Wednesday, September 11, 2013

A Diagonal For The Galileoscope

The Galileoscope has become one of my favorite experiment telescopes. I should explain what I mean by "experiment". I use this telescope for things like video imaging, solar work, testing eyepieces, etc. But it is more than just a test telescope. It can be used for some observing work. 
The chief complaint about the telescope, though, is the lack of a star diagonal. If the telescope is raised higher than 35° from horizontal, it begins to become difficult to use, especially is you use a shorter tripod. Unless the average Galileoscope user has access to a taller tripod, the only real objects are those that are closer to the horizon.
Adding a star diagonal to the Galileoscope is tricky. The draw tube focus is very limited. Adding a diagonal is not practical without modifications. There are a few eyepieces that can be used, but very few. 
Some users have modified the telescope to take a focuser. To me, that just doesn't seem very practical. In order to add a focuser, the tube has to be cut, and the last thing I want to do is weaken the tube's structural integrity. This is also something that the average Galileoscope user might not want to do, and almost everything I do I want others to be able to. 
The simplest solution is installing a transit lens. Some users have used Barlow lenses, but they add length and therefore more magnification. The trick here is to increase the focal length just enough to make using a star diagonal practical. 
The lens I used was a 29mm plano concave (PCV) with a -53mm focal length. This is actually leftover from my Galilean project. I placed this ahead of the diagonal and used the Galileoscope's 20mm Plossl. This makes it close enough to not increase magnification too much, the result being roughly 1.5x to 2x. The target for the first full test was a waxing crescent Moon, and the results were very good. The amount of focus play is sufficient to allow the use of additional eyepieces. 
The diagonal I used was a heavy 1 1/4" older Meade, which was tricky. At higher angles, the weight of the diagonal kept pulling the draw tube focuser out. A couple of times, the star diagonal nearly fell out. The solution would be to use a plastic diagonal. Surplus Shed and other outlets sell inexpensive units that should be much lighter. 

There is still some tweaking that needs to be done, however this simple modification greatly improves the usability of this telescope. When the tweaks are made, they will be posted here.

Friday, August 09, 2013

The Perseids Peak

The Perseids have been upon us now for a few weeks, and are due to peek this weekend, the nights of the 10th through 12th. The shower itself actually runs for a few weeks, starting usually the second week in July and then running through the third week in August. The peak is always near the second week of August.
Like most meteor showers, the Perseids are associated with another larger body, in this case Comet Swift-Tuttle. This comet last paid a visit to the inner Solar System in late 1992, and has since been heading back into the depths of space. 

Chart courtesy The International Astronomical Union Minor Planet Center
With an orbit that takes it out to a distance further than Uranus, Swift-Tuttle takes a leisurely 133 years to make a complete loop around. Its orbit, however, is steep compared to most of the planets.

The Perseids are the debris that Comet Swift-Tuttle left behind. This material spreads out along the comet's path, and starting in mid-July, the Earth begins encountering it. For the following few weeks, our planet passes through that path, and in doing so we get the Perseids.
In order to catch these little pieces of cometary debris, you need to stay up a little late, at least until after midnight local time. Look towards the northeast; after midnight, the constellation Perseus will begin rising over the horizon, and it is here that the meteor shower's "radiant" is found. If you follow the path of all the Perseid meteors, they should point roughly back towards this, even though they could be anywhere in the sky. This is also roughly the direction the Earth is moving. In a sense, the Perseids are akin to bugs on our planetary windshield.

Chart created with Home Planet
So, if you get a chance, try to stay up late and catch these little remnants of a comet that won't be in our part of the Solar System for another one hundred and thirteen years.

Wednesday, August 07, 2013

The Smaller Telescope, Pt. IV - Examples of Current Smaller Telescopes

There are plenty of small telescopes out there, but the buyer needs to beware; too many of them are really not good telescopes at all. It's not optics alone that make a telescope. There are two other items that need to be as important; the mount and the accessories, namely the eyepieces.
One of the most common telescopes is the 50mm. If you go to eBay, you will find hundreds of them, with a solid proportion of them being sold with the flimsiest of mounts. Even the big names, like Meade or Celestron, have been known to drop the occasional bomb.
What follows is based upon personal experience. 

  • Meade Jupiter Series 50mm - 

This telescope has been out of production for a few years, but there are still plenty of them around. Like most 50mm, its primary lens was just fine. The problems arise when we move beyond the telescope. The first big problem was the tripod. It was somewhat wobbly. Since the telescope had a threaded mount, one would expect that you could simply replace the tripod. That is where we make the discovery that not only is the mount "stepped', it isn't a standard 1/4"-20 thread, but something close. The diagonal and eyepieces were .965" standard. These days, I keep an open mind, as there are good .965" eyepieces available. These were marginal at best. You could purchase a hybrid diagonal and move to the more common 1 1/4" size for eyepieces, but then the problem with the tripod still exists. I did not keep the telescope long.
Conclusion - wasted potential.

