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Categories
You can browse through the categories and subcategories the same way you would browse through a directory structure on a hard drive. For instance, if you want to read about my solar observing sessions, just click on the subcategory “Solar log" in the category “Sun". All articles with solar observing reports will appear in the main window on the right. They will appear sorted by date. The newest entry is always at the top, the oldest at the bottom of the last page.

Archives
You can browse all entries that are in the blog, by browsing through the archives. All entries are in a SQL database, and you can browse through them by date or by category. Just click on “Monthly Archive Listing" or “Category Archive Listing" and a list will appear, with all article titles sorted by date, or by category. I personally use the Category Archive Listing a lot. It shows all the entries per Category, listed alphabetically.

Search
This is the most powerful option to find a certain item you are looking for. Simply type in the text, for instance Copernicus or Herschel, and all entries in which this word is used will appear in a list with the title, the first lines of text of the entry and the author and date. You can go the article you want to read by clicking on the title. The search option really searches the complete database, and if a word is used somewhere in this blog, the entry will appear in the listing. If you get too much search results, narrow down your search by clicking on “Advanced Search" beneath the search window.

Posting comments
This option has been corrupted (some security issue) during the last few months, but thanks to Mel it works just fine again. How can you post a comment?

You first have to be registered as a member of my blog. You can register by clicking on “Register" in the menu at the top right of the header. Once you are registered you receive an e-mail to activate your registration. When your membership is activated you can login by clicking on “Login" in the menu at the top right of the header. When you are logged in you can post comments, and to be honest, comments are highly appreciated! Maybe I can use them to help me making the content better and more interesting for you, so feel free to log in and let me hear what you think!

Newsletter
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Math
23 March 2006
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Binocular/Telescope
You can use any telescope with good optical quality to observe the Moon. A 70mm or 80mm refractor or a 4-inch reflector will be just fine for starters. When you already own a pair of binoculars, use them! There is no need to rush to the nearest astro-store and buy a telescope right away.

I will not discuss (the quality of) telescopes and binoculars in this article. There are many good other resources on the web and in astronomy magazines that can help you on deciding which telescope or binoculars to buy. You can find some useful links in my beginner's pages and equipment links on my old website, backyard-astro.com. The best advice I can give you before buying any astronomy related equipment: take your time, go to a local astronomy club or visit a star party and look through different instruments yourself, before you decide what to buy. In the end, this will save you a lot of disappointment and money.

Map of the Moon
You need a map of the Moon because you will be visiting a place that (until now) is unknown to you. You need a "roadmap" to find your way around. There are many lunar maps available from bookstores and from Internet stores like Amazon and Sky Publishing, but for outdoor use my favourite is the “Field Map of the Moon” from Sky and Telescope. This map is laminated, so it can be used outdoors under all weather conditions. You will find about 1,000 features labelled (and indexed) on the map. The map is made by Antonin Rukl, who (IMHO) is the best lunar cartographer around right now. You can get this map in two versions, the "normal" naked eye view version, and a mirror-reversed version. Before ordering, check which one you need for using with your particular binocular or telescope. This depends on the type of instrument you are using for observing the Moon. Just have a look at the three images below (click to enlarge).





Compare the views of the Moon through your telescope/binocular with these images. If you see the Moon as shown in the first two images, you will need the standard map (for naked-eye-views, binoculars and reflectors). If you see the Moon as shown in the third image, you will need the mirror-reversed map (for telescopes that work with a star-diagonal, like refractors, maksutovs and cassegrains). If you’re not 100% sure which one you need, just contact Sky and Telescope before ordering.

A lunar map will help you to identify the different lunar features, so it is one of the basic things you need when you start observing the Moon. When comparing your telescopic views of the Moon with a lunar map for the first time, you’ll probably wonder where to find east, west, north and south. The image below should help you finding your way around. I highlighted four key-features that should help you to get the directions right: Mare Imbrium (north), Mare Crisium (east), Tycho (south) and Mare Humorum (west).



