Despite the ease with which excellent planetary images can now be obtained, planetary imagers are rather thin on the ground among the population. Across the world there are only a few dozen regular planetary imagers whose results are good enough to be used by professional astronomers. Undoubtedly the main reason for this is simply the rarity of good, stable, atmospheric seeing coupled with clear skies, along with the dedication and knowledge required to get world-class results. However, a few amateurs do persevere and it can be fascinating to study their methods. The world's most experienced planetary imager is Donald Parker of Coral Gables, Florida. Don goes right back to the days of planetary photography, and his photographs of Mars, Jupiter, and Saturn were, for many years, in a league of their own. To get some idea of what results were attainable by amateurs using film in the 1980s, check out the Parker-Dobbins-Capen book Observing and Photographing the Solar System published by Willmann-Bell in 1988.
Parker's original photographic telescope was a 32-cm f/6.5 Newtonian, but his main instrument for many years has been a massive 40-cm f/6 Newtonian, shown in Figure 4.1. However, he has also used a 40-cm f/10 Meade LX200 (later mounted on a Paramount mounting) and a 25-cm Takahashi Mewlon is used on nights where the 40-cm's aperture and potential resolution is not required. Don Parker's Coral Gables location near Miami, Florida, must be a big advantage. Florida is a humid area of the southeastern U.S., not far from the Caribbean; the area is renowned for good stable seeing, especially at sites near the sea, where a laminar air flow can prevail. One renowned telescope and eyepiece manufacturer once stated that seeing in the Florida Keys was so good that he did not need a laboratory with an artificial star to test his equipment. Also, at 26° north, the planets can attain altitudes that some of us (me included) can only dream about. At their highest declinations, Mars, Jupiter, and Saturn pass virtually overhead. Of course, there is the downside of a regular battering from hurricanes! Although Parker's Florida
location and latitude (as well as his colossal dedication) placed him in a different league from other amateurs in the 1980s, the CCD and webcam era has eroded that advantage somewhat. Poor seeing (prevalent at most locations and when planets are low down) was an inpenetrable barrier in the era of planetary photography, but webcams, and their ability to freeze the seeing, have significantly reduced that advantage. The effects of atmospheric dispersion can be digitally reduced by realigning the color layers too. Nowadays, Parker uses his large-aperture Newtonian to give him better signal-to-noise images than the competition. Using just a single Barlow lens at f/6, to give an f/14 focal ratio with his 40-cm instrument, Parker's system gives a fairly modest focal length of 5,600 mm when used with a ToUcam Pro. In the last year he has started using an ATiK color webcam with 7.4 micron pixels at f/22, giving an image scale of 0.17 arc-seconds per pixel.
In the late 1980s, Japanese amateur Isao Miyazaki produced planetary photographs to equal Don Parker's best, using a truly massive and professional quality 40-cm f/6 Newtonian housed on the roof of his apartment block on the island of Okinawa. Miyazaki arrived on the scene at the same time that ultrafine-grain Kodak 2415 film helped improve image quality. Okinawa is at latitude 27° north. Miyazaki's Newtonian is now housed in a dome on top of his Okinawa house, as shown in Figure 4.2.
In the late 1990s two amateur CCD imagers raised the bar to an unprecedented level. Frenchman Thierry Legault, using a 30-cm Meade LX200 and a Hi-Sis 22 CCD camera, achieved astonishing results and was, perhaps, the first of the modern imagers to truly appreciate all of the factors involved. Perfection in the fields of telescope collimation, focusing, stacking dozens of images, and image processing were
his hallmark. His images, revealing Saturn's Encke division, astounded both amateur and professional observers.
As the 20th century came to a close another world-class imager emerged from a most unlikely location: Damian Peach from the U.K. (Figure 4.3). Although U.K. seeing is probably no worse than for most other locations in the world, the southern U.K. is at 50-52 degrees north and the vast majority of nights are cloudy. However, at the turn of the 21st century, both Jupiter and Saturn were at a very high northerly declination and Damian took full advantage of the new CCD technology and techniques from his seventh storey apartment location in Norfolk. After moving briefly to Kent, Damian decided that he just had to leave the U.K.'s cloudy skies behind and, in 2002, he briefly moved to Tenerife so that Jupiter and Saturn would be almost overhead. Damian switched from using a 30-cm LX200 to a 28-cm Celestron 11 at this time and the results Damian obtained in 2002 and 2003 raised the standards even higher than those set by his predecessors.
Moreover, his wealth of experience, from observing virtually every clear night, in the U.K. and in Tenerife, revealed some interesting information. For a start, Damian concluded that Tenerife was far from ideal in respect of atmospheric seeing. Indeed, he experienced a few nights when the planets were unbelievably blurred, mainly when he was on the leeward side of Mount Teide and turbulent air rolled down his side of the mountain. Tenerife was definitely a superior site, but largely from the point of view of the number of clear nights and the altitude of the planets and not from vastly superior seeing. The other huge advantage of course was in the comfort of the night time observing temperatures, a far cry from the subzero icy winter misery Damian was used to suffering from in the U.K. Damian has achieved extraordinary success with Celestron 11 and Celestron 9.25 Schmidt-Cassegrains and in many ways is the successor to the U.K.'s Terry Platt, who pioneered U.K. CCD imaging with his company, Starlight Xpress. Before Terry, the legendary mirror-maker and planet-imager Horace Dall was the U.K.'s top planetary photographer. Amazingly, two of the world's finest planetary imagers now live within a mile of each other near Loudwater in the U.K., as Dave Tyler (Figure 4.4), now the proud owner of Damian's original Celestron 11, is also producing fantastic planetary images.
