Given the editing system I am using for the site, links are not as obvious as I would like. The cursor does change when you place it on a link, but I wanted things to be a bit more obvious. For the moment, I am enhancing the visibility of links by enclosing them in square brackets – [sample]. If I figure out a better way, I will implement it, but this should help for the moment.
What’s In A Name?
25,000 years ago, Michigan was covered with glacial ice more than a mile thick. The great ice sheets were continuously being drained of melt-water via huge tunnels at the base of the ice sheet. These tunnels, the size of railway or huge highway tunnels, gradually filled with a stratified mix of stones, gravel, and sand. When the glaciers finally melted, the sediments in the drainage tunnels formed long, sinuous ridges, marking the course of the old drainage channels, on the otherwise flat Michigan landscape. These ridges are called eskers and one of the longest in North America is found in south-central Michigan. Known as the Mason Esker, this sinuous ridge extends from Dewitt in the north to slightly beyond Mason to the south. Its height ranges from 30 to 50 feet and its width varies from 150 to 400 feet. The first settlers from the East called this esker the Great Hogsback. Given that the observatory is located on the Great Hogsback, the only real elevation in the Mason area, Hogsback Observatory seemed an appropriate name!
One of the most obvious features of an observatory is the dome. Most amateur observatories do not have a dome or other structure, but they certainly are convenient. Here is the dome of the Hogsback Observatory under typical Michigan mid-winter conditions. The removable dome covers keeps snow and ice out of the clam-shell mechanism that opens the dome for observing. Within 15-minutes of arriving at the observatory it is ready for imaging, regardless of the season. The structure is 8-feet in diameter and 8-feet high and is built from a “kit” produced by [Sky Shed POD] (Personal Observatory Dome) in Ontario . All of the observatory electronics operate off a 12V battery system charged by a small solar panel.
Telescope Mount and Drive
In order to photograph any astronomical object, the telescope must be firmly attached to some sort of a mount. Since the sky appears to rotate during the course of an observing session (15 degrees/hour) the mount must also be equipped with a drive (operating from the observatory electrical system) to permit the telescope to “track” whatever object you wish to image. The mechanics of the mount and the motors of the drive system must be sufficiently robust to handle the weight and intertia of the telescope you plan to use. The Hogsback mount is a CEM60 mount from the [Ioptron Corporation], which can handle telescope loads up to 60 pounds. It addition to tracking, the controller for the CEM60 can automatically align the telescope to any object of interest that might be visible in the night sky.
I have had five different primary telescopes since I started my journey toward the small but functional observatory documented by this site. Each of them was capable of capturing interesting images of the moon and planets and I learned a lot at each stage in the process. Sometime within the next few weeks I will put together a page covering all five instruments, outlining their strengths and weaknesses in the context of lunar and planetary imaging – an activity which is very different from the deep-sky images that fill the pages of the major astronomy magazines. Some are excellent choices as “starter” or general-purpose instruments and, while they were not ideal for my purposes, they might be useful from the perspective of others.
One of the biggest lessons I learned was that chasing telescopes with larger and larger aperture (the well-known “aperture fever” in amateur astronomy) was not going to work given the less-than-ideal seeing here in the middle of the Great Lakes Basin. As I began thinking about the telescope I wanted to use in my retirement, several characteristics served to define my search:
A maximum aperture of 8-inches (203 mm)
A long focal length to provide a reasonable image scale without the use of a lot of accessory lenses. This would mandate the use of some sort of compound telescope as my modest dome could not accommodate a very long instrument.
Thermal stability in terms of both focus and collimation.
Peerless optics to optimize performance no matter what the seeing during any particular session.
The Holy Grail of my quest turned out to be the OMC 200 Maksutov/ Cassegrain from [Orion Optics U.K.] in Britain. With an aperture of 200 mm and a focal length of 4000 mm (f/20), this is a dedicated lunar and planetary instrument. It’s not cheap, and you may have to wait a long time to get one, but it is a telescope that dreams are made of. Unless otherwise noted, all the images on this site were captured using the OMC 200 telescope.
Most telescopes create an inverted image of whatever object they are trained on. If the telescope is designed to view everyday objects, it usually contains a prism that inverts the original/inverted image so that it is properly oriented to the reality that the user the telescope can appreciate. These prisms have the potential to reduce the light coming through the telescope, impact resolution, or to distort the image slightly. As such they are not incorporated into telescopes use for astronomical purposes.
As astronomers began to sketch what they saw through their telescopes in the early days of astronomy, they sketched what they saw and left their images inverted because other astronomers would see them the same way when looking through their telescopes. As photography became more common this standard continued in use. Many astronomers, even today, always prepare their sketches or images inverted, as they would as they would be seen through a conventional astronomical telescope. Agencies such as NASA portray objects using what I consider to be a more realistic standard. Instead of putting the North Pole of Mars for example at the bottom of the picture they rotate the image so that it is at the top – as you would expect if you were looking for example at a globe of the Earth. The point is, there are a number of standards in use and if you don’t understand what they represent it is easy to become confused as you look through your telescope and then look at pictures that published on the Internet or in magazines or television.
At the Hogsback Observatory, all images are prepared taking a NASA approach. All planetary and lunar images are displayed with geographic north at the top of the page, south to the bottom, east is to the right, and west to the left – just like a road-map. Do not be surprised to run across websites or other sources which use an inverted presentation for, after all, there is no “right way to do it” in a universe where everything is relative.
Why Only Three Planets?
Even a casual look at this website will reveal that there are only three planetary image pages – one each for Mars, Jupiter, and Saturn. These three planets can be readily imaged at a useful image scale and thus they represent the focus that most of my imaging activity.
Mercury, the closest planet to the sun, never gets very high above my eastern or western horizon and most of the time it is not visible. The planet appears so small using my telescope is not worth the bother to try to image.
Venus is further from the sun and thus rises higher in the Eastern or Western sky when it is visible and it is certainly easy to image. The problem is, Venus is surrounded by dense white clouds that never break and so one never sees anything but the white cloud tops. What you get is a brightly lit white crescent moon-like structure (much smaller than the Moon of course), but with no surface features. To me, imaging Venus is a lot like watching paint dry and I have no interest in it whatsoever.
That leaves the two outermost Gas Giants of the solar system Uranus and Neptune. These are good-sized planets, but their immense distance means that one needs a very powerful telescope to get any kind of a useful image scale. With my telescope, Uranus is rendered as a very small pale blue disc, while Neptune is an even smaller darker blue disc. Neither would be of sufficient size to see cloud features. Pluto, whatever you choose to label it, would appear as a very faint star that would be difficult to distinguish from equally dim stars around it.
Basic definitions of technical terms used on this website.