Lunar directions


When is a good time to observe the Moon?
The answer to this question is very simple. Whenever the sky is clear and the Moon is visible. The Moon always has some interesting features to observe, even the full Moon. The bright lunar rays for example, are at their best when the Moon is full. A full Moon is also very useful to train your lunar orientation and find your way around as a beginner. Try to identify all the dark area’s, the Maria or seas, when the Moon is full.

What can you observe as a beginner?
When observing the moon through a telescope or binoculars for the first time, you will probably notice two things: there are large bright and dark areas on the lunar surface and the views along the line that separates the dark and light hemispheres of the Moon are the most spectacular.

1. Dark and light areas on the Moon, the Maria and Terrae

Roughly, the lunar landscape can be divided in two types of surface, the dark areas or Maria and the light areas or Terrae. The Maria, or seas, are the grey smooth plains on the lunar surface. The Terrae, better known as highlands or uplands, are the bright and rugged areas of the Moon, full with craters, mountain-ridges and other interesting features. The image below, should give you an idea about the dark seas and bright highlands. It is heavily processed to bring out the contrast between the two types of terrain. Anyway, trying to identify the different dark and light areas is a very good starting point for a beginning lunar observer.



Dark and light areas, Maria and Highlands


2. Highly detailed lunar features along the terminator

You will be amazed by the amount of detail you can observe along the terminator, the line that separates the light from the dark hemispheres of the Moon. When you observe the moon on a few consecutive nights you will notice that the terminator creeps over the lunar surface from east to west, changing the views not only from day to day, but also from hour to hour. You can see craters, mountains, rilles, domes, wrinkled ridges and more. I shot the image below on the 28th of March 2004. It shows part of the terminator of a 7-day-old Moon. As you can see, the amount of detail is simply overwhelming.



The lunar terminator


You can try to identify some of the larger craters for starters. If you need some kind of guideline or list of features to observe, follow this link to the Lunar Club of the Astronomical League. They have an observing list of lunar features, which will keep you busy for a while.

Conclusion
So if you want to observe the Moon, get a map, a pair of binoculars or a small telescope, and start with simply enjoying the views you get from this wonderful object. Try to identify the different mare and highland areas, and if you’re up to it, maybe some craters or other interesting features along the terminator. Maybe you get hooked and want to learn more about the Moon, start imaging the Moon, get into lunar geology, or just simply enjoy the views. No matter what you do, keep in mind that the single most important thing about amateur astronomy (and in fact every hobby) is that you are having fun and enjoy what you are doing.

Happy viewing!


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Why use the Zeiss for lunar imaging anyway?

TAL 200K
My 8-inch TAL 200K is an f/10 (2000mm focal length) telescope, and is only fit for use with 1.25 eyepieces. I achieve the lowest possible magnification using the 32mm Televue plossl. This eyepiece gives me a magnification of 62.5x, and with a 50-degree apparent field of view, this results in a true field of view of 0.8 degrees or 48’. The Moon has an apparent diameter of 30’, so visually the full Moon fits nicely into the field of view, but it fills the view almost completely. There is not much “space” left around the lunar disk.

However, shooting a picture of the full Moon (or nearly full Moon) with this setup is impossible. When the camera is connected to the 32mm eyepiece and the TAL 200K, the view will suffer from severe vignetting (a kind of tunnel-view). I can get rid of this problem by zooming in on the Moon using the camera’s optical zoom, but then I cannot fit the lunar disk completely into the field of view of the camera. At the bottom and the top, a part of the lunar disk is “cut off”. So the TAL 200K is excellent for shooting detailed images of the Moon, better than all other telescopes I own, but for imaging a (nearly) full Moon, I need another telescope.

TAL 100RS
Since two years I have been using the TAL 100RS, a 4-inch f/10 (1000 mm focal lenght) achromatic refractor, to shoot my overall lunar images. With the 32mm eyepiece I get a true field of view of of 1.6 degrees or 90'. Using this telescope got me some satisfying results, but the problem with achromatic refractors is that you get a more or less bright, somewhat colored circle around bright objects like the Sun, the Moon and the Planets. When processing the images I shot with the TAL 100RS, the bright fringe around the Moon becomes even more apparent. I simply need yet another telescope for shooting the overall lunar images. The solution to the problem came from a totally different instrument, a birding scope.

