Sunday, August 14, 2016

Overlooking The Moon

For most of my time being an amateur astronomer, I have been interested in observing certain deep sky objects, such as clusters and double stars. Occasionally, I observe the planets, especially the two largest gas giants. Most of the time, I've been interested in studying historic methods, as well as sharing how to make the most with the least. And since 2014, I have been steadily observing the Sun, and have made, at this point, well over six hundred journaled solid observations and sketches, the majority of which have been used to produce sunspot counts.
One thing I haven't done is ever really study the Moon.
In all of my nightly observations, the Moon has been, for most of it, something of a bane.
Certainly, I've looked at it, sketched it a couple of times, and many times have imaged it. But I've never really taken the time to study it.
Which, when you really think about it, is somewhat sad.
Here it is, the nearest celestial object to the Earth, something often romanticized, something occasionally derided, sitting a short distance away.
For the past week or so, I have been playing with an erect image eyepiece that proved to be the only salvageable part from a low cost telescope. It is technically an 18mm, and like many of the simpler designs, has a remarkably narrow field of view (I'd say less than 20°). Yet the images it produces are sharp.
Initially, I tested it out on my classic Tasco 6TE-5, "Amelia", a wonderful 50mm, f/12, and found that it produced some rather nice views, if a bit claustrophobic. I tested it out on a crescent Moon, working its way over the pine trees west of our property. I had to extend the eyepiece haphazardly beyond the end of the focuser, using the thumbscrew to hold on to the elongated eyepiece by a narrow margin.
It worked enough, though, to show me that there was some promise here.
Next, I tested it on a small Meade 40mm 40AZ-P that I am experimenting with, and then I crafted an adapter to use it in my 50mm Galileoscope, where it seemed most at home.
Most of these tests were aimed at the Moon for a number of reasons. Chief among these is the fact that it was simply there. The other reason had to do with one of the main problems of this design. The complex optics train greatly reduces the light that reaches the eye. The Moon is big and bright, and both Jupiter and Saturn were still as sharp as ever. However, deeper sky objects lost their brilliance. M7, an otherwise bright cluster, was reduced by half when viewed through the Galileoscope, and nearby M6 was a ghost.
The Moon, though, was another matter.
It was sharp and well defined. When the eyepiece was used with a 2x Barlow, something I'd never considered until now, the view, while still narrow, was very good.
Last night, I decided to test the eyepiece out against my 45° erect image diagonal. I suppose that if one must have an erect image, this diagonal is certainly the best way to go, as you now have at your disposal a variety of eyepieces, though the angle take a bit of getting used to, at least for me. The telescope I chose for this was "Celeste", my Celestron 70mm f/10.
Again, an adapter had to be made to allow the erect image eyepiece to be used in the larger focuser. Since Celeste sits on a rather tall tripod, I thought that the viewing would be fairly easy. As it happened, the eyepiece and adapter extended the telescope even further, and the Moon, now near Sagittarius and a waxing gibbous, was higher in the sky. I had to slide down in my observing chair just to get my head to the eyepiece at all.
The view was certainly what I expected, however. Narrow FOV, but very sharp.
Next, I tried out the 45° diagonal with an 18mm Kellner. Naturally, the FOV expanded more than twice, but the target areas, the southern lunar highlands, were still very sharp, and to a degree more so.
Instead of demonstrating alternate viewing techniques, what these tests did more than ever was to inform me that I do not observe the Moon nearly enough.
I felt some awkwardness at the realization of this. A target I tell people to look at, on the the one hand, whilst simultaneously telling my more accomplished friends to avoid, is something I don't know well enough.
Perhaps the time has come to rectify this. Soon, not sure as to when, I am going to set out about observing a solid month of the Moon. This may be done on consecutive nights, it may be broken up over a period of weeks or months, who knows for sure.
But my lack of familiarization with our nearest neighbor in the universe is something I am going to actively seek to correct.