  • Meade 60mm AZ-T - 

Another one from Meade, and again also out of production. This telescope is a short tube tabletop model. It has quite a bit of plastic, but is not that bad a little instrument. It comes with an erect image diagonal, two 1 1/4" eyepieces (a 20mm Kellner, and a 9mm MA; mine had a 17.5mm MA instead of the 9mm!), a Barlow and a tabletop tripod with standard 1/4"-20 threads.  Sold with a handy carrying case. This is one of my favorite telescopes. Some people have complained about the focuser, but I've not noted any difficulties with mine. A great little "grab-n-go" telescope, it provides really nice views. The included Barlow was the only fault I could find with this telescope. I normally mount this on a heavier, and taller, tripod. I have managed to get a fair chunk of Messier's list with this telescope, even with the modest 17.5x magnification the 20mm Kellner provides. These are still to be found online at reasonable prices, and is recommended.

  • Galileoscope - 
This is the much vaunted 50mm educational telescope. When you purchase it, you are provided with just a telescope, and its accessories, all of which you assemble. The main eyepiece is a 20mm Plössl-type design, which for having plastic lenses provides very nice images. The other eyepiece is a Galilean, that is to say, a single concave lens, which also serves as the base for the 2x Barlow. Both are 1 1/4". When this telescope was announced, the initial plans was for it to cost $15 USD. It has now more than doubled, but is it worth it?

In my opinion - possibly. As an educational tool, it's great. It provides the student with hands on experience of how refractor telescopes work in their most basic form. The telescope comes equipped with a 1/4"-20 thread mount (really, a nut which is held into place in the lower part of the optic tube), so commercial tripods can be used. The Galilean eyepiece allows the student to see the sky the way Galileo did. However, there are downsides to the design as well. The optic design is straight-through; it cannot take diagonals. Well, it can, but the resulting focus range is very tight, depending upon the diagonal used. So, the telescope needs a fairly high mount; most recommend a tripod that can extend to 60" (1.524 m), as well as a chair or seat of some sort to make viewing higher objects easier. Objects that are closer to zenith, though, will be extremely difficult. 
Optically, it is a nice telescope. As stated previously, the 20mm Plössl gives good view when combined with the 50mm primary, I've used other eyepieces, and objects closer to the horizon, and feel that the telescope works fine.
Recommended with caveats.

  • Celestron FirstScope 76mm "baby Dobsonian" - 

I purchased this telescope in the spring of 2013, and am really surprised by its performance. It is a small Newtonian in a one armed Dobsonian mount, comes with 1 1/4" eyepieces, and is one of the easiest telescopes to work with right out of the box; open it up, set it on, say, a picnic table, remove the focuser and dust cover, pop in an eyepiece, and you're set. 
It does have weaknesses. For one, the included eyepieces are not the best. Of the two, the 20mm MA is the more serviceable, while the 4mm Huyghens is really not that great at all. Lack of a finder scope might bother some people. The primary mirror cannot be collimated (adjusted). 
But, how does it perform?
Ignoring the 4mm  eyepiece, with the 20mm MA it performs fine. The focal length of the telescope is 300mm, so it is a true short tube Newtonian, and operates better at low power. Still, moving over to one of my other eyepieces (a 10mm MA) revealed a great image of the Moon. 
My recommendation - probably one of the better beginner telescopes out there (along with the very similar Orion FunScope, based upon reviews and comparisons written elsewhere). Just purchase some additional eyepieces, maybe a finder scope, and you should be set.

To close, just a thought. Occasionally, you can find cheap telescopes at thrift stores and yard/tag sales. If the price is low enough, don't be afraid to purchase the instrument and give it a shot. There are always diamonds in the rough. Just keep in mind that some work might be needed, but the process of making those improvements simply add to learning more about this wonderful endeavor we call astronomy, If, in the end, the instrument is still found wanting, at least that can be said.