ZEISS DIASCOPE 85MM
During the last few years my girlfriend and I have gradually taken on the hobby of birding, not only during vacations, but also throughout the year, around our home and in our backyard. In 2005 we decided it was time for a birding scope. The choice was rather easy. There are three different top-class birding scopes available, Zeiss, Leica and Swarovski. These have all been tested many times, and you can find enough test reports on the Internet.

We chose the Zeiss because we simply liked the views we got from it, and we liked the professional finish of this wonderful instrument. Because of the high quality and the short focal lenght, this little scope is not only perfect for birding, but also for imaging the full Moon. The Zeiss Diascope 85 is an f/5.5 (focal lenght of 500mm) apochromatic refractor. With the 32mm Plossl eyepiece, the true field of view is almost 3 degrees, or 180'. So there's lot's of space around the Moon, and no colour fringe! However, for shooting detailed lunar images I will allways use the TAL 200K (shows much more detail on the surface because of higher resolution).

The eyepieces
For birding we only use the Zeiss 20-60 Zoom eyepiece. You cannot change eyepieces when you've got a bird in focus, because birds have the strange habit of moving around, especially when you want to shoot an image! Sometimes it seems like they don’t like being photographed.


Luckily the Moon moves a bit slower across the sky (and not in all different directions like those.... birds). Using an adaptor enables me to connect all astronomy eyepieces I currently own to the Zeiss. The 32mm Televue Plossl and the whole range of Vixen Lanthanum eyepieces, they all come into focus, even the 2.5mm Lanthanum, which results in a magnification of 200x. I am convinced that there are a lot of astronomy eyepieces on the market, that will not come into focus with the Zeiss Diascope, but that’s no wonder. The Zeiss Diascope is a birding scope, not an astronomical instrument. So be careful when considering this instrument for backyard-astronomy!

The setup for birding and for imaging the Moon
Shooting images of birds or the Moon has two problems in common: how do I get the object into focus, and how do I shoot the images without touching the camera, resulting in vibrations and .......blurred images. To make life a little easier I chose for a complete adaptor-set from Eagle Eye OpticZooms in the UK:

1. A digimount adaptor for connecting the camera to the eyepiece;
2. A Shutter-release arm and wing 4500 bracket;
3. A 10-inch shutter-release cable;
4. A micro fiber lens cleaning cloth.

On the images below (click on the images to enlarge them) you can see how everything is connected to each other. The shutter release cable works mechanically. You do not have to touch the camera to shoot your images. The X-tend-a-View Pro is just great. It magnifies the 1.5-inch TFT color monitor on the backside of the camera with factor 2. The view is so detailed you can even see the different colors of the individual pixels. It is a great help for focusing the camera/telescope on a bird, the Moon, or whatever other object. With the shutter release arm and the wing 4500 bracket, both the shutter release cable and the X-tend-a View Pro are connected to the coolpix 4500.







Click on images to enlarge


So this is the setup I use for birding. The setup I use for imaging the Moon is basically the same, only the eyepiece and the eyepiece adaptor are different. You find more info on how the Televue Plossl and Vixen Lanthanum’s are connected to my camera on my old website, backyard-astro.com. Just follow this link to get there. The shutter release cable and the X-tend-a-View Pro are used for shooting the lunar images as well.

Anyway, I want to finish this article with a close-up (award-winning) shot of a sparrow, shot with the birding set-up. In a contest from the Dutch Bird Protection (Vogelbescherming Nederland) my girlfriend was one of the ten prize winners with this image. Not bad for a beginner . I hope that in the next months these everlasting clouds will disappear over the city of Landgraaf, and I will be able to shoot a few lunar images with the Zeiss to present them to you in this blog.

Clear Skies to all of you!


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Lets have a look at the diagram below. The Moon travels around the Earth (blue arrow), and half of the lunar surface always is lit by the Sun (the half that is facing the Sun), while the other half is dark. The lunar phases are caused by the relative positions of the Sun, Earth, and Moon. Because the Moon orbits the Earth, different portions of the Moon seem to be lit by the Sun.