Two amateur astronomers based in the Far East, who specialized in planetary imaging, also emerged around this time. Eric Ng of Hong Kong and Tan Wei Leong of Singapore both observed from high-rise apartment buildings using relatively modest equipment. Tan Wei Leong was obtaining excellent images with a
Celestron 11 before he switched to an equally superb Takahashi Mewlon 250. He also used a 40-cm Cassegrain reflector at Singapore Observatory during the Mars opposition of 2003.
Eric Ng (Figure 4.5) uses simple 25- and 32-cm f/6 Newtonian reflectors to achieve his stunning results. His reflectors employ mirrors by the U.S. optical worker William Royce, an astronomical mirror-maker of high renown.
Ed Grafton, of Houston, Texas, (Figure 4.6) has been one of the world's leading planetary imagers for many years, although he has largely resisted the webcam revolution, preferring to concentrate on using his SBIG ST5c CCD camera. In excellent seeing the advantage of a webcam is largely negated as its main strength is in its ability to take thousands of frames, such that a fraction of the frames will be good enough to stack up to produce a less noisy composite. If your telescope was in space, like the Hubble space telescope, a single image would be enough and it would be a true snapshot of the planet in time (rather than a composite over several minutes). Astronomical CCD cameras are, generally, more quantum efficient than webcams and their capability for longer exposures, plus their cooler temperatures means that individual frames are much less noisy. Thus, a good image from a cooled CCD camera may consist of a few dozen or a hundred frames, rather than hundreds and thousands of frames. This has been Ed Grafton's approach with his Celestron 14 and the technique has worked well. Like Don Parker, 1,000 miles to the east, Ed is situated in the southern U.S. At latitude 30° north, the planets usually transit at a very respectable altitude.
Christophe Pellier (Figure 4.7) is another amateur worthy of a mention. Observing from France, Christophe has obtained exquisite planetary images with surprisingly
small apertures, including a 180-mm aperture Newtonian. His fellow countryman, Bruno Daversin, has adopted the opposite approach, using a massive 60-cm Cassegrain at the Ludiver facility (L'Observatoire Planetarium du Cap de la Hague) to obtain the sharpest lunar images ever obtained from Earth. In passing, it is worth mentioning that France seems to have had a substantial number of top planetary observers over the years, even if not all of them were actually French by birth. In the photographic era, Professor Jean Dragesco dominated the scene and produced an excellent book in 1995 entitled High Resolution Astrophotography. Dragesco observed from a number of excellent sites during his astrophotographic career, but has now retired in southern France. Another French astrophotography legend of the 1970s and 80s was Christian Arsidi, who obtained excellent lunar results using a 250-mm Takahashi Mewlon Dall-Kirkham Cassegrain and a 310-mm Cassegrain. In the 1980s and 90s, another Parisborn amateur, Gerard Therin astounded amateur astronomers with his remarkable lunar pictures taken with a 203-mm Celestron Schmidt-Cassegrain. For a time, Arsidi and Therin collaborated. Finally, Georges Viscardy (who this author visited in 1989) built an impressive observatory in the hills north of Nice featuring a massive 51-cm Cassegrain and a 30-cm f/7 Newtonian. Viscardy published a truly massive photographic lunar atlas during the 1980s, which was of the highest photographic quality.
Just before the webcam era, another Florida amateur, Maurizio Di Sciullo, using a superb 25-cm f/8 Newtonian, became renowned for routinely imaging details on the Jovian satellites! I remember the first time I saw one of his Jupiter images, showing markings on the satellites Ganymede. I was astounded. Maurizio used a monochrome Starlight Xpress CCD camera plus a filter wheel for his images. Figure 4.8 shows Maurizio's excellent 250mm f/8 Newtonian. Maurizio raised the bar to unprecedented levels as the 20th century came to a close.
In the webcam era more planetary imagers have emerged, but the highest quality imagers are as rare as ever. In Portugal, Antonio Cidadao specializes in filtered planetary imaging, such as methane band images of Jupiter. Such work benefits from large apertures and Antonio uses a 35-cm LX200 Schmidt-Cassegrain. In Italy, Paolo Lazzarotti has obtained many exquisite lunar and planetary images and in Spain, Jesus Sanchez has been that country's top planetary imager for many years. In the Phillipines, Chris Go has achieved stunning results with a 20-cm Celestron, whereas Jim Phillips of the U.S. uses 20- and 25-cm TMB apochromats. In Japan, Toshihiko-Ikemura is, arguably, the world's most prolific Mars imager.
Many of these observers live in favorable locations, but not all. However, if one lives in a cloudy, high-latitude location all hope is not lost. A trip abroad with relatively modest equipment can yield excellent results, as we will see in the next chapter.
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