Thursday, August 01, 2013

The Smaller Telescope, Pt. III - Resouces

A few of my resources, and perhaps the least I need many times.
As mentioned in part II, this part we are going to look at how some of the resources available for binocular astronomy can be applied to the smaller telescope. 
Elsewhere in this blog, I've mentioned Garrett Serviss and his pioneering "Astronomy With An Opera Glass", perhaps the first book written on the subject of small instrument astronomy. Not only was it pioneering, but it was also practical; Serviss spent very little time reflecting on the instruments themselves, instead choosing to concentrate on observations. Many of the books on binocular astronomy today are split between both, covering the tools and the trade, if you will. But Serviss' book laid out the format that many still follow. For the smaller telescope enthusiast, the technical aspects of working with binoculars are of no use. Instead, you need to look at the observing section. 
There are, of course, still plenty of star guides that will be of use. 
In my personal library, one of the best books to guide us along is the late Sir Patrick Moore's "Exploring The Night Sky With Binoculars". Once you get past the first two chapters, which, not surprisingly, deal with the instruments, you find page upon page of targets to choose from. Chapter three, for instance, deals with many of the basics of stargazing, covering subjects such as the Greek alphabet (which is crucial in the identification of stars, as well as explaining how color is an indicator of temperature. After that comes chapters covering a variety of targets, from individual stars to clusters, nebulae, constellations and even some of the brighter galaxies. Near the end of the book he covers observing the Moon.
Another handy book is "Binocular Stargazing" by Mike Reynolds. I will admit, I've had a personal hand in the creation of this book; I helped to do some of the illustrations. But like Moore's book, it covers the equipment aspects first, and then dives into observations. After covering lunar and solar observing, the book then goes into how one can use binoculars for observing some of our planetary neighborhood. There are sections that cover the sky by season as well. One feature I like about this book are that many of the finder charts are drawn within circles, fairly close to what one should see when looking through binoculars or a telescope.Or
There is a book that deals with the Moon alone, and covers both binocular and telescopic observations. Originally written in the 1960's, Ernest Cherrington, Jr.'s "Exploring the Moon Through Binoculars and Small Telescopes" covers the lunar surface features in a bit more detail than the previously mentioned books, and therefore is of more utility. While no longer in print, the splendid Dover edition can still be found in abundance.
You will need star charts as well. There are perhaps dozens, if not hundreds, of sources here. Many of the basic books by Sir Patrick Moore, Ian Ridpath, Wil Tirion et al are more than sufficient, but there is an online source that I've found so useful, I've printed them off and had them laminated. These are Tashimi Taki's star charts, found here. These charts have proven invaluable to me. While they do cover deep sky objects down to 11th magnitude, the stars go down to magnitude 6.5, allowing them to serve as guides in the pursuit of more distant quarry.
This is just a start, and here based upon personal experience. Just remember that when deling with smaller telescopes that they will not reveal the heavens like much larger instruments. But they will open your eyes, are easy to use, and are a great starting place.
Next time, we will look at some of my instruments as case studies, as well as discuss what can be had, what to look for, and what to avoid.

Wednesday, July 31, 2013

DIY Neutral Density & Lunar Eyepiece Filters

This isn't the first time I've used this little trick, but since I needed to make a few more filters for some upcoming solar observations, I thought I'd share.
You know those disposable sunglasses you get after an eye exam? They are an excellent source for neutral density filters, if they are simple dark tinted, or lunar filters if they have a brown tint. Simply cut out 1 1/4" (a little less than 32mm) disks from the material. They have the potential to supply up to six disks, which is more than adequate for most amateur astronomers. They can always be layered to add more filtration as needed. The way you use them is to put them ahead of the eyepiece if you have a diagonal. If you are using a telescope that doesn't use diagonals, say a reflector, you may need to do a little engineering, perhaps making a hood that attaches over the back of the eyepiece, putting the filter between the eye and the optics.
They help to tone down the Moon for lunar observations, and can be used in conjunction with solar filters to provide additional contrast (NEVER use these filters alone for observing the Sun, even layered. Always use proper solar filtration).
So, next eye exam, don't toss these little disposable sunglasses, add them to your astronomical tool kit.

Monday, July 29, 2013

The Smaller Telescope, Pt. II - Capabilities

Can this little instrument see galaxies and nebula? Read on.
Let's look at what a small telescope is capable of.
Most of the work done in the early days of telescopic astronomy was done with instruments of small aperture. Even when those instruments had fairly large apertures, the optics of the time usually left a lot to be desired. The modest, low end instruments we find today are at the least their peers, and more likely their superiors.
A telescope really does two things; it magnifies, and it catches light. Many novices get drawn in by magnification without consideration to the telescopes aperture, its diameter. There is a good rule of thumb when dealing with telescopes and their recommended top end magnification. Take the telescope's aperture in milllimeters and multiply it by two. Simply put, a 60mm telescope should be able to handle up to 120x maginification easily. Yes, you could push beyond that, but the images will become very murky and dark. 
The other things telescopes do is capture light and concentrate it back to the viewer. Many astronomers, amateur and otherwise, refer to telescopes as "light buckets". A better description might be "light funnel". A telescope takes the light and concentrates it. 
Not a light bucket, but a light funnel, that concentrates light back to the eye.