The phases on the image below are numbered from 1 through 8. At the bottom of the image you can see which bright part of the Moon we see.


© Image by backyard-astro.com


1. New Moon (day 0)
The Moon is between the Sun and the Earth. Its dark side is facing the earth and we cannot see the Moon in the nighttime sky. Its bright side is facing the Sun. The new Moon rises in the east around sunrise, and sets in the west near sunset.

2. Waxing (growing bigger) crescent Moon (day 3)
The Moon looks like a crescent. In the Western evening sky, it can be found to the east of the Sun. Its bright "horns" always point away from the setting Sun. It sets a few hours after sunset.

3. First quarter (day 7)
After 7 days the Moon has travelled 1/4 of its way around the Earth since new Moon. We see 50% of the sunlit half of the Moon and 50% of the lunar disk is dark. It rises around noon and sets at midnight.

4. Waxing gibbous Moon (day 10/11)
After the first quarter we see more than half of the bright side of the Moon. The visible part of the sunlit side of the Moon grows every night until the Earth is between the Sun and the Moon and we reach full Moon)

5. Full Moon (day 14)
The Moon is now halfway in its orbit around Earth, and we can now see the entire bright side of the Moon. The full Moon rises at sunset and sets in the Morning at sunrise. It is visible all night.

Now the Moon starts with its second half of the orbit around earth. It proceeds like the first half but then in reverse.

6. Waning (growing smaller) gibbous Moon (day 18/19)
The visible bright part of the Moon grows smaller night after night.

7. Last quarter or third quarter (day 22)
Again we see 50% of the bright half of the Moon and 50% of the dark half of the Moon. It rises at midnight and sets at noon.

8. Waning crescent (day 26)
Only a small part of the sunlit half of the Moon is visible. The waning crescent rises in the morning sky, before the Sun rises. It's bright "horns" are always pointed towards the rising Sun.

After 29.5 days the Moon is new again (number 1 in the diagram) and the cycle starts all over again. The period of 29.5 days (29 days, 12 hours and 44 minutes) between two successive new Moons is called a synodic month or lunation.
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Image 1: Overview of a nearly full Moon


Overview
On the image above, an overview image of a nearly full Moon (which I shot in August 2004 with the TAL 100RS mounted on a photo-tripod!), the transparent yellow patch represents the area that you is shown on overview image 2 and 3. Image 1 his been severely processed, to emphasize the contrast between the Maria and the Terrae.

Maria and Terrae

Roughly, the lunar landscape can be divided in two types of surface, the dark areas known as Maria and the light areas known as Terrae. The Maria, or seas, are the grey smooth plains on the lunar surface. The Terrae, also known as highlands or uplands, are the bright and rugged areas of the Moon, full with craters, mountain-ridges and other interesting features. But why are they called Maria and Terrae?

In the year 1609, Galileo was the first person to look at the Moon with a telescope. Galileo concluded from his observations that the Moon's geography was not so different from our earth. He saw mountains, valleys and plains. Mistakenly he thought that the dark smooth areas he saw were oceans. That's why he called them Maria (Latin for seas). The brighter parts, a much more rugged terrain, were called Terrae (Latin for lands). In reality however, the Maria tend to be the lowland and the Terrae the highland.

Copernicus-Riphaeus area
Before we take a closer look at Copernicus, I would like to point out a few other interesting features that can be seen on the images 2/3. Lets start in the Southwest with Montes Riphaeus and Euclides (Rukl 40/41). Tonight this isolated mountain range was visible near the terminator. The formation immediately drew my attention because of its distinct form. Together with the southwestern rim of Euclides P it looked like a starfish with the crater Euclides at its centre. Euclides is a young, simple impact crater with a very sharp and well-defined rim. Its diameter is 12km. In stark contrast with this young crater is the old crater Euclides P, which lies to the north of Montes Riphaeus, on the shores of Mare Insularum. The crater almost completely vanished beneath dark Mare material. The tip of the arrow that points out Euclides P touches the southwestern rim of the crater.



