Research Interests and History: : Michael Stanley BESSELL

Post: Professor in Astronomy, Associate Director MSSSO

Research School/Faculty: Mount Stromlo and Siding Spring Observatories

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).


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.