The larger the funnel, the more light it can concentrate. This means you are able to see fainter objects.
Of course, the more they will cost as well.
Let's look at what some smaller telescopes are capable of, using the online "Telescope Limiting Magnitude Calculator". "Limiting magnitude" refers to how faint an object the telescope can see with the conditions and parameters set out in the calculations.
The parameters I'm going to lay out here are for typical deep suburban conditions, using my middle aged (currently 50 year old) eyes. I'm also going to include telescope apertures that aren't that common, the two smallest ones. Let's assume that we are on the edge of civilization, the outskirts of a suburban area, with naked eye magnitude near 4.5, which while not terribly bright is not terribly dark either. On all of these apertures, we are assuming a modest 25x magnification. To give you an idea of what the telescope should be able to see, we are using the Messier object list at Wikipedia, compiled in the 18th and 19th centuries by Charles Messier and his assistant Pierre Méchain. This is considered one of the most important lists in astronomy, and is something of a stepping stone for amateur astronomers. Using the aforementioned, we arrive at the following results -  

  • A 30mm telescope can see down to magnitude 9.8. This is theoretically capable of viewing 74 of the 103 objects on Messier's list.
  • A 40mm telescope can obtain 10.1 magnitude. This means we can view 80 Messier objects.
  • A 50mm, a common size, should be capable of viewing down to 10.3 magnitude. We are up to 81 Messier objects.
  • The 60mm telescope, one of the most common sizes, can view down to 10.5 magnitude. We are now up to 89 Messier objects.
  • We end with the 70mm telescope, the largest size we will deal with here, and still fairly common. We are at 10.6 magnitude, and we are should be able to view 89 to 91 Messier objects.

There is one telescope I want to touch on by itself, a nice little beginner's telescope from Celestron, the 76mm FirstScope. This is a baby Dobsonian. It is capable of reaching down to 10.7 magnitude at 25x. Considering its price, it is one of the best little telescopes one can buy.

For its price and aperture, the Celestron 76mm FirstScope is one of the more clever telescopes available.

Now that we have established what the smaller telescope can see, we'll next look at how to find these objects. We're going to use tools designed for binocular astronomy.

Saturday, July 27, 2013

The Smaller Telescope, Part I - In Defense of Smaller Telescopes

As an advocate for smaller telescopes, I frequently find myself trying to find better methods and procedures for the amateur and small telescope enthusiast. As I have grumbled many times, many amateur astronomers tend to put anything with an aperture less than 152mm (6 inches) into the category of toy, save for a few, high end exceptions. But as their light gathering capabilities are usually similar to these higher end smaller instruments, I find this a bit puzzling.
Instead of trying to find resources for smaller telescopes, perhaps a different approach is needed. That approach is to use resources and tools developed for binocular astronomy.
In short, binoculars are nothing more than small, twin telescopes, held together. They are all almost always low power, with 7x to 10x being perhaps the most common, regardless of aperture. Most books for binocular astronomy therefore tend to concentrate on objects that can be easily observed at lower powers, such as open clusters.
A small telescope, 70mm aperture or less, has two viewing advantages immediately. The first is, of course, magnification. With a modest assortment of eyepieces, one can choose their magnification, but normally they can have higher magnification than comparable binoculars. The other advantage is a steady mount. You can buy tripods and tripod adapters for binoculars, or other devices to steady the view. However, telescopes, even inexpensive ones, almost always include some sort of mount. 
The combination of magnification and steady mount makes a small telescope complimentary or preferable in many ways. When  combined with observer guides for binoculars, the small telescope enthusiast is now armed with the tools necessary to do a fair amount of observing. 
Perhaps most binocular astronomy guides should carry "and small telescope" in their titling.
Next, we will look at some of the best resources for the smaller telescope.

Friday, June 28, 2013

Thomas Harriot's Moon

Between 1609 and 1610, Englishmen Thomas Harriot produced a number of drawings of the Moon, as well as what is probably the first map of its surface as well. The instrument he used was a simple Dutch "trunke", a telescope, of what we generally refer to as "Galilean" in design.
That is, of course, a misnomer; Galileo did not invent this optical design, he refined it. Others proceeeded him, Hans Lippershey in particular, with Sacharias Jansen and Jacob Metius also playing significant roles. 
Yet it was Harriot who aimed a telescope skyward and recorded the results.
It is interesting when we compare his map of the Moon with a modern image.

One of Harriot's Moon maps, Courtesy The Science Museum, Kensington
My image of the full Moon, early morning of the 23rd June, 2013 (the so-called Super Moon)

While not as artistic as Galileo's drawings, it is nevertheless remarkable, and proof of what a small telescope is capable of revealing to the humble viewer.

Wednesday, June 19, 2013

Galileo, Scheiner, Sunspots & Saturn

I decided to work on my Galilean-Scheiner sunspot study by conducting a test of instruments with those old optical layouts. For this, I used my facsimile Galilean and my small Keplerian.

Someone replied not too long ago that looking through a long tube Galilean telescope was akin to looking through a straw. Nothing could be more frustratingly true, but from a projection standpoint, it works much better.

However, the question must be asked, which telescope did Galileo use? The long tube instruments are incapable of projecting a full Sun; they simply have too much magnification. 

Surely, he used a smaller instrument. It was obvious, though, that it could be done, and the result is simply a mirror image.
Christoph Scheiner, however, preferred the Keplerian telescope. The Keplerian design uses plano-convex lenses for both objective and eyepiece. Like the Galilean, it is a simple two element design, but it produces a much better field of view. The tradeoff is that the image is inverted, but for astronomical purposes, this really isn't a problem. Scheiner was an early proponent of this design, and perhaps to be credited for its greater acceptance.

