Introduction

Foreword

I chose this title to remind the jaded astronomers amongst us of the major reason why we chose astronomy as a career. It also explains why there are so many dedicated amateur astronomers and why the general public readily supports astronomy. Astronomy, combining beauty with mystery and wonder, remains a formidable combination of attractions for the minds of students and others with a restless intellect.

To a few theoreticians, E=mc2 represents the highest form of beauty, but most of us are visual people stimulated more by pictures than equations. I well remember as a student attending Bart Bok's public lectures in Hobart and participating in his evocation of the wonders of Astronomy through his black and white slides of the star-forming regions in Norma, Carina and the Magellanic Clouds. This was for me, I thought.

In the current world many of the best students are turning to economics and law and many students are more attracted to astrology and creationism than to mainstream science. In addition within some of the liberal arts disciplines there has been an increasing attack on the scientific method and the absolutism of science. It is therefore essential for the 'hard scientists', especially the physical scientists, to speak out in support of the scientific method of determining the truth in the physical world and to challenge the pessimistic outlook of the Jeremiahs in the community with the optimism from scientific discoveries both on Earth and elsewhere.

Part of this fight-back is not only to attract some of the best students back into mainstream science but to educate all students and the general public about the importance of the scientific method and the importance of scientific research. A public better educated on these matters is more likely to result in governments that make well informed decisions and which will fund research and education adequately for the betterment of future generations.

School teachers, university lecturers and the media all have an important part to play in this and to assist them it is essential to provide a wide range of visual stimuli that can attract attention, maintain interest and affect the emotions. The coloured images from Mt Wilson, NASA, the AAO and more recently the HST are excellent resources but in this day of visual overload it is important to provide many new images of high impact that can be used for many different purposes and to provide these on a continuing basis.

Stimulus and Opportunities

In this presentation I would like to show some of the results from imaging projects that I have been involved with at SSO using modest optics but with a large science grade CCD. I hope that this will encourage some of you to experiment with your own images and to utilize all these images that have been produced in your lectures and presentations.

The processing into colour images is the most time consuming and in many ways the most difficult step, albeit the most rewarding. The most exciting moment is the instant three different black and white images combine to produce colour. There are invariably surprises, as, unlike earthly scenes of mountains, streams, skies and people that we see every day, we often have no idea of what colours or distribution of colours will appear in an astronomical image. I believe that maximum impact of an image requires the skills of a graphic designer/artist and an astronomer. There are few people born with these skills but it raises the possibility of collaborations. I can see many possible projects involving astronomers and creative artists and more specifically graphic design students and even a major project for producing an interactive CDROM of the survey images.

Finally I hope that it will encourage amateur astronomers and teachers from schools with access to the new low and medium cost CCD systems to take on the challenging but very rewarding and creative astronomical colour imaging projects.

The Many Uses of Colour

There are many ways in which the use of colour enhances the information in an astronomical image. Although normal broad-band blue-green-red images approximating the eye's response can be used to illustrate many topics in astrophysics, it is the use of narrow-band images that provide, more specific astrophysical information, particular that involving the gas and dust in the interstellar medium. It is also the transformation of images made in passbands in the UV, IR or radio into optical colours that enhances our insights into astrophysical properties or highlights the unusual object. Such a technique has wide spread applications one of which is to illustrate the photometric redshifts of distant galaxies. We also nowadays often make use of false-colour images to record intensity differences in an image made with a single passband. Colour is therefore the best way to present most data but its use has been inhibited in the past by the expense of colour reproduction in the main science journals. However, with more and more electronic journals being produced, the provision of coloured JPG files should not be an added expense. David Malin (eg. Malin 1992) has pioneered the use of colour in astronomical imaging and you are refered to the AAO images page (http://www.aao.gov.au/images.html) for his suite of images derived from photographic plates and film, images that inspired the CCD work reported here.

The Wide-Field Imaging Project

I had been experimenting at the 16 inch telescope with the 2.3m quartz optics reimaging camera and a 1K CCD to provide UBVI and $H\alpha$ images of the Magellanic Clouds. But because the scale was a little low and access to the imager camera was uncertain, John Hart suggested I try out a commercial Nikon telephoto lens bought many years earlier for an unsuccessful image tube project. The results were excellent. So, when Anne Green and Lawrence Cram made a request for $H\alpha$ images for comparison with their Molonglo Radio Surveys of the galactic plane (Green et al. 1999; http://www.astrop.physics.usyd.edu.au/MGPS/) we decided that this was the appropriate setup. Funds were provided from Sydney University and the IAS for a collaborative WFI project and a computer and data drive were purchased. A mechanical lens mount, filter holders and CCD mounting brackets were made and the Nikon imager providing a 6.8 degree field on a 2K CCD was installed on the 16 inch telescope mount in place of the existing telescope tube. Dome flat field screens and lamps were also provided. For the first year we used a CCD controller, computer and 2K CCD borrowed from the other SSO and MSO telescopes when they were unscheduled but recently have obtained a dedicated 2K CCD and controller for the project. More details of the $H\alpha$ survey can be found on http://www.mso.anu.edu.au/ $\sim$ buxton/halpha.html

We have also borrowed a Hasselblad lens from another ANU Department and made a new mounting so that we can image over 30 degrees of sky with a single exposure. We have also used the 40 inch telescope to obtain images at higher resolution of smaller objects, especially galaxies outside the local group.

In Table 1 are given the mountings, cameras, image scales and field sizes.

Table 1. Camera Focal Lengths and Fields

Name	Focal length	F no.	Aperture	Scale	Field
Hasselblad	80mm	2.8	60mm	60 arcsec	30 deg Nikon

Acknowledgements

Major contributors to the project have been Michelle Buxton (MSSSO) and Bob Watson (University of Tasmania). They did many of the initial observations and Bob developed all the IRAF scripts for the data processing. Other students from the Universities of Sydney, NSW and Wollongong have contributed to the observing together with a team of amateurs from Coonabarabran organised by John Shobbrook who also wrote the observing manual. In 1999 Paul Price took over the $H\alpha$ survey as an honours project and Newcastle amateur Ken Hargreaves has done much observing. Ralph Sutherland (MSSSO) has been indispensable for his instructions on the use of Adobe Photoshop and his inspired image processing. The workshop staffs at SSO and MSO have been very supportive of the project both in its construction and operation. Hwankyung Sung provided many of the 40 inch images from his work on young star forming regions.

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