive stars at
the main sequence turn-off and that when this is included the
stars evolve as red supergiants and not blue supergiants. To help
tie down this scenario, HST time was awarded and in May - June
1997 we will obtain UV photometry of the cluster stars that will
enable the temperatures of the turn-off stars to be precisely
derived.
X-ray binaries
During 1973-1974 I collaborated with
Dayal Wickramasinghe and others on a very successful investigation
of X-ray binaries detected from the X-ray satellite UHURU (papers
16*, 17, 18, 20, 21*, 23, 24, 26*). My important contribution
to the collaboration was the photometric and spectroscopic investigation
and interpretation of the primary stars which enabled luminosities,
masses and distances to be derived for the stars. We were the
first to show that the primaries of 2U0900-40 and 2U1700-17 were
genuine massive supergiants and thus put upper limits on the mass
of the X-ray secondary. We also presented strong evidence that
the primary was overfilling its Roche lobe. It took almost two
years before the alternative theories were retracted and our explanations
were accepted. In a significant paper (paper 26*), I devised a
model for gas flow in the 2U0900-40 system from the interpretation
of high dispersion Halpha emission spectra which were obtained
at many different phases of the orbital period. This model has
withstood the test of time and has since been supported by X-ray
and g-ray eclipse data from different equipment in more recent
satellites.
White dwarfs
I have worked on white dwarfs with
Olin Eggen (paper 45*) and Dayal Wickramasinghe (papers 28, 35*,
37, 38, 39, 40, 41, 48, 49, 69, 126*) and Stephane Vennes (137,
138). My collaboration with Eggen involved discovery of white
dwarfs from narrow-band photometry of stars in the south galactic
cap and subsequent derivation of their distances and space density.
This work was important for determining the contribution of the
hot degenerate stars to the local mass density. It also raised
my interest in the unusual stars found in the galactic halo.
The work with Wickramasinghe and collaborators comprised a wide-ranging
investigation of southern white dwarfs, highlighted by the establishing
of the difference between cool white dwarfs (degenerate stars)
and cool subdwarfs (very metal-deficient KM dwarfs), and the consequent
demonstration that there was not a large number of intrinsically
faint white dwarfs that could explain the "missing mass".
This work also led to the discovery of the missing low-metal abundance
KM dwarfs (papers 47* and 58*) and stimulated my continuing interest
in M dwarfs, brown dwarfs and the question of the missing mass.
I also prepared a review paper on white dwarfs for the ASA (paper
42). In our white dwarf collaboration, Dayal initiated the discovery
programs and introduced me to model atmosphere computations. We
made very significant contributions to white dwarf research during
this productive collaborative period using the recently acquired
IDS and IPCS detectors on the AAT to great effect. The quality
of the reduced spectra that we obtained for faint stars enabled
us to show the interpretation of previous image tube and photographic
spectra were misleading and that almost all the stars classified
as cool white dwarfs were in fact old main-sequence stars. More
recently, I participated in a collaboration initiated by Ken Freeman
and Joe Silk to search for halo white dwarfs in SGP fields to
see whether they could explain some of the halo "missing"
mass and with Stephane Vennes (University of California) and Dayal
Wickramasinghe to identify and follow-up white dwarf discoveries
from the EUV satellite. In addition in a new UK-South Africa-Australian
collaboration with Bob Stobie and Darragh O'Donaghue I am using
the 2.3m telescope to obtain spectra of the objects fainter than
16.5 in the Edinburgh-Cape UV survey. Many new white dwarfs and
quasars have been discovered.
Halo stars
I have worked with John Norris and
collaborators on many aspects of halo K giants. We have worked
on the colour magnitude diagrams of Globular clusters (papers
27*, 32, 34, 44, 55), photometric abundances of field stars (paper
77) and the abundances of individual halo stars (papers 54, 59,
63*, 74*, 88, 109*, 115*). Highlights of this collaboration have
been the discovery of K giants with halo abundances but disk kinematics,
a discovery that effectively modified the classic theory of galactic
collapse of Eggen, Lynden-Bell and Sandage (paper 77*); the analysis
of CD-38 5 the most metal-deficient star ever found (papers 36,
74*); the derivation of Beryllium abundances in extremely metal-deficient
stars and an improvement in the detection limit of Be by an order
of magnitude which essentially rules out an inhomogeneous Big-Bang
(papers 109*, 117*); and an investigation of nucleosynthesis from
subdwarfs with metallicities between -2 and -4 dex (paper 115*).