Sunday, August 07, 2016

Lessons From Leslie Peltier

Not too long ago, on advice from my friend Roger, I decided to start reading Leslie Peltier's autobiographical "Starlight Nights". Here, I must confess that I was only familiar with Peltier in passing. I was aware that he had written a great book on binocular astronomy, and that he was an early member of the AAVSO. Beyond that, the man was a mystery to me.
After I finished reading "Astronomy With An Opera-Glass" by Garrett P. Serviss a second (maybe third) time, I went over to this "Starlight Nights", and have been enthralled.
More than that, however, is the fact that he has touched upon some truths that I've often considered but never really have given much thought to.
The one thing that he stressed is that the best way to learn the night sky is directly, that is to say, by oneself. I suppose to a degree it is akin to that old adage from Benjamin Franklin; "Tell me and I forget, teach me and I may remember, involve me and I learn." The best way to learn the night sky is to simply go out and observe it.
The other take away I've gotten from the book so far is that the size of the instrument used to observe the night sky is really less important than the tenacity of the observer. As Serviss' book has demonstrated, something as small as an opera glass is sufficient. The great French astronomer Lucien Rudaux also felt that way. In Peltier's book, he goes into some length about how effective his first telescope, a humble 2" (50mm) terrestrial telescope was.
A terrestrial telescope, if you're not familiar with them, has a complicated optic train in order the create an erect image. From personal experience, I've found that the amount of light lost in one is quite high, certainly more so than an equivalent sized astronomical telescope.
Yet he was able to view and achieve quite a bit with this instrument. It would be easy to say it was his location, the rural reaches of Ohio, or the time period, the early 20th century, that enabled him to accomplish what he did. Perhaps so.
Though I am tempted to say balderdash.
I live in an area where, to my south, is the booming metropolis of Jacksonville, Florida. To my northeast are two paper mills that run twenty four hours a day. Nearby is a shopping area, and my own neighborhood has those bothersome sodium streetlights.
Yet I have been able to see quite a bit.
Certainly, some of the more distant objects are lost. I don't see much in the way of galaxies here, and some of the fainter deep sky objects are all but invisible. But the wonders are there.
It just requires tenacity coupled with the act of simply looking.

Sunday, July 10, 2016

Solar Adventures With Opera and Field Glass

If you've been reading the blog, you know that I've been thinking about "retro-astronomy" a bit. Recently, I decided to read, once more, Garrett Serviss' classic, "Astronomy With An Opera-Glass". My copy is over a century old now, so I find myself alternating between its delicate pages and an ebook version on my Kindle. The way it is written is a sheer delight, a peek at the way popular astronomy was handled at the time, and you can see within its pages how it was evolving.
In the last section of the book, Serviss deals with the Moon, the planets, and lastly the Sun.
The method that Serviss recommends for observing the Sun is the use of smoked glass over the eyepieces. This is pretty similar to the same method used by astronomers for some time at that point, though of course it wasn't the only one.
I could go into many reasons why this is pro and con. Today, of course, one could simply put a solar filter over the objective lenses and be set.
What puzzled me, though, was why Serviss didn't recommend solar projection.
Admittedly, with low magnification, the image would be small, but if the room where the image was projected was dark enough, the surface onto which the image was projected could be set far enough away so as to present a decent sized image.
The problem, though, is one of resolution. I've found that direct observation, by means of a solar filter and a decent sized instrument (even as small as 35mm) is best. For projection, the instrument has to be larger, at least 40mm, to present a clear image.
The other concern is the size of the spots that may be on the Sun. Smaller ones will not show up in low resolution projections. The day this was written, 10th July, 2016, the Sun only had three sunspot regions on its surface, and all of them were small.

An afocal shot of the Sun taken the morning of 10th July, 2016. Camera was a Kodak C180, telescope a Tasco 50mm 6TE-5 with an 18mm Plossl eyepiece. Processing done in Gimp. Image by the author.

This doesn't mean that solar projection with an opera or field glass can't be done, of course. These are merely some of the challenges. 
I decided to investigate this on my own. The first thing I did was to cobble together a mount on a tripod. For this, I used some corner brackets, a 4" and a 1 1/2" (100mm and 38mm). The larger bracket was bolted to the tripod head with a 1/4"-20 nut, and then the smaller bracket to the larger one, aimed backwards. This would be my main mount.
For each instrument used, a different method of attachment was required. This was done with a combination of steel straps, bolts, nuts, and coat hanger wire. The first instrument used, my old Lemaire opera-glass, was fairly straight forward, using just the steel strap and a bolt with a wing nut.