Images 2 and 3, Copernicus and Montes Riphaeus area (click to enlarge)


To the northeast of Euclides P lies the Apollo 12 landing area. To the East of the Montes Riphaeus, in the hills north of Fra Mauro (Rukl 42) you can see the Apollo 14 landing place. Between Reinhold and Copernicus (Rukl 31) lies the double-crater Fauth and Fauth A. Together they are shaped like a keyhole. On the Apollo 12 image (image 5) you can see Fauth-Fauth A in close up, lying before Copernicus.

Copernicus
My favorite crater on image 2/3 is Copernicus, a young crater from the Copernican period (somewhere between the present and 1.1 billion years ago). Copernicus is a typical Tycho-style large complex crater. It has a diameter of 93 km and a depth of 3750 meters. The crater rim rises to a height of 1100 meters above the surrounding terrain. The 54 km wide floor looks more or less flat with a group of central peaks. The walls are terraced, which you can see only vaguely on image 2/3, but if you have a closer look at the Apollo image (image 5) the broad terraces are very obvious.

A blanket of ejecta surrounds Copernicus, which is typical for a complex crater of this size. Near full Moon you can see the extensive crater ray system that surrounds Copernicus (see image 4 below, image taken with TAL 100RS). The Copernicus rays are very bright. This is caused by the fact that during the impact that formed Copernicus, pieces of bright highland material were excavated and launched into all directions. The bright material landed on top of the darker Mare lava, producing a beautiful contrast.



Image 4 (left), Copernicus crater rays (click to enlarge), Image 5 (right), Copernicus (click to enlarge) Image credit: NASA


Copernicus is definitely my favorite complex crater. Next time I will try to get some high-resolution images of the crater itself and its immediate surroundings. « Collapse

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M 42 and M 43
I took of with the Orion nebula (M42). What struck me was the fact that this nebula was easier to detect and better “visible” in my 85mm Zeiss at the lowest possible magnification (16x with the Televue Plossl), than it was in any other instrument I have been using. I checked Roger N. Clark’s book, Visual Astronomy of the Deepsky, and found out that the ODM (Optimum Detection Magnification) for this nebula is about 14x when using a 4-inch instrument under dark skies. My TAL 200K is an 8-inch and M 42’s ODM for this instrument is 27x. The lowest possible magnification on my 8-inch is 62.5x and on the Zeiss I get 16x with the same eyepiece, a 32mm Televue Plossl. In other words, the 3.3-inch Zeiss comes much closer to the ODM than the 8-inch TAL. I don’t know for sure, but maybe that’s why M 42 is best in the Zeiss. M 43 was also visible in the Zeiss using just a little averted vision. In the 8-inch 200K M 43 was not more apparent then in the 3.3- inch Zeiss.

Anyway, after studying M 42 and M43 in the 85mm Zeiss, I switched to the TAL 200K for some medium to high power views of the Trapezium. I was lucky tonight! Despite the mediocre seeing conditions, for the first time ever I immediately detected the 5th Trapezium star (at 166x with the 12mm Lanthanum), the so-called E-component, from my own light polluted backyard. I have already seen the E and F component two years ago from a dark sky site, but never from my own backyard. The central area of the Orion Nebula normally takes very high magnifications well, but tonight 222x (7mm Vixen Lanthanum) was the maximum for the Trapezium area. Higher magnifications only blurred the view.

Eskimo Nebula (NGC 2392)
The Eskimo nebula, the brightest planetary in the winter night sky, looked awesome tonight. At the lowest magnification (62.5x) it was clearly visible as a fuzzy ball of light with averted vision. With direct vision the nebula disappeared, but the 10th magnitude central star popped into view, exactly the same effect as with the Blinking Planetary (NGC 6826) in Cygnus. At 400x (this nebula did allowed high magnification tonight!) it was clearly visible that the nebula consists of a brighter inner circle and a slightly darker and fuzzier outer circle of nebulosity. This is a very rewarding object to observe. I tried all filters and magnifications available. I noticed that the OIII filter has its limitations on my 8-inch with high magnifications. Above 166x (12mm eyepiece) the OIII makes the view to dark. I can observe much more detail at high magnifications without the OIII. At 200x I found the overall image I got at its best. I did not detect the dark ring that separates the brighter inner part from the somewhat dimmer outer ring. I have not detected “the eyes” of the Eskimo.