Photometric Systems
A major component of my work has been
the use of photometry to measure temperatures, luminosities and
abundances for stars. More than half my papers in the past have
had an important component of photometry in them. It is usual
to measure colours and magnitudes for stars within a standard
photometric system, thus enabling data measured by observers at
different sites in the two hemispheres to be intercompared. Unfortunately,
there are many different versions of photometric systems with
different internal precision and whilst at KPNO in 1979 I became
aware of the large differences between these data sets which made
it very difficult to obtain accurate colours and hence temperatures
for stars. I set out to analyse these data from the different
systems with a view to establishing the best systems and to define
the transformations between systems so that one could make use
of the variety of published data. It was also clear that it was
very important to establish the passbands of the different systems
so that colours could be calculated for theoretical model atmosphere
spectra and observed spectra so that observed colours could be
properly calibrated in terms of temperature, metallicity, effective
gravity, reddening and so forth.
In a continuing series of papers (papers
31, 33, 46, 50*, 61, 81, 87, 90, 93*, 100*, 106*, 107, 108, 110*,
122, 124, 130, 131, 134, 135) I examined broad-band photometric
systems, established their passbands and absolute calibration,
and have made a major contribution to the understanding of the
colours of stars and to the precision of broad band astronomical
photometry. This work, although it started as an ancillary to
my other research, has apparently attracted the bulk of my citations,
and paper 50* has been noted as a citation classic for the Proceedings
of the Astronomical Society of the Pacific. My leadership in this
field has led to use of my work in the reference series of Landolt-Börnstein
on photometry and invitations to write an article on standard
system photometry for the Reference Encyclopedia of Astronomy
and Astrophysics and present the principal review at the IAU Colloquium
on Photometry and Standard Systems in Dublin and the Cousins Colloquium
in Capetown.
To a large extent photoelectric photometry
has been superseded by CCD photometry in the last few years and
I have made important contributions by devising glass filter combinations
which enable good standardized photometry to be obtained with
different CCD systems (130, 131, 135). I continually liaise with
other Observatories to ensure that we use the same passbands and
standard stars for this work. My filters are now in use at ESO,
KPNO and SAAO and it is hoped that Landolt who has now adopted
my filters will agree to transform his photometry onto the precise
Cousins UBVRI system that I have widely and actively supported.
The recently devised CCD filters that I developed with the 2.3m
imager will be used at Sutherland in South Africa to establish
new CCD standards.
Red giants
Another very profitable collaborative
project has been a study of Magellanic Cloud carbon stars and
red-variable stars with Peter Wood and other collaborators (papers
52, 53, 60, 64, 65, 66*, 67*, 68*, 70, 71, 75, 78, 80, 83, 86,
91). This research gained its impetus from the excellent photographic
I plates of the UK Schmidt and capitalized on the efficient red
IDS and CCD spectroscopy and IR photometry at the AAT. I had previously
been interested in carbon stars (paper 13*) but Peter's expertise
in mira variables provided the major stimulus to this project.
Highlights of this work include the delineation of the red carbon
stars as asymptotic giant branch (AGB) stars undergoing dredge-up
(paper 66*), the discovery for the first time of AGB stars with
core masses up to the supernovae limit (paper 68*) and the discovery
of young super-metal-rich M supergiants in the galactic bulge
(paper 67*). We are currently collaborating on the colour-magnitude
diagrams of Magellanic Cloud clusters containing red supergiants
and metal-rich galactic centre globular clusters.