As expected, the images produced by the Keplerian were brighter and much clearer.

In this case, the image needs to be rotated 180°. I've enhanced it somewhat to bring out some of the sunspots.

The final test will be the creation of a Galilean eyepiece for the small Keplerian telescope, and a projection made to see if that approximates the studies performed by Galileo. In the meantime, it is clear that Scheiner does deserve more recognition for his pioneering work.

Wave At Saturn Night!

Tonight is "Wave At Saturn Night". This showed up on my Facebook page yesterday. This is the first time I've seen or heard of it. Nor am I able to find it again. But it seems like such a fun idea. Silly, yes, but fun.
Holidays like this, though, will forever be moving ones; planets fail to appreciate our calendar and seldom tarry long in one place.
Tonight, Saturn is pretty close to zenith at sunset. with a waxing gibbous Moon to its east. The white moonlight should proved strong contrast to Saturn's yellowish hue. 
If you get the chance to, be sure to take a step outside and look for Saturn, that bright yellow star north and west of the Moon.

Addendum - It was Philip Astore, amateur astronomer and professional firefighter, who made the comment about looking through a straw. Anybody who loves astronomy is a friend in my book, but this fellow also has one of the toughest jobs in the world. Stay awesome, Philip.

Monday, June 17, 2013

First First Light - The Anniversary

A few entries back, I wrote about my first first light with my old Tasco 50mm. The date I included was wrong; it was actually the 14th, not the 18th. It was a Sunday night.
Anyway, to commemorate the event, on the night of the 14th, I decided to recreate that moment with my Tasco 50mm, same model I had back then. I used two of its original eyepieces, a 20 and 12.5mm, both Huygens, as well as a new 20mm MA. All three eyepieces are, of course, .965".As with that night, I chose to observe Saturn, as well as the Moon.

What a difference thirty years makes.
The Moon that night was near full. I knew back then from using my binoculars that the Moon isn't much fun to observe near full. For the 32nd anniversary session, it was waxing crescent, and glorious. In 1981, Saturn and Jupiter were near one another. in 2013, Saturn lies just east of Spica.

The sky over Jacksonville the night of the 14th June, 1981.
(Courtesy YourSky at Fourmilab)
The night sky over Jacksonville, 14 June, 2013.
And like then, the sense of wonder I felt, even with such a small instrument, was the same.
I simply love the heavens.

Such a fine little instrument. The tripod isn't original, but everything else is. I seldom use small telescopes with finder scopes, by the way.

Wednesday, June 12, 2013

A Fireball, If Ever So Briefly

Last night, at 9:48 PM, I was exiting the van in the driveway when something caught my attention up in the north-northeastern sky. I turned just in time to catch a fireball. It was easily brighter than Venus. Duration was maybe three seconds, tops.
The problem was that the beautiful live oaks that make this part of Jacksonville so alluring were in the way. Still, this object was so bright it showed through the tree canopy. 
It also led to my first fireball report to the American Meteor Society
I've seen literally hundreds of meteors, dozens of fireballs and a handful of explosive bolides. I have never taken the time to report the more significant events. Even when I worked as an astronomy educator, this little matter went to the wayside. For me, those astronomical objects of true desire for me, the planets, open and globular clusters, stellar associations and such, were far more important than these errant pieces of Solar System jetsam and flotsam. In light of the interest in the possible recurrence of the legendary Gamma Delphinids, however, I decided to, for once, be a responsible observer and report the fireball. 
From my vantage point, this is the path the object took.

As it turns out, I wasn't alone. There were two other possible sightings from two very different locales; Myrtle Beach, South Carolina and Lakeland, Florida. Taken together, with information gleaned from the pending reports at the AMS site, we get the following. 

The green lines represent line of initial sighting, the red the last. Angles are approximated. The yellow path is a potential trajectory that the object may have taken. Unfortunately, to verify that trajectory, exact times for all the sightings would be needed.
Nonetheless, it was a bit thrilling to catch such a wondrous event, albeit briefly. 
You never know when you have just observed a greater event, and when you contribute that information, you are doing, you guessed it, science.
Next time, better notes.

The AMS has compiled a total of five reports, of which mine was one. Here is the final analysis -
Event 1267

Tuesday, May 28, 2013

Three Planets in the Western Sky

The weather finally cooperated this evening to allow me to get some shots of Jupiter, Venus and Mercury in the western sky.

Here it is labelled, for your convenience.

Finally, some of the images worked out perfectly as an animation, so here it is.

Such beauty. Glad to have finally been able to capture it.