This glass has very low magnification, around 3x, so the projected image was expected to be small. For my "screen", a piece of Crescent Board was taped to another tripod head.

As expected, the image was small.

But it was sharp. It is very likely that larger spots can be seen here (though, of course, the current batch of small regions would not be).
The next instrument used was my Airguide 4x40mm field glass. This required both a strap and coat hanger wire.

While the objectives in the Airguide are achromats, they are not the best, especially on bright targets. The Sun is, of course, very bright.

The Sun's image was so bright, in fact, that it was hard to get a sharp focus. 

Is it likely that direct observation with a solar filter with this instrument would yield better results? Perhaps. That would be something to test at another time.
These tests, though, prove that it was possible to observe the Sun using a different, and safer, method that was available. More than likely, if anyone was to undertake this, it would have been best done either in the morning or at sunset, with the Sun at a ow angle, and projecting the image into a darkened room at a distance. More importantly, however is that it could be done.
Perhaps, soon, I'll attempt to try that method. For now, it is enough to know that it could have worked.

Tuesday, June 28, 2016

Thoughts On Opera Glass

In 2004, during my first visit to the Wolf's Head Bookstore in St. Augustine, Florida, following my return to the state, I picked up a classic book by Garrett P. Serviss, "Astronomy With An Opera-Glass". This was an older edition, from 1910, making it now over a century old. It is still in great shape, and was then, but because it had been a library book, the price was low.
Anyway, it is a wonderful book, one of the first really written for the average person using tools that were easily available, an opera glass. The author suggested that the reader obtain at least a 1 1/2", 4x power pair. As it turned out, these were somewhat  common, though not particularly inexpensive at the time the book was originally written (1888).
I set the book into my astronomy shelf at the time, and considered it something of a curiosity more than anything else.
Not quite a year later, I chanced upon a Lemaire Fabt. opera glass at a community yard sale. It was only a couple of dollars, so it came home with me. The book came back off the shelf.
Since that time, I have been interested in the way the night sky was enjoyed in previous eras, and especially with earlier instruments. The opera glass, and its brethren, have allowed many thousands of people to view the night sky without the heavier commitment of a telescope. After all, you could always go back to using them for other things, whereas a telescope is a bit more specialized.
But it wasn't enough for me to be interested, I wanted to have the experience as well. The opera glass I bought at the yard sale was a little smaller than the ones that Serviss recommended. A short time later, I found a pair of Tasco mini binoculars that were really not modern binoculars at all, but field glasses. Like the smaller Lemaire opera glass, these consisted of two objective lenses and two simple concave negative lenses for eyepieces, effectively Galilean. Aside from size, the modern Tasco pair had another advantage, in that the objective lenses were true achromats, not the simple single convex lens of the older Lemaire opera glass.
That didn't prevent the Tasco from being useful for getting an idea of what Serviss wrote about a century before. My first night with them provided me with views of the Hyades, the stars that make up the head of Taurus, or a faint view of the milkiness of the Great Orion Nebula.
However, this was still not an honest experience. The objective lenses in the Tasco were coated optics, something relatively unknown at the time. Even though the objectives were smaller in diameter than what Serviss recommended (30mm, a little less than 1 1/4", versus the 1 1/2" Serviss recommended), the views were probably better. What I needed were some genuine field glasses of the older optic design.
A few years back, I found such a pair, from the Chicago based company Airguide. These were 4x40mm, with the old Galilean layout and simple objectives. They are from the 1940's or 50's, but are really not much different from what Serviss wrote about.
What can you see through these?
Galilean optics, by their nature, have a narrower field of view, and that's the case with all three of the instruments, but especially so with the Airguide. Nonetheless, the views were precisely what he wrote about, accounting for some light pollution.
I've written about this before here, how I've been into "retro-astronomy". It isn't something I suspect that everyone will be into, but it is a learning, and indeed, a humbling, experience. That they were able to accomplish so much with the simple tools they had at their disposal says much about their determination. Astronomy has evolved, and we take so much for granted today. Even some of the instruments we deride as garbage were better than what they had to work with many times.
That's what this taught me, and it helped me to be a better astronomer as a result.