NGC 2903, M65 and M66
Later that night I decided to have a go at some galaxies in Leo, NGC 2903, M65 and M66. These three more or less bright galaxies in Leo stayed almost completely “invisible” tonight. I could detect the brighter core of NGC 2903, but that was all there was to see. M 65 / M 66 stayed invisible. Not a good night for galaxies, even not for the few brighter ones I sometimes can observe from my backyard.

Saturn and M 44
As time went by, the seeing became worse and worse. Around 23.00 hours UT I aimed the 200K on Saturn. High magnifications proved to be completely useless. It only blurred the view of Saturn. I decided to have a look through the 85mm Zeiss, and at 30x the view was simply wonderful! Saturn and M 44 filled the field of view almost completely. M 44 is a real object for binoculars and rich field telescopes. When it teams up with one of the planets, it always looks spectacular! This was the highlight for me tonight. The stars looked just like sparkling diamonds, and together with the bright Saturn the overall view was simply awesome.



Image from Skytools 2 by CapellaSoft (click to enlargr)


Castor, Iota Cancri, Alcor and Mizar, Sirius and Polaris
I ended my observing session with a few beautiful (double) stars. Castor at 133x showed only the AB pair as two bright white stars. At the time I was observing Castor I didn’t know that there is a C component, a magnitude 8.8 red dwarf, about 73” from the A component. I will try to observe this faint companion next time.

Iota-1 Cancri is one of my favorite doubles. Even in the 85mm Zeiss at 60 to 70x the two components are visible as a golden a blue pair, almost as beautiful and striking as Albireo. This double should be on everyone’s observing list, just like Alcor and Mizar. This naked eye-duo looks great through almost every instrument. I simply enjoyed the view through the small refractor for a few minutes, before I pointed the Zeiss at Sirius, the brightest star around. Now I could see the quality of this small instrument. Sirius looked just like a bright white star. No colors visible around the edges and no Fringe Killer needed!

Last but not least was Polaris. Believe it or not, after all these years, this was the first time I looked at Polaris with my telescope, and I found this double surprisingly easy to see. Polaris has two components A and B. A is a magnitude 2.0 yellowish star and the much fainter B (magnitude 8.2) can be found at a position angle of 218 degrees and at a distance of 18.4”.

At 00.30hrs UT I decided it was time to pack up, after four and a half hours of freezing cold. Around 2 o’clock AM local time I sat indoors, warmed by the heater, enjoying a glass of malt whiskey (no ice) and dreaming about the beautiful objects I had seen tonight. These are the nights that keep me in this wonderful hobby……..




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There were three craters visible with well-defined central peak(s), Tycho, Longomontanus and Moretus. Moretus also showed its terraced walls tonight, a very pretty sight. On the floor of Gruemberger, there was a feature that casted a needle-shaped shadow, but I don’t know if Gruemberger really has a kind of central peak. The floor of Gruemberger looked very rough, not smooth, like the floor of Longomontanus. Maginus looked like a good example of an older crater with degraded walls, while Tycho is the complete opposite, a very young crater with an extensive ray-system (that is best observed around full Moon).

I roamed through this wonderful area for more than two hours, and at the end of my observing session I shot a few images. I’m really proud of the image below, which is the sharpest single-shot image I ever managed to get of this particular interesting region. I used the 8-ich TAL 200K, the Nikon Coolpix 4500 and a 20mm Vixen Lanthanum eyepiece (equipped with a Baader IR block-filter). I also used a 2x Xtend-a-View pro from EagleEye OpticZoom. This little gadget made focusing the coolpix a lot easier.

Anyway, both images below are identical, but the image on the left is simply the image as it is and on the image on the right I added the names for the most prominent (and some not so prominent) features in the Longomontanus-Clavius-Moretus region. Click on the images to enlarge. Enjoy!





The image is a single shot image (not stacked) taken on January 9th 2006, 21.06 UT. Shutter time was 1/30s, f=5.1, 4x optical zoom, iso 100. The image was processed (unsharp masking, resize, levels, de-noised on several different levels).

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