Saturday, May 25, 2013

Aiming for the Sun

When examining the early designs of "helioscopes", specifically those of Christoph Scheiner, one thing always seemed to be puzzling to me. What method did they use to align the telescope with the Sun?
These days, whenever a solar filter is employed, we tend to use the "least shadow method", that is the smallest shadow cast by the optical tube. If the shadow is fairly circular, you're close, and it then simply becomes a matter of minor adjustments. These early telescopes weren't so forgiving. For one, they had a very narrow field of view, especially the Galilean designs. You could employ the least shadow technique, but you now had the problem of sunlight hitting your screen. That makes the following image somewhat puzzling.

We know that many of these early designs, especially those of Scheiner, had a shield of sorts. In his first design, there was not just one shield but technically two; a smaller one towards the front, followed by the main shade. The main shade was approximately the same size as the "tabella", the rear of the instrument, where the "chartis" was positioned. Since this was all one instrument, all one had to do was align the shadow of the large shade onto the "tabella", and the instrument would be pretty close.

On my little experiment, I chose to try a second shade, towards the back of the instrument. Both shades are about 8" (200mm) square. 

By aligning the shadow of the forward shade onto the rear shade, we were able to aim the telescope.

Not enough contrast, but you get the idea.

In late designs, Scheiner appears to have dispensed with shades. In a more advanced version of his helioscope, the instrument is mounted on an early equatorial mount and aimed through a small hole in the ceiling through which the Sun is visible. This design is advanced yet somehow awkward.

In all the documentation, no mention is made of how the telescopes were aimed. This is purely speculative, but appears to work and truly makes using the "helioscope" a much simpler affair.
(EDIT - It appears as if the second design did have a finder of sorts. According to an article written by H.D. Curtis, "Popular Astronomy", Volume 20 (1912), "the little holes at ε and H served as a "finder."" This is a pretty simple system, using small holes, aligned up with the top of the assembly. Very clever, and definitely present. - RL)

Friday, May 24, 2013

Chasing Galileo's Sunspots

After doing the animation in the previous post, I found myself struck by the amount of detail Galileo put into his drawings, and how they compare to modern observations. His contentious contemporary, Christoph Scheiner, came up with not only better equipment for solar observations (including what can only be described as one of the first equatorial mounts), he also developed methods that would be used for more than a century, and which in evolved form still exists, but Galileo's drawings still look better. The information supplied from the Galileo project at Rice University's website indicate that the drawings that Galileo did of the Sun were around 150-152mm  123 - 125mm in diameter, about  6 " 5". We can only guess which telescope he used (he may have even used one purpose built), but it is certain that it was a Galilean in optical design.
The question, however, is what method did he use? We know that he used solar projection, but what did his setup look like? Here, things become vague. How did he aim the telescope? There are plenty of questions that remain about how he did it.
A few years back, I built a facsimile of one of Galileo's telescopes, and in theory it would be fine for this little experiment in historical astronomy. Instead, I am using the one modern telescope that is most like a Galilean in performance, a nearly fifty year old Tasco 40mm terrestrial telescope. As an astronomical instrument, it is extremely limited. In fact, as a terrestrial telescope it is extremely limited as well, possessing a narrow field and a somewhat dark field of view. That performance is very close to the performance of my long tube Galilean facsimile, in a shorter, easier to handle telescope.
Over the next few days and weeks, I will test out these methods using that old instrument and will, as always, share the results here.
(Edit - The diameters that were initially listed were incorrect; they have been corrected. R.L.)

Friday, May 17, 2013

Galileo's Unintentional Sunspot Animation

In the late spring and early summer of 1613, Galileo Galilei conducted a series of observations of the Sun. At the time, the study of sunspots was still obviously very young. Prior to the telescope, sunspots could be observed at sunrise or sunset (usually the latter), due to the strong filtering effects of the atmosphere at low angles. As the 17th century rolled along, the telescopic projection method of observing became the standard. It was Galileo's protege Benedetto Castelli who developed the method he used. From the 2nd of June through the 8th of July, 1612, Galileo made daily drawings from these observations, though a couple of days were missed (4th and 30th June). If you take the longest set, the 5th through the 29th of June, and arranged them in order, you get a crude animation showing the rotation of the Sun.

(I am not one to take credit where it isn't due. I would like to thank the Galileo Project at Rice University for the initial spark, primarily this page. I would also like to thank Professor Owen Gingerich of Harvard for providing valuable critiques of the work.)