Model atmospheres of red giants
In order to determine the temperatures
of the red giants and red supergiants we needed model atmospheres
and sought collaboration from a theoretical group at the University
of Heidelberg. The continuing collaboration with Michael Scholz
(Heidelberg), John Brett (MSSSO PhD thesis, Uppsala) and Peter
Wood has been very fruitful (papers 82, 92, 98*, 99*, 101, 103,
112*, 136) and has provided explanations for the IR colours of
M giants and miras and an understanding of many outstanding problems
concerning mira variables. It has made a major impact on the interpretation
of the IR colours of external galaxies and the evolution of AGB
stars. We are looking forward to comparing the monochromatic radii
measured for mira and other extended cool giants with the new
generation Michelson interferometers and those predicted with
our model atmospheres.
Red dwarfs
The white dwarf searches with Dayal
Wickramasinghe on the faint high proper motion stars yielded few
cool white dwarfs. Follow up work at the AAT, and at the Steward
Observatory with Jim Liebert during 1979, showed these stars to
be exotic M subdwarfs (paper 58*) and very cool M dwarfs. Two
of these stars LHS 2397a and LHS 2065 now have USNO parallaxes,
placing them amongst the faintest 4 stars. In paper 111*, "The
Late M Dwarfs" I have defined the properties (colours, luminosities
and spectral-types) of the reddest dwarfs. This has enabled a
comparison to be made between the observed colour-magnitude diagram
of the late-M dwarfs and evolutionary tracks of low-mass stars
in an investigation of the existence of brown dwarfs and the possibility
that part of the missing mass is in the form of such low mass
stars.
Collaboration with Mike Hawkins (ROE)
(paper 94*) produced an exhaustive analysis of the luminosity
function for low-mass stars from UK Schmidt plates and suggested
that there were more low mass stars than hitherto thought. The
luminosity function appeared to be flattening at the lowest luminosity
rather than turning over, and if this continued to even fainter
luminosities, the local missing mass could be explained. We are
endeavoring to find even fainter stars using such techniques,
but the observational difficulties are severe. I co-authored a
review (paper 123*) with Guy Stringfellow for Annual Review of
Astronomy and Astrophysics on the luminosity function at low luminosities.
In this review the case is put that star counts do not support
a turnup in the numbers of old disk low mass stars at very low
luminosities that could support a large population of missing
mass. They do suggest however, that the theoretical mass-luminosity
relation for low mass stars is in need of revision and that brown
dwarfs should be very cool and found fainter than Mbol ~ 19.
Unpublished work in collaboration
with Guy Stringfellow (formerly MSSSO) and Michael Burton (U of
NSW) is a search for faint red stars in nearby young clusters
using deep I CCD and mosaiced K images taken with IRIS on the
AAT.
I have been collaborating with Phil
Ianna (U of Virginia) on a parallax program in the southern hemisphere
to determine parallaxes for white dwarfs and, more recently, M
dwarfs. Many of these objects have been found in searches with
which I have been involved. We have published joint papers on
particular objects (papers 43, 84). In the last three years we
have commenced CCD parallax observations at the 1m telescope
of red dwarfs and in 1990 Ianna measured the parallax of the faintest
of the Hawkins and Bessell stars (M18) and found it to be the
faintest M dwarf then found.
I have also been involved in model
atmosphere computations for M dwarfs with Ruan Kui (MSSSO PhD
thesis) and Rainer Wehrse (University of Heidelberg). This work
aimed to use the model atmospheres to derive the temperatures
and abundances of M dwarfs and subdwarfs. Much of this work uses
opacities generated for the red giant program but the atmosphere
calculations were quite independent. The agreement between models
and stars was excellent for temperatures hotter than 3000K but
for cooler temperatures, the temperature structure of the models
deviated significantly from that of the cool M dwarfs. We considered
it possible that this resulted from the use of the mixing length
theory of convection but it seems likely now that better treatment
of H2O opacity and the inclusion of opacity due to grains will
resolve the problem. We also showed that Kapteyn star, the bright
M subdwarf, had a metallicity of about -0.7 dex while the abundance
of VB 12, the faint M subdwarf companion of HD219617, a bright
G subdwarf, was -1.5 dex. Unexpectedly, Kapteyn star has a higher
abundance than other members of the eponymous group. John Brett
has recently produced better atmospheres for M dwarfs using the
new statistical line opacity model atmosphere programs developed
by Plez, Brett and others at Uppsala. The fluxes from these models
fit the spectra very well; however, there is still a problem associated
with models with effective temperatures below 2600K due to the
poorly handled opacity of the H2O. Bertrand Plez is still working
on this problem and expects that new line lists for water will
soon be available.