Wednesday, May 15, 2013

First First Light

Lest anyone think that is a current star chart, let me assure, it isn't.
This is a chart generated from Night Vision for Java (a nice free planetarium
program), and if you look close enough, you'll see a date - 18th June,
1981 (1981/6/18, above the chart). It was on this night that I used my
first telescope, an older Tasco 50mm. It was a great little telescope that
had a pathetic little table top tripod. While I chose to keep the table
top tripod, I re-purposed a Woolco store brand tripod to take the
telescope as needed. That sky you see up there is what awaited me my first
night out with it, and as it turned out, its first light.
For my very first observation session, I set up in my front yard in the
Sandalwood neighborhood of Jacksonville. While we still had light
pollution, as well as the sweeping beacon from nearby Craig Airport, it
was not nearly as bad as it is now. You'll notice that two planets are
fairly close together, Saturn and Jupiter. That night, it was Saturn that
I chose for my primary target, the very first object to be observed. I
would sweep to Jupiter moments later, but once I got the focus on my
little Tasco set, the image of a small, elongated, yellow Saturn set my
heart racing. I do not remember what eyepiece I used initially. I think I
used Dr. Mike Reynold's advice and used my 20mm to locate the object and
then zooming in with the smaller eyepiece, what I think was a 6mm, with
horrible eye relief. Still, there was Saturn, clearly discernible, clearly
ringed, clearly Saturn.
While Saturn may be my favorite planet, I wasn't prepared for Jupiter.
With the smaller, higher power eyepiece in place, it was remarkable. There
it was, the somewhat flattened sphere that we all know and love, with the
Galilean satellites hovering close by. Now my pulse was racing.
As the months went by, I performed many sweeps with that little
instrument. The telescope lasted until at least 1989, when I took it apart
for cleaning and did damage to the objective lens.
The fact that I was able to see so many deep sky objects, as well as
Saturn and Jupiter, with such a small telescope blew me away. What's true
that many of those early astronomers had telescopes that weren't even the
equal of this modest little instrument, and they went on to define the
science so well, to lay the necessary groundwork that future generations
would work from.
Within the amateur astronomy community, you will frequently encounter
people of all sorts, and a good many of them will give you advice like
"stay away from department store telescopes." Those are wise words, but I
also think a bit hasty. Some of those department store telescopes can turn
out to be fine little instruments, if you understand their limitations.
On that summer night, so long ago, my little telescope didn't seem to have
(Edit - the date of my first light is wrong in this entry. It was a Sunday night, and my journal indicates it was 14 June, 1981. The wonder was there, nonetheless. - RL)

This is why you should never do solar astronomy when you're sick.

This is why you should never do solar astronomy when you're sick.

Tuesday, May 14, 2013

Just A Shot Of The Moon (Or Perhaps Two)

Just some shots of the Moon taken with my Mavica through my Galileoscope.
Not bad for an older camera and a simple afocal setup. First image was
taken on 13th May, 2013, the second the following night.

Some Thoughts on Solar Observing

After my experiments yesterday with my Galileoscope and solar observing, I
find myself thinking more about ways to observe the Sun. The damage to the
inner face of the eyepiece was a visible reminder of the hazards where
amateur solar astronomy is concerned.
Back on the 7th of March1970, I had my first opportunity to observe an eclipse, one that
passed, partially, over Jacksonville, Florida. I was in first grade at the
time, and unlike most of my classmates, I was pretty handy with making
things. They presented instructions to the older children on how to make a
pinhole solar eclipse viewer. My memory gets a little foggy here, but I
also believe that these were available at some of the local stores.
Suffice to say, I managed to make one, but the weather locally did not
cooperate, and soon it became somewhat overcast.
For a few days afterward, though, I used that little viewer to view the
Sun. A few years later, in fifth grade, I found an astronomy book at our
school's annual book fair, and naturally picked it up for something like
$1.98. I was so pleased with it, and one of the first experiments in it
was making a bigger pinhole viewer, one that separated the two pieces by
ten feet or more.
Before I attempted that viewer, the book disappeared from our house. Not
really sure what happened, but I do know that it really upset me.
As time progressed, other ways to view the Sun presented themselves. The
most common seemed to be projecting the image through a telescope and onto
a screen. Prior to my obtaining my first solar filter, that was always the
preferred method.
Still, the idea of viewing the Sun via pinhole projection has fascinated
me. I had the chance to play with the technique again during the 1991
eclipse, which again was a partial one for us here in Jacksonville. The
Museum of Science and History set up booths where visitors could make a
two paperplate version, using aluminum foil to make the pinhole section in
the center of the upper plate. Very simple, but as with other design from
many years earlier, the only real detail visible would be that of the Moon
as it passed in front of the Sun.
Some may be familiar with something called "pinhole photography". This is
a long exposure technique that can produce some beautiful, long depth of
field images. The times necessary to obtain images can be very great, but
if care is taken, wonderfully detailed images can be obtained.
So the question is, what level of detail can be obtained by a long length
pinhole setup, akin to the one from my fifth grade astronomy book?
This is something I am apt to try.