Abundance analyses
Abundance analyses have been an important
part of my research (papers 11, 25, 36*, 51, 54, 59, 62*, 73,
74*, 88, 97, 104*, 109*, 114, 115*, 116*, 119, 120). Part of it
has been outlined above in the halo star research. My thesis work
involved the derivation of abundances for the variable F stars
from photographic coudé spectra. The advent of image tubes,
photon-counting detectors and the 3.9m AAT stimulated work on
faint stars, and my sabbatical stay at KPNO enabled me to use
and bring back the fine-analysis program WIDTH6 (Kurucz) which
enabled me to investigate a wide range of stars with confidence.
Peter Cottrell (MSSSO PhD thesis) developed a spectrum synthesis
program which we have used with great success to investigate molecular
features due to CH, NH and OH in K giants and dwarfs.The fine-analysis
abundance work that I have been involved with has made major contributions
to our understanding of stellar abundances for a variety of stars
and systems. An analysis of the line strengths in three K giants
in the late-type globular clusters 47 Tuc and M71 (paper 62*)
showed the clusters to be significantly more metal-rich than indicated
by previously published fine-analyses. The incorrect low abundances
were in serious disagreement with estimates of metallicity from
colours and caused much controversy at the time regarding the
efficacy of colour analyses and the reliability of echelle spectroscopy.
I offered an explanation for the low abundance derivations by
other authors.
The analysis of CD-38 5 (paper 74*)
showed it to be the most metal-deficient star ever found; at the
time its abundance was 100 times lower than the previous lowest
abundance star. CD-38 5 remains the most deficient star and the
relative abundance of the heavy elements places important limits
on theories of galactic chemical enrichment. Recent echelle spectra
of CD-38 5 have enabled the derivation of FeI and FeII abundances
for the first time. These abundances differed by 0.5 dex, a very
large discrepancy, which has been explained (unpublished) in collaboration
with Holweger and Steenbock in Kiel as being due to non-LTE phenomena.
Analyses of other halo stars (paper
102, 115* and 116*) have shown oxygen enhancements (relative to
Fe) in halo stars of a factor of 8. In the important paper (116*)
the abundance of oxygen in halo dwarfs was derived from the ultra-violet
OH lines, a technique used by no-one else in the world at that
time, and one which enabled us to work with cool giant stars of
100 times lower abundance. Oxygen abundances were derived for
K subdwarfs which were up to 0.5 dex lower than those derived
from the high excitation far-red OI lines the technique normally
used. We argued convincingly that the lower abundances are the
correct ones and that the model atmospheres of metal-poor K dwarfs
must be much hotter in the deeper layers than the actual stars,
resulting in the erroneously derived abundances from high excitation
lines. Oxygen was then shown to behave like other a-elements in
metal-poor stars removing a large uncertainty in the ages and
evolution of halo stars. The pioneering high resolution observations
that I made down to the ultra-violet cut-off in the Earth's atmosphere
also showed that the Be lines could be reasonably measured from
the ground and subsequent analysis of the Be lines in very metal-deficient
K dwarfs (paper 109*, 117*) have placed very stringent limits
on the non-uniformities of the Big-Bang. We plan new observations
of even more metal-poor stars that could rule out non-uniformities
completely but this work awaits the provision of detectors with
higher sensitivity in the UV.
Stephen Russell (MSSSO PhD thesis)
and I (papers 89, 97, 104*) analysed several F supergiants in
the Magellanic Clouds and derived abundances of -0.65 dex and
-0.30 dex for the Small and Large Cloud respectively. This work
was a definitive result for the Clouds. Extending this work, I
have obtained coudé échelle spectra of B stars and
K stars in young clusters in the Clouds and preliminary analysis
(unpublished but presented at several conferences) indicates similar
abundances for these stars. This result was significantly different
to that derived by other observers for an SMC cluster NGC 330,
and part of the explanation appears to be that the cluster NGC
330 suffers considerably more foreground reddening than hitherto
accepted. A reanalysis of Cloud reddenings (papers 113* and 114)
ensued. Stars in one of the Large Cloud clusters NGC 1818 appear
to have abundances midway between the values of the two Clouds.