Monday, May 13, 2013

The Galileoscope As A Solar Observation Instrument

One of my favorite telescopes from an experimenter's standpoint is my Galileoscope. It has been used with my various video astronomy cameras, my Meade Lunar and Planetary Imager, afocal photography, and of course traditional astronomy. I've been looking at ways to use it for solar work, which is tricky, and of course somewhat risky.
(Warning - looking at the Sun with any astronomical instrument, without the proper filters and tools, is dangerous, period. Not only is it dangerous to your eyes, it is also potentially damaging to your instrument, as we will soon discover)
It was actually Galileo himself who made some of the first solar studies, and used his telescopes in this extensively, primarily through lens projection. These observations were almost always made with the Sun low on the horizon, either at sunrise or set. Contrary to legend, these are not what led to his eventual blindness.
I already have a homemade solar filter that fits the end cap of the Galileoscope perfectly, however due to the straight through nature of the telescope, it is somewhat risky to use, primarily because once you move your eyes away from the eyepiece, you are looking straight down the telescope, and at the Sun itself. What is needed is a shield.
I made a shield from a 10" x 10" (250mm x 250mm) cardboard. In the center of this square, I cut a 2 1/4" (56mm) circular hole that allows the shield to fit smoothly over the back of the Galileoscope dew cap. It should fit flush against the back of the dew cap extension.
Initially setup, it worked great with my solar filter; I normally use a neutral density filter as well, and this fits over the eyepiece.

Here we see it with an afocal setup, which sadly did not work, primarily because the camera has a hard time with focus (wanting to focus on the eyepiece or the shield; you cannot disable the auto-focus on some models). Aiming the telescope proved a little tricky, but was not too difficult.
But what about solar projection?
This is where caution is needed. Even with the Sun at a 30° angle above the western horizon (a point where its energy is cut almost in half), the amount of sunlight coming down is more than enough to damage the inside of the telescope, and especially the eyepiece. The lenses weren't damaged, but the internal face of the eyepiece was.

Still, it worked. I used a circular plastic to-go food container as my screen

One thing I'd recommend, however, is to move the screen back. Optimally, using the 20mm (Plossl) eyepiece, I'd recommend between 12" to 14" (300mm to 350mm) distance from the eyepiece to the screen.

At 8" (200mm); the image is small but bright.
At 12" (300mm), the brightness drops, but contrast improves, allowing for more details.
Using this technique, you can clearly see sunspots. 

The sunspots

Based upon my experiences today, I'd recommend the following to anyone who wants to do solar projection with the Galileoscope - 
  • Use another 20mm eyepiece, one that uses metal in its construction. This should prevent the sort of damage we witnessed to our Plossl.
  • To help in aiming the telescope, a hole might be cut in the shield that lines up with the sights. This hole should be no more than 1/4" (6mm) in diameter. Try not to look directly into the hole, instead look to see if the sunlight that comes through it projects over the sights and onto, say, the screen or even your hand. 
  • Try to focus the telescope before aiming for the Sun. Find some very distant object and preset the focus, not only to simplify the operation but to make it safer for equipment.
As usual, I will share any additional findings and improvements I may make.
But remember, if you choose to try this, remember, again, be careful. And as always, have fun.

Wednesday, May 01, 2013

The Bucket Solution

One of the biggest challenges facing me whenever I'm doing a little stargazing is, well, my big tuckus. Hours at the telescope get tedious, and for us heavy, older guys, the legs start to ache. Add to that the fact that a few of my favorite telescopes sit low, and you can see how this can be a bother.
The solution is obvious; you need a seat. There are all sorts of folding chairs, and carrying them in your vehicle and unloading them where you plan to set up is easy enough. But what if you are not going to be viewing near where you park? Easy, right? Folding chairs or stools. Now, you've just added another item to carry. 
Let's consider. You are already carrying your telescope, its mount, eyepieces, other assorted odds and ends like repellent, gadgets (possibly a smart phone, tablet or e-reader), laser pointer. Now, we add in a portable seat of some sort. This is becoming a lot to lug. 
There are solutions, such as dollies and other devices with wheels. These aren't perfect either. If the soil is soft, it becomes even more tedious trying to move all of this stuff. 
What we need to do is reduce the number of items to a bare minimum and reduce the number of trips, preferably to one.
This solution might not apply to larger instruments, but for smaller and so called "backpack" telescopes it should suffice. 
The answer is the humble bucket. Five gallon sized.
My initial tests haven't been with one of those readily available buckets but with recycled cat litter buckets. 

The larger ones have a similar capacity to the five gallon bucket that anyone can pick up at the local hardware store. The bucket serves the dual purpose of being a container for lugging most of your stuff to the field and providing you a handy place to sit. You can use the bucket inverted to do just that, or you can buy special "lids" that turn a five gallon bucket into a stool. Or you can make your own; this is DIY astronomy at its finest!

My little experiment with the recycled cat litter buckets proved how easy a concept this is. For most back packer type instruments, two buckets should be the maximum, with one inverted bucket serving as the platform upon which the telescope could sit (they generally have a 10"/25cm diameter). The one that will serve as a stand can carry the cargo bucket, as they are normally designed to fit inside one another. For larger instruments, a single bucket would simply serve the humble task of reducing the number of trips needed to set up. 
Regardless, the bucket solution seems to me to be a great one, especially given my fondness for smaller telescopes. Give it a try.
As for me, just waiting for the next clear night. Anytime now.