Work is continuing in collaboration with Observatoire de Paris
astronomers.
As part of the work involving K giants
in the Clouds, abundances were derived from AAT coudé echelle
CCD spectra of galactic K giants and supergiants. These analyses
indicated that there were several problems associated with the
existing model atmospheres of K stars which can result in systematically
different abundances being derived. It appears that the temperature
structure of the model atmospheres of G and K stars is different
from that of the actual stars, probably due to insufficient line
blanketing. This affects the analyses in two ways; firstly, for
solar composition stars it is necessary to adopt a temperature
scale hotter than indicated by empirical temperature scales and
secondly, gf values should be derived from a K giant model rather
than a solar model. The neglect of these procedures results in
systematically too low abundances being derived. Preliminary results
(119, 120) have been published but final results are now in preparation
following a recent important breakthrough. In 1993 I approached
Bertrand Plez for model atmospheres for K giants and supergiants
from the NMARCS grid computed using statistical line opacities
for atomic and molecular lines. These models differed sufficiently
from those in the old MARCS grid for stars cooler than 4400K to
enable the empirical temperature scale to be used. Using the NMARCS
models I can now derive abundances for the cool stars in M67 that
agree with the hotter stars when using the Ridgeway temperature
scale. I will publish the M67 results with Plez soon. These
models have also been used by Vanessa Hill (Meudon) for some beautiful
work on K supergiants in the Clouds.
Another aspect of this work has been
the analysis of K giants in the strong-line globular clusters.
Several stars have been analysed so far and observations are being
sought for some field stars in the bulge. The highest abundance
cluster was found to be NGC 6528 which gave an Fe abundance only
0.1 dex below solar. This value is important in calibrating the
low dispersion abundance scale of the globular clusters and
elliptical galaxies. I have been collaborating with Elaine Sadler
(U of Sydney) and David Pfitzner to follow up and continue this
work with a wider range of bulge field stars. Preliminary analyses
for some elements indicates that some of the bulge stars are up
to +0.3 dex higher than the sun in Fe abundance and we are in
agreement with the revised Rich results.
Interferometer photometry
I was involved in a collaborative
program of speckle photometry of miras, planetary nebulae and
SN1987a (papers 79, 85, 105). My contribution was solely as an
instrumentalist and facilitator. The important data reduction
and analyses were done by Wood and others. I was discussing collaboration
with the Russian astronomers on the Crimean 6m telescope to obtain
speckle data for mira variables, and have had discussions with
Gordon Robertson on interpretation of aperture mask interferometry
of red giants with the AAT. I made lunar occultation CCD spectroscopic
observations of Alpha Sco on the AAT with Schmidtke (Arizona State).
Instrumental
At the Yerkes Observatory in 1967
I was involved in the commissioning of a new 40-inch telescope
and its spectrograph. I developed interests in photographic photometry
and hypersensitizing techniques (paper 6), very high resolution
spectroscopy and spectrograph design.
My interest in high dispersion spectroscopy
initiated the construction of an échelle spectrograph at
the coudé focus of the MSSSO 74 inch telescope. A PhD student,
Harvey Butcher, and I designed and built a temporary wooden construction
which was used for several years enabling the observations for
a PhD thesis to be made; it has now been replaced with a refined
metal construction. In the near future I would like to proceed
with a very efficient white pupil design coude echelle spectrograph
for the 74 inch MSO. The success of the early échelle spectrograph
led to the provision of a cassegrain échelle spectrograph
for the 1m and 2.3m telescopes at SSO and ultimately to the installation
of the magnificent coudé échelle spectrograph at
the AAT. I was involved in early meetings in the UK discussing
the specifications of this spectrograph for the AAT and was invited
to the ESO workshop on High Resolution Spectroscopy for the Very
Large Telescope Project. I was one of the commissioning astronomers
for the RGO spectrograph on the AAT. I was also involved with
Peter Gillingham in discussions concerning the provision of a
coude feed for the AAT.
I was an original member of the Observatories Instrument Committee from 1974 to 1979 and rejoined the Instrument Committee in 1986. At the end of 1993 I was appointed Associate Director of MSSSO with responsibilities for the workshops, telescopes and associated instrumentation. I co-chair the Observatories Instrument Committee with the Director.
As a regular user of most telescopes, I have adopted responsibilities for the overseeing of the standards of operation of the older telescopes and domes at SSO, and have proffered many improvements to existing spectroscopic and photometric instrumentation. I take a continuing interest in all our spectroscopic instruments and have written user manuals for some of them and designed modifications permitting the use of CCD detectors. I was responsible for photographic plate provision and sensitizing. I have taken a major interest in photoelectric detectors and equipment, and pioneered and encouraged the use of new red sensitive photoelectric detectors. Extensive tests carried out with glass filter combination and the new detectors enabled duplication of existing photometric systems. The published successful combinations have become the standard filters in use at most observatories throughout the world. The use of CCDs within existing photometric systems or the design of new standard systems is an increasingly important aspect of photometry and the IAU Colloquium in Dublin tackled these questions. The South African astronomers at Sutherland have agreed to use the new filters I have recently designed to establish new CCD standards for the south.
With personnel from the design office
and electronics section at MSO I designed and had built a two-channel
star-sky chopping computer controlled photometer and single channel
computer controlled photometer for photoelectric photometry. These
instruments have been widely used for faint star photometry on
the 1m and 2.3m telescopes. I was also involved with the early
design stages of the imager-spectrograph for the 2.3m telescope
and pushed strongly for the construction of an instrument similar
to ESO's EFOSC. I designed a suite of grisms that are being made
for the imager.
Over the last 5 years I have been
the astronomer responsible for the CCD program at MSSSO. During
this time I worked solidly at building up the knowledge, expertise
and confidence of the technical staff responsible for the day-to-day
running of the program and at building a team of people who carry
the responsibility for the future directions of the program. I
think that this has been a very successful exercise and the CCD
program at MSSSO is now in excellent shape and ready to tackle
the next generation of CCD controllers and CCDs. Peter Conroy
and I designed and had built a test rig for performance evaluation
and electronic adjustment of CCDs.
Most recently, I initiated the installation
of a wide-field imaging facility at the 16 inch telescope. There
was a clear need for quantitative imaging of the sky over wide
fields of 7 to 35 degrees for a variety of programs from cosmology
to radio-source identification. We installed a 400 mm lens in
front of a 2Kx2K CCD and using glass filters and interference
filters have taken 7 degree images of the LMC and SMC in H alpha,
[SII], [OIII] and continuum. These are being used for comparison
with the Australia Telescope HI images of the Clouds. Anne Green
(University of Sydney), Michelle Buxton and I have now commenced
a survey of the complete galactic plane in H alpha (and as many
other filters as possible) for comparison with the Molonglo Radio
Interferometer high resolution maps. We have the dedicated use
of this instrument and expect to complete the survey within 18
months.
Related areas in education and outreach
I have always maintained an interest in community education especially in the field of astronomy. I was very actively involved in the writing and design of the Astronomy exhibition at Siding Spring and initiated the astronomy program for the Centre for Continuing Education. I have been on the Accreditation Panel for Astronomy in ACT Colleges since its inception and am the current chair; I have spoken several times to science teachers' conventions and advised individual schools concerning the content of their courses. I have arranged the supervision of work-experience students and arranged mentor programs with two of our female PhD students. I have been chairman of the Duffy Primary School Board and I conducted a fortnightly talk-back radio program on astronomy.
I have also been responsible for obtrusive lighting codes and community lighting education since becoming associate director. I organised a visit by David Crawford to Australia and talks by him to lighting people in Coonabarabran, Canberra and Sydney. I have regular contact with local and state government officials on good lighting practice.
I have a continuing involvement with amateur astronomy groups in Australia, New Zealand and Malaysia offering advice and assistance with standardized photoelectric and CCD photometry.